Non start when hot

I have a 90 Chevy G20 van with 170,000 miles. When ever I drive for more than 20-30 minutes at hwy speed (55-65) and then stop and turn the engine off, it will not start for atleast 30 minutes. Whe I try to start it there is NO sound or action, none not even a click. After about 30 minutes it will start up. In the last 60 days I have replaced the starter and the battery, but the issue remains. The problem seems to be electical, but what?



Any good suggestions?

Was the solenoid also replaced with the starter? The next thing to look for is a starter relay problem. I am not sure if GM uses this on this van so I may be misguiding here.

You may have to do some troubleshooting when the problem occurs. These systems are not complex so power transfer should be traceable. You or the mechanic need to trace while the problem is present.

Let us know what finaly cures this problem

This wiring for start is as simple as they come. Power (12 volts) comes to the ignition switch, and goes directly to the starter solenoid (purple wire) if an automatic transmission); or, if a manual transmission, the yellow wire goes to the clutch switch, to the starter solenoid.
Use an el cheapo voltmeter to check for voltage at the starter solenoid when it doesn’t start. If there is 12 volts there, the starter solenoid isn’t tripping. The connection may be faulty, or the solenoid may be faulty.

Early '80s GM vans had a recall for the solinoid spring in the starter: it would constrict and act just like there was no battery in the van. GM was supposed to correct this problem but this keeps resurfacing occasionally - thats GM for you! Also, it wouldn’t hurt to make sure the battery connections are clean. You can wire brush all the corrosion but still have residual crap. Scrape mateing surfaces with a knife or screwdriver. Make sure all your heat shields are in place. GM may be using the same kind of solinoid spring but using heat shields to protect the starter.