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I don't think that's a lot of fuel pressure bounce. There is something going on causing the bowl to be overfull. Dirt on needle seat, flooded float, crap on pivot. Time for carb surgery.
I agree that the bounce doesn't seem excessive for a mechanical pump. I couldn't tell what the pressure read, though. If it's greater than about 8psi that's too much.
the little rubber nub on the float needle is pretty flat. the seat is also a little funny, from the wear mark, looks like the needle was sitting a little offset.
tried to get parts local but the repair kit was crazy money, $95 before sales tax. rockauto had the same thing for $16 so i went that route. i like to support local shops but not for that price difference.
parts should be here in a few days.
quick update, carb kit showed up, i didn't replace everything, just the base and air horn gasket along with the float needle and seat. kit looked pretty nice for $16, and made in the USA.
the car ran good before and i wasn't prepared to go thru the Qjet tuning learning curve, so i didn't mess with any adjustments and put it back the way i found it. only thing i checked was float height, which was correct at 1/4in.
with the carb back on it's running right again and not spitting gas out the vent, so i guess it's safe to assume the needle/seat seal just gave up.
another update, and this thread is becoming more of a blog, but anyway..
back to my fuel problem, the pressure seemed low and the fuel filter barely filled, the car still ran so i didn't think much of it.
well it got to the point where i had to squirt fuel in the vent to fill the carb bowl to start the car. then it would die after about 30sec. hooked my pressure gauge up and discovered pressure was bouncing between 1 and zero psi.
i pulled the fuel pump and checked it by securing it vise and pushing the foot thing, it had good suction. dang, now put it on and ran the feed hose into a can of gas , now the pressure gauge bounces between 6 and 7 psi.
So, crap. Clogged tank? I assume there is a screen or sock in the tank? hopefully pulling the tank is not too bad.
Carefully inspect the fuel lines. A cracked or rusty fuel line will cause the pump to suck air instead of fuel. Air is much easier to pump than a liquid, a small leak could cause your exact issue.
you're most likely right. i pulled the fuel tank and it's super clean, along with the sender. must have been replaced recently. it says "made in Canada" on it.
the rubber lines look poor so good chance to replace those.
just a quick look and the lines seem to disappear behind things. I'll have to trace them out tomorrow in the daylight.
BTW, the tank has 4 hoses attached, the feed line in the sender, not sure what the others do, assume one is a vent.
Anybody have a fuel tank/line diagram?
Have you tried blowing compressed air through the lines yet? It's possible they could be clogged.
The other lines go behind the rear seat frame to an oblong canister. The main lines are on the drives side and go through the chassis rail just past the hoses. Not an easy change without separating the body from the chassis. Check all the rubber first. If you still have an issue after that you will need to look at the lines. You will most likely have to replace the line in sections. Remove the rubber and plug the line on one side with a vacuum plug, then run compressed air into the line from the other side and see if there is a leak. I just went through this on my 71' Cutlass.
Blocked off the hose at the tank side, had my neighbor operate the blow nozzle at the front of the car while I crawled under, sure enough the rubber hose from hard line to sending unit was rotten.
Fortunately the fuel tank was one of the easier ones I've fought with, getting it back in took just a few minutes. Made me feel better about unnecessarily removing it in the first place.
all back together, gauge at the carb is bouncing between 6.5 and 7psi.
September 2nd, 2018, 11:14 AM
