87 Bronco - Runs inconsistently - Seriously need advice.

Bronco87-90

New member
Joined
Feb 28, 2021
Messages
3
Location
Alabama
Greetings, New to Broncos. I have two of them in the family now. An 87 and a 90. The 87 has been a challenge since we bough it. It ran perfectly fine during the test drive. About a month after we got it home it started running like it was only hitting on a couple cylinders. We changed the plugs, and it didn't do anything for us. To it to a mechanic, and they ended up replacing the EEC. After that, we had issues with the fuel pump running continuously, but it wouldn't start. Mostly on rainy days. Eventually the fuel pump quit running continuously. Ran great for a while, Last Saturday my son pulled into his parking spot and it died before he could turn it off. Then it wouldn't start. Went back few hours later it started fine. We drove it about a mile and it died. It started again and went about 1/2 mile then died. No stutter, or warning, just no longer running. Any thoughts on what we should be looking at? Forgot to mention, there for a while, it'd run fine, but wouldn't start if the engine was warm. We've replaced the fuel pump under the driver seat, and put the right size battery in it. We've replaced the starter. Bottom line is it's not consistent when it won't start, or when it'll die. Thoughts? Thanks, Paul
 

Tiha

Active member
Joined
Jul 22, 2020
Messages
153
Location
Midwest
The fuel pump sticking on concerns me, that maybe the replacement EEC was no good?

beyond that, rainy day problems for me was always cap, rotor, plug wires.

Sounds like you have a heat soak issues, like ignition module or pick up module. Maybe even a bad coil.

Can you get a fuel pressure gauge on it? Sounds like you only replaced one pump, need to make sure the other one is running as well. Fuel pressure gauge is a quick way to trouble shoot that.
 

chrlsful

Member
Joined
Oct 13, 2009
Messages
123
Location
S. Amherst, MA 01002-1827
Any 'new to me' vehicle I wanna ck out ALL systems (ele, fuel, breaks - ad infinitum). Could this B a ground? Older vehicles DO HAVE poor grounds...
Here U have a fuel/ele systems involved issue. I would start at 1 end & wrk toward the other (duz NOT mean replace every component - throw $ at it is not something I am capable of). Many keep a good/affordable Hanes or Chilton's manual handy. The shop manual is very expensive, but worth it.
 

miesk5

96 Bronco 5.0
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Oct 18, 2005
Messages
7,965
Location
Coronado, CA
Yo Paul,
Welcome!
As TIHA advised, the EEC could be faulty. If EEC IV PCM goes BAD internally, it activates the fuel pump continuously as long as the key is in the RUN position (but with the engine Off).

Or,
Pump Runs w/Ignition Switch Off; "...The relay probably has the points welded. ."
Source: by Seabronc (Rosie, Fred W) Rest in Peace friend... at Ford Bronco Zone Forums

Try a Self Test for Diagnostic Trouble Codes by my pal, BroncoJoe19 @ https://www.fullsizebronco.com/threads/something-wrong.511054/

Here's the 1987 Bronco Dealer Brochure @ https://www.xr793.com/wp-content/uploads/2020/07/1987-Ford-Bronco.pdf

1987 Owner's Manual, partial (Towing it & 4 speed manual transmission shift patterns & operation) by Ford via Mikey350 @ 1996 Ford Bronco 87 Bronco Owners Manual pictures, videos, and sounds | SuperMotors.net

Haynes Red Manual for 80-95 Bronco & F Series @ Hanes guide 80-96 bko f series.pdf found by BroncMom!

Here are the 1990 Bronco Pre-Delivery Shop & Electrical & Vacuum Troubleshooting Manuals (EVTM), Partial by member Kingfish999 in Google Drive @ 1990 Ford Truck service manuals - Google Drive
&
1990 Ford Truck Emissions Manual.pdf by Ford via member 90.CaliBronco in Google Drive @ 1990 Ford Truck Emissions Manual.pdf

Suggest you download both for faster scrolling and to use the table of contents index.

1990 Ford Bronco Brochure by Ford via Dezo's Garage @ https://www.xr793.com/wp-content/uploads/2020/07/1990-Ford-Bronco.pdf
 

Bronco87-90

New member
Joined
Feb 28, 2021
Messages
3
Location
Alabama
Thanks to all for the replies. I've not had the time yet to look into the distributor cap. Going to try and get to that today. In regards to the fuel pump, we've not had the issue of it running continuously for a while. That was an earlier issue. I've printed the instructions for running the codes. We'll give that a try to night as well. Two nights ago my son realized that he simply doesn't have a bulb in the check engine spot in the dash. Guess we'll be using the volt meter option. More to follow, sorry I'm so slow in getting back to this with updates.
 

Bronco87-90

New member
Joined
Feb 28, 2021
Messages
3
Location
Alabama
Yo Paul,
Welcome!
As TIHA advised, the EEC could be faulty. If EEC IV PCM goes BAD internally, it activates the fuel pump continuously as long as the key is in the RUN position (but with the engine Off).

Or,
Pump Runs w/Ignition Switch Off; "...The relay probably has the points welded. ."
Source: by Seabronc (Rosie, Fred W) Rest in Peace friend... at Ford Bronco Zone Forums

Try a Self Test for Diagnostic Trouble Codes by my pal, BroncoJoe19 @ https://www.fullsizebronco.com/threads/something-wrong.511054/

Here's the 1987 Bronco Dealer Brochure @ https://www.xr793.com/wp-content/uploads/2020/07/1987-Ford-Bronco.pdf

1987 Owner's Manual, partial (Towing it & 4 speed manual transmission shift patterns & operation) by Ford via Mikey350 @ 1996 Ford Bronco 87 Bronco Owners Manual pictures, videos, and sounds | SuperMotors.net

Haynes Red Manual for 80-95 Bronco & F Series @ Hanes guide 80-96 bko f series.pdf found by BroncMom!

Here are the 1990 Bronco Pre-Delivery Shop & Electrical & Vacuum Troubleshooting Manuals (EVTM), Partial by member Kingfish999 in Google Drive @ 1990 Ford Truck service manuals - Google Drive
&
1990 Ford Truck Emissions Manual.pdf by Ford via member 90.CaliBronco in Google Drive @ 1990 Ford Truck Emissions Manual.pdf

Suggest you download both for faster scrolling and to use the table of contents index.

1990 Ford Bronco Brochure by Ford via Dezo's Garage @ https://www.xr793.com/wp-content/uploads/2020/07/1990-Ford-Bronco.pdf

Thanks you so much for the manuals. I look forward to looking through them. They'll be a great resource.
 

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