Need help-problems starting 1999 Tahoe

[m1009]

Our Tahoe started giving us trouble recently-starts up fine in the cool mornings, but after sitting outside in the hot sun, it takes at least 2 tries to start. Cranks strongly, and just when you let off the key because it catches, it dies immediately. Feels like there's a hesitation where something should take over and keep the engine running, but it doesn't happen. Usually starts up on the second try, but once in a while it takes a third time. Runs fine after that. Took it to a shop and they said needed a tune up. Replaced wires, rotor, cap, plugs and still the same problem. The fuel pump was replaced earlier this spring, along with the starter. We also just replaced the ignition module, ECT sensor, and also checked the fuel pressure with a pressure gauge and it held fine. Still does this. Even does it after it's been running and you try to restart it after it's been shut off for a little while. I swear there's a hesitation between the time where it should start running and either dies or manages to 'catch' and keep running. Idles smoothly, no jerks or roughness. Anybody have any ideas? Is it a fuel problem or an ignition problem? Please!

 

[73shark]

Try running 2-3 bottles of Techron thru it. Will clean injectors.

Also might ask over in the earlier Tahoe section.

 

[Zed 71]

When they replaced the fuel pump, was it just the pump or the pump/housing? Also, for the fuel pressure did it hold after 10 to 30 min?

As discussed before, there is a check valve in the fuel pump housing that seems to go bad (very small part) and the symptoms are the ones you stated above. If the fuel pump is ok (check voltage & amp draw through OBDII), and the fuel pressure drops after 10 min or longer; there is a good chance that the fuel pump check valve is bad.

Good luck and keep us up to date.

 

[m1009]

Re: starting problems..

We replaced the entire fuel pump assembly, just this last spring, around April or May. From what I remember, the pressure was over 60 and it held steady when we just checked it a couple days ago.
The weird thing is, it starts perfectly in the cool morning. Not a hitch. Started today in the cool rainy weather without a hitch after work too. But when it warmed up, after getting back in it after a store stop, it did the same thing, started, and died immediately. It runs smoothly, doesn't hesitate, no problems accelerating, the pump runs as it should, and there are no codes being thrown out. We put a scanner on it, and no codes. Everything reads good.
I just get the feeling that something that should kick in to keep it running in the initial startup isn't 'grabbing' it to keep it running. We did check the idle control, took it out and looked at it, and it moved freely. A little dirty, but not stuck. Cleaned it up and put it back in. The only thing we did initially, we cleaned the throttle body BEFORE changing any parts, and that seemed to solve it for a few days. Then it started acting up again. If it were an injector, wouldn't it have this problem all the time, and not just with start up after being warm or sitting in the hot sun? Appreciate the help! Any more ideas, please feel free to share!

 

[Zed 71]

You replaced a lot of parts, and completed a tune up. The hot and cold part is hard to diagnose...

Have you replaced the fuel filter or inspected the MAF sensor? At this point just throwing things out there. Also try the pre-2007 section of this forum.

 

[m1009]

Thank you, but we changed the MAF when we put in a new transmission. Also the fuel filter is fairly new as well, and again, there are no problems in actually driing the truck. I will check out the pre-2007 forum, though. Thanks!
We do try to keep it maintained, it gets whatever it needs to keep it running well. Regular oil changes, tune ups, brakes, any hoses that seem to look worn, etc. This is one of the most use vehicles so we have to keep it up. Through the years, we've rplaced the O2, the MAF, filters, etc. I would think that we would be showing codes and we're not if it were something major. Sigh.

 

[BountyHunter]

My 2007 Tahoe was having a hard time starting. Would crank and crank and not start on the first try, but almost always started on the second try, but would have to crank a bit too. Code reader showed Camshaft Sensor problem. Replaced that and it fixed the problem.