I got a 1988 f150 302.. It won't start it has fuel pressure and spark.. I've replaced the ICM, MAP, and EEC relay.. It will start and idle fine with starter fluid but runs very rich. If anyone has any ideas please let me know..

 

You say you have spark. What color is the spark? You must see a bluish purple for good spark. If not, you have a weak spark which could mean your coil is on its way out.

 

The spark was tested with just the light tester. But it's supposed to be strong.. I have another guy I work with help me and he said it has good spark..

 

This is one of the first things I thought of.. If the spark was good or not

 

If it runs on start-'em-up fluid then you probably have a good spark. So check your fuel pressure. If that's good then try to get the PCM to dump it's fault codes. If it won't do that, then between that and running rich I'd say it's time to take the PCM out and crack it open. Plenty of them here with failed caps.

 

Yea the fuel pressure is fine. It's 40 psi with the key on. And I was leaning toward the PCM next but I'm not tryna spend anymore money without it for sure fixing the problem. So I do want to test everything to be sure..

 

Well it won't cost a dime to take the cover off the PCM and see what shape the components are in.

 

Sounds like a bad Temp sensor to me. Either the air or water (2 wire) sensor.
Note the these two Temp sensors may not give a code when bad.

 

No it won't lol I looked at it today and all looks good there..

 

A temp sensor?? How could that cause a no start? I haven't tested it yet..

 

The fuel mix has to be right to start.
The PCM relies on the two temp sensors for the fuel mix.
The PCM has no idea if the temp sensors are lying or not so you get no codes most of the time when they are bad unless the the sensor is open or shorted.

 

O ok.. I'll definitely check that for sure tomorrow. But the check engine light is on by the way.. So the PCM is sensing something wrong. But today the only thing I had time todo was re check spark. And it does have GOOD spark and it's not an ignition coil and I check the wires going into the PCM all seems good there..

 

I checked a few things today and I'm very confident it needs a PCM or EEC as they call it. I checked power going into the ignition coil and fuel injectors.. They only have two wires one power one ground. I got the same voltage on both wires which means they are not grounded. And of course they ground through the PCM. Also I have no communication with a scan tool and the fuel pump won't stop running. It's supposed to run for 2-3 seconds then stop. But the whole time the key is on it runs.. So with all that and everything else I have checked I would say the computer is at fault and needs to be replaced. I got one coming on Monday so I'll let you know what happens. Thanks for the help.

 

Ok I got the EEC (computer) installed today and that is the confirmed fix. I did take the old one apart and seen that the capacitors were leaking.. Starts right up and runs fine. I think I got the timing off a little bit but I'll get that all sorted out soon.. I really appreciate all the help and I hope this thread will help someone else someday. So if you have a no start condition and have spark and fuel pressure. Another obvious symptom is if you can't pull any codes with a scan tool ( you have no communication and aren't getting any power to the EEC test connector or OBD 1 port). It may even start with starter fluid because you are bypassing the fuel injectors. And also the fuel pump will run continuously (the whole time the key is on) it should run for about 2-3 seconds then cut off. Then you can start to suspect a defective EEC. I would check the EEC relay first make sure it's working properly since the fuel pump relay is right there too go ahead and check that as well. Now my relay was actually blown.. The turn the key on and with a multi-meter or test light check both wires that go into the ignition coil and on a couple of fuel injectors. If you have power on both wires you can almost guarantee your computer is bad because they ground through the computer. Now before you condem the computer check through your wires and connectors and make sure all looks well.. Make sure none are torn, broken, cracking, etc. I would also check through the grounds on the firewall (the one for the EEC is right next to it on the firewall) but I doubt a bad ground could cause the same problem.. I would think if it wasn't grounding properly that the whole computer wouldn't function. And by the way some people even have no check engine light at all. Then at this point I would pull the EEC on out and take the cover off and check for leaking capacitors or if it looks burnt up. The capacitors on these old computers tend to go bad over time so that's most likely what happened but it wouldn't hurt to make sure you aren't touching ground anywhere or causing a short especially if it is burnt. But if you see any of that you can pretty much guarantee that's the problem. So I hope this thread helps somebody some day who was where I was with no clue where to look and what to check. And once again thanks everyone for your help.

 

I understand ur truck had probs. But make ur own post cause I have same problem as Calvin 17 and it is not computer cause I put motor in another truck and it still did it I replaced one sensor were the pipe goes in to intake still does gotta hold the throttle till she warms up or it will cough out until warm