my 1987 z28 lg4 305 4bbl keeps stalling on me, starts and runs great when its cold and after about 20 minutes when its to operating temp it starts to sputter then stall out on me. i used to be able to start it right back up and make my way home. now it stalls out on me and wont start back up till about 20 minutes. ive recently replaced the water pump, im not sure if that would affect it at all, ive also replaced my icm, ignition coil, new fuel filters, alternator, and my issue is still there. plugs and wires along with the cap was replaced not to long ago, any one have any ideas on what my issue is? im completely stuck at this point and im tired of getting stranded on the road.

EDIT: so today i let it idle for about 30 minutes got her to temp then i drove her pretty hard for another 20 mins or so, brought it up to about 85 a few times and problem never occured, but today was a cooler day so on the next warmer day im pretty sure its gonna act up again, still gonna change the distributor, hoping that will solve the issue, ive spent enough $$ this week lol

 

can anyone help?

 

Even though you say you replaced the ICM , it sure sounds like typical ICM failure . Remember , brand new is not 100% proof of perfect functionality and brand new parts do fail occasionally . Tell me , this new ICM , did it come with the clear thermal paste ? That stuff is garbage and the only thermal paste I trust between the ICM and the distributor comes from the local electronic hobbyist store (even radio shack , if there is one near you) . Also , the "test" that gets done at the autoparts store is not to be trusted either as to an ICM being good . If the test says it's bad , then it very likely is , but plenty of times the test will say it's good , when it won't actually work in the car . The test doesn't simulate "real world" use , and as such it can't detect if the unit will overheat and fail 20 minutes into each run .


All things being equal , I'd try a new ICM with the right thermal paste under it . If what I think happened did actually happen , your recently installed ICM got cooked by the inadequate thermal paste they are all shipped with nowadays .

 

A car this old I would buy a new pickup coil, ICM and a new coil. Replace with all gm parts.

 

you think i should just get a new distributor? i still have the original gm rotor on there, was never able to get it off without the worry of breaking it, so its long overdue, would rather throw the extra $ and replace it all as opposed to the icm

 

a new distributor is not a bad idea. not saying that the dist is your issue but a new one from RA runs around $70 or so.

Next time it dies you can check for fuel and spark. if the fuel feed and return lines have been mucked with...

check for proper operation of the in-tank fuel pump too. jumping the relay with the hose to the mech pump off should show fuel flow. a failed in-tank will allow a heat soak/vapor lock issue to cause issues.

 

so i went out today and got a new distributor, cap, rotor, and icm, hoping to try and get that in tomorrow, if that doesnt fix my issue, ill double check my spark and fuel