Generator Will Not Run While Driving

[High Road Travelers]

Originally Posted by wog099

I have a Onan QG7000 gas generator model 7HGJAB-900L in the MH with only one problem. It will not run while we are driving.
It will run for hours just sitting still, and will run for only a short time while driving (anywhere from 5 minutes to 30 minutes).
The oil is clean, the proper level and proper type and I never get below a half tank of gas in the MH. It has always done this; but now I live in Texas and it is hot, so I would like to drive with the house AC's running.
It only has 120 hours on it and the oil and filter has been changed twice, the fuel filter and air filter changed once.
It runs fine sitting still, but shuts off when driving, no matter the road condition; slow and smooth, level, mountainous, etc.
I have followed some other posts on generator problems but haven't seen one for my issue. Some posts suggest a possible fuel pump problem. Does anyone know where the fuel pump is on this model? I may can change it myself. I'm sorry I do not remember what codes it has given; I checked in the past but they were generic and of no real help.
Has anyone encountered this issue before?
Thanks for any suggestions,

From the OP:
I called Onan and got some suggestions from them, noted suggested ideas from responses here and took the motorhome to the Foretravel factory and laid out the situation to them, as they are Onan certified and near me. Their service tech was very good and listened to me.
At first he thought it was an air flow problem and installed a bracket behind my rear mudflap as it looked like it may be flying back while driving and blocking air flow (generator is behind my back wheel and engine exhaust comes out in front of that real wheel). That did not help (generator quit after driving 17 miles).
He started looking for a fuel problem next and discovered that when it would quit running the fuel line from the gas tank to the fuel pump would maintain gas in the line, but the fuel line going from the fuel pump to the carburetor would be empty, so he ordered a fuel pump. When it came in and he went to replace it he saw that the barb on the old pump was not the correct type and the fuel line was not the correct size, so he replaced the barb and put the new fuel line in between the old fuel pump and carburetor and it worked fine. May have been an air leak in the old line because it didn't fit the connections correctly (I'm really not sure). I had him put the new fuel pump on also, so now I have the old one as a spare. I drove it about 40 miles and it ran perfect.
I have a big trip planned in about two weeks, so will give it the ultimate test then.
All of the ideas and suggestions from you all were very much appreciated and I really learned a lot about what all can go wrong with a generator. I hope all those responding with issues of their own, get theirs fixed also.
Thanks,

[triplewide]

Good news. Sounds like this tech knows what he is doing.
Happy camping.

[dmctlc]

Congratulations glad it's fixed and hopefully this is begin you and you have years of trouble free camping. Enjoy your trip and let us know how everything went. Thanks and enjoy...

[yeloduster]

Originally Posted by wog099

From the OP:
I called Onan and got some suggestions from them, noted suggested ideas from responses here and took the motorhome to the Foretravel factory and laid out the situation to them, as they are Onan certified and near me. Their service tech was very good and listened to me.
At first he thought it was an air flow problem and installed a bracket behind my rear mudflap as it looked like it may be flying back while driving and blocking air flow (generator is behind my back wheel and engine exhaust comes out in front of that real wheel). That did not help (generator quit after driving 17 miles).
He started looking for a fuel problem next and discovered that when it would quit running the fuel line from the gas tank to the fuel pump would maintain gas in the line, but the fuel line going from the fuel pump to the carburetor would be empty, so he ordered a fuel pump. When it came in and he went to replace it he saw that the barb on the old pump was not the correct type and the fuel line was not the correct size, so he replaced the barb and put the new fuel line in between the old fuel pump and carburetor and it worked fine. May have been an air leak in the old line because it didn't fit the connections correctly (I'm really not sure). I had him put the new fuel pump on also, so now I have the old one as a spare. I drove it about 40 miles and it ran perfect.
I have a big trip planned in about two weeks, so will give it the ultimate test then.
All of the ideas and suggestions from you all were very much appreciated and I really learned a lot about what all can go wrong with a generator. I hope all those responding with issues of their own, get theirs fixed also.
Thanks,

We are looking forward to your report after you have taken a long trip. Let us know!

[Petrolero]

Originally Posted by Elwood58

I think it may be oil level related. Try adding a small amount of oil and see how it works.

I had this precise problem in mine- genset shut down after rounding a sharp corner down the road from our house.


Turns out it WAS low oil level even though I had just changed it and thought I had it to proper level. WAITER21 suggests overfilling by a slight amount to prevent the oil from uncovering the low oil level sensor.

[triplewide]

My armchair guess is it was the fuel pump. If the outflow line was not fitting properly it should have been leaking fuel as it should be under pressure at that point.

[High Road Travelers]

Originally Posted by yeloduster

We are looking forward to your report after you have taken a long trip. Let us know!

We are just completing a two week trip with plenty of opportunity to test the generator. It works perfectly both sitting still and driving down the highway. Works exactly as it should.
Triplewide, I feel as you that it was probably just the new fuel pump that fixed it, but I feel better with the proper fuel line and fitting on it now.
It's great having a generator that you can depend on. It was 92 degrees today and we had the AC going for hours while driving today.
Thanks,

[Coarsegold]

Good to hear, seems a fuel pump replacement solves many problems, so when in doubt change it out, fairly quick and cheap fix.

[triplewide]

Well done, another gremlin victory! Thanks for the update.

[George Schweikle]

Thanks

Originally Posted by triplewide

Found the post with the part numbers:

https://www.irv2.com/forums/f121/ace...ml#post4295688

[yeloduster]

Glad you got it working. Many happy miles and hours camping to you!

[Perezl2576]

Good afternoon everyone. Unfortunately im posting as I'm having the infamous Onan 5.5 HGJAB-1038L generator shuts down with Flash code 33 (has had 34 and 36 in the past). This issue happened right off the lot on a 2019 Jayco Precept 36A. I've taken to Cummins and they've stated issue was the fuel pump(replaced), P board(replaced). I'm so frustrated at this. I cant use my RV during the summer or anything above 90 degrees. My RV currently sits at Cummins for the 8th time since June of 2019 for the same issue. I just got a call a few hours ago stating they cant replicate the issues. OF course when I asked them was the truck running and was it outside? They were like no, just load tested the generator. I lost it, lol. I told them I will be there this afternoon , but until its fixed it will just sit there. RV is still under warranty, but does anyone have any TSBs that might address this issue? I've read through these forums but I don't know what my Cummins Service Center has done. Here's what happens:
Generator shuts off when truck and generator are running. Has only happened once while actually driving the RV, but has happened multiple time while above 90 degrees, truck and generator running. Camping World techs checked(supposedly) the fuel lines and said they were fine and were not pinched anywhere. I checked the oil before starting it this last time and it was about 3/4 to full line. I'm ready to drive this thing off a bridge! Ughhh, and directions or way ahead would be greatly appreciated.

[Perezl2576]

Just came across this. Anyone tried this?

https://www.youtube.com/watch?v=vzXDlln8aUw

[DAN L]

Try disconnecting the lead to the low oil pressure switch below the dipstick.