Needs throttle or choke

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VonCramp

VonCramp

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I let my Cuda set for 3 weeks without starting her. Now she doesn't want to run unless I keep working the throttle or close the choke. I cleaned out my Edelbrock carb and reinstalled. No luck. I installed another Edelbrock carb. Same results. I installed a Demon carb. Still no luck here either. As soon as I let off the throttle the motor dies instantly. I checked my inline Russell fuel filter. It's clean. Tried W-D40 to look for a vacume leak. No luck there either. I disconnected fuel line and let the pump run. Getting lots of fuel. So, I am starting to think something electrical perhaps.
 
I am running a Holley blue pump and a Holley regulator. I honestly do not know what my pressure is. I don't have a gauge installed. I do have the regulator adjusted out pretty far though if that helps. Thanks for helping out!
 
I discovered that if I spray carb cleaner directly into the carb that it idles up and runs until the cleaner burns off without working the throttle. Hope that helps guys.
 
Sounds like it is a large vacuum leak....you're compensating for the extra air with the accelerator pump, the choke, or the carb cleaner. Check all the lines and vacuum connections... very carefully. Do you have a vaccum guage to check? If so, is the engine cammed? (It will effect the vaccum readings.) Whne it runs with the choke, is it running smoothly, and at what RPM's?
 
My only line is the advance on distributor. I have tried different carbs (all used) with the same results. So, I am lead to believe that it is some kind of vacume leak. Any other possibilities I may be over looking? Crane 509" cam. So, no crazy vacume being pulled. 340 motor ran great. She just sat for a little while. Thank you so much for the advice!
 
At first look, the vacuum leak/lean condition surely looks like a problem, and hopefully you tried blocking off the advance hose to make sure.....But if the WD test showed nothing, and the fact that you've tried several carbs, leads me to the ignition as you have speculated.

This is a complete shot in the dark, but how do the plugs look? If you're running a electronic box, has the ground become compromised/corroded? Is your battery/charging system putting out 12+ volts? And then there's the coil? I'd probably look to try another one if you can't find another issue.

Like I said, these are guesses, and just a attempt to get you thinking about other things. After all, it could still be a vacuum problem that's just eluding you?
 
OldmanRick said:
At first look, the vacuum leak/lean condition surely looks like a problem, and hopefully you tried blocking off the advance hose to make sure.....But if the WD test showed nothing, and the fact that you've tried several carbs, leads me to the ignition as you have speculated.

This is a complete shot in the dark, but how do the plugs look? If you're running a electronic box, has the ground become compromised/corroded? Is your battery/charging system putting out 12+ volts? And then there's the coil? I'd probably look to try another one if you can't find another issue.

Like I said, these are guesses, and just a attempt to get you thinking about other things. After all, it could still be a vacuum problem that's just eluding you?
Click to expand...
I had checked #3 plug and it was a lite tan color. I am not sure of charging system other than I've been cranking for 3 days and it still starts and runs without jumping the battery. The box is a new orange box. I have motor grounded to the frame. I am running an old electronic distributor with a big Mallory coil. The coil is old too.
 
Where did you spray WD40 to test for leaks? This test is not 100% valid unless you sprayed it on all sort of intake system locations. And, you seem to have a pretty large leak. A vaccum leak could come in from anywhere in the intake system. Again, put a vacuum guage on it and see what you have.

BTW, do you have power brakes? If so, remove the vaccum line to the booster and plug it and try. Plug any vaccum line to the trannie too.

Have you set the idle speed screw up to see if it will idle at at, say, 1500 rpm without any help? Then recheck your fuel pressure and let everyone know what you have on that and the vacuum. We're all shooting in the dark without some definitive tests and data.

Changing the carbs 2x is very likely to have eliminated the possibility of a plugged idle passage in the 1st carb, which was my other thought.

Battery sounds OK. I owuld keep it on the charger as much as you can.
 
I know it sounds crazy but a ballist resistor going bad sometimes shows the same symptoms. It would be cheap and easy to try another one.
 
Make sure you have a good ground for your electronic ignition box (I am presuming you have electronic ignition). A bad ground or no ground can cause a lot of troubles that seem like carb troubles, but is actually due to a very weak spark.
 
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