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Bucking issue under load?


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I could not wait till the "real test" tomorrow. I used the truck last 2 days to / from work about 120 miles.

I could feel the miss more when the motor was cold and seen it run lean so I wanted to swap the pickup coil in the dist.

Well did not go good. It was a easy swap but the out come was really really bad.

As soon as you gave it throttle the motor bucked even worst than when pulling the trailer.

I have seen it posted others having problems when they replaced the coil so I think I am one of them now.

I also pulled all the plugs, #4 looked rich? #1 & #6 looked lean the rest looked good.

I tried to take a compression test the only gauge was a push in and the rubber was rock hard :nabble_smiley_cry: time to hit HF for new compression tester.

I got 90 psi with it not sealing so as a guess 120 or so but I call the compression good.

I swapped the 2 rich plugs for #1 & #6. lean plugs.

When swapping pickup's I seen the old unit had a gap between the coil and reluctor, and the plate the coil was on did not have the plastic pads so it flopped all over.

The new unit when installed the coil and reluctor were way to close (touching?) at the top and gap at bottom but the plate had the pads.

I think the 2 parts hitting is why it ran like crap and bucked.

My fix was to use the new plate with pads and the old coil. It came out with a nice gap and the plate did not flop around.

When I got the dist. installed, I marked everything so I did not have to use the a timing light.

It cranked over like the timing was way to advanced? I backed it off a bunch and it started but ran like crap but also way better than the bucking with the new coil as you could raise the RPM.

Timing light showed it was at 40* BTDC!!!! but no kick back on start up now but had a miss at idle and lean on the AFR.

I adjusted the timing to 15* BTDC and the idle miss went away and the AFR went to the rich side and I was ok with both.

I also checked the dist. advance, RPM it cam up with RPM but it was pretty high. Think that is what I worked it out with vacuum advance to stop pining.

Next was the vacuum advance and that was NG! No wonder why I was not getting any pinging with the new carb.

Port did not have vacuum when the RPM went up, nice china carb NOT!

I may rework the factory carb and put it back on stay tune on the carb.

The road test with out trailer went really good. I did not feel any miss on the run but will see with the trailer to

Dave ----

edit: I also checked for vacuum leaks, none found

Well, it looks like you found the problem - the pickup. But introduced another problem along the way, which you solved. Well done! :nabble_anim_claps:

I hope the run with the trailer goes well and you have turned a corner. :nabble_crossed-fingers-20-pixel_orig:

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Well, it looks like you found the problem - the pickup. But introduced another problem along the way, which you solved. Well done! :nabble_anim_claps:

I hope the run with the trailer goes well and you have turned a corner. :nabble_crossed-fingers-20-pixel_orig:

I hope it is the right turn and not into a wall :nabble_anim_crazy:

I am running out of things it could be, to the point of thinking about HEI dist.!

Dave ----

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Well, it looks like you found the problem - the pickup. But introduced another problem along the way, which you solved. Well done! :nabble_anim_claps:

I hope the run with the trailer goes well and you have turned a corner. :nabble_crossed-fingers-20-pixel_orig:

I hope it is the right turn and not into a wall :nabble_anim_crazy:

I am running out of things it could be, to the point of thinking about HEI dist.!

Dave ----

Good job! Hope it goes well!

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Good job! Hope it goes well!

Good news it is fixed!

Pulled the trailer 20 miles to the cruise with no issues.

Talking to a member on that other forum kind of had the same thing happen.

The star wheel was hitting the coil.

I think the pads missing let the coil move all over causing the miss leading to the bad #4 plug and bucking.

Being the new pickup was hitting the coil and it would not take any throttle with out bucking was a clue.

We are good now and hope for another 28k miles :nabble_smiley_evil:

Dave ----

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Good news it is fixed!

Pulled the trailer 20 miles to the cruise with no issues.

Talking to a member on that other forum kind of had the same thing happen.

The star wheel was hitting the coil.

I think the pads missing let the coil move all over causing the miss leading to the bad #4 plug and bucking.

Being the new pickup was hitting the coil and it would not take any throttle with out bucking was a clue.

We are good now and hope for another 28k miles :nabble_smiley_evil:

Dave ----

That's great!

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Good news it is fixed!

Pulled the trailer 20 miles to the cruise with no issues.

Talking to a member on that other forum kind of had the same thing happen.

The star wheel was hitting the coil.

I think the pads missing let the coil move all over causing the miss leading to the bad #4 plug and bucking.

Being the new pickup was hitting the coil and it would not take any throttle with out bucking was a clue.

We are good now and hope for another 28k miles :nabble_smiley_evil:

Dave ----

Excellent! Glad you got it fixed. :nabble_anim_claps:

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