Onan Marquis 7000 Generator

[hayesfamily]

Onan Generators

this is one of those where I should have gone with my gut feeling

Couple days ago I posted about replacing the starter motor on this generator. When I took the starter out everything in me said replace the fuel pump. With the starter removed the fuel pump wiring and everything else is 100% visible so replacement is about 3 minutes. Typically when I do a job like this on my car I will replace everything that is difficult to get to simply because I don't feel like going back in there. This was one of those instances where I should have followed my instinct.

Yesterday I start the generator just to exercise it and it cut off on me. It was obviously starving because it ran perfectly up to that point. I look at the motor coach and I have a half of tank of fuel so fuel quantity is not a problem. I tried to start the genny again and this time it starts and runs for two and a half hours. I'm thinking in my problems are solved but what I quickly learned is that fuel pumps sometimes will come back to life only to fool you and play games with you. Today I go to start the generator and nothing. I pulled the hose off of the filter going into the carburetor and when I hit the start button fuel dribbled out with no pressure at all. Guess we found the problem ...

Only other generator I've ever had to deal with was a Gentech I believe was the name so I have to ask a question is this type failure common and the Onan genset because it is obvious to me that somebody has been in this generator before doing the same job I'm about to do?

I am really going out of my way not to have to remove the generator from the coach so off the top of anyone's head is there anything else I need to deal with before it becomes problematic while I have my hands stuck in this coach's rear?

 

[kaypsmith]

I would start with a can of gasoline and a short piece of hose to place in the can and other end directly connected to the fuel pump. If the pump now pumps to the carb, then I would look next at fuel filters, then at the fuel line. If this fuel line has never been replaced and the coach is 18 years old, at that age they have a tendency to collapse. Of course if the can fuel does not pump, then the pump would obviously be bad, much easier to test first before going to the trouble of pulling the fuel pump.

[hayesfamily]

So this is what I did, i disconnected the positive wire from the fuel pump and probed it. Probe light came on so I know I'm getting voltage to the fuel pump. I checked all of the grounds and my ground is solid.

 

From there I disconnected the fuel line from the filter connected to the carburetor and hit the starter. I got little dribbles of fuel coming out.  I'm going to stick a hose down into a gallon of gas to see if the fuel pump will suck it out of there but my gas tank on the coach is full and I don't believe that the line coming from the gas tank to the generator fuel pump is bad so if that does not produce results than the fuel pump has to come out.

Now that you mention that the coaches 18 years old you're right I'm going to go ahead and replace all of the fuel lines but here is the thing, to replace the fuel line going to the copyright of the pump has to come out anyway so it probably is in my best interest to just go ahead and replace the pump for 30 bucks. It keeps me from having to go back in there.