Well, my check engine light if finally off thanks to the help from the other posts I made. Exhaust gasket fixed the MAF sensor, and 2 bottles of injector cleaner fixed both banks lean....

Now the latest

2003 GMC 1500 van 5.3L
New water pump / thermostat / exhaust gasket 2 wks ago

Last week it started starting differant. It is VERY sporadic. It cranks for a few seconds longer before it starts.

I am kind of leaning towards fuel pump, but it is so sporadic, and NOT always after it has been sitting for long periods of time. It will crank fine after sitting over night, run to the store and will crank awhile before starting.

I thought if it was the fuel pump, it would mostly in the morning since the valve is letting the fuel drain back into the tank and has to repressure the system.

Any ideas? The injector pressure regulator???

I don't want to drop the tank and put a new pump in unless I have to.

How old is your battery?
A weak battery or corroded terminals will cause this also.

Oh, also try turn the ignition on, the off then back on again.
This will make the cold start injector spray twice.
If it start instantly, the cold start injector is faulty.

I'm not familiar with your rig but some of the newer stuff will have a booster pump that supplements the main fuel pump. When these go out it can lead to extended cranking time before the engine fires off.

The battery is the original, 5 yrs old. I thought that too because the green eye was gone, but came back. Just had it tested and it passed the load test at auto zone. Not sure how accurate those are though.

Replace battery. If you got 5 years life out of original you did well. Even if not the culprit, it will be soon.

The battery will be dead on the first dry, hot day.

Definately sounds like the fuel pump is dying.

We had a pickup at work doing the same thing until it would not start, but you could hit it with a hammer while starting it, and it would come to life and run.

The only way to know for sure is to put a pressure gauge inline on the fuel line in front of the pump.

could be an air leak into the fuel system also....
which could be caused by a faulty fuel pump....

I'm not familiar with your engine though....SC & Mars sound like their onto the right track....

Check the battery first though. Its the easiest thing to check....and possibly the cheapest fix. Always do those items first.

It could also be the starter relay or starter itself picking up corrosion......check those. If the starter relay is cheap....change it and see if that makes a difference.

One of GM's weak points is their fuel pumps.

The real way to make sure is to have a fuel pressure gauge hooked up at these various times to see what the pressure is doing. Does it take a while to build proper pressure? Is there enough pressure?

To me it doesn't sound like a battery problem or starter problem. From how you described it, the engine just takes longer to fire, but does not crank slowly.

Have you replaced the fuel filter? I'm leaning towards an underachieving fuel pump.

If and when you go in to change the pump, be sure to look at all of the hoses for splits or holes.
I've seen splits in the hose coming directly from the fuel pump before.

det293,
look at the fuel rail on the engine, there should be a connector that looks like a tire valve....that's where you connect a hi press fuel gauge. you might be able to rent/borrow one from autozone if you don't have one.
also, depending on which exhaust gasket you replaced....double check the spark plug wires.

If the battery is five years old..start there first.
You said the "green" went out on it once..and that's a sure sign it's on the way out.
You can't do anything without amperage.

I saw that you used alot of injector cleaner recently, but have you put any drygas in it?often times the cleaners will break stuff loose in the lines and plug up again. I'd say try some more cleaners for a fill up or two, and don't forget the dry gas. And if it does end up needing a fuel pump, BUY THE GM ACDELCO PARTS!!! Everybody I know who has bought an aftermarket pump for half the price is buying another one within 2 months. You're going to spend the money anyways, so do it once.