Sounds like injectors...

 

The truck runs fine and doesn't smoke. Do any of you have any tips on diagnosing injectors or lift pumps? I pulled the filler tube and checked the injection pump seal again, I can't see or hear any fuel coming out of there when I stroke the lift pump.

 

wrong thread

 

If its not the front ip seal...or lift pump...then its got to be the injectors. Find you a good used set and swap them out.

 

Or the lift pump that i put on wasn't any good. It came from Advanced auto so who knows how good it was. I'd like a way of testing it. I'm getting sick of dropping $45 on oil changes.

I have a hard time believing that the injectors could pump that much diesel past the rings and the truck run as good as it does. I can't hard a miss or a stumble at all, and this truck doesn't smoke.

 

Pull the lift pump and run air pressure through it maybe? Not to much but maybe 15psi. Thats a hard one to test.

Ive had engines fill the crank case full of engine oil just idling for a few minutes due to injectors. Most of them had a audible stumble or miss but there were two you couldn't hardly hear at all. All of the above also didnt smoke any at all unless they sat and idled for long amounts of time...the one cylinder would load up with fuel.

 

I think I'm going to unbolt it from the engine and hook the lines back up to it, then stroke the lever and see if fuel pours out around the part that gets sealed to the block.

I know when I was younger, we'd replace those diaphragm pumps on old Chevy gas engines, and it wasn't uncommon to get a bad one. In fact one time we got about 3 bad ones in a row.

 

When you replaced the front ip seal did the pump shaft have any play in it?

 

It seamed really tight to me. I couldn't wiggle it round, or push it back and forth. I pulled the fill tube again (for the 4 time) and checked that seal for leaks again last night. I can't see a drop coming out of it while manually stroking the lift pump.

Before I replaced that seal, when I'd do the same thing, fuel was squirting out of there and I could even hear it raining down the front cover.

 

Sounds like it is in good shape then. Id get a lift pump from a different source, if that doesn't work, it has to be injectors.

 

I just pulled the pump off. The more I thought about the suggestion to pressurize it, the more I liked that. I rigged a regulator and a hose to the inlet and put 10psi to that and held my thumb over the outlet. Then I dunked that down in a bucket of diesel. I played with it for a while and at first I couldn't see any bubbles, but then I started cycleing the air on and off since I used a blowgun to hook up to the hose. For about 20 cycles, I was getting a bubble, then it would quit and a little latter it would come back. I'm still not positive that it was leaking fuel, but if it was intermittant that would answer some questions.

 

I just pulled the lift pump off. The more I thought about the suggestion to pressurize it, the more I liked that. I rigged a regulator and a hose to the inlet and put 10psi to that and held my thumb over the outlet. Then I dunked that down in a bucket of diesel. I played with it for a while and at first I couldn't see any bubbles, but then I started cycleing the air on and off since I used a blowgun to hook up to the hose. For about 20 cycles, I was getting a bubble, then it would quit and a little latter it would come back. I'm still not positive that it was leaking fuel, but if it was intermittant that would answer some questions.

 

Your oil pressure reading sounds normal idle/at rpm. The port on the filter head is as good as it gets. I might try bypassing the lift pump with a cheap Procomp black for testing purposes. They can be had for around $50. If you confirm it's the LPs, install a piston pump and keep the electric for backup, not that you'd ever need it with a piston pump. <<PLUG FOR PISTON PUMP (no pun intended) >> I just unclogged the pickup from my bed tank yesterday after it had sucked in some junk that got caught in the selector valve and it managed to hold anywhere around 3-12psi in normal driving around NEARLY CLOGGED SHUT that day until I got home and found the problem.

I doubt it's injectors if it's running good and not smoking/hazing.

 

I'd suspect the VE front seal you just replace.

Take off the oil filler elbow and use the primer lever on the lift pump to pressurize the VE front seal. Use a mirror and a flashlight to watch for fuel running down inside the timing case.

 

I've done that about 6 times now. I can't see a leak. I put another new lift pump on it today aNd changed the oil. That didn't fix it. Either that seal only leaks then the shaft is turning, or its injectors