'86 EFI Problems
Thread Starter
|
Freshman User
Joined: May 2002
Posts: 39
Likes: 0
From: Winnipeg/MB/Canada
'86 EFI Problems
Hey guys, I've got an '86 F150 4X4, 5.0L EFI, AOD trans., Here's the problem. It starts great, runs open loop, come off of fast idle and runs good until it reaches operating temp. Then it begins to stumble, surge, knock, and lightly backfire, like there's water in the fuel. (Can't get much more than 30mph after that) I've replaced the PCV, upper & lower intake gaskets (no vaccuum leaks), dist. cap & rotor, coil, front fuel tank with brand new,& fuel filter. No trouble codes are pressent & the emissions light does not come on during this ordeal. I've checked all the sensors and nothing seems to be wrong? What gives?!!
New User
Joined: Apr 2002
Posts: 9
Likes: 0
From: Hanover USA
'86 EFI Problems
Replace the TFI? module that conects to the side of the distributor and replace the Stator thats on the bottom of the distributor. I had these exact same problems with my 87 Tbird. Replaced them and it runs great.
Thread Starter
|
Freshman User
Joined: May 2002
Posts: 39
Likes: 0
From: Winnipeg/MB/Canada
'86 EFI Problems
Yesterday, I replaced the coolant temp. sending unit(to the computer, not the gauge) Checked the ignition modual & pick up coil both hot & cold. It all checks out good. Still no go. Same problem. I'm wondering if it's the computer itself. Am I not seeing the forest for the trees? Help!!!
New User
Joined: Mar 2002
Posts: 15
Likes: 0
From: Golden USA
'86 EFI Problems
If it starts when you op. temp. check for bad head gasket. Once system pressurizes you could be pushing water into cylinders. Exhaust smoke with a green tint, antifreeze smell. Check plugs and O2 sensor. If it's not antifreeze leak wouldn't hurt to replace O2, since you have it out.
Senior User
Joined: Mar 2002
Posts: 154
Likes: 0
From: Crustucky (Crestview) Florida
'86 EFI Problems
Cast might be right, I've even seen a cracked head cause that problem. The truck started up fine but when it got to normal operating temperature it stumbled and then stalled. There were signs of coolant out the exhaust and that led to us looking at the heads. I hope yours is not as bad, good luck.:-X23
-Ry
1985 F-150 302 4X4
Dana 44 TTB / 9 inch
4.56:1 Front/True-Trac
4.56:1 Rear/Detroit Locker
C-6 Tranny, NP208 Transfer
6 inch Skyjacker Class II lift
35 X 12.50 BFGoods AT's
https://www.ford-trucks.com/user_gallery/displaythumbnail.php?&photoid=3725&.jpg https://www.ford-trucks.com/user_gallery/displaythumbnail.php?&photoid=3536&.jpg
-Ry
1985 F-150 302 4X4
Dana 44 TTB / 9 inch
4.56:1 Front/True-Trac
4.56:1 Rear/Detroit Locker
C-6 Tranny, NP208 Transfer
6 inch Skyjacker Class II lift
35 X 12.50 BFGoods AT's
https://www.ford-trucks.com/user_gallery/displaythumbnail.php?&photoid=3725&.jpg https://www.ford-trucks.com/user_gallery/displaythumbnail.php?&photoid=3536&.jpg
Thread Starter
|
Freshman User
Joined: May 2002
Posts: 39
Likes: 0
From: Winnipeg/MB/Canada
'86 EFI Problems
[updated:LAST EDITED ON 20-May-02 AT 11:04 AM (EST)]First of all thanks for all the info. Much appreciated! I pressure tested the cooling system overnight. I even pulled the plugs just to have a look see. The systems tight. I'm told by one Ford guru that the ECM on these models is pretty rock solid. He suggested the O2 sensor might be to blame. Waddaya think?
"All the trees are bent, not from the wind but from the people hangin' on"!!
"All the trees are bent, not from the wind but from the people hangin' on"!!
Trending Topics
Thread Starter
|
Freshman User
Joined: May 2002
Posts: 39
Likes: 0
From: Winnipeg/MB/Canada
'86 EFI Problems
Further update, I changed the 02 sensor today, drove around for about 4 or 5 hot to cold cycles. It ran great, could hardly know it was running. The very last start up it did the same thing again. Could a leaking injector be my problem? Loading up one cylinder, then the 02 picking up the ball to tell the computer to go way lean causing this situation. Help!! I'm throwing some serious cash at this trouble already and still can't figure it out!!! FTE Stories
Ford Trucks for Ford Truck Enthusiasts
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
Thread Starter
|
Freshman User
Joined: May 2002
Posts: 39
Likes: 0
From: Winnipeg/MB/Canada
'86 EFI Problems
I don't believe this !!. Three (driving) days later, re-booted the computer (still ran rough). after the re-boot I noticed that the same "Bull#####" trouble codes still existed. I figured how can the codes still be there after a reboot? The answer is if you just unhook the neg. bat. terminal, the stupid thing still thinks the same problem(s) exist. Too bad Ford doesen't tell ya that ya gotta hack to drive. Totally stupid!! Once the system "learns" that you've replaced sensors this truck runs like it should. Why me?Thanks for all the help, you guys steered me on to the solution.
Big thanks!
