86 Bronco (EFI): FP Relay or EEC Relay

15686 Views 16 Replies 6 Participants Last post by Gacknar, Mar 26, 2010

Xris

Discussion Starter · Mar 22, 2010

Hey guys...my truck completely stalled out last week and have been diagnosing since. Here is waht I have, hope someone can help.

1) Turn key ON and I get NO fuel pump running but I hear the FP Relay click. Turn key fully and the starter truns over but does not want to start.
2) Meaured pressure at the fuel rail = 40psi.
3) Jumped the FP Relay at the DLC and I can hear the high pressure pump turning.
4) Haynes manual said that if the pump does not turn when the key is on but if it does turn on when jumped, then the problem is between the EEC and FP Relay.

Any ideas? Can the FP Relay still click and not run the pump? Is there a way to test relays? Could not find a way according to the book.

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crash315

· #2 · Mar 22, 2010

Could be your low pressure pump in the tank. This was my problem. I had to replace the whole thing in the tank (not a fun or easy task). As far as your other questions regarding the relays, I'm not sure. My problem was a bad pump that did not run (corroded), however there was still pressure in the system. We tested our fuel/ignition problem by squirting some gas down the throttle body to see if it would start/run (shortly). NOTE: I am not a mechanic, nor am I claiming to be one. If you try this, please do so with caution and with someone knowledgeable. I am not responsible for any damage you may do to you, another person, or your vehicle. You can have a backfire very easily (flames and everything). If you're not very knowledgeable I would suggest finding a local shop you can trust to help you diagnose your problem(s) or maybe another member can provide some better insight.

jopes

· #3 · Mar 22, 2010

first if you have 40 psi of fuel it's probably not your fuel pumps causing your no start issue.

I would check for spark.
then
pull codes on it

you have a 1986 bronco, they had 2 fuel pumps and 2 fuel filters.

fixxor

· #4 · Mar 23, 2010

Check the EEC relay. It is located under the dash on drivers side in middle area. It's right next to the ECM. When I was messing around with the wiring from PO I moved the EEC relay wiring a bit, after that it wouldn't work. Jiggling the wires it started to work, got a new relay and it works great now. Just something to look at.

Xris

Discussion Starter · #5 · Mar 23, 2010

crash315 said:
Could be your low pressure pump in the tank. This was my problem. I had to replace the whole thing in the tank (not a fun or easy task). As far as your other questions regarding the relays, I'm not sure. My problem was a bad pump that did not run (corroded), however there was still pressure in the system. We tested our fuel/ignition problem by squirting some gas down the throttle body to see if it would start/run (shortly). NOTE: I am not a mechanic, nor am I claiming to be one. If you try this, please do so with caution and with someone knowledgeable. I am not responsible for any damage you may do to you, another person, or your vehicle. You can have a backfire very easily (flames and everything). If you're not very knowledgeable I would suggest finding a local shop you can trust to help you diagnose your problem(s) or maybe another member can provide some better insight.

Thanks Crash...the pumps power up when jumped...gotta be between the Fp Relay and the EEC.

Xris

Discussion Starter · #6 · Mar 23, 2010

jopes said:
first if you have 40 psi of fuel it's probably not your fuel pumps causing your no start issue.

I would check for spark.
then
pull codes on it

you have a 1986 bronco, they had 2 fuel pumps and 2 fuel filters.

Yep...the pumps are powered when jumpered...and 40 at the rail. The 86s have two pumps (low in the tank and high on the rail) But...only one filter which is on the rail.

I'll be checking relays...I suspect a faulty ground opr bad eec realy. Thanks guys!

Xris

Discussion Starter · #7 · Mar 23, 2010

fixxor said:
Check the EEC relay. It is located under the dash on drivers side in middle area. It's right next to the ECM. When I was messing around with the wiring from PO I moved the EEC relay wiring a bit, after that it wouldn't work. Jiggling the wires it started to work, got a new relay and it works great now. Just something to look at.

Thx Fixxor...that will be my next objective!

jopes

· #8 · Mar 23, 2010

Xris said:
Yep...the pumps are powered when jumpered...and 40 at the rail. The 86s have two pumps (low in the tank and high on the rail) But...only one filter which is on the rail.

I'll be checking relays...I suspect a faulty ground opr bad eec realy. Thanks guys!

there is 2 filters, one between the tank and high pressure pump on the frame and the other is between the high pressure pump and the engine.

do you have spark?

if your needing to jumper the relay to get the pumps to come on it's a good chance that relay is bad.

also the main EEC relay has been known to have wiring issues under the hood.

Xris

Discussion Starter · #9 · Mar 23, 2010

jopes said:
there is 2 filters, one between the tank and high pressure pump on the frame and the other is between the high pressure pump and the engine.

do you have spark?

if your needing to jumper the relay to get the pumps to come on it's a good chance that relay is bad.

also the main EEC relay has been known to have wiring issues under the hood.

Yeah have to check spark yet...gotta get my 11yrold out there with me. Do you know where the EEC relay is located on an 86? FP relay is by the master cycliner on the firewall...correct?

miesk5

· #10 · Mar 23, 2010

yo X man,

Check for moisture/corrosion in connectors

Consider swap to Bosch style relay used in later years;
Color Codes for Troubleshooting/Swapping to Bosch Style Relays
Source: by Steve83 (Steve, That dirty old truck) at FSB

miesk5

· #11 · Mar 23, 2010

This is a common problem in all pre-'92 EFI F-series & Broncos. These Ford-style relays (BROWN socket = EEC power; GREEN socket = fuel pump)are notorious for causing intermittent failures in the EEC & fuel pumps Yesterday, this EEC PWR relay decided to lock on, killing the battery. Today, its contacts are so bad that the truck won't run. So it's about to be TRASH.

See the NEXT caption
by steve83

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crash315

· #12 · Mar 24, 2010

This just hit me. First off, when you jumper, do you hear both pumps turning?

Secondly, when I was having these problems, I was getting info from a Ford Tech over the phone via relative. If I remember what he told me correctly, my new pumps worked when jumpered b/c the jumper wire grounds out the system (for testing purposes). Turns out there is a small wire that connects to the negative battery terminal connector that I missed putting back on. When I got this wire back on, it all worked again. Also make sure to check connections b/c right after this, I had a wire fall off and I was back to diagnosing (luckily I check this quickly and it didn't take long). Because of that, I never had to buy new electrical pieces. Might fix it... might not.

Check these out and let me know how it goes or of any new updates to your problems.

Xris

Discussion Starter · #13 · Mar 24, 2010

crash315 said:
This just hit me. First off, when you jumper, do you hear both pumps turning?

Secondly, when I was having these problems, I was getting info from a Ford Tech over the phone via relative. If I remember what he told me correctly, my new pumps worked when jumpered b/c the jumper wire grounds out the system (for testing purposes). Turns out there is a small wire that connects to the negative battery terminal connector that I missed putting back on. When I got this wire back on, it all worked again. Also make sure to check connections b/c right after this, I had a wire fall off and I was back to diagnosing (luckily I check this quickly and it didn't take long). Because of that, I never had to buy new electrical pieces. Might fix it... might not.

Check these out and let me know how it goes or of any new updates to your problems.

Yep...that's on my order of business too...
1) Check for spark
2) Check for lose connections/corrosion
3) Check EEC and Fuel Pump Relay

I am still lost as to WHERE the EEC Pump Relay is on an 86?????

Pictures would be great if anyone has them!

crash315

· #14 · Mar 24, 2010

Do a search in the forum. There is a picture of the 86 EEC, FP, and one other thing (forgot what was in it). Use a manual if you have one. My 88 has it on the drivers side hanging loosely (shop broke the clips), but it should be clipped to the body inside the hood. The search feature is your magic friend!!

Xris

Discussion Starter · #15 · Mar 26, 2010

UPDATE

Hey guys...first...thanks for all who posted...much appreciate the answers I got.

Second...I took a 1/2 day today with all intentions of Dx this problem to its fullest. My thought from the beginning was that I was having either a EEC Relay problem or a wiring problem. But the first thing I wanted to eliminate was a no spark issue. BINGO...no spark! So I knew the EEC Relay wa no longer suspect. Next thought was TFI...did some checking with the mechanic and sure enough! Went to the parts store installed a new one and BANGO...beasty is running like a rapped ape!

Thanks again guys!

LOOP CLOSED!!!

BTW - for future reference for all you 86 bronco's out there...the 86 must have been a change out year in regard to the EEC Relay. On some you will find the fule pump relay and the EEC Relay under the hood, driver-side by the master cylinder/vac. On some 86's (like mine) you will find the EEC Relay in the cab to thr right of the gas pedal...sorta where your ash tray would be.

Tan = EEC Relay
Green = FP Relay

Hope this helps for those who are searching for the location! CHEERS

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fixxor

· #16 · Mar 26, 2010

Glad you got it fixed.

Gacknar

· #17 · Mar 26, 2010

jopes said:
there is 2 filters, one between the tank and high pressure pump on the frame and the other is between the high pressure pump and the engine

Negative Jopsey :toothless
My 86 has only one filter, It's inside the fuel reservoir. The only thing between the high pressure pump and the fuel rail is hard line.
:thumbup

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