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Engine losing power cutting out **fixed**

br0nc0xrapt0r

Loves pickles
Joined
Sep 28, 2007
Messages
5,437
Yesterday it was fine today it starts and idle's/revs fine. but as soon as you put it in gear and take off it cuts out and then surges forward like it's catching up. Its a 351M C6 in a 78 bronco, I changed the fuel filter and tried running it with no air cleaner and no change at all. I want to check the hei dizzy but don't have enough time I gotta go back to work.

any ideas?
 
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cwcorbin

Jr. Member
Joined
Sep 12, 2009
Messages
53
Check for a loose coil wire... Had one of the factory friction connectors get loose on me, and just the wire moving under accel/decel would cause it to stall/start. Felt like the float levels were low, and it was sloshing /starving. Good luck
 

broncnaz

Bronco Guru
Joined
May 22, 2003
Messages
24,341
Check to see if the accelerator pump is working. Also check the vacuum line to the modulator and the tranny.
 
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br0nc0xrapt0r

br0nc0xrapt0r

Loves pickles
Joined
Sep 28, 2007
Messages
5,437
Working in the dark still. I may have found about 40 vacuum leaks but no massive improvement, hopefully I'll get the weekend off and I can fix it.
 

markperry

Bronco Guru
Joined
May 8, 2009
Messages
4,175
Check for a loose coil wire... Had one of the factory friction connectors get loose on me, and just the wire moving under accel/decel would cause it to stall/start. Felt like the float levels were low, and it was sloshing /starving. Good luck

HEI has no coil:-* Well not the kind I think your talking about?
 
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br0nc0xrapt0r

br0nc0xrapt0r

Loves pickles
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Is it possible that the mech fuel pump is dying? it now doesnt even want to rev but still idles fine.
 

airbur

Bronco Guru
Joined
Jun 3, 2008
Messages
2,763
Loc.
Castle Pines, CO
I just had a similar issue...I went through and replaced all the plugs and wires and it's disappeared for now. Sounds like you've already covered that though.
 

garberz

Bronco Influencer
Joined
Jun 24, 2007
Messages
6,856
Loc.
Conejo Valley, Ca.
Is it possible that the mech fuel pump is dying? it now doesnt even want to rev but still idles fine.

I've seen symptoms where it idles but won't rev, turned out to be a bad coil. The coil had enough strength to idle but couldn't handle the demand of current for increasing RPM's. Coils are cheap, good to carry a spare also.
Mark
 
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br0nc0xrapt0r

br0nc0xrapt0r

Loves pickles
Joined
Sep 28, 2007
Messages
5,437
I've seen symptoms where it idles but won't rev, turned out to be a bad coil. The coil had enough strength to idle but couldn't handle the demand of current for increasing RPM's. Coils are cheap, good to carry a spare also.
Mark

I'm really scared of that since it's an HEI unit. I replaced the fuel pump with little to no improvement and also checked cap and rotor things seem to be in order.
 
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br0nc0xrapt0r

br0nc0xrapt0r

Loves pickles
Joined
Sep 28, 2007
Messages
5,437
At this point, I would just buy another one and see if it solves your problem. If it doesn't, at least now you have a spare.

Touche but I am trying to sell said bronco, it eats up too much funding for the 69. I don't really want to but another dizzy and find out thats not the problem. what else could it be?
 

DirtDonk

Contributor
Bronco Guru
Joined
Nov 3, 2003
Messages
47,275
Should be a spec for testing the coil with an ohm meter. Maybe someone here knows what the GM spec is?
Is it a standard coil as far as you know, or is it an updated aftermarket one? What brand is the distributor?

Paul
 
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br0nc0xrapt0r

br0nc0xrapt0r

Loves pickles
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Sep 28, 2007
Messages
5,437
No clear markings on it, this is what it looks like. Perhaps it's an ebay special.
 

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broncnaz

Bronco Guru
Joined
May 22, 2003
Messages
24,341
Should be a standard ch#vy hei coil availible at any parts store. If you check the web I'm sure you'll find instructions on how to test the coil. It could also be a bad module again standard ch#vy part and the parts store should be able to test the module.
 
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br0nc0xrapt0r

br0nc0xrapt0r

Loves pickles
Joined
Sep 28, 2007
Messages
5,437
Should be a standard ch#vy hei coil availible at any parts store. If you check the web I'm sure you'll find instructions on how to test the coil. It could also be a bad module again standard ch#vy part and the parts store should be able to test the module.

this looks exactly like what I need
 

broncnaz

Bronco Guru
Joined
May 22, 2003
Messages
24,341
I'd probably just hitup the local parts store as the coil does come out of the cap all you need to replace is the coil. Should be way cheaper and quicker to get than a whole cap setup.
 
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