Carb trouble
Thread Starter
Instructor
Joined: Nov 2005
Posts: 243
Likes: 0
From: KC Kansas
Carb trouble
She was running great an hour ago.
Got on the highway and when I got off she wanted to die and not hold idle. (Died at stoplight)
Now while cruising down the road with idle at 1300 I gently press on the pedal and nothing happens for a second then idle goes down for a second then jumps up to 2300 and jerks the car.
I love the power and had great throttle response just earlier today. Nothing was wrong. Did something come loose on the carb? Bad fuel?
Help please, I was having so much fun finally having my baby after almost 2 years of work.
Got on the highway and when I got off she wanted to die and not hold idle. (Died at stoplight)
Now while cruising down the road with idle at 1300 I gently press on the pedal and nothing happens for a second then idle goes down for a second then jumps up to 2300 and jerks the car.
I love the power and had great throttle response just earlier today. Nothing was wrong. Did something come loose on the carb? Bad fuel?
Help please, I was having so much fun finally having my baby after almost 2 years of work.
Le Mans Master
Joined: Apr 2007
Posts: 7,353
Likes: 72
From: Graceland in a Not Correctly Restored Stingray
Sounds like fuel starvation, which raises more questions than answers at this point. For starters...
Was anything in the tank for those 2 years, and is the gas fresh?
Did you check your filter(s)?
How old and what type is the pump?
Is the carb new or newly rebuilt?
Hang in there, maybe one of the gurus will hit it on the head...
Was anything in the tank for those 2 years, and is the gas fresh?
Did you check your filter(s)?
How old and what type is the pump?
Is the carb new or newly rebuilt?
Hang in there, maybe one of the gurus will hit it on the head...
Racer
Joined: Jul 2006
Posts: 337
Likes: 10
I had a sudden problem with my 77 q jet a while back. Not quite the same issue as yours, but it happened suddenly none the less.....and she had run fine a day before. The problem turned out to be air and/or internal fuel leaks due to old gaskets. I think my issue was exacerbated by the use of carb cleaner in and around the carb, and allowing it to sit overnight before starting. A simple rebuild kit and 3 hours fixed it....ran better than ever.
Thread Starter
Instructor
Joined: Nov 2005
Posts: 243
Likes: 0
From: KC Kansas
Thanks for the quick replies but its a brand new Demon carb, filter looks good, gas was cleaned out and new installed, although the pump is old. I have a new one I might have to put it on just to rule out one more thing.
Veteran
Joined: Oct 2005
Posts: 1,284
Likes: 81
From: Nashville, TN
First off with the Demon carb, check and make sure your float bowls are in the middle to bottom range, next make sure all the carb bolts are tight(not talking about the mounting bolts), I have had a few BG carbs come through that the bottom throttle plate bolts were loose. If all the base adjustments are set good then I think your problem lies in one of two areas.
1. put a vacuum gage on your manifold carb vacumm and read it at idle in gear. Whatever it says put in a power valve at least 2 sizes smaller or 1/2 the reading. For example at idle I pull between 6" to 7" of vacuum and I run a 3.5 power valve.
2. If it is an off idle stumble condition then you could try opening your idle mixture screws open at a 1/8 turn at a time. If your idle is too lean you will stumble going to your secondary circuit.
If neither of these two fixes your problem then you might try a different squirter size or check your pump linkage too make sure it starts to open right with the throttle linkage and not before. Also check your transfer slots to make sure they are at .020 and equally spaced.
Hope this helps,
Rich
1. put a vacuum gage on your manifold carb vacumm and read it at idle in gear. Whatever it says put in a power valve at least 2 sizes smaller or 1/2 the reading. For example at idle I pull between 6" to 7" of vacuum and I run a 3.5 power valve.
2. If it is an off idle stumble condition then you could try opening your idle mixture screws open at a 1/8 turn at a time. If your idle is too lean you will stumble going to your secondary circuit.
If neither of these two fixes your problem then you might try a different squirter size or check your pump linkage too make sure it starts to open right with the throttle linkage and not before. Also check your transfer slots to make sure they are at .020 and equally spaced.
Hope this helps,
Rich
