Greetings. This is my first post. My 1991 Honda Accord wagon will sometimes start very rough after sitting overnight or after a long while. It does not happen every time. It turns over fine but has a hard time firing up. When it does this, the check engine light stays on and the "S" sports transmission light flashes. After it warms up, it drives fine but the idle goes very low and when at a stop it feels like it may stall. If I shut the engine off after it is warm and restart it, the check engine light goes out and the s light goes out but it still idles low. I changed the fuel filter, plugs, wires, dist cap, rotor. Battery and starter are fine. I sprayed starter fluid around the engine after it was warm and got no change in rpm. I once had a "hot start" problem and changed the fuel relay which took care of that. It has 298,000 miles and I haven't changed the belt in about 100,000 miles. Here's my procedure: when I start it, I turn the key on and listen to the fuel pump. When the pump stops, the check engine light usually goes out and the car runs fine. On cold mornings, the check engine light stays on, the s light flashes and it runs rough till warm. Sometimes I turn the car off and onn a few times but when it gets in this mood nothing will change it's mind. I hope this is enough info. Thanks for your help.

 

A few possibilities...

Main Fuel Relay(MFR)- This seems less likely since replaced fairly recently. You can rule out be carefully listening. When you turn keyswitch to On, you should hear soft clicks under dash, fuel pump in fuel tank buzz for 2-3 secs, and go off. Check Engine Light (CEL) should go off w/ fuel pump. If you get these, MFR is OK. If you don't hear fuel pump get an assistant to help and listen at fuel inlet to be sure no fuel pump buzz.

Fuel Pump- If in 1) you hear MFR clicks, but no fuel pump buzz, try "hammering" the keyswitch on/off/on/off... until you hear (or not) the fuel pump come on. If this gets fuel pump going, engine will now start. However, a new fuel pump is indicated.

Injectors- put a screwdriver on each injector and on your ear and listen to it for clicking noise

 

Thanks. I hear the pump when I turn the key on. The pump stops and then the check engine light stays on. The sports transmission light then starts to flash. The hard start does not happen every time. Today the engine started fine. Once it starts hard, the idle remains low almost to the point of stalling. This continues even after the car heats up. Since it's intermittent it will have to remain at the shop overnight until it happens again. Maybe a computer code might reveal the problem if it's not obvious to someone out there. If it were bad injectors, would they be intermittent?

 

Clean your throttle body, IACV and FITV. Easy to do and excellent write ups on this forum. A clean FITV fixed my 92 with similar cold start issues.