I will start from the top. I have an 87 Ford Bronco II 4X4 2.9 Eddie Bauer edition. I bought it about 4 1/2 years ago with 117,000 miles on it. I am up to 230,000 miles. I put a new radiator, heater core, and hoses in it 2 wks ago, a fuel pump a year and a half ago and a fuel pump relay at the same time. I change my oil & filter, air filter, fuel filter religiously.

Now to my problem, 2 days ago it was raining real bad I stopped at a red light and out of no where it started idling rough. I went to take off and it had no power and if I tried to give it too much throttle it wants to stall. Also to let you know I am a heavy equipment mechanic IE H.E.mech with 15 plus yrs experience if it was a bulldozier, front end loader, track hoe it would be simple for me. I do have experience with gas engines.

When I first looked at it to troubleshoot it I listened for the fuel pump when I turned the ignition on. The fuel pump came on I could hear both of them running, but to my surprise they did not shut off after a few seconds. I left the ignition on and went to the engine because I could hear noise under the hood and found that I could actually hear the fuel running through the fuel lines.

I started the engine and disconnected the vacume line going to the fuel pressure regulator and it made no difference. I wanted to check the fuel pressure but did not have the guage ( no use for it on H.E.) it was 40 bucs the regulator was 40 bucs so I bought the regulator. But it did not solve the problem. I tested the throttle position sensor it tested good.

The fact that the fuel pumps don't shut down with just the ignition on and the engine not running kind of makes me think that it is related. Can anyone tell me exactly what tells the fuel pumps to shut down. I origionally thought that it might have something to do with fuel pressure, but now that I have changed the regulator with no difference I guess not.
I know that it is probably controlled by the ECM but does something else tell it when to shut down possibly a sensor?

 

The computer controls the fuel pump according to the following simple alogrithm:

Pump turns on for a few seconds after turning the key on then turns off
Pump turns on when Tach signal received indicating that the engine is turning over.

A pump that stays on continuously like that either has a bad relay or has been hard wired to bypass the relay (by someone who was too cheap/lazy to replace a bad relay). Take a wiring diagram and see if you can see any obvious faults in the fuel pump wiring.

A stuck on fuel pump shouldn't cause the engine to run rough like that. My BII went for years with a hard wired fuel pump and ran beautifully. I finally got a round tuit and replaced the relay so it worked as designed. Best first thing to do usually is to pull codes from the computer. See Ken00's tech info post for instructions.

 

The tach has never worked right. Will check the sending unit after I pull codes . although it has never had a check engine light on.

 

That's because, from the factory, '87's didn't come with a check engine light. I know there's a spot in the dash for it, but, if you get behind there, you will likely be missing a bulb, socket, and wires for a light. '88's were the first year to get a functional check engine light.

 

There are no codes at all. I mean the needle goes to 13 volts and stays there. According to Ken00's tech info post it refers me to pinpoint test step AO1 which is on page 19-240 and his post doesnt go that high.

 

Be certain you've hooked everything up correctly.
If you PM him (or wait until he sees this post), he is usually willing to email out specific pinpoint tests. I've also found you can usually find pinpoint tests in Mitchell or Motor manuals in the reference sections of many libraries.

 

I am sure I even went and bought a new analog meter. I have a Haynes manual and it describes the same technique for pulling the codes but nothing about the pinpoint tests. As soon as I turn the key on the tach goes to 500 rpms. So it might be telling the ECM that the engine is running if such is the case then it is not going to let me pull codes if it (the ECM) thinks that the engine is running.

 

I have to agree with mrshorty.

You can access the test you need here

 

What is the breakout box that the pinpoint test refers to ? I am not familiar with a breakout box. It states " Install breakout box, connect processor to breakout box" also in all of the rest of the steps it states "Breakout box installed, processor diconnected". What is a breakout box?????

 

Breakout box is an expensive gadget that installs in the wiring harness between the connector and the PCM, and allows you to easily and safely probe each circuit with a DVOM. If you are careful to not damage the connector or short any connections, you can do the same thing by backprobing connectors.

If you want to see what a breakout box looks like, put "ford EEC-IV breakout box" in your favorite search engine and you should get several hits for sellers of such items. New, they tend to run in the $400-500 range. I've seen them used on ebay frequently, and they tend to go for $150-$250.

 

I went through all of the steps. It tells me to replace the Processor. Guess I will go find one out of a junk yard I gotta have my Bronco II back. I will keep you informed.

 

Update $ 135.00 later for a reman EEC IV and running great the tach that never worked since I got now works the fuel pump shuts off after a few seconds and I can actually pull codes. Thank for all of the great help and tech procedures.

 

Glad to hear you got it fixed!!