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Main Forum => General Discussion => Topic started by: Ron Dittmer on September 16, 2020, 12:25:47 am

Title: My Generator Needs A New Fuel Pump
Post by: Ron Dittmer on September 16, 2020, 12:25:47 am
About a month ago, I was making a video how my PC V10 engine and generator started after sitting idle for two years.  It went uneventful until 20 minutes after I started the generator.  With the a/c cooling down the rig, the generator stopped dead.  I stopped the video and scrapped the idea of posting the event because of the generator dying.

After a while, I was able to restart the generator, but it shut down a second time after 10 minutes.  During the cooler time of day (still hot and humid but less hot), the generator with a/c on ran for 1.5 hours without incident so I shut it off thinking all is well.  When camping the following weekend, it was again hot outside.  The same shut-down happened again.

I researched this to be a very common problem with the Onan generator.  There are so many U-Tube videos on this.  Basically, the fuel pump becomes sensitive to hot operating conditions.  I wonder why the fuel itself is not enough to keep the pump cool.  Anyway, I ordered a new fuel pump and fuel filter (they are removed together) costing me roughly $45 for the pair.  I await their arrival.  The weather is now much cooler so I'll be changing parts without official confirmation that the problem is solved.  According to the videos, changing the fuel pump with the filter seems easy enough.

If you wonder, my 2007 Onan-4000 has only 162 hours of use.

Has any one here had a similar experience?
Title: Re: My Generator Needs A New Fuel Pump
Post by: CalCruiser on September 16, 2020, 02:25:24 am
Here you go. Save or bookmark this pdf.

page  86-88 fuel pump testing procedure 

https://www.rvwithtito.com/wp-content/uploads/2017/08/Onan4000MaintenanceManual.pdf
Title: Re: My Generator Needs A New Fuel Pump
Post by: Joseph on September 16, 2020, 09:54:36 am
Ron, itís a very easy job. I think I did mine around 190-200 hours.  Carb I replaced two season ago with an after market carb. I change the air filter every year and the oil every season regardless of hours run.
Title: Re: My Generator Needs A New Fuel Pump
Post by: Ron Dittmer on September 16, 2020, 09:58:53 am
Thanks Cal for manual.  I had found it earlier when trouble shooting my Onan.  That pdf file is stored in my computer PC file folder.

I should have mentioned this one detail in my opening post, how I determined the fuel pump was bad.

Before the trouble began, I was always able to hear my fuel pump run when priming from inside the motor home.  When the trouble began, I could barely hear that humm.  I then went outside to attempt to start the generator from there to hear things better, and to bypass the remote control panel inside our PC.  The pump sounded normal during a successful start, but sounded very weak during an unsuccessful start.  Without testing flow rates and using instruments, it was easy to conclude that the fuel pump weakens under extreme high-temp operation.

I then got on-line, did a little research finding You-Tube videos describing my exact situation.

The generator is a very hot-operating piece of equipment.  I surely do not recommend doing this, but if I were in a third world situation without resources, I would relocate the fuel pump outside the generator housing where it is much cooler.
Title: Re: My Generator Needs A New Fuel Pump
Post by: Ron Dittmer on September 16, 2020, 10:04:01 am
Ron, itís a very easy job. I think I did mine around 190-200 hours.  Carb I replaced two season ago with an after market carb. I change the air filter every year and the oil every season regardless of hours run.
Thanks Joseph for sharing that.  I wondered if I was the only PC owner who experienced a fuel pump failure.

Regarding my carburetor, mine works great when the fuel pump is working.  My air filter is the original one.  It looks quite clean, but I have new ones coming in the mail so I will replace it when replacing the fuel pump and fuel filter.  You say, replacing the fuel pump and fuel filter is an easy repair, and I believe you.

Another thing I did not mention was about changing the engine oil.  The owners manual states 15W-40 motor oil.  That oil on the shelves is now labelled "For Diesel Engines".  While at the store, I called the 800 number on the label.  The consumer help line told me that oil is normal motor oil, but labelled as such so people don't think about using it in their gasoline vehicles which all require a lower viscosity oil.
Title: Re: My Generator Needs A New Fuel Pump
Post by: Joseph on September 16, 2020, 10:12:21 am
Ron, my air filter doesnít always look like it needs replacing when I change it.  We boon dock on BLM desert and in Joshua tree which is all desert and I guess I figure weíre around more dust than many places so for the few bucks it costs I change it out. The oil change in my opinion is a must being thereís no filter and no oil pressure.

My fuel pump was acting up but more frequently than yours at the time. It fixed my problem till my carb gummed up with crap Ca gas. Cheaper and less frustrating to change it out than attempting to clean/fix it.
Title: Re: My Generator Needs A New Fuel Pump
Post by: JJCruiser on September 17, 2020, 09:00:35 am
. . . . .  Basically, the fuel pump becomes sensitive to hot operating conditions.  I wonder why the fuel itself is not enough to keep the pump cool.  Anyway, I ordered a new fuel pump and fuel filter (they are removed together) costing me roughly $45 for the pair.  I await their arrival.  The weather is now much cooler so I'll be changing parts without official confirmation that the problem is solved.  According to the videos, changing the fuel pump with the filter seems easy enough.  . . . .

Ron,

Based on the description of the fuel pump being sensitive to hot operating conditions, you have me wondering if the generator is experiencing "vapor lock".  As I understand it, gasoline starts turning into a vapor at 140 degrees.  As the generator gets hot, it heats up the gasoline in the gas line and filter to the point it starts to turn the gasoline into a vapor.  The fuel pump cannot pump vapor, just liquid.  I had this happen to a 25HP zero turn mower.  Similar symptoms as your Onan, it would run great for a while but on days above 85 degrees, it would stop after 30-45 minutes of mowing.  After I let it sit for 10 minutes, the vapor in the gas line would cool enough to let the it return to a vapor such that the pump could pump again.  To fix the zero turn, I added an insulating fuel sleeve around the gas line prior to the fuel pump, focusing especially in areas where the gas line runs close to heat generating sources like the engine block or exhaust manifold.  It is really easy to install around the existing gas line:

https://www.amazon.com/Design-Engineering-010669-Sleeve-Length/dp/B079S1XLM7/ref=sr_1_4?dchild=1&hvadid=78615206577519&hvbmt=be&hvdev=c&hvqmt=e&keywords=gas+line+insulation&qid=1600350398&sr=8-4&tag=mh0b-20

https://www.amazon.com/vdp/fbc35aa9b1b94669aa647cd36427d9f4?ref=dp_vse_rvc_0

I have not tried it on the Onan generator, I have not had the need yet.  But it might be worth a try providing even more protection against the heat.

JJ
Title: Re: My Generator Needs A New Fuel Pump
Post by: Ron Dittmer on September 18, 2020, 05:55:00 am
Hi JJ,

Thanks for that interesting theory.

In the case with the Onan, the fuel line enters from a "forward cool" location and the fuel filter and pump are right at the point of entry.  I don't think the fuel has enough opportunity to heat up and vaporize within.

Given in the past, I have run my generator with a/c running under even hotter conditions without incident, I strongly feel it's my fuel pump.  The parts are cheap enough, surely worth replacing them because of my suspicion.
Title: Re: My Generator Needs A New Fuel Pump
Post by: JJCruiser on September 18, 2020, 09:34:28 am
Hi JJ,

Thanks for that interesting theory.

In the case with the Onan, the fuel line enters from a "forward cool" location and the fuel filter and pump are right at the point of entry.  I don't think the fuel has enough opportunity to heat up and vaporize within.

Given in the past, I have run my generator with a/c running under even hotter conditions without incident, I strongly feel it's my fuel pump.  The parts are cheap enough, surely worth replacing them because of my suspicion.


Hi Ron,

I agree, a new fuel pump will likely overcome the problem.  Since the generator works while cool, I do think vaporization of the gasoline in the lines when hot is contributing to the problem.  A new fuel pump should be able to pump the fuel/vapor combination better when compared to an older/worn pump. Like you said, your generator worked fine in the past.  If this ever happens to my Onan, I will likely remove the generator cabinet door temporarily to see if the increased ventilation has any impact on the issue.  It may prove or disprove the theory.  It would be interesting to know how hot it gets in that Onan cabinet when running at heavy load like with the AC running.  As packed as that cabinet is, it is bound to get quite hot in there.

I did look at my Onan and I see your point about the filter and pump being located just as the fuel line enters the Onan cabinet.   The pump/filter appear they are going to be hard to get to . . . maybe removing the air filter cover will improve the accessibility.  I will be interested to know how difficult a job it turns out to be and if you had to remove anything in the way to get the job complete. 

Good luck!

JJ



Title: Re: My Generator Needs A New Fuel Pump
Post by: Ron Dittmer on September 18, 2020, 02:30:30 pm
I watched a couple of You-Tube videos on replacing the pump & filter.  After disconnecting the batteries, you remove that potted circuit board controller and the solenoid to the left of it and then the pump is easy from there.

As far as running the generator without the Onan cover, I had understood that with the cover installed, cooler air is directed in better and hotter air is exhausted better.

When camping without neighbors, I open the PC access door to help with cooling.  But that did not help when testing at home.
Title: Re: My Generator Needs A New Fuel Pump
Post by: SteveLange on March 17, 2021, 10:33:43 pm
Hi Ron,

I just joined the forum and donít know if you solved your gensetís possible fuel starvation issue but I thought Iíd offer my experience with my gensetís fuel pump issue. Might help someone else.

I believe your generator's symptoms were exactly as mine experienced 18 months ago, and indeed, replacing the pump cured the problem. Once I felt there was a 'pump plus run time heat' relationship, I intentionally tested the hypothesis over two days of cycling the starting of the generator, first from dead cold. It would run 20-30 minutes before quitting. Let it rest for 1/2 hour and it would run again but now only for 5-10 minutes. The shorter the rest periods, the sooner it would quit. Same processes the second day = same results. On two occasions when it quit, I did pull the fuel line into the carburetor and no fuel came out of the carb as the bowl was empty. I felt it had to be the pump.

Along with replacing the air and fuel filters, I replaced the fuel pump. Though not hard to do, the effort was more stressful (to me anyway) than installing the heavy-duty sway bars F&R and/or the SUMO Springs (Solo on front, Maxim on rear). I really didn't want to damage the green colored printed circuit board that had to be moved to gain access to the pump related stuff routed underneath it. And there is twisting and turning the board "just so" in order to get it back in place. Indeed, it is a DIY but it takes one's time and patience. I added extra long electrical leads for future use should it happen again. I would just abandon the faulty one in place and mount a new pump and filter outside the Onan box next time, hence the long leads.

Good fortune to you and thanks for all your sage advice and insight.

Steve
Title: Re: My Generator Needs A New Fuel Pump
Post by: Ron Dittmer on March 17, 2021, 11:39:03 pm
Thank you Steve for your detailed reply.  I had considered mounting the fuel pump outside the Onan to avoid the "Hot Zone", not sure I will actually do so.  I still have my new pump, fuel filter, and air filter sitting on the PC counter top, waiting for better weather.

I am focused on tires right now.  Just tonight, I took a front tire to my church's auto shop and was able to get the tire off and back on the steel wheel, a textbook process, but the balancing machine could not handle it.  Unless something new develops, I think I will rely on a tire shop to take care of everything.
Title: Re: My Generator Needs A New Fuel Pump
Post by: Volkemon on March 18, 2021, 10:00:28 am


Curious, has anyone replaced the fuel filter BEFORE replacing the pump to see if the pump was just supply starved? Forgive me if I missed it.


  A supply starved pump would not deliver enough fuel and cause the pump to sound different. When replaced with a new pump and filter it would solve the problem. Probably why the filter check precedes the pump check in the manual.


 ""Change the fuel filter at the interval recommended in the Operatorís Manual, or if performance problems occur and bad fuel is suspected.""
(Manual pg  8-19 or PDF pg 86) ( https://www.rvwithtito.com/wp-content/uploads/2017/08/Onan4000MaintenanceManual.pdf   tymote CalCruiser!!)

In Ron's case, we had performance issues, and 2 year old fuel certainly could fall under 'bad' fuel guidelines. So fuel filter replacement would be diagnostic step one.

 The diagnostics for the PUMP say:

Quote
A negative fuel supply line pressure
(more than minus 1.3 psi or three feet of lift) will prevent the pump from delivering enough fuel. Measure the pressure at the pump inlet. Inlet pump
pressure must be between a minus 1.3 psi and a
positive 1.5 psi (minus 8.3 kPa and positive 10.3
kPa).

Source - Manual Pg 8-20   or   PDF page 87   https://www.rvwithtito.com/wp-content/uploads/2017/08/Onan4000MaintenanceManual.pdf

So, they want you to add a 'tee' between the filter and the pump. Then measure the pressure to see if there is an inlet restriction. NOT sure how you would end up with a positive supply line pressure, but they do allow for that. Did anyone here actually do this test? In a shop, to avoid unnecessary charges to the customer, I would see where the procedure is a CYA. In the 'shadetree' / 'Throw parts at the problem' mechanic world, i would bet this is never done.

Interesting they do NOT specify a volume outlet check on the pump, which seems to be the indicator people are using here.  (WH)  An omission, or not a good diagnostic indicator for the pump? Dunno.

Proper diagnostic procedure would say that one checks/replaces the filter before a diagnosis of pump failure is performed. BUT... if the labor cost/effort is easy enough, and parts cheap enough, I guess it makes sense to just replace the pump/filter as a unit. I defer to those who have been in there, I am going by the manual procedures,  but it seems that the fuel filter is a pretty easy job compared to pump replacement. To be fair, i could not find the procedure for fuel pump replacement in the manual. Found 49 occurrences of the phrase 'fuel pump' and not one procedure to replace it.  :help






Title: Re: My Generator Needs A New Fuel Pump
Post by: Ron Dittmer on March 18, 2021, 10:59:38 am
Hi Volkemon,

My generator ran for multiple hours with the a/c unit on, but only after the worst heat of the day had passed.
Title: Re: My Generator Needs A New Fuel Pump
Post by: Volkemon on March 18, 2021, 01:34:06 pm
Hi Volkemon,

My generator ran for multiple hours with the a/c unit on, but only after the worst heat of the day had passed.

Gotcha.   With a pump at $30, its certainly not too expensive. Heck, the filter was $15.  We have a gathering of people that had changed their pump here, looked like a good chance to see what other diagnostic efforts might have been tried.  Steve did state that replacing the pump was stressful, be nice to avoid that. I (try to...) avoid unnecessary dirty work with diagnostics. And I freely admit I sorta have OCD's  (nod) (exactly) to 'Find the problem' not just correct the symptoms.  :)(:  I am the type of guy that cuts apart filters to see what went on.


I was curious if anyone had tried replacing the filter only, then seeing if the condition persisted. I would be a fool to think I wont have similar problems someday. This forum has been a GREAT early warning system.  The filter is a 450-500 hr item (!)  on the maintenance schedules I found, wonder how many have the original. Bet mine is...  :beg  I am at 446 hrs,  16 years after being made.   
Title: Re: My Generator Needs A New Fuel Pump
Post by: Joseph on March 18, 2021, 01:55:48 pm
Not me, oil and filters are cheap, change mine every year and oil every spring regardless if I used it 20 hours or 50. New carb is $50 and the original isnít rebuildable. I used to fight it running intermittently and many times erratically spending frustrating hours trying to clean it etc. No more.  Cost for a fuel pump is cheap, relocate it if itís a pia to get to and be done with it.
Title: Re: My Generator Needs A New Fuel Pump
Post by: donc13 on March 18, 2021, 04:29:21 pm
Put a tank of fresh gas in it and see if it will run.   Every spring, the first time I used the generator, it'd quit running after an hour or so.  Let it sit for half an hour, it'd run again... For about an hour.  I use Stabil in a FULL tank for over winter.  Which also means it's winter blend gas in the tank.   After I drive off about 1/2 a tank and put in fresh gas, the generator runs fine... For hours on end.

Don
Title: Re: My Generator Needs A New Fuel Pump
Post by: 2 Lucky on March 18, 2021, 04:58:35 pm
Wondering if everyone runs the generator under load for at least an hour every month as recommended by Onan and still have these problems, and use Stabil like Donc says?
Title: Re: My Generator Needs A New Fuel Pump
Post by: donc13 on March 18, 2021, 05:31:14 pm
Wondering if everyone runs the generator under load for at least an hour every month as recommended by Onan and still have these problems, and use Stabil like Donc says?

I used to do that and it didn't make any difference.  The main purpose according to Onan is to dry out moisture in the generator windings and to try to keep gum from forming in the fuel lines or carburetor.

As you well know, moisture isn't much of a problem here.

 2o2 :-D
Title: Re: My Generator Needs A New Fuel Pump
Post by: mikeh on March 18, 2021, 06:37:24 pm
Wondering if everyone runs the generator under load for at least an hour every month as recommended by Onan and still have these problems, and use Stabil like Donc says?
Parked my rig with full fresh tank of fuel (but no Stabil) at the end of 2019, and tried to follow the monthly generator exercise while laid up during 2020.  Succeeded for several months, but got lazy early summer, missed 3 or 4 months, and when I tried to start the gen in October--crank, crank, crank, but no start.  I knew what the problem would be--pulled the carb bowl--and sure enough, green pasty gunk in the bottom.  Ran the fuel pump to flush the line and the E-10 gas still looked and smelled good (Ford V-10 running fine on it).  I thought the problem would be with the solenoid shut off valve in the bottom of the carb bowl gunked up, but that still worked freely; the restriction was in the main jet needle that has the altitude adjustment.  Pulled that apart, cleaned up the bowl and all pieces with brake cleaner, reassembled everything--fired right off and ran like a top.

I went ahead and ran all the (almost) year-old gas out of the rig, filled fresh, and added Stabil this time.  Been a little more conscientious about the 4 to 6 week generator starts since then--no more problems.  I did buy an extra carb to add to my on-board spares; at thirty-something bucks I chalked it up it as insurance since I've confirmed what everyone else has told me---that the problem absolutely can occur.
Title: Re: My Generator Needs A New Fuel Pump
Post by: Ron Dittmer on March 18, 2021, 11:53:46 pm
Wondering if everyone runs the generator under load for at least an hour every month as recommended by Onan and still have these problems, and use Stabil like Donc says?
The main purpose according to Onan is to dry out moisture in the generator windings and to try to keep gum from forming in the fuel lines or carburetor.
I understood that too.  Given our indoor storage, I never run the generator until testing it prior to a trip.

Last August, I started the generator for the first time in two years.  I don't know if my fuel pump issue was related to that or not.  But the generator started right up and ran for 20 minutes before the fuel pump over-heated.  It was very hot outside during the test run.
Title: Re: My Generator Needs A New Fuel Pump
Post by: Volkemon on March 19, 2021, 07:07:48 am
Wow!  I guess we do have the range of maintenance schedules from 'Replace filters every year' to 'not start in two years'  and it seems everyone has fuel related performance issues. Thanks to all for contributing.

We dont have a large sample group, but it is widespread across the country. I almost wonder if the fuel is more the variable than generator maintenance.


From   https://www.eia.gov/energyexplained/gasoline/  -
Quote
""In addition to the different grades of motor gasoline, the formulation of gasoline may differ depending on the location where it is sold or the season of the year. Federal and state air pollution control programs that aim to reduce carbon monoxide, smog, and air toxins require oxygenated, reformulated, and low-volatility gasoline. Some areas of the country are required to use specially formulated gasoline to reduce certain emissions, and the formulation may change during winter and summer months. These area-specific requirements mean that gasoline is not a homogenous product nationwide. Gasoline produced for sale in one area of the United States might not be authorized for sale in another area.""

Not very readable, but does show the variety - ( source - https://www.caranddriver.com/news/a15339380/the-vapor-rub-summer-versus-winter-gasoline-explained/)

(https://hips.hearstapps.com/hmg-prod/amv-prod-cad-assets/wp-content/uploads/2017/09/US-Gasoline-Requirements-Map-Exxon-Mobil-626x383.jpg)

And hey!  Evidently here in  Florida they dont even switch from Summer to winter blend anymore. Since 2014. ( source - https://askthetrucker.com/no-more-summer-gas-blend-for-florida-north-carolina/  and similar found here - https://www.spglobal.com/platts/en/market-insights/latest-news/oil/032814-us-epa-approves-florida-north-carolina-requests-to-change-summer-gasoline-rvp)

Quote
2014 was the first year that Florida remained with the 9.0 blend through the Summer season, eliminating the usage of the formerly required 7.8 blend. Florida, as well as North Carolina, will no longer be mandated to use the 7.8 RVP blend during the Summer season.

Looks like there was only 6 counties that did switch between blends, and they no longer have to. (I am not in those counties)


Lessons I take away from all this is:
 For less than $100 we can have a spare pump, carb and filter on hand, might be good 'generator insurance' for the time we start putting in fuel formulated for other places when we travel.  2o2 

Make it a policy to let the tank run low before a final fill up when back home in Florida. ESPECIALLY when the summer 7.8 blend is used in surrounding areas. Just like the food we eat, the fuel the vehicle gets is directly responsible for its 'health'.
Title: Re: My Generator Needs A New Fuel Pump
Post by: Joseph on March 19, 2021, 02:40:37 pm
Since I changed out to the generic carb made for a variety of engines including John Deere etc I have never had a fuel issue. No matter how long it sits.   Knock on wood!


Filters. And oil changes . Iím just a believer in them and lab tests! You canít tell by sight or a book when your oil is done.
Title: Re: My Generator Needs A New Fuel Pump
Post by: Volkemon on March 19, 2021, 03:01:21 pm
Got a link I can use to get the carb?   :-D
Title: Re: My Generator Needs A New Fuel Pump
Post by: mikeh on March 19, 2021, 04:22:44 pm
Volk---

There's a bunch of them on Amazon at a variety of prices, but except for the OEM's (which are prohibitive), I couldn't really see any significant difference.  I went with the least expensive:

https://www.amazon.com/gp/product/B085G6LJXH/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1 (https://www.amazon.com/gp/product/B085G6LJXH/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1)

Haven't tried it obviously, but looks just fine.  (Can't match Joseph's guarantee about no issues---no matter how long it sits, though :))

Mike
Title: Re: My Generator Needs A New Fuel Pump
Post by: Joseph on March 19, 2021, 06:09:55 pm
I mean to go run mine once a month but if it gets started once during the off season thatís about it. My original carb the last year I had it if I didnít run it every few weeks it was a fight and I often lost.
Title: Re: My Generator Needs A New Fuel Pump
Post by: RonJ on March 27, 2021, 01:44:16 pm
Ron Dittmer,

At the beginning of this thread you said "I was making a video how my PC V10 engine and generator started after sitting idle for two years."
Do you have a YouTube channel related to your owning a Phoenix Cruiser?  If so I would love to subscribe.  Link?

Thanks!!
Title: Re: My Generator Needs A New Fuel Pump
Post by: Ron Dittmer on March 27, 2021, 08:09:34 pm
Ron Dittmer,

At the beginning of this thread you said "I was making a video how my PC V10 engine and generator started after sitting idle for two years."
Do you have a YouTube channel related to your owning a Phoenix Cruiser?  If so I would love to subscribe.  Link?

Thanks!!
I have two youtube accounts, not sure how that happened.  I guess they are called "channels".  I have some videos posted but they are totally unrelated to what we talk about here and on other RV forums.  I decided some time ago to avoid videos.  I was going to make one exception with that generator video, but it's just too much work creating, editing and managing videos.  So I limit myself to pictures and typing.
Title: Re: My Generator Needs A New Fuel Pump
Post by: RonJ on March 27, 2021, 08:15:32 pm
👍
Title: Re: My Generator Needs A New Fuel Pump
Post by: Ron Dittmer on March 27, 2021, 08:46:03 pm
👍
Awe heck, you can check out our ballroom dance competition at a PADS (Public Action To Deliver Shelter) charity fund-raising event HERE (https://www.youtube.com/user/RonDittmer), ha, ha, and our younger son back in 2004 in middle school in a talent show with two friends HERE (https://www.youtube.com/channel/UCRQn4QZdFRga6Y9eh3G_eLQ) who called themselves "The Bucket Boys".
Title: Re: My Generator Needs A New Fuel Pump
Post by: RonJ on March 28, 2021, 01:37:40 pm
Wow...  what a talented family! Thanks for sharing.

RonJ
Title: Re: My Generator Needs A New Fuel Pump
Post by: Ron Dittmer on May 21, 2021, 05:40:04 am
After 8 months, I am finally able to report that I replaced the fuel pump, fuel filter, and air filter, and all is well.

A few days ago when installing my new Alcoa wheels and flushing my brake system, I ran the generator to see if my "Runs For 20 Minutes, Then Dies" problem continued, and it repeated just as predicted.  Many months ago, I ordered the new parts, waiting for an opportune time to install them.

Wow, the project was a challenge for me.  This morning I still have indents on my right forearm.  I had to disconnect so much wiring and pull the wires and cables out from the compartment, just to be able to remove the solenoid, followed by the control board unit.  There is a connector with maybe 30 wires that plugs to the underside of the control board that is very hard to disconnect because of the confined work area.  Once disconnected, I was able to work it out with determination.  With the cables and wiring out of the work area and the solenoid and control unit removed, I could finally get to the fuel pump with fuel filter.

Once back together, I started up the generator, ran it for about 10 minutes without a load, then another 30 minutes with the a/c running and I am happy to say that all is well.

There are a few different fuel pump designs for sale.  I recommend one that looks like the original design as shown.
(https://ae01.alicdn.com/kf/HTB1eYtpatzvK1RkSnfoq6zMwVXaD/Electric-Fuel-Pump-for-Onan-4000-4Kw-Gas-RV-Cummins-Generator-Microlite-MicroQuiet-Replaces-Airtex-E11007.jpg_Q90.jpg_.webp)

Because of the price and "supposed quality", I bought one that was styled like this.
(https://i.ebayimg.com/images/g/VmIAAOSw5cNYIcEh/s-l400.jpg)
It requires this elbow purchased separately.
(https://i.ebayimg.com/images/g/rSUAAOSwHqpbJ9kC/s-l500.jpg)

It worked fine, but required filing the screw-mounting hole a tad bit more elongated to address a gentile interference problem.  The original design has no interference.
Title: Re: My Generator Needs A New Fuel Pump
Post by: flei on May 21, 2021, 11:47:09 am
Nice job Ron! And as always, thanks for the useful info.  tymote

Sounds like one heck of a job. You've written about many repairs and modifications you have done and you are obviously very skilled at this sort of a thing.  2o2

I might have the skills to do it but I know I do not have the patience! .   pyho   Hopefully I never will never have it tested by this repair!  (nod)
Title: Re: My Generator Needs A New Fuel Pump
Post by: CalCruiser on May 21, 2021, 06:14:35 pm
How user friendly is the fuel filter? 

Itís mind boggling that Honda doesnít own the rv generator market too. They really should  make a bolt in replacement for the green monsters.
Title: Re: My Generator Needs A New Fuel Pump
Post by: flei on May 22, 2021, 06:48:18 am
How user friendly is the fuel filter? 

Itís mind boggling that Honda doesnít own the rv generator market too. They really should  make a bolt in replacement for the green monsters.

 2o2 You're not kidding. Those Onan generators are such antiquated tech. Cummin ought to be ashamed.

Also, one has to wonder why they named something that is supposed to be a very reliable back-up after a biblical character who was anything BUT? https://en.wikipedia.org/wiki/Onan
Title: Re: My Generator Needs A New Fuel Pump
Post by: Joseph on May 22, 2021, 08:32:27 am
Iím not sure A Honda gen would be the best alternative or that theyíre interested in the market. Honda isnít any quieter unless itís an inverter/ gen which requires a heavy enclosure. That inside the enclosure of a motorhome will really restrict the air flow. So it would need to be a standard generator. Iíve seen onan gens with over 15,000 hours that have never been opened, carbs replaced yes. Now they claim inverter gens have a 3,000 hour life span. Even if itís double their estimate itís low in comparison.

I used to battle with this trying to think of ways to replace it with a Honda etc but for me that war is over.
Title: Re: My Generator Needs A New Fuel Pump
Post by: Ron Dittmer on May 22, 2021, 11:13:35 am
How user friendly is the fuel filter?
Hmmmmmmm.......

I did not examine mine close enough to determine if the fuel filter can be easily serviced, but I think it can.  It would NOT take much investigation to determine that.

Here is a picture of the fuel filter.
(https://tweetys.com/images/products/detail/1492457.jpg)
The ribbed inlet on the left end protrudes outside the generator.  The fuel line connects outside the unit with easy access to disconnect it.  I would remove the fuel line and then the huge rubber grommet that the fuel filter passes through.  If the remaining hole is larger than the body of the fuel filter, you should be able to use a deep socket, unscrew it, and pull it out from the outside.  When screwing in the new filter, I would first wrap the threads with Teflon tape.
Title: Re: My Generator Needs A New Fuel Pump
Post by: Lieutenant on June 16, 2021, 11:40:14 am
change the circuit board  I had the same problem  changed fuel filter/pump and stator    stopped working after a few mins  changed circuit board and my Onan now runs like a deer  good luck