Fuel Pump part numbers

[Bigpig455]

I've got a 65 Gran Sport that I think has a fuel pressure problem - I've had 3 diffeent carbs on the car, 2 AFB's and now a QJet and they all flood when shut off (and the QJet while running) I checked all the needles, seats and foats on the AFBs, and set everythign to factory specs. I'll do the same on the Q-Jet, but I think the problems is the car. Both the qjet and one of the AFB's were run on test engines with no issues.

The car is pretty straight forward, its a non A/C car, no return line, and I've got the heat blocked at the carb base. The heat riser is stuck, but open. I've got the metal shield under the carbs for insulation, and the manifold is cool to touch (150-170f ?)

I've had a guage on the line, it has 5lbs while running and quicky drops to 3-4 at shut off - however it holds it for a while and will shoot fuel everwhere if you remove the line from the carb (more than other vehicles I've had).

Some time ago Doc suggested insulating the pump with a phenolic spacer to cut heat, and I'll try that next but I'm wondering if I should just replace the pump while I'm at it...it's a old/old AC unit, and it works well, maybe too well!

My question is: are there two different part numbers for fuel pumps - one for A/C applications and one for non A/C? If there are and I've got a pump on there desinged for a return line vehicle, that might explain some things...

Thanks,

[WkillGS]

1966 has different fuel pumps, 40033 for non AC and 40250 for AC cars.
I'm only finding one number for 1965, AC 40371.
My '65 pump has the bottom portion held on with screws, the 66 pumps have a bottom that is crimped on.

I vaguely remember a service bulletin stating you could add a gasket between the carb and metal plate to help insulate it. I'll take a look.

[Bigpig455]

Thanks Walt -

Mine is crimped too. This thing is driving me crazy... I could see if it showed up on a gauge, but it doesnt  -maybe it's intermittant but I've watched the AFB flood over at 4lbs of pressure.....


Rhett

[WkillGS]

I vaguely remember a service bulletin stating you could add a gasket between the carb and metal plate to help insulate it. I'll take a look.

Not really related to your problem....
The bulletin I was think of is dated March 5, 1965. States that Buick switched to a better insulating gasket beginning Feb 22, 1965.  Complaints were (1) fuel was boiling causing aerated fuel that caused a lean condition after a hot start. (2) The more-volatile part of the fuel was boiling off after shutdown, causing a hard start next time.

Do you see exactly where the fuel is coming from after shutdown?

[Bigpig455]

I still might try it - it does act as if the pressure comes up after shutdown - on the qjet it coming out the accel pump shaft, at the fuel inlet threads (? - regular gasket, no teflon tape but I did remove the filter and spring and run the inline GF-94) and  and along the base to body gasket..on the AFB it was coming out the vents and along the primary thottle shaft...

it never was the best hot starter with the AFB, but I never thought much about it.

RT

[Brian]

I have had this same problem before, and the only way I fixed it was to add the fuel filter with the return port on it and run a return line to the tank like the AC cars came with.  That relieves the pressure and keeps it from pushing past the float needle after shutdown. 

[Bigpig455]

Thanks Brian - I might be doing the same thing -

I did find a place in MA (Then and Now Automotive -  http://dragsite.tripod.com/antique_auto_parts_cellar.htm) that had the correct AC, non-A/C fuel pump (40371) for the car - cool place with alot of NOS AC stuff...

I'm going to try it and insulate the base first..I dont really want to string a return line if I dont have to.

Rhett