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1989 F-250 efi 460 motor back fires out the tail pipe

Tiny
FORD4X4250
  • MEMBER
  • 1989 FORD F-250
  • 128,000 MILES
Back fires so bad I see flames when even slight acceleration, misfires at idle runs very rough, I put in new plugs wires, cap, rotor less than two months ago, this issue just started yesterday when I moved the battery ground cable from the original position on the exhaust to the driver side intake manifold using the wrong gauge cable, ran the cable under the ignition module then behind the alternator to the neg side of battery. Did I fry something or short out the module? I'm stumped cause it ran fine before this now won't even get out my driveway. Can you help?
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Monday, October 3rd, 2011 AT 5:01 AM

15 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
If you put it back where it was, is there a difference?
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Monday, October 3rd, 2011 AT 5:03 AM
Tiny
MHPAUTOS
  • MECHANIC
  • 31,937 POSTS
Have you checked for any fault codes as yet?
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Monday, October 3rd, 2011 AT 5:07 AM
Tiny
FORD4X4250
  • MEMBER
  • 12 POSTS
I put it back and did not change anything seems worse, a guy told me to remove both battery connections from the battery, connect them together for an hour or longer then reconnect them to the battery and start it (ford reset procedure he called it?), It made it run smooth for a few then went back to misfiring and backfiring at acceleration,
i don't know how to check fault codes
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Monday, October 3rd, 2011 AT 5:20 AM
Tiny
RIVERMIKERAT
  • MECHANIC
  • 6,110 POSTS
Most parts stores will scan for codes for free, unless you're in California. You can also check for local shops that will do it for free. Pull the vacuum line from the side of the distributor and plug it. Test drive it. Next check the timing.
10 Degrees
Application:
With automatic transmission

Note :
Before top dead center
*Base timing specification
*Set at warm idle speed (electronically controlled -
not adjustable)
*Disconnect single wire spout connector (yellow/light
green) or remove shorting bar on double wire spout
connector at ignition module (terminal #5)
*All accessories off
*Transmission in park

same with the manual transmission.
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Monday, October 3rd, 2011 AT 8:08 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
I have to agree with rivermikerat, it sounds like a timing issue. However, I can't understand how the timing would have changed if you didn't move the distributor. Try what he is asking and let us know what you find. Also, as mentioned, have the computer scanned for trouble codes. I have another question. Is the back fire constant or does it come and go? Is there anything other you did to the truck other than moving the ground which seems to have caused this? One last thing, have you tried placing the ground straight to the engine block rather than the intake?
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Monday, October 3rd, 2011 AT 12:02 PM
Tiny
FORD4X4250
  • MEMBER
  • 12 POSTS
Update on problem: I did the timing test and got it set where it should be and did not get rid of the backfire or miss so I gave up for the night
i started the truck cold this morning after setting all night, it started right up and ran smooth, was even able to drive it around the block, however once it got to max running temperature it started backfiring and misfiring again and the base / shaft of the distributor seemed to be very hot. Any thoughts?
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Monday, October 3rd, 2011 AT 4:49 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Chances are that is just heat transfering from the engine. Just so I know. Did this problem exist before you moved the ground? It makes no sense.
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Monday, October 3rd, 2011 AT 5:05 PM
Tiny
FORD4X4250
  • MEMBER
  • 12 POSTS
It had a miss before moving the ground but was able to drive it. Just could not romp on the gas peddle, had to ease into the peddle, never backfired until now though.
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Tuesday, October 4th, 2011 AT 5:22 AM
Tiny
RIVERMIKERAT
  • MECHANIC
  • 6,110 POSTS
Is there any knocking and pinging? Does it have a temp gauge that works? If so, does it read hot?
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Wednesday, October 5th, 2011 AT 3:56 AM
Tiny
FORD4X4250
  • MEMBER
  • 12 POSTS
Temp reads normal, has a knock once backfire starts when applying the gas
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Wednesday, October 5th, 2011 AT 5:55 AM
Tiny
RIVERMIKERAT
  • MECHANIC
  • 6,110 POSTS
Do a compression test with the engine warm.
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Wednesday, October 5th, 2011 AT 6:11 AM
Tiny
FORD4X4250
  • MEMBER
  • 12 POSTS
I have decided to take it to a mechanic instead of play this run around game. No offense but I have gotten better answers from back yard mechanics on this issue than this site, several have narrowed it down to the ignition module not proper grounded or loose, considering that is the area I was working when this all happen it makes sense. However Ty you all for your help, but I'm done here.
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Wednesday, October 5th, 2011 AT 2:51 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Sir, we are sorry that we couldn't help. However, based on your original post, nothing makes sense. You moved a ground and the problem started. Something other had to happen that we don't know about. Things don't go bad when you move a ground from one place to another unless you lost ground, but you placed it in a better location. I would like to know what the shop finds.
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Wednesday, October 5th, 2011 AT 4:39 PM
Tiny
FORD4X4250
  • MEMBER
  • 12 POSTS
Well when I explained it to the mechanic just the way I did on here as well as a few craigslist help, they all said one thing I must have bumped or loosen the ignition module (grounds to the distributor) that was the area I described all along I was working in (original post) the mechanic says a loose module will cause this problem and possibly other related problems. TY very much for the help but it is now at the shop and yes I will let you know what they did or didn't find. Again thanks
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Wednesday, October 5th, 2011 AT 4:54 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Yes, a loose module can cause the problem. I hope that is it. I look forward to hearing from you.
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Wednesday, October 5th, 2011 AT 5:08 PM

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