Help finding right fuel pump


New Member
Hey Buick guys, new guy here and right out of the gate need some input. I have a 1970 Buick Skylark Custom Convertible 350 4brl numbers matching engine, transmission. We’ve had the car about 5 years now and have enjoyed 4 trips to Cruising the Coast, we skipped this year. The fuel pump has gone out on it and I’m having trouble finding the right replacement. To begin with I went to auto parts store asked for the fuel pump for the 1970 Buick 350 with air conditioning, it has been in the trunk for 4 month. I went to Chang it out and the new pump had only nipple to connect line from gas tank, the one I took off had two nipples and I do have two lines coming from the gas tank. The other issue is that the old pump has one bolt hole (one closest to the front) that is threaded, the back hole is not, and the bolts are two different sizes. There is also a plate about 2” long on the top of the arm that goes in the block on the old one, new one does not. Can anyone tell me what’s going on here? Oh and the parts store said the old one is for a 72???
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It looks to me that a '70 with a/c air car should use 6470694 ('68-'74) and without a/c 6417173 ('68-'75). That's according to GM, in 1979. Looking at the fuel section of the parts manual, found here, you will see the third fitting described as a vapor return. and was used on all 350's. I have 350's that do not have the return line, so I can understand the confusion.

Those years could have some variances due to state pollution requirements. Your car was supplied with a return and you should use it. The earliest return I have is on a '66 Riviera.

Here are a bunch to look at on Ebay:
When I looked up your fuel pump on, it did not show a 3 line pump, which is the one you want. The vapor return line returns hot fuel and vapor to the gas tank to fight vapor lock. Buick used the vapor return on all A/C cars, and others. Having said that, there is no reason you can't use the 1972 and up fuel pump. The connections are the same, the inlet is 3/8" fuel line, the vapor return is 1/4" fuel line, and the outlet is 5/8-18 inverted flare metal line. Not sure why the 70 listings do not have the right pump. I would just use the 1972 pump.

The stock fuel pump does not have threaded holes. If one of yours is threaded, someone did that. The threads are in the timing chain cover. The fuel pump bolts to that. If you have two bolt sizes, I bet some one forced a bigger bolt into the hole they stripped, and it also tapped the fuel pump hole. What happens very frequently it seems, is that people strip out the threads in the timing cover. The reason for that is the fuel pump eccentric on the cam shaft needs to be in the low spot. If not, you are fighting the fuel pump spring when you try to bolt it up. People do that while tightening the two bolts that attach the fuel pump to the timing cover, and they strip out the threads in the aluminum timing cover. The way to avoid that is to crank the motor until the #1 cylinder is at TDC firing. If you have any doubt, just take the distributor cap off and crank the engine until the firing point of the rotor is pointing to the #1 distributor cap tower. In that position, the pump arm slips right in and you can thread the two bolts by hand.
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Active Member
california cars the A/C gets taken out. someone replaces the fuel pump and filter with a no A/C type. Now you have an open vapor return. New owner finds it one day, "where's this line go?"

anyways, it is very possible wrong part. this very common. we all know.