'95 bucking & surging. Help!
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More Turbo
Joined: Nov 2000
Posts: 715
Likes: 11
From: Erie, PA
'95 bucking & surging. Help!
1995 351 engine.
Engine has a ping while it bucks and is clearly felt when driving. I can also feel it while at idle. As it warms up it gets a little worse and levels off. It never get bad enough to make it stall. Seems to sound and act like IGN system rather than fuel.
Replaced plugs, wires, cap, rotor & primary ign coil. Dealer replaced distributor & ign ctrl module with no improvment. Dealer checked fuel pressure, wiggle test, they scanned it and found no codes and no sensors out of range.
I am at the end, no idea what else could be wrong. Would a timing chain cause this, maybe somthing else that I am not thinking about?
Engine has a ping while it bucks and is clearly felt when driving. I can also feel it while at idle. As it warms up it gets a little worse and levels off. It never get bad enough to make it stall. Seems to sound and act like IGN system rather than fuel.
Replaced plugs, wires, cap, rotor & primary ign coil. Dealer replaced distributor & ign ctrl module with no improvment. Dealer checked fuel pressure, wiggle test, they scanned it and found no codes and no sensors out of range.
I am at the end, no idea what else could be wrong. Would a timing chain cause this, maybe somthing else that I am not thinking about?
Postmaster
Joined: Mar 2008
Posts: 2,703
Likes: 7
From: Des Moines, Iowa
do you have dual gas tanks? IF so does it have the same problem on both tanks?
Sounds like fuel/fuel delivery to me...
when was the last time you replaced the fuel filter? Any conditions that might lead to water in the gas??? Maybe some heet and a new fuel filter would solve the problem.
Just because you have good fuel pressure doesn't mean it's going to be constant fuel pressure. I don't know how your truck is set up but my old ones have a low pressure pump in each tank. If you only have the problem with one tank, it's the in-tank pump going bad. My truck also has a high pressure pump under the cab (on the frame) that increases pressure to the fuel rail. If you have a high pressure pump, they can go in and out (making the truck jump and buck) like mine did. Hitting it with a hammer sometimes "freed" it up and would run smooth for a while... I replaced the high pressure pump and everything is fine now...
Sounds like fuel/fuel delivery to me...
when was the last time you replaced the fuel filter? Any conditions that might lead to water in the gas??? Maybe some heet and a new fuel filter would solve the problem.
Just because you have good fuel pressure doesn't mean it's going to be constant fuel pressure. I don't know how your truck is set up but my old ones have a low pressure pump in each tank. If you only have the problem with one tank, it's the in-tank pump going bad. My truck also has a high pressure pump under the cab (on the frame) that increases pressure to the fuel rail. If you have a high pressure pump, they can go in and out (making the truck jump and buck) like mine did. Hitting it with a hammer sometimes "freed" it up and would run smooth for a while... I replaced the high pressure pump and everything is fine now...
Postmaster
Joined: Mar 2008
Posts: 2,703
Likes: 7
From: Des Moines, Iowa
I'd spring for a new fuel filter... they are a cheap and neglected maintence item.
Also don't quote me on it but I think a TPS going bad can cause bucking problems too... I'm just spitballing until someone more familar with the 92+ years jumps in.
Also don't quote me on it but I think a TPS going bad can cause bucking problems too... I'm just spitballing until someone more familar with the 92+ years jumps in.
Thread Starter
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More Turbo
Joined: Nov 2000
Posts: 715
Likes: 11
From: Erie, PA
Wouldn't a fuel filter cause it to bog down under WOT acceleration? Although it is underpowered, it really does not run worse at WOT. I could try but I really think it is IGN system related.
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