Ran SOOO Fine until Now!!!!

[dabmdb]

Been searching for a past thread about this but can't find one that fits. Here's my situation:
2003 Chev Duramax with 33K miles. Wouldn't start last week, so I would open the fuel filter vent, give it a few pumps and eventually I could get her started, then she would run fine. After a few days of this, the fuel filter trick no longer worked. Had her towed into the dealer.
Dealer says you were out of fuel, I say gauge read 1/4, they say gauge was defective. They replace gauge (did not change fuel filter), I pick up truck last Friday and I still have to prime the pump, not everytime, but several over the weekend. Also, when it does start, I no longer get that quick "snap" when the engine fires up. Engine has to crank before starting. I hear a little more "dieseling" when driving. AND this may sound strange, but I swear that the truck is running faster while this situation is going on. I do run a Hypertech programmer so I know what is faster than stock. (I returned to the factory program early on before I took it to the dealer). Maybe it's my imagination, but whatever. I'm thinking early signs of injector problems. Any suggestions? Thanks,
Don

[DmaxMaverick]

You are getting air sucked into the system somehow. The first thing you should do is replace the fuel filter, or at least remove it and ensure it is sealing.

It could also be the fuel pick-up in the tank. It has a restriction bypass on it that will allow it to draw fuel from higher on the pick-up if the bottom gets gelled (froze). This is about the 1/4 tank area. If your problems only happen when you are near the 1/4 tank area, then that could be your problem. Also check that the fuel cap is venting. If it is not, it could cause the same symptoms. Next time it happens, open the cap. If you get a rush of air inward (vacuum), then the cap is bad, and likely your problem. (of course, it can't be that simple)

It doesn't sound like an injector problem. Air in the system will cause excess noise, low power and slow starts (as well as no starts). If you get enough air in the system and continue running the air through it, there could be injector problems later.

Good luck and keep us posted.

[Kennedy]

It's hard to say as to the air issue, BUT it has been a fairly common occurrence that priming is necessary to overcome excessive return volumes of a bad injector(s)

The bad injector theory can be tested by running up the PSI with a Tech 2. If the pump cannot acheive desired psi, it is likely due to an injector problem.

Give it a week or so ;) before you act on it though...

[sdaver]

mine was a stuck injector return......dealer has a step by step chart to diagnose.........invloves removing valve covers and measuring the flow of each side then each injector once a bank is determined........time consuming but it works

[Kennedy]

In the VERY near future, the symptoms Sdaver presented with will dictate 8 new injectors... ;)

[mps007]

Mr kennedy That interests me, since this is the problem I have been having ....... Prime it way too often

[HD-Nate]

Well since the other place is down for now I can only paraphrase my own post.

I had a similar problem, it started to be only a problem when it was cold but became worse.

John is correct, you will probably end up replacing all 8 injectors, which will be a good thing since it is still under warranty.
Have your dealer reference bulletin 04-06-94-007. As of Monday it was not published to the dealers but GM T.A.C. can fax them the bulletin.

They replaced my injectors on Monday and it now starts immediately with zero hesitation.

[dabmdb]

We're going back into the dealer shop tomorrow. FOr what it's worth, here's my observation of how the truck acted this week whether it has something to do with the problem or not. As I said earlier, had to continue to prime the filter to get truck to start. Somedays, maybe on 4 or 5 different occasions, other days never. Did it two times in a row today (Thursday)and I noticed the fuel gauge (which was replaced last week) was at about the same spot when I had it towed in. Ah ha, so maybe this is the problem! Filled the tank full and still have to prime it by hand EVERY start I've done today. I will print up this thread and take it with me to the dealer this afternoon. I'll keep you posted.