My brother has an 89 Si and after it has been running for a while (warmed up) and is turned off then on (after only a few min.) it just cranks (engine turns over) but won't catch. It's an intermittant problem that seems to be getting worse. Also if I just let the car sit for about 3 mins (after it fails to start) it starts right up. There have been no changes to the car in several months. The plugs and plug wires are new and seated. It seems as if a relay is going bad but I have know idea of where to start looking.

 

does it ever set a code when just cranking? and when you turn it back on and it doesn't crank, can you hear the fuel pump whirring? my two suspects are the ignitor or the main relay because both will cause a failure when in a heat soak condition.

 

Nope, no codes are displayed. I do hear a whirl. I thought that was the engine fan though. Never really listened for the fuel pump. How do I check these 2 "relays"?

 

change the pgmfi main relay under you dapoo poo is labeled. it is bolted to the side of the car near the fuse box. i had the same problem. just change that and you should not have that problem any more.

 

they're right. i'd suspect the main relay. when it gets hot, the main relay doesnt want to work. and if you wait a few minutes for it to cool down it usually will then work. really common so buy i a new one.