1994 Club Wagon, 5.8, E4OD 242,xxx Miles.

I had been having this issue for a long time, The van not starting after driving it a while in hot weather and having to let it sit a while before it starts,

(did not do it when cold) speculating it was the fuel pump failing or getting hot, ICM going bad, PIP sensor going bad, Etc...

Just before summer I wrapped the computer in heat reflective wrap that I got at Oreilly`s and used heat resistant aluminum tape for water heater

vents to seal it and keep it in place. Since then I have drove the van all summer and it started up ever time no matter how hot the ambients temps

were or how far I drove. This is the first summer in many years that ive been able to not worry about it not starting.

I came up with this idea because I had to replace one of the capacitors a while ago on the computer`s board and I thought maybe the computer is

overheating, So I decided to give that a try before the more involved/expensive things and since theres no codes pointing to anything in particular
I am pretty sure that was the fix.

 

Doesn't wrapping the ECM prevent it from cooling itself?

 

After a long drive I used a very good infrared thermometer to check the difference between the heat of the ECU, the radiator, the battery and a few other items at random, I dont remember the numbers (I have them written down somewhere) but the ECU was very hot in comparison.
Seeing how hot the engine compartment gets and where the ECU is located its hard to imagine much airflow there, but im sure the engineers took that into consideration like the ICM on the distributor.....
This is the only thing I did that made a clear difference right away. I can always pull off the heat reflective wrap for a day and take it for a long trip and see what happens, but for now Its working.

 

interesting. On the 94, doesn't the PCM go through the firewall on the drivers side near the gas peddle? Only the connector is in the engine bay. On the older style vans the PCM is through the firewall but under the HVAC cover on the passenger side. So the PCM itself is inside
Did you insulate the connector in the engine compartment or the PCM itself?

 

Yep, electronics belong in the furnace by the engine, at least GM put the box under the drivers seat inside.

 

This ECU getting too warm and not starting could be pointing to it developing issues that might lead to a complete failure at some point. An automotive electronic device especially one in the engine bay has a finite life and don't last forever. I'd find a suitable replacement, have it "gone through" by a repair facility and be ready to swap it in quickly.

 

Yes, about half of it is in the cab and half in the engine compartment where the connector is. Mine slides out from the engine compartment.
I insulated all of the ECU in the engine compartment, and the connector down the wiring as far as I could.

 

A long time ago I replaced a leaking capacitor on the computer and that fixed a major bucking problem. A few years ago I purchased a cardone ECU, using the numbers off of my ECU and VIN (Thinking that it was going bad, turned out to be the transmission) Installed the ECU and had a horrible time, would not drive right, gave it a couple weeks to see if it needed to adjust, but the van would not drive right at all. The ECU was supposed to be pre flashed with the correct firmware but maybe it was not. I reinstalled my old ECU and it returned to driving good, after having the transmission problem addressed. I may try again sometime.

 

Yep, i drove a '95 GMC Suburban with the 6.5L turbo diesel engine. This was the first year for the PDM module (electronic pump driver module). The PDM mounts to the diesel injection pump body located in the valley of the engine. These are notorious for going bad, causing the engine to stall like the fuel was shut off.
An '89 Honda Civic I owned used to have a common fault of the ICM (ignition control module) going bad (from heat) causing the engine to not restart promptly, when at operating temperature.

Therefore, I could believe the heat shielding of the foil may be a home-fix.

 

Not so fast.........aaarrggghh. It did it again, for the first time in a long time. Crank no start after driving only few miles and right after replacing the

battery with a new interstate and the ICM two times within a week and a half. I had to let it sit for about 5 minutes then it started right up as usual.

My mechianics electrician installed a duralast (autozone brand ICM) and there was a noticeable hiccup accelerating from a stop and while idleing,

wich was not there before, so I installed a Motorcraft ICM and got a refund from my mechanic (for the part only) and hicckup is gone and it accelerates

and drives great. Except for the Crank no start when hot but this time................... ambient temps were not hot But its only done it once in a couple weeks.......... Until summer comes, Lets see what happens.........