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Okay so i need to figure this out before I put the new fuel pump. The original pump had the fuel lines facing up. Most other gm make an models have the fuel lines facing down. Is up really correct!? I've had to literally return 2 different pumps until I finally got the right pump. Also is there a difference between ac and non ac cars?
car is 77 pontiac lemans
Last edited by Flashflood; Feb 1, 2026 at 01:47 PM.
Here's an old thread that has some pictures of a fuel pump mounted to the engine, then scroll down to see one with the timing cover off so you can see where the arm goes.
Make sure you keep the old fuel pump. If there's a core charge it's not worth the $10-$30. You can always have the old one rebuilt while the car is still on the road.
Make sure you keep the old fuel pump. If there's a core charge it's not worth the $10-$30. You can always have the old one rebuilt while the car is still on the road.
Yeah, it is upside down compared to other engines. Apparently Edelbrock didn't even realize it was an issue with their heads. Now fixed unless you want the RobMc high output mechanical fuel pump. Hopefully you get one that doesn't put out too much pressure. I am throwing an inline gauge to see what my 45 GPH Carter has. The pump output varies between different models, according to Carter. The correct 1970 pump was only rated at 30 GPH, according to Carter.
Okay so i need to figure this out before I put the new fuel pump. The original pump had the fuel lines facing up. Most other gm make an models have the fuel lines facing down. Is up really correct!? I've had to literally return 2 different pumps until I finally got the right pump. Also is there a difference between ac and non ac cars?
car is 77 pontiac lemans
Here's a hint. Not all GM engines are Chevrolets. And it's the Chevy pump that's "upside down"
Seriously, if your prior experience is Chebby, you can forget pretty much all of that when it comes to an Olds motor. Get a factory Chassis Service Manual if you plan to do any real work on the Olds.
Here's a hint. Not all GM engines are Chevrolets. And it's the Chevy pump that's "upside down"
Seriously, if your prior experience is Chebby, you can forget pretty much all of that when it comes to an Olds motor. Get a factory Chassis Service Manual if you plan to do any real work on the Olds.
well also buicks are facing down. I just couldn't remember how it went lol. Oh trust me owning this car i know how different olds motors are from buicks and pontiacs but honestly that's what makes me love it even more.
... is there a difference between ac and non ac cars?
Most Olds models with A/C had a return line to the tank. The corresponding pump had an inlet fitting, an outlet to the carb, and an outlet for tank return.
Use either the A/C pump or non-A/C (inlet and single outlet) depending on the plumbing in your car.
Most Olds models with A/C had a return line to the tank. The corresponding pump had an inlet fitting, an outlet to the carb, and an outlet for tank return.
Use either the A/C pump or non-A/C (inlet and single outlet) depending on the plumbing in your car.
that's why that other fuel pump had two lines for the tank. OK, I believe pontiacs equiped with olds motors don't have that.
Okay so i need to figure this out before I put the new fuel pump. The original pump had the fuel lines facing up. Most other gm make an models have the fuel lines facing down. Is up really correct!? I've had to literally return 2 different pumps until I finally got the right pump. Also is there a difference between ac and non ac cars?
car is 77 pontiac lemans
The fuel pump can only be installed one way, there's a notch which runs through a stud on the block which prevents it from being installed upside down. And yes, it is supposed to be facing up.
The fuel pump can only be installed one way, there's a notch which runs through a stud on the block which prevents it from being installed upside down. And yes, it is supposed to be facing up.
The two bolt pattern and flange are symmetric - they go on either way. The pump arm will prevent you from installing it incorrectly.
The two bolt pattern and flange are symmetric - they go on either way. The pump arm will prevent you from installing it incorrectly.
yup figured that with the chevy pump. Will get my new correct pump installed when the weather warms up a little bit. Hopefully i didn't mess the cam up by trying the wrong pump.
Just to mess with everyone, both of these are Oldsmobile fuel pumps. Both are shown in the as-installed orientation. Yes, the bottom one is an Olds diesel lift pump.
That Oldsmobile diesel lift pump would make a good addition to the "rarest Oldsmobile part ever" thread. Of course, every Oldsmobile diesel still on the road has one, but every mechanical lift pump I've bought recently for my 86 Ford diesel truck is junk and shortly fails. I'm surprised that the mechanical lift pump in my 71 98 is still working.
That Oldsmobile diesel lift pump would make a good addition to the "rarest Oldsmobile part ever" thread. Of course, every Oldsmobile diesel still on the road has one, but every mechanical lift pump I've bought recently for my 86 Ford diesel truck is junk and shortly fails. I'm surprised that the mechanical lift pump in my 71 98 is still working.
Although my 67 442 non air had 3 lines and my 67 vista with air doesnt.Also the vista has plastic inner fenders wheels.
Fuel return was typically used on cars where higher underhood temperatures were expected. 442s and many (but not all) A/C cars got it. Plastic inner fenders were phased in part way through the 1967 model year. The PIM shows that the call out for the plastic inner fenders was added 12-29-1966 (note G in the change block on the drawing). Both metal and plastic are shown as optional from that point on.
