Engine misfiring sputtering on highway..
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Engine misfiring sputtering on highway..
Reason I say the highway is because a few years ago I'm on the highway and car begins sputtering than backfiring....I pull over,car sounds like it's running on six cylinders......I thought bad gas, because everything looked fine......I let it cool down.....Not that it was running hot.....Car was fine, got it home .....
Next day I tried starting it, no start but cranks....I had no spark...Two days later car starts......???? Took it to my mechanic couldn't find anything wrong....
Next month on highway, same thing sputtering backfiring....Pulled over, let it sit for awhile, started, got it home.....
Last season didn't do it....Car ran fine..Put about 700 miles on it last season..
Today on highway and guess what? Started again.....Pulled off nearest exit and called AAA.........Towed to my house where the car started and I put it in garage...
Car is a worked small block four speed .....I'm thinking it may be a spark problem? Car has MSD 6 AL.....The times I bought it to my mechanic he says it's hard to diagnose because it's not doing it when I bring it to him..
Any idea what could be causing this......It's not something that happens all the time and car is well taken care of.....
Car is a 1973 ....
Next day I tried starting it, no start but cranks....I had no spark...Two days later car starts......???? Took it to my mechanic couldn't find anything wrong....
Next month on highway, same thing sputtering backfiring....Pulled over, let it sit for awhile, started, got it home.....
Last season didn't do it....Car ran fine..Put about 700 miles on it last season..
Today on highway and guess what? Started again.....Pulled off nearest exit and called AAA.........Towed to my house where the car started and I put it in garage...
Car is a worked small block four speed .....I'm thinking it may be a spark problem? Car has MSD 6 AL.....The times I bought it to my mechanic he says it's hard to diagnose because it's not doing it when I bring it to him..
Any idea what could be causing this......It's not something that happens all the time and car is well taken care of.....
Car is a 1973 ....
Last edited by zrc3john; May 7, 2017 at 05:14 PM.
Racer
Joined: Jun 2016
Posts: 336
Likes: 29
From: Il.
Sounds like it could be a fuel filter or something in the tank that when in the right position blocks the fuel inlet.Or a wire rubbed bare and touches to ground.
Last edited by sparky77; May 7, 2017 at 09:21 PM.
Le Mans Master
Joined: Dec 2006
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Reason I say the highway is because a few years ago I'm on the highway and car begins sputtering than backfiring....I pull over,car sounds like it's running on six cylinders......I thought bad gas, because everything looked fine......I let it cool down.....Not that it was running hot.....Car was fine, got it home .....
Next day I tried starting it, no start but cranks....I had no spark...Two days later car starts......???? Took it to my mechanic couldn't find anything wrong....
Next month on highway, same thing sputtering backfiring....Pulled over, let it sit for awhile, started, got it home.....
Last season didn't do it....Car ran fine..Put about 700 miles on it last season..
Today on highway and guess what? Started again.....Pulled off nearest exit and called AAA.........Towed to my house where the car started and I put it in garage...
Car is a worked small block four speed .....I'm thinking it may be a spark problem? Car has MSD 6 AL.....The times I bought it to my mechanic he says it's hard to diagnose because it's not doing it when I bring it to him..
Any idea what could be causing this......It's not something that happens all the time and car is well taken care of.....
Car is a 1973 ....
Next day I tried starting it, no start but cranks....I had no spark...Two days later car starts......???? Took it to my mechanic couldn't find anything wrong....
Next month on highway, same thing sputtering backfiring....Pulled over, let it sit for awhile, started, got it home.....
Last season didn't do it....Car ran fine..Put about 700 miles on it last season..
Today on highway and guess what? Started again.....Pulled off nearest exit and called AAA.........Towed to my house where the car started and I put it in garage...
Car is a worked small block four speed .....I'm thinking it may be a spark problem? Car has MSD 6 AL.....The times I bought it to my mechanic he says it's hard to diagnose because it's not doing it when I bring it to him..
Any idea what could be causing this......It's not something that happens all the time and car is well taken care of.....
Car is a 1973 ....
Safety Car
Joined: Jan 2009
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From: New York
Of course fuel filter , but you can not rule out ignition which will behave badly such as you describe.
If you had a GM HEI in there you would be getting told the Ecm is bad because they would do just as you describe sometimes when they started to fail
If you had a GM HEI in there you would be getting told the Ecm is bad because they would do just as you describe sometimes when they started to fail
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Yes I have HEI....Its not the original motor..
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Race Director
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From: Long Island
Filter sock is in the tank on the end of the pickup.
When the car reacts to heat, normally I look at the Heli electronics or the coil is bad.
An oddball I had was a fuel line too close to header pipe causing a boiling situation in the fuel line.
Hope you find it.
When the car reacts to heat, normally I look at the Heli electronics or the coil is bad.
An oddball I had was a fuel line too close to header pipe causing a boiling situation in the fuel line.
Hope you find it.
Melting Slicks
Joined: May 2012
Posts: 2,192
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From: Allenton Wisconsin
You mentioned MSD, what coil are you using, I've had numerous MSD coil failures cue to coil overheating and leaking oil. I now use the ceramic coil. As coils heat up when failing the problem you described, well maybe a new coil is your cure. To bad there aren't any Sun 1020 scopes around any more. T
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Le Mans Master
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You mentioned MSD, what coil are you using, I've had numerous MSD coil failures cue to coil overheating and leaking oil. I now use the ceramic coil. As coils heat up when failing the problem you described, well maybe a new coil is your cure. To bad there aren't any Sun 1020 scopes around any more. T
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Racer
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Suggest concentrating on whether there's a problem with the ignition box. If it will start/run okay at cold start, shut it off, and leave a trouble light with an incandescent light bulb, you know the old style bulbs that heat-up on top of the MSD control box, in an effort to simulate normal under hood heat. Once the box is really warmed up, (hot to touch) try starting it up. No-start=bad ignition box.
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You mentioned MSD, what coil are you using, I've had numerous MSD coil failures cue to coil overheating and leaking oil. I now use the ceramic coil. As coils heat up when failing the problem you described, well maybe a new coil is your cure. To bad there aren't any Sun 1020 scopes around any more. T
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Thanks for all the replies....Spoke to my mechanic about it this morning...At times over the years my fuel pressure gauge sometimes would read 2-3 psi...This was a concern but the car always always ran great...Only issue was what I posted...He feels it could be a fuel issue, will see...
I'm going to change the fuel sock anyway....I'm not running the tire carrier and the spare so taking the tank down will be easier....
I'm going to change the fuel sock anyway....I'm not running the tire carrier and the spare so taking the tank down will be easier....
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I have a Holley 750 CFM on it, it's not the stock carb....Fuel filter is on the fuel line in front of carb....It was changed two years ago...Should get it into the shop at end of week .....Will keep everyone posted in case they run into a similar problem..
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Well my mechanic changed the fuel sock..He explained to me that it was totally clogged up basically.......Could this be the problem? Let's hope...In his words he was like ,it was something he did not like....Fuel pressure was checked and everything seems good...
May take a 150 mile trip this week so I'm keeping my fingers crossed...
Thanks for all the replies...
May take a 150 mile trip this week so I'm keeping my fingers crossed...
Thanks for all the replies...
Le Mans Master
Joined: Dec 2006
Posts: 8,837
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Well my mechanic changed the fuel sock..He explained to me that it was totally clogged up basically.......Could this be the problem? Let's hope...In his words he was like ,it was something he did not like....Fuel pressure was checked and everything seems good...
May take a 150 mile trip this week so I'm keeping my fingers crossed...
Thanks for all the replies...
May take a 150 mile trip this week so I'm keeping my fingers crossed...
Thanks for all the replies...
