My 1986 F150 5.0 EFI is hard to start when cold and bucks and jumps when warm, why?


Asked by Aug 22, 2014 at 05:09 PM about the 1986 Ford F-150 XL Standard Cab LB

Question type: Maintenance & Repair

Have replaced EGRw/solenoid, TPS sensor, IAT sensor, thermostat, plugs, distributor cap and rotor. Checked fuel pressure and was fine, but not while driving when bucking occurs. Starts fine once the truck has been started. Runs very rich, checked timing w/ spout disconnected. Any clues?

3 Answers


I have that same problem with my 92 f150 5.0 efi somebody PLEASE HELP US. I installed new vacuum lines which helped a lot but not completely. Running really rich and gas mileage is horrible... I'm getting about 5-7 miles a gallon. Thanks


I had same problem with other problems , new oxygen or 02 sensor improved problem a lot ,still have unstable idle problem. i have 4.9 l inline 6 engine.

Lance Dean

Do a self check and pull the computer codes. Let us know what you get.

Your Answer

Add photo

Related Questions


Looking for a Used F-150 in your area?

CarGurus has 216,692 nationwide F-150 listings starting at $1,000.


Search Ford F-150 Questions

Ford F-150 Experts

#1 OJ
Reputation 6,000
#2 dandyoun
Reputation 3,880
#3 tennisshoes
Reputation 2,290
View All

Related Models For Sale

Used Ford F-250"
605 listings starting at $3,995
Used Ford Mustang"
746 Great Deals out of 41,448 listings starting at $900
Used Ford Ranger"
265 Great Deals out of 7,819 listings starting at $988

Used Cars For Sale

2017 Ford F-150 For Sale
5,815 listings starting at $17,015
2016 Ford F-150 For Sale
153 Great Deals out of 138,731 listings starting at $16,985
2015 Ford F-150 For Sale
250 Great Deals out of 9,045 listings starting at $17,958
2014 Ford F-150 For Sale
504 Great Deals out of 10,946 listings starting at $10,450
2013 Ford F-150 For Sale
678 Great Deals out of 14,758 listings starting at $7,727