1986 M1008 losing power

Lg86

New member
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Location
Oklahoma
Have a 86 m1008 after about 30 minutes of driving I start to lose power and not be able to get over 20 climbing hills. Any ideas?
 

Barrman

Well-known member
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Location
Giddings, Texas
Check your fuel filter, air filter and such. If you have replaced them. Then it could be several things. The TM tab at the top of this page is a way to download the Technical Manuals for this truck. The one ending in -20 has a great almost 100 page section on troubleshooting and talks you through symptoms and how to test to see what the issue really is.

Most of us have found fuel pick up sock clogged, fuel cap not venting and a clogged return line check valve on the IP as the cause of this issue. Which is why those were the first things suggested above. By the way, a clogged return line check valve is clogged because the IP is coming apart inside and needs to be rebuilt. Just a warning.
 

cucvrus

Well-known member
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Location
Jonestown Pennsylvania
How long fuel pumps usually lasts on CUCV?
Fuel pumps or injection pumps? I do not think there is a defined time line as to when the pumps fail. I had brand new injection pumps fail in less than a year. I have removed some from engines and replaced them just because I didn't know how old they were. The lift pump I replace as a precaution and just to add more reliability to the vehicle. Get a good lift pump and make sure it is the correct one. Remove the fuel tank and change or remove the sock from the sending unit. I have seen them both ways. No harm either way. The fuel will all have to go thru the filter anyway. I was surprised to find that newer cars and light duty gas vehicles don't even have a serviceable fuel filter. So any time and place for a failure is possible. No set dateline on parts to fail. When they fail the need diagnosed properly and replaced with competent replacement parts. Good Luck.
 

vanaisa

Active member
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Location
Tallinn, Estonia
Thanks!
My lift pump is working fine now, but who knows, when it changed. Not in my ownership, so at least 6 years old...
Injection pump also in working order.
I must remove fuel tank anyways, sending unit is dead.

Oh, and sorry to hijacking thread :oops:
 

Keith_J

Well-known member
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Location
Schertz TX
How hot is the injection pump when it loses power? The pump is cooled by fuel returning to the tank. If there is no return fuel, pressure in the case retards timing and decreases injected quantity.
 
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