69 SMall Block Fuel Pump

[Erv M.]

I was told that the Ac/Delco fuel pump has been discontinued which is hard to believe. Does anyone have the part number for this pump? I need to buy a new fuel pump and at least wanted to put an AC/Delco on since I do not have an original.

Also doesn't the pump have a check valve in it to stop the fuel from draining from the carb creating a terrible cold start condition?

[Dick W.]

Re: 69 SMall Block Fuel Pump

AC is not in the manufacturing business anymore. You can buy a fuel pump in an AC box, with the correct numbers, but it will be most likely an Airtex manufactured pump. It will not have the AC cast into the body either

[Erv M.]

Re: 69 SMall Block Fuel Pump

Does it have the built in check valve that eliminates gas draining out of the carb?

[Guest]

Re: 69 SMall Block Fuel Pump

Check Paragon to see if they still have any.

http://www.corvette-paragon.com/cata...0-AF345743055A

[Erv M.]

Re: 69 SMall Block Fuel Pump

I am having a problem of the gas siphoning out of the carb and creating terrible cold start conditions. Do these fuel pumps have a check valve in them to stop the back flow of gas? If not what does dtop gas from siphoning out of the carb through the fuel pump?

[William C.]

Re: 69 SMall Block Fuel Pump

Are you sure the problem is the fuel pump and not the carburetor? Q-jets are famous for leaking out of the plugs at the bottom of the carb center section and emptying the fuel bowl, taking lots of cranking to refill the fuel bowl before a car will start.

[Erv M.]

Re: 69 SMall Block Fuel Pump

I took the carb off the car. Put it on some sockets to lift the base from the bench top and filled it with gas, no leakage. Car was not sitting long enough, 12 hours, for the gas to evaporate.

[Scott Marzahl]

Re: 69 SMall Block Fuel Pump

Do you have the correct carb to intake manifold gaskets on. I saw your post over on the C2 forum and there was a recent discussion from Lars on the same type of issue. If your intake has the smiley face on it, couldn't this be a heat/percualtion/evaporation issue?

[Jack H.]

Then your problem is elsewhere...

If you've ever taken apart a rebuildable fuel pump, you'll see how it's constructed internally. There are two umbrella valves which allow fuel to flow in ONE direction only and they open/close with the oscillation of the pump's main diaphram.

For a fuel pump to 'leak' you either have a tear/rupture in the main diaphram (look OUT for raw gas to flow into the crank!), or you have a defective umbrella valves. If you want to verify the pump's integrity, simply remove it and 'try' to force fuel to flow in the reverse direction!

[Tom S.]

Re: Then your problem is elsewhere...

Erv
I had the same problem with a 69 L-46. I pulled the carb, put it on the bench, no leaks. I changed gaskets no differance.I had the carb rebuilt, no differance. I pulled the carb again put in well plugs, no differance.I put on a NOS fuel pump, no differance.I sold the car! I never did figure it out! If you find out what the problem is please post it!Tom

[Erv M.]

Re: 69 SMall Block Fuel Pump

Time for me to go back to square one and take a closer look at the carb. No plans on selling the car, ran great with the old carb on her. Just gotta give it some more love!!

[Dick W.]

Re: Then your problem is elsewhere...

Erv, maybe you bought Tom's car.

[Scott Marzahl]

Re: 69 SMall Block Fuel Pump

Hmmm, maybe Lars was just looking for an excuse to go to LA and drink a few beers with you.

[Joe L.]

Re: 69 SMall Block Fuel Pump

Allen and Erv-----

1969 Corvettes with 350 cid engine did not originally use the AC type 40709 as seen in the Paragon catalog. The type 40709 was originally used for 1970-71 LT-1's and became the SERVICE fuel pump for 1968-69 Corvette small blocks MANY years ago when the original pump, AC type 40658, was discontinued through the GM parts system. Curiously, the type 40658 was available for many years thereafter through the Delco parts system. However, neither the 40709 or the 40658 are currently available through Delco or GM.

FUNCTIONALLY, the 40709 will work perfectly in replacement for any 68-69 small block. However, it is not correct, configuration-wise. It is VERY easy to discern a 40709 from a 40658. It could be done at a glance by any informed observer.