Hi everybody,

I was working with my friend on his 87 F150, and we can't get it to start. Here is the situation . . .

1987 F150 2wd

Straight 6, Fuel Injected

Cranks, but won't start.

It will start and run smoothly when you spray starting fluid into the intake.

We replaced the EEC relay (it looked corroded) and the Fuel pump relay

Both the high pressure pump and low pressure fuel pumps are working (we removed the front tank to make sure the low pressure pump was working because we could not hear it . . . turns out it was.

Fuel pressure test reads 50psi with the key on

Fuel filter is not clogged


I don't want to jump to the conclusion that we need to buy a $100 computer for this truck . . . it was running just fine a few weeks ago.

Any helpful suggestions as to what to check next (or how to check if the ECU is any good) would be greatly appreciated.

Thank you!

Joe

 

Is it possible for the truck to run off of starting fluid if the computer is bad?

 

You need to check for spark from the coil. If you have a good spark from the coil, you have to check for good spark from the distributor.

 

I do have spark coming from both the coil and distributor. The truck will actually fire up and run smooth for a few seconds if I spray starting fluid into the intake.

 

Starting fluid is much more volatile than gasoline and will burn much easier. Having spark doesn't mean it is good spark. You still need to check it visually and make sure it is a good solid spark.

EDIT: Next thing to check would be if you are getting injector pulse or not

 

I replaced the coil with a new one and it is still doing the same thing.

How do I check for injector pulse?

Thank you for your help!

 

Bump -

Sorry guys, this is still a mystery.

is there anything else that I can check before I go and buy a new computer?

Thanks everybody

 

Read this thread and see if it helps any.

https://www.ford-trucks.com/forums/1...tor-pulse.html

 

Before buying a new "computer" I'd just replace the e-caps on the board itself. For a buck and a half, it's worth a try. They need it by now anyway, ten years is doing good.

 

at this point, it might be a good idea to pull codes and see what comes up .

 

Hi guys,

thank you all for the replies.

yardbird - thanks for the link. It has given us some more to work on.

Tedster - I am not sure what you are referring to when you mention e-caps on the board . . . could you help me understand that better?

Joey2fords - We hooked it up to the OBD 1 code reader, and it said that it could not read the ECU.

Thank you all!

 

Electrolytic capacitors. Modern cars and trucks have a passle of the critters on electronic control units and other components. A soldering iron, some 60/40 rosin core solder, and a few replacement caps and the board will be good to go.

Not saying this is your problem necessarily, but the capacitors that are on the board were made in 1987, if the board IS the culprit, then this is a pretty easy repair. A junkyard board would likely have the same age on it. Just throwing that out here.

 

inability to read codes points squarely at a bad computer.
as tedster says, pull it out and open it up. you are looking for swelling or leakage from the capacitors, although neither is necessarily going to be apparent.

 

Actual leakage is the exception not the rule. 30 year old caps need to go just on principles.