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Backfire through exhaust first, now through carburetor too

Tiny
DAWGHOLIEO
  • MEMBER
  • 1977 FORD F-150
  • 5.8L
  • V8
  • 4WD
  • MANUAL
  • 1,000 MILES
351c engine with approximately 1,000 miles. Had pick up wire rub on water outlet. First backfire it was huge saw flash from under truck. What I have checked; first changed pick up, cap, rotor, o/h carburetor change jets, rods (Edelbrock 1405), inspect spark plugs. I am leaning to a possible overheat issue, causing detonation problem. Also can not hook up vacuum advance. Being a 351 Cleveland it gets to temperature very fast. Two to three minutes. I don't remember if the restrict-or is under thermostat.
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Wednesday, April 10th, 2019 AT 7:01 PM

31 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good morning,

Backfire in the exhaust usually come from a timing issue. If the timing is retarded from the factory spec, it will backfire out the exhaust.

Do you have an air pump on the engine?

Roy
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Thursday, April 11th, 2019 AT 3:13 AM
Tiny
DAWGHOLIEO
  • MEMBER
  • 1 POST
I've double checked timing, no air pump. I'm pulling thermostat today, to check restrict-or. Thanks
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Thursday, April 11th, 2019 AT 6:08 PM
Tiny
NRIEMER1
  • MEMBER
  • 5 POSTS
  • 1983 FORD F-150
Engine Performance problem
1983 Ford F150 6 cyl Four Wheel Drive Manual

I have suddenly had a backfiring problem, and it is stumping me, as it seems to only happen when I am turning. The problem is twice as bad when turning left, but have noticed the occasional miss when driving straight
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Thursday, April 11th, 2019 AT 6:10 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
When the last time you had it tuned-up? Check the sparkplug wires if its leaking and also the distributor cap.A/F mixture could be too lean or rich, Air injection diverter valve and the lis tgoes on.
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Thursday, April 11th, 2019 AT 6:10 PM (Merged)
Tiny
NRIEMER1
  • MEMBER
  • 5 POSTS
Just started suddenly, but what would make it happen primarily when turning?
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Thursday, April 11th, 2019 AT 6:10 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
But what would make it happen primarily when turning?

Honestly I've never heard of such problem-I will check the sparkplug wires they move around when not secured properly and could be leaking into one another
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Thursday, April 11th, 2019 AT 6:10 PM (Merged)
Tiny
NRIEMER1
  • MEMBER
  • 5 POSTS
I figured this one out last night, I had a partial break in the coil power wire, and the retainer for the wire had broken, letting it swing back and forth while turning. This momentarily broke the connection, letting gas build up in the cylendars and exhaust until it fired again, then BOOM! Fixed the wire, and replaced the coil connections also, seems to run fine now!
THANKS FOR THE HELP!
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Thursday, April 11th, 2019 AT 6:10 PM (Merged)
Tiny
PAGER_722
  • MEMBER
  • 2 POSTS
  • 1995 FORD F-150
  • 5.0L
  • V8
  • 4WD
  • AUTOMATIC
  • 151,000 MILES
Engine backfiring through intake after it gets hot fuel pressure was low put on new fuel pump and fuel filter fuel pressure back to normal now still has the same problem
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Thursday, April 11th, 2019 AT 6:10 PM (Merged)
Tiny
RIVERMIKERAT
  • MECHANIC
  • 6,110 POSTS
Backfiring through the intake is usually a timing problem. Make sure the timing is set to spec and that the timing chain is in good condition.
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Thursday, April 11th, 2019 AT 6:11 PM (Merged)
Tiny
PAGER_722
  • MEMBER
  • 2 POSTS
But if it was that would it not do it all the time only does it while cruzing not idleing or while youre getting on it hard
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Thursday, April 11th, 2019 AT 6:11 PM (Merged)
Tiny
RIVERMIKERAT
  • MECHANIC
  • 6,110 POSTS
Maybe. Cruising puts the least strain on the engine and lets the timing chain bounce. It could be happening at idle too, just not badly enough to hear it. The timing could be currently set so that the problem only shows up while cruising, advance taking up the slack at idle and under load.
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Thursday, April 11th, 2019 AT 6:11 PM (Merged)
Tiny
TMAJ9447
  • MEMBER
  • 78 POSTS
  • 2002 FORD F-150
  • 308,000 MILES
Hears the deal; this all started when I changed the spark plugs. Truck ran fine I was just doing pms. Changing the plugs ended up with having to rethread one of the coil pack bolt holes in the intake. One that was repaired I installed new upper and lower intake gaskets, torqured everything to specs, installed 2 new coil packs (broke 2 getting them out), replaced all 8 plugs with ngk oem replacements, buttoned everything up and to my suprise this lopeing and sounds like intake backfiring. Please help! Engine is a tritron 4.6
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Thursday, April 11th, 2019 AT 6:11 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Go to this link: https://www.2carpros.com/articles/engine-backfires-while-running
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Thursday, April 11th, 2019 AT 6:11 PM (Merged)
Tiny
TMAJ9447
  • MEMBER
  • 78 POSTS
Checked fuel pressure at rail 40 psi
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Thursday, April 11th, 2019 AT 6:11 PM (Merged)
Tiny
TMAJ9447
  • MEMBER
  • 78 POSTS
If this helps rpm goes from 700 to 1500 radically.
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Thursday, April 11th, 2019 AT 6:11 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Check for vacuum leak and clean the idle air control valve and see what happens
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Thursday, April 11th, 2019 AT 6:11 PM (Merged)
Tiny
STEVEJAY
  • MEMBER
  • 2 POSTS
  • 2000 FORD F-150
  • V8
  • 4WD
  • AUTOMATIC
  • 320,000 MILES
Occasionally, some days more than others it sputters, I'll have to play with the gas pedal to get up a hill or to take off, backfires once in awhile, seems to be more in the afternoon than morning, some days does good, other days real bad

have added fuel injection cleaner
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Thursday, April 11th, 2019 AT 6:11 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,170 POSTS
Has the check engine light come on? Have you checked fuel pump pressure?
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Thursday, April 11th, 2019 AT 6:11 PM (Merged)
Tiny
TMAJ9447
  • MEMBER
  • 78 POSTS
Okay still no change, I took the 4 spark plugs on the rightside out and they are sooted and dry. Should I check the injectors, seems like it is not getting fuel to the cylinders. Not sure
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Thursday, April 11th, 2019 AT 6:11 PM (Merged)
Tiny
STEVEJAY
  • MEMBER
  • 2 POSTS
The check enghine light hbas been on for 2 years, before this latest action. A mechanic the other day did a quick diagnostic, said something about a temperature reading being off, some code indicated that, needed more diagnostic too tell specefics.
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Thursday, April 11th, 2019 AT 6:11 PM (Merged)

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