Truck starts runs cuts out after a minute of running

Denace

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Bfield
I have a 1986 6.2 CUCV. New remote filter, all new lines, new lift pump still have air in the fuel filter. Truck ran fine, I had to pull a head off to get a glow plug out, put it back together it runs for a minute to a minute and a 1/2 then cuts out and will not start again.
 

cucvrus

Well-known member
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Jonestown Pennsylvania
Check your lift pump. There are 2 that fit and one is the wrong one. The lever on the correct one has resistance pumping action immediately upon depression and the lever is short and the spring is inside under the lever. The wrong pump has no resistance and the pumping action resistance takes place about 1" into the lever depression. The cam eccentric can not depress the wrong pumps lever arm enough to get fuel moving fast enough to the pump. The injection pump will pump a minute amount of fuel but not enough to keep the engine running. Been there 2 times. I lived and learned. If you have your old pump look at it. Show a picture here. Good Luck. Check the pump.
 

2INSANE

Well-known member
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Belgrade, Montana
Pressurize you’re fuel system to 10 psi threw the fuel tank neck. Check all fuel lines for wetness or leaks.
 

markg

Member
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Location
hutto,tx
if you find that the lift pump is not pumping fuel check the pump rod. i have seen them break after installing a new pump. been there and done that multiple times.
 

Davetheplumber

"Moose"
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Corbett, OR
I had to just keep runnning it and running it forever to get ALL the air out.. one time it took hours. It’s nice to put an electric pump near the tank.. then you can open the line just before the IP and bleed it out with the electric pump instead of fire the engine up 100 times. Also, if you fire it up with a bit of throttle to keep the rpms about 1500 is will sometimes stay running while blowing the air right threw the injectors

permanent fix for me was a big block 454 gas engine
 

Slabofmeat

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Irvine
Hello all, new to the site...
I'm not a certified mechanic but I am a do it yourselfer. I get a lot of info how to fix these beasts from you tube videos. My question today is when installing a new fuel pump am I supposed to use rtv or just the paper gasket provided? Also, it came with 2 gaskets, should I use both?
 

cucvrus

Well-known member
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Location
Jonestown Pennsylvania
Hello all, new to the site...
I'm not a certified mechanic but I am a do it yourselfer. I get a lot of info how to fix these beasts from you tube videos. My question today is when installing a new fuel pump am I supposed to use rtv or just the paper gasket provided? Also, it came with 2 gaskets, should I use both?
First off I would make sure you have the correct pump. After you have discovered it is the correct pump I would remove the push rod cover plate and replace that gasket as well. I think that gasket and the fuel pump to cover plate gasket are the 2 gaskets you are referring to. Also a little tip. I find it much easier to change the pump top side with the Gen 2 removed and set aside. No need to remove the wires. just disconnect the batteries and have at it. Also get all the bolts hand started and let them loose until you get the hard steel flare nut started. That bottom cover plate tends to misalign on you if you tighten it up first. And yes I use the paper gaskets and Permatex The Right Stuff more or less to seal any slight imperfections and act as an adhesive to keep the gasket in place. But at a fault I would make sure the correct fuel pump has been procured before you proceed. Post a picture if you would like or read up on the issues others have had. Good Luck. Be Safe.
 

cucvrus

Well-known member
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Location
Jonestown Pennsylvania
If you have lift pump #mf0030, that is the incorrect pump. You need #chfp906. That is the correct lift pump.
I don't even go by part numbers anymore. I go by visual and hands on depression of the lever. the correct lift pump has immediate resistance and pumping action when the lever is depressed. The incorrect one has about 1/4"-1/2" free ply in the lever before the resistance begins. As I showed in the past I have received 3 pumps 2 with the same part number and one was correct and the other was different. Boxed incorrectly? I don't know but I leave nothing to chance at this point. Being towed home is not fun. Good Luck.
 

Slabofmeat

New member
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Location
Irvine
First off I would make sure you have the correct pump. After you have discovered it is the correct pump I would remove the push rod cover plate and replace that gasket as well. I think that gasket and the fuel pump to cover plate gasket are the 2 gaskets you are referring to. Also a little tip. I find it much easier to change the pump top side with the Gen 2 removed and set aside. No need to remove the wires. just disconnect the batteries and have at it. Also get all the bolts hand started and let them loose until you get the hard steel flare nut started. That bottom cover plate tends to misalign on you if you tighten it up first. And yes I use the paper gaskets and Permatex The Right Stuff more or less to seal any slight imperfections and act as an adhesive to keep the gasket in place. But at a fault I would make sure the correct fuel pump has been procured before you proceed. Post a picture if you would like or read up on the issues others have had. Good Luck. Be Safe.
Thank you for the quick reply and the info, you were right about checking if its the right part, I ordered the part online before I had the original part out, first mistake, probably not the last and it said it was for the 6.2L, maybe not for the military hmmwv and for the civilian hummer, IDK. As sneekyeye said above I need the fuel pump with the straight arm not the one with the bend, so I just ordered the right part, came to $30 out the door, im not sure if I should post where I ordered it, I dont want to undercut anyone because I know there are a few poeple selling parts on here trying to make a living or some side cash... I found the right gasket sealant not to be confused with gasket maker its made by LOCTITE, MR GS1 gasket sealant part#30510 its the only stuff I could find that actually says resistant to gasoline, fuel oils, diesel oils and some other stuff, if anyone has used this or knows of better stuff to use drop a line. Thanks again!
 
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