Welcome to DC! We have a lot of C3 experts here, so I'm sure one of them will be able to get to the bottom of your problem. :thumbsup:
I have owned the car for 10 years and have rebuilt it frome the ground up. Fuel pump is 3 years old as is the sock in the tank. I think I may have had tunnel vision on this problem and "ass" umed it was ignition. I have a electric fuel pressure gage installed and the pressure always stays at 7-8 PSI. Could a bad pump show good pressure, but not deliver the flow? I have another pump I can try, but changing the pump is a PITA.really does sound like a fuel issue, like it's starving for some gas. How long have you owned the car? Any chance a previous owner put an extra filter in the fuel line somewhere?
You said it has good power once it gets past the bucking. I would not think the pump wouldn't be working under a light load and then start at higher rpm.Thanks for the ideas. I think I have now ruled out the dist since I have had 2 complete different systems on it and both did the same thing. Lars just rebuilt the carb and ran it on an engine so I will eliminate that. I have removed and plugged every vacuum line to no avail. I will attack the fuel pump next.
No back firing at all. I have not made any changes other than the Lars carb rebuild. It does still have last falls gas in it. I will try a different coil.You said it has good power once it gets past the bucking. I would not think the pump wouldn't be working under a light load and then start at higher rpm.
Any back-firing during the bucking? Carb base tight on the manifold? Vapor-lock? Water in the fuel? Other than the carb, have you made any major changes to anything? I dunno, just throwing spaghetti at the wall.
Try adding a pint of alcohol. Will absorb the water and burn .No back firing at all. I have not made any changes other than the Lars carb rebuild. It does still have last falls gas in it. I will try a different coil.
Added 42 bucks worth of premium gas (1/2 tank!!) and a jug of alky. Still runs like crap:down: . Tomorrow I will check the plug wires and replace the fuel pump.Try adding a pint of alcohol. Will absorb the water and burn .
Shouldn't the pressure be around 4 PSI ? That's what it is on my BB 800cfm....maybe you're getting too much fuel ?......I have a electric fuel pressure gage installed and the pressure always stays at 7-8 PSI......
I have no idea what it should be, but I thought 6-7 PSI was a good number. Anyone know what the spec is?Shouldn't the pressure be around 4 PSI ? That's what it is on my BB 800cfm....maybe you're getting too much fuel ?
7.5-9I have no idea what it should be, but I thought 6-7 PSI was a good number. Anyone know what the spec is?
You don't think I have a vacuum leak? I just got the carb back from Lars a couple weeks ago. It did this even before he rebuilt the carb. At the risk of sounding stupid, what is "APT"?Check to make sure your secondary air valve is operating smoothly and doesn't open too quickly
Then check to make sure your APT is operating smoothly and not sticking. It may have to be removed and both the barrel and piston polished a little.
I'm sure Lars set both correctly, but with the great gas we get these days, winter storage may have gummed up the apt a little causing it to stick at times. If you end up taking the top off, clean it out with some Injection Throttle Body Cleaner in a spray can.
Some crap in the gas may have gotten in the carb from installation. It is a good idea to run a long hose to a bucket and pump out a pint or so with the sarter before changing carb filters or carb.
Here is a pdf GM downloadable manual for the qjets.
http://www.bdub.net/manuals/Quadrajet_Service_Manual_1981.pdf
Good luck.:thumbsup: