'97 Astro: Turns Over But Does Not Start

[wew]

'97 Astro Cargo with 4.3 Vortec has 87K miles...
Problem reared its ugly head 1 month ago...
Ordinarily would start fine, then one morning turned key and it would crank just fine but that is all it would do...Then next morning it started fine, and since it is my service van it was turned off and restarted numerous times that day just fine...Couple weeks later the same no start condition was back, this time it sat two days and started just fine...It now is the third time it would not start in the exact same manner...I replaced the fuel pump relay because it was the least cost and easiest first attempt to correct the problem, but that was not it...The van runs great and everything works great, that is when it is running...Have not had any major trouble, had only replaced battery, alternator, brakes, spliced vacuum hose, replaced tires and wiper blades...Turn key on and can hear fuel pump running for the first few seconds...If it had a caburetor one would think it was flooded...Any ideas or help would be appreciated before bringing it to the local mechanics...???
Thanks...!

[Blue Bowtie]

You'e on the right track. You suspected fuel, and that could be it. It may also be lack of spark, however, that usually doesn't go intermittently unless there is heating involved. Lack of spark from heating isn't common on cold starts.

The new relay was not a bad idea, since it is relatively easy and inexpensive. My first suspicion would be fuel pressure that is on the edge of being inadequate. A fuel pressure test would be very revealing, but if the fuel filter has not been changed in 87,000 miles, it may be time, just because.

Another possibility is the pump. The fact that you hear the pump run is good, but it may not be making adequate pressure. That is not always the fault of the pump, however. Electric fuel pumps are very sensitive to voltage. Lower the input voltage just a little and the pressure will fall off significantly. The connections in the top of the tank are suspect, and fail frequently enough so that a couple aftermarket companies offer replacement tank wire harnesses to solve the problem. There is also a pulsation damper on some pumps, and these can rupture and lose fuel back into the tank, thereby dropping output pressure.

The unfortunate part is that all those items (except the new fuel lifter) require tank removal to check, so a pressure test is a very good idea before diving into a job like that blindly.

[wew]

Thank you very much for your input...!
Will replace fuel filter and have pressure checked...
...wew

[drew300]

As my '97s' van pump got weak, if it started, it would re-starteasily.
I used a "carb cleaner" as starting fluid to check that it wasn't ignition. Just a one second spray into the air cleaner area would start it, and it would run fine.
If you want to check the relay, the A/C one is the same.
I measured current draw of the pump by putting an ampmeter into the CORRECT pins of the relay. (I don't remember which pins, be careful).
The old pump drew 4-5 amps, the new one about 10.
Also, the connections at the tank can go bad. I found a loose ground wire, but that wasn't it. Also, I'm surprised at how small the coonectors are for the pump. Over heating and corrsion can happen at the pump connector.
But if you can get a fuel pressure guage, that's a big help. A GM service rep said "minimum 60" psi for starting.

[kamenz]

I had the same problem on a 1998 Astro with 70k. Changed rotor and distributor and solved the problem. Good luck!