Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem

hard start hot and white vapor out top of eddy #1904

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kelly76:
Hi, this is my first post but I've searched for hours looking for a solution. I recently kit'd an Edelbrock #1904 quadrajet with Cliff's standard kit. From what I could tell (and I'm no pro on the internals of the quadrajet yet but getting closer), the carb is all stock along with the 73 jets and the rods. I put this on a 250 hp 350, stock engine and performer intake. It fires right up cold and runs awesome down the road, at WOT, etc..  However, when I shut it off, anytime from 45 seconds to 30 minutes after shutdown, it is very hard to start when hot. I can pump the throttle and fuel squirts out but eventually have to hold throttle wide open and crank for 15-30 seconds or so.

Upon shutdown when hot, I can pull air cleaner and see a white vapor pouring out of the primaries. What is this a sign of?  Sorry for the long story.

Float is set at 3/8" according to edelbrock information. Choke is staying open when hot and cranking. Timing is at 14 base and 34 total. Car idles great and throttle is very responsive while running. Fuel pressure is unknown at this time but a regulator/gauge should be here Tuesday. I'm thinking with the stock mech fuel pump I'm running a bit high. It is rated at 7-9 psi.

This setup is in a '64 rambler American so the engine bay is tight and things are hot. Would a spacer under the carb help or insulating the fuel line?  Thanks for all your help.

Zac Agee:
I'd listen for any gurgling sounds that will let you know if its boiling fuel can happen befor and after the fuel pump specially with headers. If its boiling can fix by insulating lines or running a return if possible

kelly76:
I tried that a few times over the last several days. Can't hear anything, just see the white 'smoke' that comes out of a passage in the primaries. No headers, just exhaust manifolds, but the engine bay is small and gets hot in there. I did try to insulate the lines with what I had laying around (funds depleted for now).  I used 1/2" copper pipe foam insulation wrapped in hvac foil tape.  After driving for 5 miles today (95+degrees), I popped the hood and couldn't hold onto the first 6" of fuel line coming out of the carb for more than couple seconds.

I'm guessing heat is my enemy here.  I'm gonna open up the shroud some more (I think it's not allowing enough air past it during hwy use as the car gets a tad warm on the hwy  or remove it completely and go with dual electric fans.

As always, thanks everyone for their suggestions and please keep them coming.

kelly76:
Well, I installed a pressure regulator. Have set it anywhere from 4.5 to 6 psi and still have same issue. I then installed 1" phenolic spacer.....still have same issue. Idles great, drives down road great, runs great at wot. Upon shutdown, white vapors, fuel dripping on primaries and hard start.

Anyone have any suggestions?

kelly76:
Ok. Last attempt to resolve before swapping on my Holley. Please if anyone has any suggestions I'm all ears. Today I spent a lot of time setting the float at different levels. 1/4, 5/16, 3/8, and 11/32". Same result each time. I did find out that on a cold engine, if I fire it up, run it for about 3 min and shut it down I will still get the white vapors with fuel dribbling onto primaries and leaking out throttle shaft.

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