Mechanical fuel pump replacement

kdaniels

Member
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11
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Dothan, Al
I knew that. I just seen schematics of HMMWV engines in another post on this thread.
Well I tried to fire her up this morning and it was a no go. New pump and filter with no leaks at either. Unplugged the IP and primed both pump and filter. I did notice a big difference in the volume of fuel the new pump is moving compared to the old one.

Filled a small water bottle about 3/4 full priming filter but I still notice I had some air in the clear drain line, or so it appears. Got the batteries on charge to try again this evening. This is the first time in 15 yrs this truck has had any starting issues that weren’t dead battery related. 100% stock truck except a in dash radio.

For something to kill the engine on acceleration like you turned off the key has me puzzled now that the fuel pump is out of the equation.
 

chevymike

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Have you cracked any of the lines at the injectors and see if you are getting any fuel to them? Could be the injector pump is bad or something related to the injector pump.
 

kdaniels

Member
192
11
18
Location
Dothan, Al
Have you cracked any of the lines at the injectors and see if you are getting any fuel to them? Could be the injector pump is bad or something related to the injector pump.
Weather has killed outside for the day BUT....1st thing in the morning I’ll do just that. I’ve been reading some other threads about the IP so I can get an idea about what that project entails. See if it’s within my skill set. I’m more of a “ parts changer” with some mechanical abilities. THANKS

Semper Fi
keith
 

kdaniels

Member
192
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Location
Dothan, Al
With that kinda inspiration how can I fail. 🤔🤔🤔🤔👍. Oh and thanks for the info on the correct fuel pump.
I think it was original to the vehicle. THANKS again!

Semper Fi
keith
Reading some other threads you and others have committed on it dawned on me that on a Kubota I had a few years ago it quit running cold turkey under full power mowing because the fuel solenoid crapped out. It’s got a distinct “click” when it engages and disengages. Very much like this event with my M1009. Would this also cause a stoppage on this vehicle ..under power...???

Semper Fi
keith
 

dpaulus

Member
49
2
8
Location
Fort Smith, AR
The rod can only go in the hole. If you push it up with grease on it and it stays you got it in the hole. I use Permatex The Right Stuff. There is nothing in the fuel pump area that is critical tolerance. It is just an old diaphragm pump. And as long as the area is clean and not gouged the sealer will seal. Thank you for sharing. I was assuming you were working on a CUCV. This is the CUCV forum. No problem I have replaced 2 engines in HMMWV also. Same basic set up. I put 2 HMMWV 6.2 engine long blocks in CUCV's also. Good Luck. Be Safe and Take Care.
Is the correct fuel pump the AC Delco 43254, and is Permatex an acceptable substitute for the gasket between the block and the mounting plate? If not, do you happen to know the part number for that gasket? Thanks!
 

gestut

Member
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Location
az
It is pretty easy once you figure it out. It's just kind of a pain. Like was said, you'll never get the push rod to stay back up if you don't take the second plate off and put a gob of grease on the end of the push rod. Hold it up in there while you rotate the engine using the crank bolt until it is as far back in as it will go. Then just slap it all back together. I've never had a rod fall back down once you put a goodly amount of grease on the end and jam it in.
my rod is in but not flushed so the pump cam is hitting the rod and the pump is not going all the way in. how do you crank the engine ?by hand?
 

sneekyeye

Active member
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ALABAMA
my rod is in but not flushed so the pump cam is hitting the rod and the pump is not going all the way in. how do you crank the engine ?by hand?
That is correct. You will need to turn the crank bolt clockwise and rotate the engine over with a big ratchet. If you can turn it and have a helper holding the rod in the bore, they can tell you when its up and to stop.
You could bump the starter with everything out of the hole, and just try again wherever it stops.
 

gestut

Member
33
1
8
Location
az
It is pretty easy once you figure it out. It's just kind of a pain. Like was said, you'll never get the push rod to stay back up if you don't take the second plate off and put a gob of grease on the end of the push rod. Hold it up in there while you rotate the engine using the crank bolt until it is as far back in as it will go. Then just slap it all back together. I've never had a rod fall back down once you put a goodly amount of grease on the end and jam it in.
i am having that problem where the rod is not completely in and the pump wont go in dur to the rod sticking out a bit, where is the crank bolt to hand crank? thanks
 

cucvrus

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Jonestown Pennsylvania
I never cranked or turned an engine to get the rod up in the engine. I can't be that lucky every time. I just put chassis grease on the rod and shove it up in there. Then I put the engine cover plate on with the 2 bolts finger tight and reach up in again and assure that the rod is up in. I then put the new fuel pump on and tighten the outer bolt finger tight. I align the rear bolt and crank the front one in with a ratchet slowly till I can get the back one started by hand then I get the metal fuel line started by hand while the pump can still wiggle and move a bit. after everything is started I tighten the pump mounting bolts and the metal fuel line. I already installed the rubber line first thing before I put the pump down there. It is that easy. Start to finish about 1 hour top side with Gen 2 and the brackets removed. Good Luck. I hope that helps.
 

gestut

Member
33
1
8
Location
az
I never cranked or turned an engine to get the rod up in the engine. I can't be that lucky every time. I just put chassis grease on the rod and shove it up in there. Then I put the engine cover plate on with the 2 bolts finger tight and reach up in again and assure that the rod is up in. I then put the new fuel pump on and tighten the outer bolt finger tight. I align the rear bolt and crank the front one in with a ratchet slowly till I can get the back one started by hand then I get the metal fuel line started by hand while the pump can still wiggle and move a bit. after everything is started I tighten the pump mounting bolts and the metal fuel line. I already installed the rubber line first thing before I put the pump down there. It is that easy. Start to finish about 1 hour top side with Gen 2 and the brackets removed. Good Luck. I hope that helps.
Well you might be lucky idk. As other have said about hqnd crank. The rod goes in and stays there but when you put back the pump the rod is little bit out pushing the pump and not sitting flush and with tension about bit more then 1/8 inch. I cranked by hand a bit although i could not tell the rod was moving but the pump sits almost flush to the plate now. .
 
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cucvrus

Well-known member
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Ok that may be but I think when I start the bolts by hand loosely the fuel pump lever depresses as I evenly tighten both bolts. I never gave it much thought as to why the bolts tighten with a bit resistance till you mention it but I knew they weren't cross threaded that is why I started them by hand as I do all bolts. So I guess that would explain why I never turned an engine over during changing the fuel pump. I never had to. But shoving the greased rod up in the block and taking the bottom M6 bolts and cover plate off were always a great advantage. Everything loose and started made it much easier also. Good Luck.
 
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