86 Ranger fuel pump problems

[nova801428]

All the fusible links are fine, whats next?

 

[BrooklynBay]

Did you check for broken ground wires near the battery area?

 

[nova801428]

Yep, they are all fine

 

[410Fortune]

okay so your fuel pumps both come on when you jump the relay, correct?

you have 12V + constant (from the battery) to the relay hot all times, correct?

But when you turn the key the fuel pumps do not prime like they should. even with all new relays, correct?

You still have no spark?

 

[whisperer]

Where in OR are you? You have no city in your profile.

 

[nova801428]

okay so your fuel pumps both come on when you jump the relay, correct?

you have 12V + constant (from the battery) to the relay hot all times, correct?

But when you turn the key the fuel pumps do not prime like they should. even with all new relays, correct?

You still have no spark?

Yes or ground the relay, Yes and from the ignition, Yes thats correct

I have spark, I have left the key on a couple of times and screwed up the coil. Replaced it and I now have spark

I took my truck to a local shop, and a mechanic told me it was the computer that was screwed up. I bought a new computer and will be here tomorrow, he is going to install it, the correct way not like I did. Hope it works out fine though

Where in OR are you? You have no city in your profile

Sorry, I am not on this site a lot, I am also a member of a few other sites. I live in a small town called Jefferson, its between Salem and Albany along I5. I was in Sisters at a High School Basketball tournament a last week when it snowed heavily along the pass, and when I went home their was two accidents (one, a honda civic/accord was totalled, the driver and passengers were both killed, I guess truckers said that it blew the aluminum heads off of the engine (BTW they hit a truck head on) Then the second was a roll over at the 20/22 split. I stayed at the Super 8 motel by Wal-mart. I don't know bend that much but I do occasionally go dirt biking at East Fort Rock. Where in bend do you live?

 

[410Fortune]

The computer may/ may not be faulty
it appears as if the computer is not telling the fuel pumps to prime and then to run when the engine is cranking or running.

The means 1 of these things:
computer is bad (usually other circuits fail, you get a mess of codes, etc)
computer is not getting signal from key switch
computer is not sending signal to fuel pump relay

The EEC relay is what controls power to the computer.

it is quite possible that this is a broken wire somewhere, a bad terminal/clip/pin in the relay box itself. You are getting battery power to your power distribution box, but not the EEC power feed when the key is ON



I hope you dont pay $300+ for a computer, and if you did I hope it fixes the issue.

 

[whisperer]

I'm in Bend and figured if you were in the area maybe we could get together and figure this thing out. Weird, I was in Corvallis last weekend playing music in a band and drove over the pass going your way. I also stayed next door at the Holiday inn on new years night.......... OMG, we've found the reverse of each other! How weird.........Ha!

Cool, you found the ignition problem, that makes things easier.

410fortune has the right question - you DO have 12 volts to the relay, right? As I remember this the ECU grounds the relay to opperate it so you need the 12 volt on 2 terminals at the relay, the main power feed that gets switched in when the relay operates, and the feed for the relay coil (which the ECU grounds the other side to opperate it).

If the pump runs when you ground the ECU wire at the relay then the problem is upstream from the relay, either the wiring, the impact switch, the ECU (not likely actually in my experience), or the signal telling the ECU to ground the relay. I don't have a wiring diagram in front of me to trace this down but that is the jist of it. Maybe somebody here has a wiring diagram handy? The next place I'd go would be identify the FP relay wire at the ECU, disconnect it and ground it. If the pump runs then go upstream again.

 

[410Fortune]

Eeek whisperer the relays get a power feed from the computer when the key is switched to on.

true the fuel pump signal may be a - but the red acc + wire powers many relays and sensors in the engine bay. the power for this red wire comes from the PCM and the PCM draws this power from the + feed att eh EEC fuse.

confusing I know, the red wire is + and goes to each injector, the coils, the MAS, the TPS, etc etc
it powers the fuel pump and AC WOT relay as well.......
if you dont have 12V+ at any of the red wires, the first thing to check is the EEC fuse and relay.

 

[whisperer]

Eeek whisperer the relays get a power feed from the computer when the key is switched to on.

true the fuel pump signal may be a - but the red acc + wire powers many relays and sensors in the engine bay.

OK, confued as to the Eeek. He says the pump runs when the relay is jumped out so the actual pump 12V feed (goes through the relay when opperated and to the pump) is live. What did I miss. The other 12V feeds one side of the relay coil and the ECU grounds that to pull in the contacts. At least on all other Fords of this vintage that's how these work. What are you seeing in the diagrams that are different about this?

 

[410Fortune]

The question is what did he jump? - or +
are both + feeds to the relay showing 12V+ when the key is on

one is constant 12V+ at all times
the other is switched 12V+ when key on

As I understood what he wrote he has the 12V+ from the battery but never gets the 12V+ with the key on.

Of this is the case I would check for 12V+ at one fuel injector when the key is on (red wire 12V+ Acc feed from PCM)

 

[whisperer]

The question is what did he jump? - or +
are both + feeds to the relay showing 12V+ when the key is on.

Gotcha, I just think in the terms of jumping the relay by using a jumper wire on the relay. Just where my mind goes.....

Ok then, I'd pull the (supposed to be) switched wire from the relay connecter insert a wire into the relay connector and wire that to a 12V source. Then turn the key and see if the pump runs. That would test the entire circuit to the relay from the ignition switch. (ASSUMING that the ECU is grounding the relay coil like all the others). If that's is the case it get's down to a fairly simple curcuit supplying 12 volts switched to the relay.

 

[nova801428]

I jumped hot +12 volts form the battery at the fpr to the fuel pumps, and they both jump on. This thread is really old and not really up to date. So, the pumps don't come on when the key is on, also when cranking they don't come on. When I jump the pumps and try to start their is not start but i have spark, meaning that the injectors are supposed to be pulsed from the eec, and I think the eec is shot, I bought an eec before and I neglected it (put it into my truck without disconnecting my battery) probably causing to to fail. My mechanic could not pull codes from either computer in my truck (one from a junkyard and the other was original). I bought a new computer from NAPA, because my mechanic told me both Shucks and Knects sell junk, most of their stuff might work but they slap a label on it and sell it...so I bought from NAPA for $100. I got my computer in today and I am going to give it to my mechanic tomorrow and well see what he figures out with it.
Thanks

 

[nova801428]

it is quite possible that this is a broken wire somewhere, a bad terminal/clip/pin in the relay box itself. You are getting battery power to your power distribution box, but not the EEC power feed when the key is ON

Nope, I checked it out thoroughly and my mechanic also told me all the wires were fine, he just couldn't get a signal out of the computer to pull codes.

you DO have 12 volts to the relay, right? As I remember this the ECU grounds the relay to opperate it so you need the 12 volt on 2 terminals at the relay, the main power feed that gets switched in when the relay operates, and the feed for the relay coil (which the ECU grounds the other side to opperate it).

Yep, I get 12 volts from the ignition when the key is turned on and I get 12 volts from the battery constant. But, when I ground the relay, my pumps jump on and do not shut off...meaning that the eec controlling/grounding the pumps for 3 or so seconds does not work.

if you dont have 12V+ at any of the red wires, the first thing to check is the EEC fuse and relay.

I have 12V everywhere I need it, just not the pumps. Checked the fuses at least 20 times

Ok then, I'd pull the (supposed to be) switched wire from the relay connecter insert a wire into the relay connector and wire that to a 12V source. Then turn the key and see if the pump runs. That would test the entire circuit to the relay from the ignition switch. (ASSUMING that the ECU is grounding the relay coil like all the others). If that's is the case it get's down to a fairly simple curcuit supplying 12 volts switched to the relay

That would work if I wasn't getting any power from the eec at all, but I am, its just not grounded and I checked all grounds. I even replaced the battery cable clamp post things and ran a wire from one ground to another several of times in hope of getting my pumps to run.

As I understood what he wrote he has the 12V+ from the battery but never gets the 12V+ with the key on.

I am getting 12V+ from the ignitions when the key is turned on, thats what is making this so confusing.

 

[410Fortune]

I have seen 4 EEC-IV computers fail in my time, it is very likely the power supply circuits in your PCM are shot. My fingers are crossed your new PCM fixes the issue.
Before I bought a computer I would have also checked for the ACC 12V+, with key on, at an injector and other engine sensors.
This would tell you if the problem is the entire computer power feed or just the relays.


Let us know how it goes!

On my BII I have had it all happen.
I have had broken coil wires, bad - wire to the fuel pump, bad battery cables, bad alternator cables, a bad/old PCM, a PCM got fried by the exhaust shop (left key on when welding, genious) bad relays, bad relay wires, shorted power wires, bad fuel pump connection, bad ground strap, etc
Shes 19 years old has 290K miles on her now and no issues, every wire I installed.

 

[nova801428]

Nope, my mechanic told me my peice fo **** didn't work. I bought a new computer from NAPA. Except the part number is different than what I am supposed to really have in my truck. But, I looked up eec numbers and it simply does not exsist??? This really pisses me off, also their is a rattle in the computer when I bought it, and the ####ers at NAPA said if I even take off the plastic wrap around the eec, I could not take it back, but the eec was never wrapped in anything. So, I am either going to start throwing fist or throw my truck off a damn cliff. Any ideas?

 

[410Fortune]

check for power at the injectors when the key is on

 

[nova801428]

How is that going to help me? Is a rattle in the computer a problems, my other computers did not rattle

 

[410Fortune]

if the new Napa computer is defective return it
when you have a PCM plugged in, turn the key on and check the red wire at an ijector for 12V+, this will tell you if the PCM is powering up all the engine sensors, relays, etc. If not then the power feed from the PCM is bad, or the EEC relay/fuse and power feed to the PCM is not working

 

[nova801428]

If their is no power to the injectors will the fuel pumps still come on? I remember testing the red wires and they were hot, what does that tell me?