Fuel pressure problem in 1967 Cadillac Calais

[richardbergquist]

If I run him every day he’s fairly easy to start. If he sits for 2-3 days I’ll have to crank him for probably 10 seconds before he starts. If he’s sat for a week or two i will have to pour gas down the carb to get him to start or crank him forever (which I don’t wanna do). Fuel pressure problem? It loses fuel pressure quickly when it’s not running? What could cause that?

[rajeevx7]

Are you dripping petrol into the intake mani or into the bowl vent tube? Stabilizer may help reduce evaporation. A couple alloy one way valves on the feed and return lines would be an easy and rapid install to ensure petrol stays at the engine bay.

[TJ Hopland]

Has your carb been 'rebuilt' recently?   The early Quadrajets were very prone to having internal leaks that would let the fuel in the bowl leak into the engine.   The leaks are at the plugs that plug up holes from machining.   Its fairly easy to fix, most people just cover them with epoxy.  I'm sure it doesn't last forever so if it hasn't been done in a while it could need to be done again.

To check if that is your problem take the lid off the air cleaner and stick something like your finger in to hold the choke open then stroke the throttle while looking down the throat.  You should see a steady stream out each side.   A full bowl will give you 2 or 3 good squirts.   I don't know what the throttle linkage is like on that car or if you have cruise, you may need to remove the whole air filter assembly to access the linkage. 

The big round tube that stands up just in front of the choke is the bowl vent.  If you pour gas down there it will go into the bowl where it normally would be.   If you fill it and then get squirts you will know that is the issue. 

[Jeff Rosansky CLC #28373]

Cranking after it has been sitting for a few days is somewhat normal. But having real issues after sitting a while is not. The trick is to find out if the bowl is draining/evaporating, which it will, or if your fuel line is losing prime. That one is going to be harder to figure out. Is the fuel line original? How about the rubber lines from the tank to the metal lines? Don't forget it is relatively low pressure suction so it won't show leaks when it is running.
I would suggest you look at the fuel line very carefully especially at the clips because they rust under them. The problem is that any fuel seepage will evaporate so hard to see.
What I did was undo rubber at the tank and cap off the metal line (a piece of fuel line with a bolt in it will do). Then I undid the line at the pump and filled the line with mineral spirits. Then I blew light pressure shop air into the line. After a couple of minutes under pressure I started to notice seepage at a couple of the clips so I knew I had a line problem.

[richardbergquist]

Can I easily take the carb of and inspect this?

So you’re saying that if the car has sat overnight and it doesn’t get squirts from the jets the fuel then has leaked out from the bowl? Is there and easy and effective fix? Would I have to make all sorts of adjustments to the carb when I reinstall it if I take it off?

[Dave Shepherd]

Take the carb off, remove the top of the carb, fill the bowl, let it sit overnight, if the bowl has lost significant amount of fuel more than likely the lead plugs under the primary jets in the bowl are leaking, very common Quadrajet issue.  I've used slow set  JB weld to seal them. TJ's advice is spot on.