carb experts needed
Thread Starter
Racer
Joined: Jul 2004
Posts: 450
Likes: 0
From: Fredericksburg VA
carb experts needed
Ok. Last week car was running fine, took it to the gas station and filled up. Came out of the gas station and the car started bucking really bad and then quit on me. It would start to fire up but then die immediately. I killed the battery trying to restart it, so I had to get the battery charged. At the time I tried messing with the throttle and saw that the accelerator pumps were squirting. Today I finally get the battery charged and go out to try and diagnose. Carb bowls are full of fuel, gas is getting pushed past the fuel filter, but no gas is coming out of the accelerator pumps...and I assume anywhere else because the car still won't fire, but turns over fine. Before I go tearing the carb apart in the rain what should I look for/what could be the possible causes? It's a holley 4150 750 mech secondary if it makes a difference.
Cliff Notes: Gas getting to, but not through carb. What to look for?
Cliff Notes: Gas getting to, but not through carb. What to look for?
Burning Brakes
Joined: May 2007
Posts: 945
Likes: 0
From: Ventura California
Stuck float needle? Although you stated the bowls are full. That being the case, the only thing I could think would be foreign crap in the carb but I'm not what you would call an expert. I've rebuilt more than a few though. My best advice would be to send Lars a P.M. and see if he might point you in the right direction. He IS what I would consider to be the premier expert on the forum with carbs. Good luck with it and let us know what you find.
Pro
Joined: Nov 2004
Posts: 607
Likes: 0
From: North Alabama
Ok. Last week car was running fine, took it to the gas station and filled up. Came out of the gas station and the car started bucking really bad and then quit on me. It would start to fire up but then die immediately. I killed the battery trying to restart it, so I had to get the battery charged. At the time I tried messing with the throttle and saw that the accelerator pumps were squirting. Today I finally get the battery charged and go out to try and diagnose. Carb bowls are full of fuel, gas is getting pushed past the fuel filter, but no gas is coming out of the accelerator pumps...and I assume anywhere else because the car still won't fire, but turns over fine. Before I go tearing the carb apart in the rain what should I look for/what could be the possible causes? It's a holley 4150 750 mech secondary if it makes a difference.
Cliff Notes: Gas getting to, but not through carb. What to look for?
Cliff Notes: Gas getting to, but not through carb. What to look for?
Thread Starter
Racer
Joined: Jul 2004
Posts: 450
Likes: 0
From: Fredericksburg VA
Ok, had a little more time to play around with it after work yesterday. Drained both bowls all the way and removed them. There was no obvious damage or grime or anything of that sort, but it was getting dark fast so I will admit I didn't spend a huge amount of time carefully observing. What I did notice is that when I had the bowl removed the accelerator pump was working. What I mean is when I depressed the pump cam on the bowl with it disconnected from the body gas would squirt from the little hole it's supposed to come out of. Not much obviously, just a squirt or two or whatever was left in the pipeing. I put the bowls back on, reconnected the lines and tried to fire it up again (wishful thinking I know). Both bowls filled up as they should, but still no gas coming from the accel pumps and still no start up. Don't know if this helps much or not, but it would seem to isolate the problem to something in the carb main body. Any ideas? I have a spare carb at my parents house, and if I can't figure anything out I might swing by there this weekend and put it on to see if it will start up with a different carb and work from there.
Safety Car
Joined: Oct 1999
Posts: 4,101
Likes: 10
From: NorCal
This might be a stretch, but I'd guess you picked up some water somewhere. Too bad it was dark when you pulled it apart or you might have seen it in the fuel. Best bet to check it is to pump some into a clear glass container and watch for the seperation. Be sure and disconnect the PRIMARY coil conection (the little wires) and not just the coil wire to the distributor, or in the case of HEI, pull the red connector on the side. No spark that way.
If it looks clean, hook it all back up and prime it with something like Berrymans B12 (pray carb cleaner, somehere between gas and ether in flameability, good stuff) and see if it runs clean and dies. That will eliminate any other issues and you can then pull the carb, take it apart and use said cleaner to clean it out and then use high pressure air to blow out the center section thuroughly. If you don't have air, take it to someone who does. I gotta say, those accellerator pumps almost never quit, they usually leak!
Keep plugging away, you'll get it.
Hans
If it looks clean, hook it all back up and prime it with something like Berrymans B12 (pray carb cleaner, somehere between gas and ether in flameability, good stuff) and see if it runs clean and dies. That will eliminate any other issues and you can then pull the carb, take it apart and use said cleaner to clean it out and then use high pressure air to blow out the center section thuroughly. If you don't have air, take it to someone who does. I gotta say, those accellerator pumps almost never quit, they usually leak!
Keep plugging away, you'll get it.
Hans
Thread Starter
Racer
Joined: Jul 2004
Posts: 450
Likes: 0
From: Fredericksburg VA
This might be a stretch, but I'd guess you picked up some water somewhere. Too bad it was dark when you pulled it apart or you might have seen it in the fuel. Best bet to check it is to pump some into a clear glass container and watch for the seperation. Be sure and disconnect the PRIMARY coil conection (the little wires) and not just the coil wire to the distributor, or in the case of HEI, pull the red connector on the side. No spark that way.
If it looks clean, hook it all back up and prime it with something like Berrymans B12 (pray carb cleaner, somehere between gas and ether in flameability, good stuff) and see if it runs clean and dies. That will eliminate any other issues and you can then pull the carb, take it apart and use said cleaner to clean it out and then use high pressure air to blow out the center section thuroughly. If you don't have air, take it to someone who does. I gotta say, those accellerator pumps almost never quit, they usually leak!
Keep plugging away, you'll get it.
Hans
If it looks clean, hook it all back up and prime it with something like Berrymans B12 (pray carb cleaner, somehere between gas and ether in flameability, good stuff) and see if it runs clean and dies. That will eliminate any other issues and you can then pull the carb, take it apart and use said cleaner to clean it out and then use high pressure air to blow out the center section thuroughly. If you don't have air, take it to someone who does. I gotta say, those accellerator pumps almost never quit, they usually leak!
Keep plugging away, you'll get it.
Hans
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
No. Water in the gas causes the fuel filter [paper] to restrict fuel from getting to the carb. Put some Heet de-icer in your gas tank and drive it around (low speed) for a bit. It will clear up. [Either that or you had some mechanical malfunction in the fuel system.]
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Racer
Joined: Jul 2006
Posts: 266
Likes: 1
From: S.E. Michigan
St. Jude Donor '07-'08-'09-'10
I had similar symptoms. When I rebuilt my QJet, I found a really stuck check ball (had to chip it loose). Ran MUCH better, then. This was caused by gunk, I guess.:o I used StaBil every winter. Not no more! 
Instructor
Joined: May 2007
Posts: 118
Likes: 0
From: Michigan
I had similar symptoms. When I rebuilt my QJet, I found that the float had warped enough to drag on the side of the bowl locking it in the up (full) position. This only happened at random - and I suspect it was temp related.