after running great for a hour or so starts back firing and knocking. won't run not over heating, pull over for 30-60 minutes runs great again

Asked by Jun 19, 2013 at 09:01 PM about the 1991 Ford F-150 XL 4WD Extended Cab SB

Question type: Maintenance & Repair

got two gas tanks. fuel pumps in both, no booster pump try to swicth tank, when it happens no luck so don't think its the fuel pumps, try a new fuel pump relay. new computer relay. should i try a new  ecm computer, got three codes code 33 insufficient e g r flow, was told that would not cause the problem. code 62  and 65 trany codes, don't thing the traney would cause it.truck runs great for a hour or so than starts back firing and knocning. pull over 30-60 minutes run great not over heating. can anyone tell me what i should try and in what order thanks Howie

4 Answers

83,145

Backfiring sounds like ignition problems, have you replaced the distributor pickup and module?

1 out of 1 people think this is helpful.
22,455

That's the first place I would look too. Check for spark as soon as it dies. The electronics fail in the module because of the 99% duty cycle. An ignition coil can cause these troubles too but usually a coil fails and stays failed.

1 out of 1 people think this is helpful.
740

try laying a bag of ice on the computer when this happens. [if the computer is heating up] this should correct what's happening. will tell you if you have to replace the computer

1 out of 1 people think this is helpful.
16,030

Had the exact problem with a hopped up early 70's grand torino sport. "I'm not quite as old as Clint Eastwood" but not far away either." Would run absolutely teriffic for about half an hour, then dead. Cool off, would run great then die again. Old mechanic stated the power pack was going bad. Suggested next time it dies, dumb cold water over the pack to cool it off. WORKED. Had to reroute the power pack from the side firewall fender well to a location closer to the front near the radiator to keep it cool. Sounds like you have a problem with an electronic part overheading then sending incorrect signals.

1 out of 1 people think this is helpful.

Your Answer

Add photo

Related Questions

F-150

Looking for a Used F-150 in your area?

CarGurus has 205,083 nationwide F-150 listings starting at $1,779.

ZIP:

Search Ford F-150 Questions

UK Questions

Are you a UK consumer? CarGurus now has a discussion forum in the UK.

Ford F-150 Experts

#1 OJ
OJ
Reputation 6,680
#2 dandyoun
dandyoun
Reputation 4,130
#3 tennisshoes
tennisshoes
Reputation 2,470
View All

Related Models For Sale

Used GMC Sierra 1500
1,057 Great Deals out of 58,692 listings starting at $1,599
Used Ford F-250
586 listings starting at $1,357
Used Ford Mustang
580 Great Deals out of 41,215 listings starting at $1,699
Used Ford Explorer
1,207 Great Deals out of 71,146 listings starting at $1,000
Used Ford Ranger
228 Great Deals out of 7,053 listings starting at $1,200

Used Cars For Sale

2017 Ford F-150 For Sale
70,919 listings starting at $18,904
2016 Ford F-150 For Sale
223 Great Deals out of 64,668 listings starting at $8,843
2015 Ford F-150 For Sale
224 Great Deals out of 7,724 listings starting at $18,891
2014 Ford F-150 For Sale
532 Great Deals out of 11,287 listings starting at $11,988
2013 Ford F-150 For Sale
686 Great Deals out of 14,351 listings starting at $8,450