95 Astro acts like vapor lock

I have searched high and low on these forums and can not find a similar problem. After traveling at highway speed for longer than a hour or two in hot weather, if you shut the thing off, forget about restarting for at least 2-3 hours. This can be a real problem in highway construction areas if the thing stalls which it has. The thing will also idle rough and almost stall and sometimes idle fine. Have had it in the shop and replaced ignition module and said that was the problem. The next day it stalled at the toll booth and had to push across four lanes of traffic. Ready to drive this bad boy off a cliff. Please HELP

Check your fuel pressure. You need at least 60psi.

It could be several things fuel related: the pump, the spider, regulator

Ok, thanks for the help. They did check the fuel pump pressure and it was OK. I tried to restart last night after a three hour drive in hot weather when I got home, it turned over but not an ounce of an indication that it would start. This morning it fired up just fine. I did pull a spark plug last night after cranking and it was dry. So, you are right that it is in the fuel delivery somewhere.

Check the fuel pump relay then. Sounds like when it gets hot it fails.

Make sure you are getting 12V back at the pump when the van won't start.

Ok, replaced fuel filter today. Not sure exactly where the pump relay is. I checked autozone componet locator. Says its under hood, driver side and I dont see any relays there.

Try this......
The next time it won't start, hold the throttle on the floor while cranking. If this makes it ANY easier to start, you probably need a fuel injector assembly (spider).

The fuel pressure regulator is part of the spider, and sometimes the diaphram will leak, right into the plenum. This isn't so much of a problem when running (not real good for gas milage), but when you shut it off - the fuel continues to leak, effectively flooding the engine. If you let it sit for a few hours, the fuel evaporates, and the engine starts.

Holding the throttle wide open while cranking turns off the injector (oddly enough, it's called clear flood mode), allowing the plenum to 'dry out', and the engine to start.

Good Luck.

If that doesn't help, check your distributor pickup coil.

Pull the distributor cap, and unplug the pickup coil from the module. Probe the two leads from the pickup coil using a voltmenter on the AC volts scale. While cranking the engine, you should see at least 2.5 volts. If not, she's weak (and may stall and not start when hot).

Thanks for the help and info. While cranking, I tried pumping the pedal, flooring and holding it, and still no start. I just replaced the fuel filter and did some running around, got home, and it restarted right away. That doesnt mean the problem is solved, as this is a very intermitent problem, which seems to rear its head always in hot weather. Yesterday, it died with me and the kids and we walked to the autoparts store in 90-100 plus heat, (I had to put on my R. Lee Irmy face to get them going, ha ha) bought a fuel filter and pump relay. Replaced the filter, thought I knew where the relay was, now I am not sure. The filter was somewhat plugged. This was a surprise, I didnt realize they could get that plugged. I replaced it about 20,000 miles ago and after reading these forums I see it is very important.

If that doesn't help, check your distributor pickup coil.

Pull the distributor cap, and unplug the pickup coil from the module. Probe the two leads from the pickup coil using a voltmenter on the AC volts scale. While cranking the engine, you should see at least 2.5 volts. If not, she's weak (and may stall and not start when hot).

:iagree:, I have seen in some cases distributors failing particularly in hot weather. You gotta think, they're just like us. Eventually they get old, worn out, and tired... and just don't want to work anymore. Definately listen to this guy helping you out, he knows his stuff

Hi, thanks for the info. The first garage I took it to supposedly checked the ignition system and replaced the ignition module, cap and rotor. I took every thing apart to do your check you suggested and it scares me around that distributor and coil even though I unplugged it. I also checked the plugs after cranking a no start condition and they were dry. Also, checked the FP relay and it was OK. I checked the voltage at the pigtail disconect under the van near the tranny while my daughter cranked the engine. The reading was 10.5 volts while cranking. Someone wrote in another thread these fuel pumps are very voltage sensitive and I am wondering it the Voltage regulator in the alternator may be acting up. (My headlights wont maintain a constant brightness, they will change intensity ever so slightly. Also, I had my blower switch on the instrument panel smolder a while back, although that has stopped.) I am sure it is fuel delivery, but I am skeptical it is the pump because it only wont start after running around and taxing the electical system and in hot weather. The alternator looks original and the van has 150000mi on it. Could it be a ground wire? Is 10.5 volts normal because of a drop from cranking the starter? Is the battery weak because it cant maintain 12 volts? Am I barking up the wrong tree? I have no problem taking it to a garage,(2 so far) but they are just guessing like me, and its a lot cheaper to change parts myself. I guess I will buy a pump pressure gauge and try to recreate the condition and see if there is any pump pressure.

I took every thing apart to do your check you suggested and it scares me around that distributor and coil even though I unplugged it.


So what was the pickup coil voltage while cranking?

On the AC volts scale while cranking, I get a reading of .6 volts.

That's a problem.

You need a new pickup coil. I would recomend a rebuilt distributor; It should have a new shaft & magnet, shaft bushings, as well as a new pickup coil.

OK, Thanks, I really appreciate all the help!!!!