6.5 diesel

DeanRV said:

Good evening, so I've replaced the fuel line from the ffm to the injection pump, replaced the line from ffm to drain valve, replaced the short 3/8 line from hard line to the ffm, replaced the return line with a clear line that's rated for diesel. Not one bubble in the line. If it was a bad injector you would think I would get some sort of smoke when I'm on the peddle? Is it possible it's the lift pump? At idle it's showing close to 7psi.....anyone on this forum from Vancouver B.C. who can recommend a diesel shop that understands 6.5?

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Lift pump pressure of 7 psi is good, does it hold that pressure at 2000 rpm or even 3000 rpm?
6.5 injectors are a bit weird. They can be bad without causing smoke. If it were me, I'd be dumping some 2 cycle oil in the fuel. Throw a quart into the fuel tank, see what happens. Or, some injector cleaner.

CumminsFever said:

Lift pump pressure of 7 psi is good, does it hold that pressure at 2000 rpm or even 3000 rpm?
6.5 injectors are a bit weird. They can be bad without causing smoke. If it were me, I'd be dumping some 2 cycle oil in the fuel. Throw a quart into the fuel tank, see what happens. Or, some injector cleaner.

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I always put 2 cycle oil with every fill up and injector cleaner with every oil change that I do at every 5000km. Got my hands on a ac delco ep158. If that doesn't fix it then it's a trip to a diesel shop. Anyone on this forum from British Columbia?

Replaced the lift pump and no difference. When running idle I've been watching the clear tube from the return and no bubbles. I turned off the engine and watched the clear tube for about a minute and a bubble came up from the hard line return. Started the truck up, bubbles go away and when I turned it off bubble came up from the hard line into the clear tube. Once I installed the lift pump I took it for a good 20 minute drive, mixture of town and freeway, would that be enough time for the air that was let in when I swapped out pump to get out?

DeanRV said:

Replaced the lift pump and no difference. When running idle I've been watching the clear tube from the return and no bubbles. I turned off the engine and watched the clear tube for about a minute and a bubble came up from the hard line return. Started the truck up, bubbles go away and when I turned it off bubble came up from the hard line into the clear tube. Once I installed the lift pump I took it for a good 20 minute drive, mixture of town and freeway, would that be enough time for the air that was let in when I swapped out pump to get out?

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Any air left in the line from your lift pump replacement was gone in a minute or 2 or running. The injector pump does a fair job of getting rid of air.
How old is your pmd? Not that I've seen the pmd do what you describe, but it is possible.

95 OBD1 can set codes without engine light coming on.
have you checked for any codes? (search engine of your choice OBD1 check codes)
once in check mode, engine light flashes to give you the code.

CumminsFever said:

Any air left in the line from your lift pump replacement was gone in a minute or 2 or running. The injector pump does a fair job of getting rid of air.
How old is your pmd? Not that I've seen the pmd do what you describe, but it is possible.

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I've got a new one for a spare, swapped it and no difference.

1997 said:

95 OBD1 can set codes without engine light coming on.
have you checked for any codes? (search engine of your choice OBD1 check codes)
once in check mode, engine light flashes to give you the code.

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That I didn't realize would happen, always thought the check engine light would come on if I had an issue, will check it out later this evening.

DeanRV said:

That I didn't realize would happen, always thought the check engine light would come on if I had an issue, will check it out later this evening.

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You guys won't believe this, I jumped a and b check engine light doesn't light up....burnt bulb...replaced bulb and I get code 29 and 46. My book says 29 is glow plug relay circuit. Code 46 is service engine soon lamp circuit problem. I believe 46 may have something to do with the burnt bulb and would 29 make it run rough?

A burnt out "check engine" bulb? That is the longest lasting bulb on earth! Staying lit for YEARS of service, blinking and flashing, it is a stark reminder of just how robust the non-led bulb is.
Anyway, the glow plug "generally" doesn't affect running once the engine has heat in the combustion chamber, the 1st minute of engine operation. It's highly doubtful the glow plug circuit failure would cause a rough running issue. It could cause hard starting or no-start.
Still, fix the issue, which consists of the relay, glow plugs, or possibly a wiring issue in the glow plug system. There is a water temp sensor for the system, which may be failing, and that sensor may also be the main water temp sensor, which "could" cause your rough running issues.
A scan tool would tell you a few simple parameters that may clue you in on the problem.

Given the age of the truck, the suction side of the lift pump is suspect. There are o-ring seals at the fuel sender on the tank and by this age they are toast or even disintegrated, allowing air into the system. In my case, I replaced everything: tank, seals, fuel lines and lift pump. This cured the problem.