There will be 2 relays on the driver's side inner fender, possibly tucked into a plastic bracket on the back of the coolant/washer fluid resovoir, one is the fuel pump relay and the other is for the EEC. The computer itself is in the drivers side kick panel under the dash.
Thank ya brother!
I'm seein em now and starting to see the light!
The truck starts cold just fine- but after running a while it doesn't wanna restart, but will eventually. I thought the fuel pump relay might be a good place to start since they are cheap.
One simple thing you might want to check are the fusible links. I had the same mysterious no start problem with my 88 F150. As it turnes out, someone at some point had changed the fuse link that provides constant power to the ECM and the connections were corroded on the inside of the crimps. Also, the eyelit connector where the link bolted on to the solenoid was also corroded as well.
It took me weeks of fustruation to try and determine what the problem was, and I went through the same things you're looking at now (change ECM relay, change Fuel Pump relay) and all to no avail. I'd recommend you just have a peek at this and see what, if anything you find.
For what it's worth, I did speak to the dealer in the process of troubleshooting and they did recommend I change the ECM power relay regardless. It's not particulaly expensive ($30.00 or so) and they told me they do get a little tired after 20 years of service, so you might want to consider changing it regardless of the outcome.
I forgot about something when I orignially posted this. There's a way to tell if it's a power problem to the ECM. As you know, when your key is on, but the engine isn't running, you'll see both the red engine warning light, and the check engine light on. If when your truck stalls you only get a red warining light, and no check engine light, it's a good clue that the ECM is either not recieving power, is toast or the light is burned out (lol).
Last edited by sconut1; 03-20-2008 at 06:15 PM.
Reason: spelling mistake and more info
don't know if you still need to know, spout connector is a few inches from the distributor plug-in, but only if you have a TFI type setup ( a 6-pin plug on the side of distributor ). when disconnected, computer reverts to "limp-home" mode. also must be disconnected to set timing to spec.
I echo what sconut1 said, I chased a bunch of stuff on my truck, if the chack engine light is acting funny, check the ecm. Mine was bad, truck had been having the issue with not wanting to start when warmed up, then all of a sudden when the keyswitch was turned on, the check engine light would not light up. When I turned the key to start the truck, the truck then turned over, and the check engine light flickered, the truck tried to start and immediately died. Found out it was a bad computer the whole time, it just hadn't completely died and had been trying to hold on a little longer.