89 won't start when hot

[marathon26]

My '89 has decided not to start after the engine has been run for a while and become hot. Say I go for 20 or 30 minutes, stop and go into a store and come out and it will not start. It turns over fine, but won't light. After a while, colls down, it will start. The pressure when I remove the fuel cap is really high and sometimes there is a strong smell of gas. I suspect a problem with the vapor capture system or the fuel pump. The first I can probably fix. The second I think is more of a challenge than I am up to tackling. Any ideas? The parts store thinks the injectors and some emission valves are dirty and wants to sell me some stuff to clean them. What are your thoughts?:confused

 

[Schrade]

Check the fuel pressure - static and dynamic. (just like puttin' a pump on a bicycle tire valve.

Static is motor off. Connect the gauge, turn the key to 'On', and get a reading. Then time it as it drops (don't start the car).

Then do dynamic - connect, and turn the motor on. It should stay steady. Then kill it, and disconnect the vacuum line from the fuel pressure regulator, and measure it again.

I'm guessing weak, leaky injectors, that aren't spraying hard enough to vaporize fuel for a hot start. Also take not of the exhaust on a cold overnight start. A strong puff of black = leakers...

 

[marathon26]

Check the fuel pressure - static and dynamic. (just like puttin' a pump on a bicycle tire valve.

Static is motor off. Connect the gauge, turn the key to 'On', and get a reading. Then time it as it drops (don't start the car).

Then do dynamic - connect, and turn the motor on. It should stay steady. Then kill it, and disconnect the vacuum line from the fuel pressure regulator, and measure it again.

I'm guessing weak, leaky injectors, that aren't spraying hard enough to vaporize fuel for a hot start. Also take not of the exhaust on a cold overnight start. A strong puff of black = leakers...

Many thanks. I will give it a try.

 

[formul8]

Either fuel related, or another common problem is heat soaking the starter motor. Get a heat shield wrap.

 

[k2bob]

My 89 had bad injectors. They did not leak during a pressure test but the ohm readings went from .3 to 14 and everything in between when they were warmed up. No two were even close. Get it warm then shut it off and use a digital ohm meter to see what you get on each injector. They should be around 17 ish and consistant. I have been told that the readings should not vary by more than .5.

I ended up putting in all new Echlin injectors from NAPA and so far it is still performing like a 'Vette should.

I have seen many posts that this problem could be other things as well. Check out posts to dallask threads on pages 2 or 3.

Bob