Running Rough

This weekend I took advantage of the great weather we're having, removed the top and had a nice little drive in the hills. Bronco ran fine through all of this. Monday and Tuesday I drove around town running errands, Bronco still ran fine.

This morning I'm driving to work, got about a mile from home, and it started popping and running rough, even backfired a couple times, so I turned back towards the house.

It would idle fine in neutral, but as soon as I applied some thottle, it would start popping again. It acted like it was out of fuel, but I topped off on Sunday and only put about 60 miles on it since then. The gauge still stays it's nearly full. I can hear the whine of the rail-mounted fuel pump, so that's running. I don't normally hear the in-tank pump, so I can't tell if it's going or not. The Fuel Pump Relay was replaced a couple months ago and it seems to be ok.

I'll pull some codes tonight when I get home, but I was wondering if anyone had any ideas of where to start looking?

yo BB,

Ok on your DTC tests later;

Self Test for Diagnostic Trouble Codes (DTC)s by my pal, BroncoJoe19

http://broncozone.com/topic/14269-code-reader/page__pid__74587__mode__threaded

Joe has a vacuum leak test

The engine temperature must be greater than 50° F for the Key On Engine Off (KOEO) Self-Test and greater than 180° F for the Key On Engine Running (KOER) Self-Test.

Run it around to heat the engine up and shift thru all gears incl Reverse. Then turn off all accessories/lights, etc.

Make sure A/C is off and transmission is in Park (automatic) or in Neutral for a Manual & release clutch.

Do Key On Engine Off (KOEO) portion first.

Post em here according to:

KOEO

&

KOER

for now;

THIS IS BY FORD

RUNS ROUGH - MISSES - BUCK/**** - HESITATION/STUMBLE - SURGE - BACKFIRES

Check vacuum lines for leaks or wear.

Here is my vacuum leak test http://broncozone.com/topic/22770-low-idle/

Check;

air intake system (filter, air tubes to throttle body)

POSSIBLE DTCs MAY SHOW UP for:

IAC solenoid

MAP sensor

TP sensor

IAT sensor

Check for correct fuel pressure.

Check for fuel contamination/quality.

Check;

fuel filter.

POSSIBLE DTCs MAY SHOW UP for:

HO2S(s)

Fuel Pump System:

FP circuit

FP relay

Ignition

Check for correct base timing.

Check distributor cap, adapter, and rotor.

Inspect spark plugs and plug wires.

Inspect ICM for damage.

POSSIBLE DTCs MAY SHOW UP for:

Ignition System:

PIP circuit

SPOUT circuit

Power and Grounds Check for generator/regulator noise interference.

Inspect electrical connections, wires, and harnesses.

POSSIBLE DTCs MAY SHOW UP for:

EEC Power:

VREF

EEC Grounds:

SIG RTN

Other Check engine coolant level.

Check thermostat for proper operation.

Check EGR valve sticking.

Check PCV valve for correct operation.

Check for restricted exhaust.

Check camshaft timing and cylinder compression.

Check for broken or weak valve springs

POSSIBLE DTCs MAY SHOW UP for:

ECT sensor

EGR Systems:

EGR, EVP

EGR solenoid(s)

EPC solenoid

TCC solenoid

---------

When I got home last night I tried starting it again, this time it would just crank but never catch. I did get my head down by the tank and I could hear the in-tank pump going. I just need to make sure I've got fuel up to the rail, and spark at the coil.

I couldn't find my trouble light (still unpacking from the move, but it's a great thing to have a garage of my own now) so I couldn't pull any codes. I did find an ODB-1 reader on Amazon for Fords ( Equus 3145 Ford Digital Code Reader ) and for $25 + $4 1-day shipping, it sounds like a good deal. It'll be here tonight, so we'll see how it goes.

Ok, got my code reader and got a code from it.

First up, this code reader is awesome. A great investment for $25.00. No blinky lights, just plain old 2 or 3 digit codes, and a handy reference manual to decode them.

On the KOEO test, I got an 87. The book says that's a primary fuel pump circuit failure. But I can hear both pumps, and I have fuel pressure at the rail. I tried the test again after taking out the fuel pump relay, this time I got 11, All Clear. But there was no fuel in the rail, obviously.

I did the eyeball and wiggle test on the electrical harness, but so far I haven't seen anything wrong.

Any ideas?

Ok, this may be a silly question. The EEC relay. I thought my '86 5.0 has one, near the fuel pump relay, right around the drivers-side hood hinge.

But I can see no sign of it, no harness with wires, nothing. Is it someplace else?

Hey Bebop,

I'm not 100% certain for your 86, but the EEC relay may be under the dash above the gas pedal. It may be green or brown if it's an original.

Real head scratcher here huh? Did you put the FP relay back in and get the 87 code again? If so I would think there is some problem with the relay. OR...the relatd wiring has an issue such as a wire touching ground.

Have you cleared the codes and tested again?

yo BM,

Some info from my archived site;

EEC Relay Location in an 86; "...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..."

Source: by Xris

Check for moisture/corrosion in connectors

DTC 87 - FP relay circuit failure; suspect inertia switch, fusible link, FP relay

Source: by miesk5 at Ford Bronco Zone Forums

If you have adequate pressure and both pumps are running; it is caused by the scan tool grounding the fuel pump(s) diagnostic lead.

Pressure Test Gauge Overview & pic; "...To test the fuel pressure you’ll need this tool. You will need to ***** it onto the schrader valve on the top of the fuel rail, it looks like a tire air valve stem. After attaching the fuel pressure tester, run the fuel pump for 10 seconds. Check that the pressure is within specs, and it doesn’t leakdown more than 5PSI within 60 seconds after pump shutdown..."

Source: by Ryan M (Fireguy50) http://oldfuelinjection.com/?p=12

Wiring Diagram in an 86 5.0 Source: by Ryan M (FireGuy50)

Just in case BM, do you have this happening?

No Start, Low State of Battery Charge or Buzzing or Humming Noise from the Fuel Pump after the Engine has been Shut Off Caused by Sticking Fuel Pump Relay TSB 90-18-3 for 83-90 Bronco, Bronco II, Econoline, F-150, F-250, F-350, Ranger & Many OthersSource: by Ford via Chilton

Troubleshooting Basic Fuel Systems Problems by Chilton

Rons beast said:

Hey Bebop,

I'm not 100% certain for your 86, but the EEC relay may be under the dash above the gas pedal. It may be green or brown if it's an original.

Real head scratcher here huh? Did you put the FP relay back in and get the 87 code again? If so I would think there is some problem with the relay. OR...the relatd wiring has an issue such as a wire touching ground.

Have you cleared the codes and tested again?

Click to expand...

Yup, I found it right next to the computer, under the dash.

Clearing codes and retesting with the FP Relay in-place resulted in another 87 code. I'm traveling this weekend, but when I get home I'll trace the voltages pins on the relay with my multimeter and see if everything is OK. I may end up swapping one or both of the relays, we'll see.

miesk5 said:

yo BM,

Some info from my archived site;

EEC Relay Location in an 86; "...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..."

Source: by Xris

Check for moisture/corrosion in connectors

DTC 87 - FP relay circuit failure; suspect inertia switch, fusible link, FP relay

Source: by miesk5 at Ford Bronco Zone Forums

If you have adequate pressure and both pumps are running; it is caused by the scan tool grounding the fuel pump(s) diagnostic lead.

Pressure Test Gauge Overview & pic; "...To test the fuel pressure you’ll need this tool. You will need to ***** it onto the schrader valve on the top of the fuel rail, it looks like a tire air valve stem. After attaching the fuel pressure tester, run the fuel pump for 10 seconds. Check that the pressure is within specs, and it doesn’t leakdown more than 5PSI within 60 seconds after pump shutdown..."

Source: by Ryan M (Fireguy50) http://oldfuelinjection.com/?p=12

Wiring Diagram in an 86 5.0 Source: by Ryan M (FireGuy50)

Just in case BM, do you have this happening?

No Start, Low State of Battery Charge or Buzzing or Humming Noise from the Fuel Pump after the Engine has been Shut Off Caused by Sticking Fuel Pump Relay TSB 90-18-3 for 83-90 Bronco, Bronco II, Econoline, F-150, F-250, F-350, Ranger & Many OthersSource: by Ford via Chilton

Troubleshooting Basic Fuel Systems Problems by Chilton

Click to expand...

I'll check those out. I think I've got a fuel pressure gauge in the big box of tools I inherited from my uncle. I know I have pressure at the rail, but it does seem to fade fast.

Also, this may or may not be related, but ever since I replaced the under-cab fuel pump a few years back, the fuel pump runs constantly. Before, I'd only hear it for a few seconds at a time.

I also checked the inertia switch, it was not tripped. I'll verify voltages when I'm checking around with my multimeter

Ok, I swapped out both the EEC and Fuel Pump relay. After clearing the reader, I'm still getting a code 87. I've got +12 at inertia switch, the switch is enabled, and there's continuity on both sides of the switch. There's +12 at Pin 1 of the EEC, and I have +12 at the EEC relay. I've got spark at the coil when I try to turn it over and fuel pressure at the rail (sprays out when I press the pin in the schraeder valve).

Needless to say I'm a little frustrated. I hope someone has some ideas.

yo BB, finally got a better Comcast cable connection! (we pay for highest speed Blast and usually get 1999 speeds)

for the heckuva it, pull vac hose from fuel pressure regulator; any gas or aroma of gas, replace regulator

here is a post showing Ford's Pin-Point test for DTC 87;

Where breakout box is cited, go to the EEC (ECA) CONNECTOR pin instead

Use EEC IV Connector Pin Depiction Pic http://oldfuelinjection.com/images/eec04.gif

and LEGEND http://oldfuelinjection.com/truckpinouts.html

by Ryan M (Fireguy50)

VPWR -Vehicle Power supply voltage (regulated 10-14 volts)

Keep Alive Power (KAPWR): Dedicated, unswitched power circuit that maintains KAM

KAM: Keep Alive Memory.

Keep Alive Memory (KAM): A portion of the memory within the PCM that must maintain power even when the vehicle is not operating.

Hey B-Man,

It's a pain that you have so much trouble. I feel for ya.

Get a fuel preasure tester, and get a true reading on how much pres. ther actually is at the rail. 10# can seem like a lot when shooting out of that shrader valve, but not enough to get a cold engine running. You want to see 30- 45# on the fuel gauge. It should increase about 5-10# when you pull off the fuel regulator hose.

Good Luck

Well, it turned out to be my MSD coil. I did the sixlitre tuneup last year and put in an MSD 44kv coil. I plopped in a spare, and it fired right up. I had to change the timing back to stock to match the coil, but it runs nows.

The MSD is still under warranty, so as soon as I get my replacement, I'll re-tune it again.

Thanks to everyone for all the help and suggestions.

Now I can go back to my previous project(s) : A bikini top / tonneau cover and making my pop-up camper trail worthy behind the Bronco