Help? 1994 S10 Pickup

[Drew]

Hi,
I'm trying to help out a family member who does not have the income to have a mechanic fix his car. He has a 1994 Chevy s10 pickup with a 4 cyclinder engine.

The engine starts easy, has plenty of power although it has 157,000 miles on it.

Here is what it is doing:

For the first 20 minutes after the car is started it runs like new. After 20 minutes of city driving, it cuts out at various rpms and throttle positions. It feels like the ignition is temporarly not working.

The vehicle has gotten a complete tuneup which included new spark plugs, fuel filter, oil, airfilter etc...

Any idea what it can be? Are there any common failures in this vehicle which can mimic these symptoms?

I'm thinking that my next step is to replace two of the distributorless ignition modules that are on the vehicle but not sure if that would be wise.

Any help would be appreciated.
THANKS,
Andy

 

[-Clayton-]

Check engine light on?

 

[Oldmoparguy1]

Either the pickups, or the coil(s). Could even be distributor cap or wires. Sounds heat related.

 

[-Clayton-]

It's a distributorless system. I bought coil packs and module for mine for $35 a my local pick-a-part.
Check for codes first though.

 

[labman]

May use some of the same ignition parts as I kept replacing on my 92 Grand Am Quad 4. The bad when hot really sounds like a coil pack. Also, the conductors in the coil pack housing can short killing 2 cylinders. That would also be heat related.

 

[jmacmaster]

It could be water in the gas tank. Drop the tank and drain it. If that's not easy to do, try two bottles of HEET in each of the next three tanks of gas.

 

[55Test]

I'm thinking an ignition module, or worse, the ECM. I had a problem similar to that in my 93 Crown Vic where the ignition was totally cutting off rapidly at various times. Turns out in my case it was a dead ignition module.

 

[Drew]

Since its a 94, I believe it has OBDI. Can a code be pulled if there is NO check engine light?

Clayton, what module are you talking about?

 

[Drew]

Its not water in the tank. We ran the tank dry, and used a Pela extractor to get every bit of fuel out. I then dropped the tank to check the fuel pump pickup. After some cleaning we put it all back together.

 

[-Clayton-]

The module behind the coil packs. Even though theres no Check engine light you can still check to see.

Here
is the ignition module