CUCV Mechanical pump not pumping fuel

[milradioman]

Working on my son's M1009; it is having problems with hard starting, and I have read many good suggestions here.
I finally figured it was time to replaced the leaking (fuel) fuel pump with a NAPA part. I had to remove the metal mount plate to put grease on the push rod so it would stay up in the engine while bolting the pump in.
Just a note: after I installed it I noticed the fuel inlet tube where the fuel hose clamps on is now rubbing against the cross member, made me wonder if I had the correct part.
Attempted to bleed the air out at the fuel filter, but would not draw fuel, I had to apply air pressure to the tank to finally get fuel to the pump. Engine finally started though it still starts hard (long cranking).

The vehicle ran for about a month like this, then it would not start at all. I thought the NAPA pump failed out of the box, and bought another brand and replaced it, this time I was very careful to make sure the push rod was in position when I installed it, I also checked and there were no odd wear marks on the push rod to indicate it slipped or was not lined up with the pump. The fuel inlet tube where the fuel hose clamps on does not rub on the cross member like the NAPA part did.
The new pump did not pump fuel either, I tested the new pump by putting the intake line into a can of fuel and did not pump fuel out of the can!

Summary; the old fuel pump did pump fuel when I removed it, two new fuel pumps are now not pumping fuel, I have no reason to believe the push rod is not lined up with the pump, especially since I replaced it twice.
I must be missing something, the push rod may "appear" lined up but isn't? or the cam is no longer moving the push rod? Have the wrong pump part again and is not moving the pump arm enough to move fuel?

Any ideas would be greatly appreciated.

 

[Drock]

It sounds to me like it's sucking air from somewhere. I'd start by (temporarily) replacing the short return line on top inject pump with a piece of clear tubing so you can see if your getting air OUT of the I.P. If so then start tracing it back from there. My guess is if the lift pump isn't priming then it could be the rubber lines on top of the tank, or clogged or leaking at or around the fuel filter.

 

[Cucvnut]

Push air into the tank with compressed air but seal the fill neck opening with something.

 

[MarcusOReallyus]

Yep. Before you go messing with the pump, make sure you can get fuel from the tank. Your sock might be clogged.

 

[GPrez]

If all else fails put an electric fuel pump on it. I had troubles with the mechanical pump on my M1009 & M1028. Never had another issue after putting the electric ones on. Easier to bleed the system too.

 

[jpg]

Having driven 800 miles with a dead 12v alternator, I'd like to point out that a mechanical pump works when the electrical system doesn't. I used a jump box to get it started, and then it ran fine without electricity.

 

[milradioman]

Drock, I will try your suggestion, I am thinking there is an air leak somewhere, but have not found it so far. I had to applying air pressure to the fuel filler to get the first mechanical pump to prime, after I filled the fuel line with fuel, I continued to apply pressure to look for a leak in the line, but none appeared. I had to temporarily replace the pump with an electric pump because I could not get the new mechanical pump to move fuel. My biggest issue is the mechanical fuel pump is not pumping fuel, and I cannot figure out why.

 

[Volvo740turbo]

Drock, I will try your suggestion, I am thinking there is an air leak somewhere, but have not found it so far. I had to applying air pressure to the fuel filler to get the first mechanical pump to prime, after I filled the fuel line with fuel, I continued to apply pressure to look for a leak in the line, but none appeared. I had to temporarily replace the pump with an electric pump because I could not get the new mechanical pump to move fuel. My biggest issue is the mechanical fuel pump is not pumping fuel, and I cannot figure out why.

Any resolution to this yet?

 

[milradioman]

Hey, thanks for getting after me about an update.
Recently cucvsrus pointed out the differences between what the auto parts stores are selling and the correct part for the mechanical fuel pump.
I previously replaced the pump twice with the same (wrong) part number, and neither pump is pumping fuel, rather confusing at the time, but now I know why!
My son works nights and we have not had time to replace the fuel pump yet, but I am confident the correct pump will fix the fuel pumping issue and the general ruff running condition. I will try to remember to update to confirm the above after I replace the pump.

I replaced the fuel pump on my M1009 a couple of weeks ago with the correct part number ( AC Delco from Rock Auto), and that fixed a lot of intermittent ruff engine running issues I was having. Note:I followed the procedure to bleed the fuel system, remove pink wire on IP, open bleeder on filter, and it just took a few cranks of the engine to bleed the fuel out of the filter, reconnected everything and the engine started right up and ran without any hesitation.
Now it starts and runs so smooth, just like I would expect it to after a rebuild on the injector pump and all the other stuff I have done.