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1986 Ford F150 has me batty...


Dandy Dave
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This thing is 34 years old so I suppose it qualifies here. Solid old Ford truck that refuses to run. This is a OBD1 EFI system with a 5 liter/302 engine. Has great spark. Will jump 3 inches out of the coil. It is in time. The rotor goes around. Cap and rotor is good. It has a new fuel tank. New fuel pumps, New fuel filter, New injectors. Has 40 LBS of fuel pressure. Turns over but refuses to run. Will pop out of the exhaust once in a while. Timing is NOT out 180 Degrees. It did not have a battery in it for years so no codes in the system to retrieve. Any ideas about why this finnicky old pig won't run? 

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Reguardless I'd start with triage. Pour about 1/2 oz of gasoline into the intake. Throttle wide open. Crank. If nothing happens is ignition. If pops a bit then is fuel.

 

Said EFI so need an injection noid (yes, noid) to see if injector(s) are cycling.

 

OBD-1: need something like an OTC-2000 scanner with a Ford cartridge & connector.

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 I really hope that someone comes up with a solution to this problem.

 I have the same truck that has drove me crazy to the point that it is destined for the scrap yard.

 I suspect that it is the fuel pump but I am told that it is easier to remove the bed to get at the pump rather than dropping the tank.

 It has been too hot to even think about it lately.

 I think that once I get the bed off that I will sell that and junk the rest.

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6 minutes ago, Roger Walling said:

I am told that it is easier to remove the bed to get at the pump rather than dropping the tank.

You may be able to move the bed back about a foot to get access to the pump without having to remove the bed completely--MUCH easier.  Two guys to do the lifting + an assistant with four 1-ft sections of 2x4 lumber to insert as spacing.

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I changed out my fuel pump on my 2007 Silverado and it wasn't bad. I watched a Youtube video on how to do it.  You have to remove the bolts on the left side of the bed and loosen the ones on the right but don't remove them. Disconnect the tail light harness at the connector by the bed. Then tilt the bed and support it with a board. I used and engine hoist. Something to research on. 

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I'm with Padgett, drop a capful of fuel down the intake and crank. If spark OK, it will try to start. Just like troubleshooting a points and carburetor engine!

 

Just do NOT pour in a half pint of fuel.....😲  You could hydro lock the engine or worse.

 

Since the distributor turns, I assume it has some compression (tell by starter dragging sound). Wait, you said spark jumps out of coil, does it also spark a plug put in a spark plug wire with the plug laying on the engine?

 

If no fuel is coming out of the injectors, probably no codes will set anyway.

 

Noid light is an LED type tester that you probe a fuel injector connector to see if the computer is sending the voltage (or ground) to open the injector. A DMM will work too. One person looking at DMM the other cranking the engine. Or an oscilloscope! Got one of those in your back pocket?🤔

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Assuming the fuel makes it try to run, check the fuses.

 

6 hours ago, Dandy Dave said:

It did not have a battery in it for years so no codes in the system to retrieve.

 

That may not be true. EEC-IV Fords don't work like you are probably thinking. The diagnostics are all built in to the computer (not the scan tool). There are 3 kinds of codes, 1) KOEO (key off engine off) 2) KOER (key off engine running) and 3) memory.

 

There are 2 tests, KOEO and KOER. Yeah, you wont have memory codes and you cant do the KOER test, but that isn't how things are done in the EEC-IV world anyway. You always start with a KOEO test. Then, you do KOER after you fix anything you found wrong during the KOEO test.

 

It is possible to do it without a scan tool using a couple of test lights and maybe a resistor or a paper clip or something. I have a scan tool for these since the 80s and I have forgotten how to do it without. You'll have to look it up. There's no magic though. You need a test light. Then all you need to do is figure out how to initiate the test, and then if it finds anything obviously wrong with the FI system it will flash out the code on the light. That is literally all the scan tool does on an EEC-IV Ford. It initiates the test and counts the flashes.

 

If the computer is dead and wont come to life and run the test, then it probably has a blown fuse or a broken ground wire back to the powertrain or something.

 

One final thought, at the battery cable there was a third? wire with a big beige plastic bullet connector. Thats the power for the EEC-IV. Sometimes battery acid got down there and fouled it.

 

Edited by Bloo (see edit history)
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Are there no good Ford mechanics in your area? With the latest diagnostic equipment they should be able to tell what is the matter in a few minutes. As for not having codes, it is routine to wipe the codes before testing so the information will be fresh. No use worrying about a fault that came and went months ago.

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The Ford EEC-IV doesn't care. It is going to show you the faults it finds right now. It does have memory, but those are the third step in the process, after you have fixed any KOEO or KOER codes. By then, the car is probably fixed and you should clear it and see if anything comes back.

 

Pulling the codes is even easier than I remembered. Look here: https://www.fordtruckzone.com/threads/how-to-retrieve-trouble-codes-on-your-eec-iv-system-without-using-a-code-scanner.659319/

 

I guess a manual might be nice, but the code list is probably online. For any deep troubleshooting the Ford manuals sucked. The useful one came from Target Training Systems. Good luck finding that now....

 

Edited by Bloo (see edit history)
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Thanks for all the info. Got into it a little deeper today. The truck has been sitting since around 2004, so that is at least 15 or 16 years. Did a compression test today and it is low. Number one is 60 LBS, Number 2 is 35 LBS. Number 3 is 50, Number 4 is 60. Number 5 is 120. Number 6 is 60. Number 7 is 50, number 8 is 60. I put some oil in the cylinders and tried it again. and tested the lowest cylinder and it came up to 60. From what I have read the cylinders should be 120 or better across the board. It tries to start and must be hitting on the cylinder that is 120. I'm thinking the problem is the valves as I hear some of them leaking when I stop cranking it. Looks like it will require a teardown and a valve job. I read some where that low compression will cause a no run symptom in these engines. I tried the gas down the intake without any luck. I know a wheezing intake valve will push fuel back up into the intake. Yes there is spark at the plugs.

Edited by Dandy Dave (see edit history)
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9 hours ago, Roger Walling said:

 I really hope that someone comes up with a solution to this problem.

 I have the same truck that has drove me crazy to the point that it is destined for the scrap yard.

 I suspect that it is the fuel pump but I am told that it is easier to remove the bed to get at the pump rather than dropping the tank.

 It has been too hot to even think about it lately.

 I think that once I get the bed off that I will sell that and junk the rest.

Rodger, The 86 Ford I'm working on has two fuel pumps. One in the tank, and one up stream on the frame near the steering box.

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check the switch module down  on the steering post ,This is where  the switch working  is .

the switch  by the steering wheel is just  got a rod that runs down the the module  on top of the stiring shaft check the wires also at the module

Another option is put in a HEI distributor.

DONT GIVE UP.

 MY 1980 FORD HAS A DELECRON ALTNATOR

ALSO CHECK THAT YOU HAVE A GOOD  GROUND FROM THE BATTERY TO THE MOTOR.

Check both ends of the battery cables .

Edited by Isaiah
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20 minutes ago, nickelroadster said:

You just need to get an older truck.  Then it would be easy to fix.

 

Funny...I've just done that. I bought a 76 Blazer...low milege, no rust very basic model that is pre-all OBD crap. I've had it with electronics and even this in'st completely free of them but the less the better.

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So.........  when the ignition switch goes from start to run the engine stalls? Is the system still getting (enough) operating voltage with the switch in that position?  I would be looking there first. I used to work weekends in local repair shop in the late 80's early 90's. There was another guy who worked there on weekends as well. He was a Tech at a Ford Dealer full time during the week. He was always saying that most of the problems he found were ground related on those vehicles which were new at that time

Edited by John348 (see edit history)
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2 hours ago, nickelroadster said:

You just need to get an older truck.  Then it would be easy to fix.

 

I've got an 84 F-150 with the 300 cu in six. Easy? Carburetor (Carter YFA) has electric solenoids, TPS,  and ignition is Thick Film Ignition Module. And there is a computer (ECM) in there somewhere. Easy? No! 

 

Ah, you mean one from the 60s or earlier!😁

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 The computer or brain box on that 84 ford is in left fender  ahead of the left hand door.  the later ford  have the computer in the firewall  on the left side

You have to take  the inside kick panel off to get at it.

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