Having an issue with gas feed for my Onan Generator

[clown1]

I have a 2005 Dutchmen class C on the Chevy Chassis and of course an Onan 4000. I noted the generator was not running well so I changed the fuel filter and fuel pump which had not been changed in forever, no change in running so poor I couldn't use it. YES, THE TANK IS FULL. I opened the line that connects to the filter and there is just a drip of fuel coming out. I can't see where the hose connects to a line as it disappears into or above the frame. I can't find any information online for the routing of the generator fuel line so I came here in hopes of someone helping me.
Thanks in advance!

Dave McCanna

 

[Henry J Fate]

Better way to test for gas flow is to pull the fuel line off the carburetor and place it into a container. Use the prime feature to energize the fuel pump. You should get a good flow of fuel into the container. If no fuel arrives, probably a bad fuel line between pump and tank.

If the generator has been sitting for an extended period, good chance you will need a carburetor cleaning.

It would be a good idea to have a copy of the Service Manual for reference.

 

[zulutron]

Same thing happened to me on my 2001 SeaView Class A. Tried everything . . .

• New fuel pump and fuel filter
• Cleaned carb
• Blowing out gas line
• Dropping fuel tank

Couldn't drop the tank as it was way too difficult for our service shop.

So I added a new 5 gallon gas tank . . .

 

[clown1]

Thanks, Zulu, I had never even considered that route but I am gong to look into it for sure!

 

[clown1]

Better way to test for gas flow is to pull the fuel line off the carburetor and place it into a container. Use the prime feature to energize the fuel pump. You should get a good flow of fuel into the container. If no fuel arrives, probably a bad fuel line between pump and tank.

If the generator has been sitting for an extended period, good chance you will need a carburetor cleaning.

It would be a good idea to have a copy of the Service Manual for reference.

Thanks Henry, Unfortunately I have tried all of that with no luck so I am assuming it is a kink or blockage in the line. I can't crawl under it so I am making arrangements to have someone look for that. I am hoping that the fuel line is kinked and a new fuel hose will solve the problem.

 

[Kirk]

I am hoping that the fuel line is kinked and a new fuel hose will solve the problem.

One thing that sometimes happens when you have an engine mounted fuel pump like the Onan and then a rubber line to supply fuel to the pump is that when the rubber line ages it get soft and the fuel pump draws a vacuum in trying to pull fuel from the tank but the rubber collapses and blocks the line. You may just need to replace the rubber tubing. My Onan generators have both had a rubber line that connected to a metal one to the tank.

 

[clown1]

Thanks Kirk
That would be fantastic, a couple of bucks for new hose sure beats most of the other things that have come up. I have gone as far as I can physically so am reaching out to a man known for repairing Onan issues. Fingers crossed it can be taken care of for less than 3 figures

 

[John From Detroit]

I recall years ago a car that was giving me fits... When I did the "pull the fuel ilne and run it into a container) the flow was low but when it pooled in the container it looked like it was beign blown on....

Sure enough the pump was sucking air via a rusted fuel line. I replaced with a hose.. and VAROOM.

 

[clown1]

I will report what is found. I am contacting a guy who is well known in our area for working Onan gen sets and fuel lines. Hope he can figure it out and I can still afford it.
Dave

 

[CharlesinGA]

Many people report the same problem Kirk mentioned, rubber hose cracked and allowing air in and genny won't run. Use only a OEM replacement fuel pump if you go that route, many folks have had problems with aftermarket pumps putting out too much pressure.

Charles

 

[clown1]

Same thing happened to me on my 2001 SeaView Class A. Tried everything . . .

• New fuel pump and fuel filter
• Cleaned carb
• Blowing out gas line
• Dropping fuel tank

Couldn't drop the tank as it was way too difficult for our service shop.

So I added a new 5 gallon gas tank . . .

Talked with my guy today and he said that my particular model used a straw (I am sure it has a fancier name) that is inside the tank which breaks/rusts off. In order to fix it the tank (which I just filled) needs to be drained and the tank dropped so your option is going to the top of the list for sure. I will have to mount that type of tank across to the other side of the unit to a bay I don't use. Not a big deal for sure and no doubt less expensive than a mechanic doing the drain and drop method.

 

[zulutron]

Talked with my guy today and he said that my particular model used a straw (I am sure it has a fancier name) that is inside the tank which breaks/rusts off. In order to fix it the tank (which I just filled) needs to be drained and the tank dropped so your option is going to the top of the list for sure. I will have to mount that type of tank across to the other side of the unit to a bay I don't use. Not a big deal for sure and no doubt less expensive than a mechanic doing the drain and drop method.

That's what I concluded.

My 5 gal tank is good for a few hours before I need to fill up again. Good luck.

 

[clown1]

I am happy to report the generator is running! I took it to a specialist and he found 2 things that hindered it running. The owner before me had put a new carb on it and hooked the choke up backward. This was very obvious to the man in the know (not me) and then they had to really hunt and discovered that the ignition switch for the vehicle had to be in the "on" position and then the generator ran like a top. IS THIS NORMAL FOR A 2005 CHEVY DUTCHMAN? If not then I know what my next adventure will be.

 

[DonTom]

Use only a OEM replacement fuel pump if you go that route, many folks have had problems with aftermarket pumps putting out too much pressure.

I am using an after-marked fuel pump, but the PSI specs are the same as a stock Onan fuel pump.

But just in case, what are the symptoms of too much fuel pressure in the Onan genny? My genny is fine until I get up to 7,000' elevation then all types of issues.

-Don- Why, AZ

 

[Domo]

Different chassis but, on some builds, the ONAN will have a filter AND the coach manufacturer may add their own in-line filter. This happened (in the past?) on tiffins where the original chassis filter would end up getting coated with spray insulation/sealant so it would be hard to find. Many folks had to literally follow the line back from the gennie and look for a suspicious BUMP that they would then dig into and cut out/bypass/replace.

Just a thought..