I have a 2000 class C motorhome with a V 10 engine. It will not start. I have done some diagnostics and have found that the fuel pump does not run. Can I put some air pressure on the fuel supply line at the fuel filter back to the pump, to try and clear the pump or at least get the pump to turn. It will be a nightmare to try and replace the in-tank pump. Too low, too heavy, parked on dirt and can't be towed. Would just adding a high-pressure pump to the frame rail work? Could it pull fuel past the in-tank pump? Any thoughts would be appreciated.

 

Welcome to the site.

First step may be to check for power distribution 'through' the closed inertia switch. It would prove out the fuel pump relay, and that its being PCM commanded ON. It's 'timed' meaning the PCM will only apply the grounding at the relay to run the pump for a few seconds.
Checking at the inertia helps rule out any circuit/power distribution or relay issues upstream of the inertia. It helps to prove out a direction to go. Could be the pump, more so if system current is active at the inertia.

 

I have used a test light at the relay box to confirm that the PCM is turning on the fuel pump relay. It does light for a second or two. I have confirmed that there is power feed at the relay to run the pump. I have applied voltage to the fuel pump wire and the pump does not run. I have not been able to confirm wiring to the pump as the cause. (Cut wire, etc.) Getting under the vehicle has become nearly impossible. SO, for information's sake, could I put air pressure into the pump at the fuel filter to try to clear it or shook it into working, even if only temporarily so I could move it to a more desirable workspace. OR would an inline fuel pump at the frame rail be able to pull fuel through the in -tank pump. Thank you for your response. Jim

 

I don't know if any air applied to any fuel lines would help As was suggested by Hayapower, you might verify you have power going to and out of the inertia sw for that 2 seconds when you first turn the key on.

If you do have power there , something I have come across more than once, if you can have someone be cranking over the engine and you give the fuel tank a good kick at the bottom of the tank. This will usually work only once , so if it starts then, put the vehicle where you want because it may not start anymore until the fuel pump is replaced..
If this didn't work , follow the procedure Hayapower suggested earlier.

 

Thanks hanky and Hayapower, All good procedures. Since I look at replacing the pump as a nightmare, I wanted to explore any possible other things I could do to help the situation. I hope to able to tow the RV up the hill to give me a better angle to get under that beast. It doesn't sound like I have any other options but to do the hard work of replacing the pump. I appreciate the time you guys took to try and help me. I'll post later as to the final results. racerjim

 

You cannot guess how many good fuel pumps get replaced because the diagnosis stopped in the engine compartment.

A thorough diagnosis means you verified the ground and power were available AT the fuel pump. If power and ground right at the pump is absent, it can't run.

The way you can do this is,,,, if you ground the fuel pump terminal on the diagnostic plug with the key on that fuel pump should run. So check that to be sure the pump is the problem. and not a possible poor connection there. Please let us know how you make out with this, thanks.

 

Thanks hanky, I will have to drop the tank to continue the diag. It won't be anytime soon; we are in our rainy season. I'll keep you posted. racerjim

 

Hanky's suggestion about giving the tank a 'hardy' swat with the key on has worked on many occasions. If the tank bump gets the pump to run, you have your answer. Pulling the relay and bridging the load/supply connections helps to make pin out checks on down to the tank as well

 

Thanks, Hayapower, I will give that a shot before I actually pull the tank. We shall see what happens. I'll keep you all posted. racerjim