Injectors

[Bigdog]

I replaced all the injectors on my 6.5L Chevy two weeks ago. My electric fuel pump worked well in priming them and I didn't have any problem starting it. They still run a little rough at the stoplight though. After two weeks of driving, would they still need to be bled? Thanks.

[trbankii]

Unless air is leaking into the system, I’d see no reason to need to bleed the injectors after the initial start-up.

[Kennedy]

As stated above no need to bleed, but there are plenty of suspect quality (cheap) injectors out there.

[Bigdog]

I'm still having problems with starting that I hope someone can help me with. I've replaced the mechanical fuel pump with the Kennedy electric lift pump setup, replaced the injectors (Kennedy) and the glow plugs (Kennedy Quick Heats). I have a manual switch for the GPs to give more glow time but it still is hard to start and white smoke belches out when it catches. But no more smoke afterward. It idles a little rough but revs up quite nicely. It runs pretty good around town and on the highway, but I can tell from the sound that it's not the way that it used to be.
Is there any conclusive tests that I can perform to zero in on the problem rather than throwing parts at it. I also put a clear fuel line on the return line. No bubbles.
Thanks for any suggestions.
My specs are shown along with my signon bio.

[Bigdog]

I must also add that it sputters and shakes a lot at first unless I rev it for a few seconds until it catches up. This happens especially after sitting for 2-3 hours.
My fuel pressure is 3 lbs at idle.

[arveetek]

Have you checked timing and the timing chain? If timing was a bit retarded, it could cause your symptoms.

Casey

[Yukon6.2]

My Guess is an air leak into the fuel system.
What filter are you using? Large rectangle on the firewall?

My 90 6.2 started like that after i got it on the road.Turned out one of the plugs on the filter base was almost corroded through.Wouldn't leak fuel but would suck in air when it wasn't running.It was the rectangle one on the firewall.
I ended up pressurizing the system and found the leak then.

[Bigdog]

Casey,
I haven't checked the timing because I don't know anyone that has the diesel timing equipment.
Yukon. I have previously been chasing the air in the system theory as you suggested. Thanks Yukon! But to no success! I made and used "the gutted out filler cap." However, I can't get the system to hold much pressure. I will set my air compressor regulator to 10 lbs and fill the fuel tank and system with my air chuck. I would think that if you then unscrew the filler cap, you would hear the pressure escaping. But I don't! Am I doing something wrong. I didn't see (or hear) any leaks but then again I don't think it holding much pressure. I don't want to rupture anything by putting in too much pressure.
The funny thing is, that I don't see any air bubbles in the clear fuel line. All my instincts tell me that I've got air in the system but I just can't seem to get an indication of "where".
Any other suggestions would be appreciated.
Thanks.

[sctrailrider]

Have you tested the glow system to make sure all are working, the white smoke leads toward unburnt fuel.... that will cause the motor to stumble..

[DmaxMaverick]

Also check the HPCA (Housing Pressure Cold Advance - Very important for MFI systems). Make sure it is connected, and getting power. If it isn't powered, or has failed, (relative) cold starts can be difficult, rough, and smokey.

[Bigdog]

I think I finally got my answer. About a week ago, after I stopped at a little market, it wouldn't start again. Turns over ok, but never catches. I'm getting fuel to the injector pump and the glow plugs are fine. I had it towed home. Last weekend, I removed the oil filler tube so that I could see the injector pump end that runs off the camshaft gear. I could see it turning. I hope that, that rules out a timing chain issue.
Soooo, does this basically say that the injector pump has failed and it's time to remove for a rebuild? Is there anything else that I can test to be sure that it's the injector pump?
Thanks for any suggestions and/or replies.

[sctrailrider]

I didn't read every word in this thread again so I'll ask....

When it won't start have you tried pouring cold water on the pump??

If it starts when cold water is poured on it then it's time for another pump...

[Robyn]

Another test is to dump a gallon of 30W motor oil in the tank (Mix with some diesel first)

This will add lubricity and THICKEN the mix some.

If the hot start issue is better then the IP is worn out and needs a rebuild.

A good rebuild requires a head and rotor replacement.

What happens is the plungers and their bores wear out to the point that once they heat up they leak enough that they can't build pressure.

As mentioned COLD WATER ON THE IP can cool things enough that it will start.

If you can spin the engine fast enough (Stick shift being towed/pushed) it would likely start.


Give the oil a shot.

Robyn