what can i do to fix these problems, starting up,popping or backfire and making it move or roll in drive

Asked by Jul 02, 2014 at 02:31 AM about the 1991 Ford F-250 2 Dr XLT Lariat Extended Cab LB

Question type: Maintenance & Repair

spraying quick start in it to start , high rpms ,popping or backfiring when accelerate , putting it in drive it will roll slowly ,slowly, in 1 it will move like in drive. all other gears work fine. also fuel pump keeps running will not turn off when starting up.          THANK  YOU.

4 Answers

165

It may seem silly but check your air in take if if is electric control remove the connector run car if this works you will need a new air control unit

41,205

What engine is in your truck? Sounds like a bad vacuum leak but your description of your concern isn't very clear. Won't start? Starts but won't run? Runs poorly? Fuel pump runs when? Sorry but your description is difficult to follow.

12,315

So it is running rich. I'm not sure I follow the "roll slowly, slowly" part unless the rich fuel ratio is bogging the engine? But the high rpm would kind of negate the bog. It is kind of unclear but I'm going to guess something measuring air flow is enriching the A/F ratio and I don't know what sensors are inline from your filter to throttle body. So it could be MAF / VAF / a fuel switch sticking. Another guess would be an open injector? or your idle air control valve (or comparable sensor) is sticking open (high rpm). I could honestly be wrong as well, and there are plenty of scenarios to make issues with EFI sadly. @Barry, do you mean a throttle position sensor?

12,315

any updates to this?

Your Answer:

F-250

Looking for a Used F-250 in your area?

CarGurus has 2 nationwide F-250 listings and the tools to find you a great deal.

Postal Code:

CarGurus Experts

  • #1
    G A Arne
    Reputation
    1,410
  • #2
    F_O_R
    Reputation
    760
  • #3
    MikeSt
    Reputation
    680
View All

Find great deals from top-rated dealers

Search

Related Models For Sale

Used Ford F-150
272 Great Deals out of 12,288 listings starting at $4,096
Used Ford F-350
4 listings
Used GMC Sierra 1500
95 Great Deals out of 9,532 listings starting at $2,500
Used Ford Mustang
38 Great Deals out of 1,773 listings starting at $5,750

Used Cars for Sale

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use. Content will be removed if CarGurus becomes aware that it violates our policies.