Need some help with a fuel problem

First off, let me say the FB groups are almost useless when it comes to real problems.

So every morning no matter what, truck coupd have been sitting for days and she fires right up, almost instantly. Kicks into high idle and sounds great for a second, then starts skipping or spitting and sputtering. Not sure if its one cylinder or happening everywere.

I can drive and cruise in the truck to me what seems fine. Doesn't lack power, and doesnt seem to spit and sputter while cruising. Now in slow and stop traffic or idle its pretty bad and starts get worse but never really dies or anything, just sounds like it has a big cam. If I put it in neutral I can idle it up to 1,000 rpms and still feel it a little, the higher the less and at about 1,800+ don't notice it.

2 new fuel filters in it.

I pulled the schrader core out and tested the psi, its about 4-5.

Heres the thing, if I pull the schrader core out, hook a hose up to it and crank for 10 seconds I get less than a 1/4 of a pint.

Hook to hardline from pump and I get way more, well over a pint.

Is there something going on at the filter head? Should I clean it and maybe block off filter return and test or is that difference between schrader and pump line normal?

Thanks

This sounds like a fuel restriction but more info is needed. How many miles are on the injection pump and injectors? How mny miles on the engine too. Many times the rubber fuel line from the frame to the lift pump fails because its always moving with engine vibration. Might try changing it. This line is 3/8 rubber line.

icanfixall said:

This sounds like a fuel restriction but more info is needed. How many miles are on the injection pump and injectors? How mny miles on the engine too. Many times the rubber fuel line from the frame to the lift pump fails because its always moving with engine vibration. Might try changing it. This line is 3/8 rubber line.

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236k on engine 20k ish on IP, unknown on injectors.

Currently installing clear lines, will report bsck.

heres what im seeing

Return line from filter to inj #1 will drain from fuel once motor is off.

How I know this is I hooked a clear line up, the clear line fit tighter. Started the truck and it had some air, over a minute it worked all the air out and idle smoothed out. Shut truck off, the fuel held in the clear line, didnt lose prime or get any air in.

So I cut me a new piece of return line, nice and bendy. Pulled clear line off and put return line on and problem came back. I let it sit for 5 minutes and kept idling rough. So I put the hose/worm clamps on to make sure it was tight at filter and inj 1 and it kept happening, still bad idle.

Shut truck off, waited a minute and pulled return line off, no fuel. That was this morning.

It sounds to me like you have a fuel drain off when you shut off the engine. Maybe you disturbed the seal on the o-rings on #1 when you used the clear line. Maybe it's on #3. I'd suggest replacing your injector o-rings and maybe the return lines.

Okay well installed clear lines from mech pump to filter, filter return to inj #1, filter to IP, IP return to inj #2.

Drove around and after I got back absolutely no air in any of those lines, not a single bubble. Shut the truck off and the prime held, no bubbles entering any of those clear lines. Still spitting and sputtering. Drives fine, no smoke.

Also getting about 2 psi at idle from schrader with valve core out. The needle is real jumpy, when I give it throttle gauge smooths out and sticks at about 2.5psi.

With schrader core left in and if I screw pressure gauge on I read a steady 2psi even if I give more throttle.