wgiles

I have a 1994 F150 with a 5.8L engine that has been trouble free for years. In the last year it has been occasionally having starting / running problems. When I start the cold engine, it runs OK for a few seconds, the Check Engine Light comes on and it kicks up into fast idle. At that point, it may die. If it dies, it will not restart for at least an hour. I assume that the engine is flooded and that is why it won't restart. Once the engine has sat long enough, it will usually restart and run fine. I have had the truck in and out of the shop, but it starts and runs just fine and they can't find any problems. This week, it misbehaved Monday evening when I started it. I was outside looking at something while it was parked and it revved up, died and wouldn't restart. I pulled it back in the driveway and charged the battery for an hour and it restarted. This time, it didn't run smoothly, but didn't die. The CEL would come on and the engine would speed up for a while and the CEL would go out. The engine idle speed would slow down and the CEL would come back on and go through the whole procedure again. I let it run for several minutes, while I sat in the cab and it seemed to settle down. Tuesday morning, I started it and took off, thinking that opening the throttle would get the engine past the problem. It didn't. Even while going down the road, the CEL would come on for a few seconds and the engine would run rough, but not die. This was at 6 AM and I didn't want to run the risk of getting stranded, so I drove the truck to the local repair shop, about 10 miles from my house. The CEL would come on periodically for a few seconds and the engine would run rough, even once the engine had warmed up. The CEL came on for one final time as I was parking the truck at the shop. I got a ride back to the house and picked up another truck. About 8:30, I drove to the shop to talk to the service manager. We went out and started the truck and it ran OK. I don't know that it had sat long enough for the problem to reappear, since it has only done this at a cold start. Just in case, I had put new plugs, wires, cap and rotor on, but this didn't seem to make any difference. The last time that it died and wouldn't restart, I checked the fuel pressure and it came up into the normal range as soon as I cranked the engine. There never seem to be any codes in the EEC, so that hasn't helped. This is my go to truck for bad winter weather, but I can't take the risk of getting stranded if we can't figure this out. Does anyone have any suggestions?

sdmartin65

Go to O'Reilly or Zone buy 3145 Innova code reader and run KOEO test. Code reader is 32 at O'Reilly. Also buy a ect sensor, about 15. The symptoms sound like ect to me and it's a cheap part to throw at it.

When the ect goes bad they dont normally stop reading completely, they read but get stuck mid range reading from 130 - 170. This can cause all kinds of strang problems. Try these couple things I bet you wont need the shop. Remember most shops wont have a tech real experienced working drivability issues with obd1.

Edit. KOEO test is where the code will show from when the cel came on. It will store the codes from the last time cel came on.

wgiles

ECT is Engine Coolant Temperature, right?

sdmartin65

Yes