GM Truck Club Forum banner

99 Tahoe won't start

15918 Views 6 Replies 3 Participants Last post by  klhoe
My Hoe cranks over but won't fire. Have had 2 fuel pumps installed the last one 6 weeks ago. Getting spark and fuel. A friend told me he had the same thing on his truck and it was the converters. I took out the o2's and still nothing. Also no service engine light on. Any help for this hoe?????
1 - 7 of 7 Posts
How have you verified fuel? Fuel pressure spec is 60 psi, and I've heard tell that it takes at least 50 psi to get the poppet valves to open (I'm assuming you still have the original injector spider and not the upgraded kit). What is the fuel pressure? Are the spark plugs "wet" with fuel after attempting to start?
Ignition modules can cause this type of problems, under 50 bucks. It can be tested but for the life of me I can’t remember how.

I had one go on a Ford Van and it never started again until I replaced it.

I had one go on my Burb and it would start if you primed it.

Test, test, test before replacing anything.
The guy that installed the fuel pump came over and checked the psi, said it was good. Removed plugs and all were wet with fuel. He said he thought it was plugged converters. Let sit overnight with plugs out. Cleaned them reinstalled them. Pulled the o2 sensers and tried to start.... same thing. Some times it sounds like it is going to start just for a sec, but won't.
Clogged converters don't usually cause a no start. They will cause many other driveability problems, but you can usually get it started. Put a vacuum gauge on the engine. If the cats are clogged enough to prevent it from starting, I would expect you'd see pressure build up instead of vacuum.

4 things are needed to start: Air (in the right amount), compression, spark (at the right time), and fuel (in the right amount).

It's pretty difficult to block off the air flow to the point of not starting, so that usually isn't the problem.

Compression would have to be out on multiple cylinders. Any signs of coolant/oil loss that might indicate a catastrophic failure in the block? Any desire to try a compression test? Because this usually has to be pretty catastrophic to cause a no-start, this isn't usually the problem.

You said you've verified spark. How did you verify spark? Have you messed with the plugs, wires, or distributor recently? I've heard of a lot of people who do a tune up and then it won't start because they get the firing order off. Does it appear to be firing at near the right time? ICM's can be tested, I think some parts stores like autozone will test them for free.

There appears to be fuel getting into the engine. Any sign of leakage from the FPR inside the intake manifold? It's not common, but I have heard of cases where the FPR leaks so bad that the engine won't start. Did the guy who checked the fuel pressure do a "leak down" test to see if the fuel system holds pressure? That would eliminate something like a leaky FPR or injectors stuck open. Does the pressure stay near spec while cranking or does it drop off.

Also no service engine light on.
What do you mean by this? Does the SES light come on key on engine off? The SES light should come on before starting to indicate that the PCM is powered up and ready. If the SES light isn't ever coming on with the key on but the engine off, that indicates that the PCM isn't powered or grounded or something, which will often cause a no start because the PCM controls everything.
See less See more
It's the ignition module!
Had to have it towed in and tested. The dist. cap and rotor were bad. He said it was giving of a spark but it was intermittent. replaced cap and rotor. Had it reflashed and all is good.
1 - 7 of 7 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.