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PostPosted: Sun Aug 23, 2015 4:27 pm 
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Joined: Sat Aug 22, 2015 1:09 pm
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Here is the scenario: I bought a 1980 Chevy Luv with only 70K miles. It was a California truck and in pristine condition. The truck has had a run away engine since it rolled of the car shipper. It revs so high, I am affraid I'll blow an engine. This truck is too nice to not becareful, so I bought a new rebuilt carb, assuming the choke was bad. I owned the exact same truck in high school and never had this problem before. So I installed the carb and the problem is the same!! The throttle is not hung up. The carb should have been a plug in and go, so I am really frustrated. Anyone got any ideas?

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1980 Chevy Luv yellow 70K miles
1978 Chevy Luv red 80K miles
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PostPosted: Mon Aug 24, 2015 4:56 pm 
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LUVTruck.com Lifer

Joined: Mon Apr 07, 2008 12:36 am
Posts: 607
Location: Northern, East Bay, Calif
What do you mean a run away engine ?
So this truck ran this way when you bought it ?...i'd ask the seller he should know the history

sounds like its getting all 3 elements Fuel, air, spark, have you tried to adjusting anything ?

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PostPosted: Mon Aug 24, 2015 6:16 pm 
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Joined: Fri Jul 01, 2005 9:41 pm
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Location: Camarillo, CA
Check for vacuum leaks, make sure the brake booster is not leaking, pinch off the line to the booster.

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PostPosted: Mon Aug 24, 2015 11:58 pm 
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LUVTruck.com Lifer

Joined: Sun May 15, 2005 4:57 pm
Posts: 680
Location: Cornelius Ore
I too am wondering what you mean by "reving". If the engine is cold and the choke is set it will rev a bit high after it starts, maybe 2000 rpm. You just blip the throttle a bit and it should drop down a bit. You said the throttle is not hung up, so have you removed the air cleaner and with the engine off looked down into the carb? Push open the choke, look down in, and see that the primary and the secondary throttle plates are closed completely.
With these both closed there is no way it can rev up. No air--no fuel--no rev.
One other thing--make sure all vacuum hoses and lincages are connected properly so that vacuum when the engine starts is not pulling open the secondary throttle plate or something like that. Let us know.


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PostPosted: Sun Oct 04, 2015 11:21 am 
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Joined: Sat Aug 22, 2015 1:09 pm
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Let me clarrify the description of a run away engine. When I crank the motor, it starts and it immeadiately goes to max RPMS possible (sounds like 5-6K). Its almost like a hung up throtle, but it is not. I can't see any disconnect vaccum lines. I tried swapping out for new carb, thinking it was a hung up choke or something. It did the SAME thing. That has me stumped. Has this happened to anyone else?

I appreciate any advice.

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1980 Chevy Luv yellow 70K miles
1978 Chevy Luv red 80K miles
"Don't tread on me"


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PostPosted: Sun Oct 04, 2015 6:11 pm 
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Did you crimp off the brake booster line yet?

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PostPosted: Sun Oct 04, 2015 10:14 pm 
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LUVTruck.com Lifer

Joined: Sun May 15, 2005 4:57 pm
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Location: Cornelius Ore
I assume you looked into the carb to see the throttle plates both closed? Have a helper start the truck while you look at the carb lincage, does anything move? Make sure you don't have an after market cruise control installed that is toast? Two carbs with the same problem means there is something external to the carb that is wrong. Vacuum line connected to the wrong place or something. Keep us posted.


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