BUICK Tips/Advice Replacing a 3.8 231 Mechanical Fuel Pump

ssn696

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OK, I'll get this overwith now. "Replace it with a SBC". Maybe later.

This is last piece of the jigsaw puzzle to make this thing run reliably. I put a rebuilt E2MC on it and enjoyed an instant improvement. But I kept smelling gas.

There was a spot on the driveway, and when I looked up fuel was weeping out of the crimped seam. RockAuto has exactly one option, so I hit send over special ordering the same part number from Oreallys.

It's hard to believe, but this is a 35 year old car. When I was in high school, the same vintage would have been a Tri-Five. 😳 Do any of my fellow old-timers have any specific 'watch out fors' when installing this pump into the block? I have to move the power steering pump out of the way, break all the fuel line connections, and put a dab of assembly lube on the end of the cam lever. I also remember almost having a SBC fuel pump inserted and it hung up on something, all while not trying to smear the RTV from the gasket everywhere. So, any little BTDT stories would be helpful.

The end goal is to prove to my doubting spouse that, yes, I can actually make an old car run reliably. My kids will be safe behind the wheel because they won't want to be caught dead in it. 😜
 

303'505rollin

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Sep 4, 2020
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Colorado2newmexico
Haven't done a buick FP, is there a rod Like a sbc or a arm like an Olds. My kids love the older rides my daughter already wants the Olds and my sons like to show there friends when I pick them up from school in one
 
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ssn696

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Based on the picture on RA, it looks like an arm that rides on an eccentric on the cam or cup bolted to the timing chain gear, but I'm not an expert on Buick engine design.
3523AAF0-A6E5-452E-ADBB-4D42D6B48E1C.jpeg
 
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ck80

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Feb 18, 2014
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Haven't done a buick FP, is there a rod Like a sbc or a arm like an Olds. My kids love the older rides my daughter already wants the Olds and my sons like to show there friends when I pick them up from school in one
No rod, just an atm that tides on the eccentric. You've just got to rotate the engine over so it's in the relaxed position and it more or less slips right in.

Buick 3.8 being what it is, and orientations being what they are, you may find it easier to disconnect your metal fuel line from the carb, then attach the line on the new pump, then pump to block, then line back to carb instead of fighting with getting it tightened down with the pump on the block.

Only other tip, strange as it sounds, not every mechanical rwd buick 3.8 fuel pump is created the same. When switching the pump on my Canadian assembled 1987 cutlass with the 231 the normal parts house fuel pump had a much shorter arm than what came out of the engine. I sourced one based on my own research instead and while the arm was still yet another slightly different shape, the length was sufficient for it to actuate properly and it was good to go.

So. Check the old one against the new and don't get alarmed if it doesn't match exactly - just look for functionality. To this day I can't explain if it was a year difference and certain brands were trying to make one part for both odd and even fire engines, of if it was a Canadian thing, or what the deal was. Only that it happened.
 
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ssn696

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Advice was helpful. Thanks to all. Had to pull off the power steering pump and the AIR pump, quite the Rube Goldberg of bracketry. Replaced a missing bolt, and tightened a few missed by PO's mechanics...
C599D5F1-A73B-4815-9869-5373CFCE3A46.jpeg
When I pulled off the old pump, it had 'AC' cast into it. Either factory or maybe a GM service part. Unlike the replacement, It had a rub/reinforcing plate riveted to the top, but the replacement dropped in just fine. Does not have to last that long.
28C8E42C-D1CF-4209-BFF0-901FE24D8298.jpeg
I put some engine assembly lube on the lever arm and stabbed it in. The bolts had white sealant on them, so I put some Loctite thread sealer on them before bolting them in. I replaced some crumbling wire loom and rerouted some previously mangled wiring.

But it runs now, no check engine light and no gas fumes.

Has four wheels. Check.
Goes. Check.
Meets spouse's criteria to be called 'a car'.
 
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ssn696

Living in the Past
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Jul 19, 2009
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Buick 3.8 being what it is, and orientations being what they are, you may find it easier to disconnect your metal fuel line from the carb, then attach the line on the new pump, then pump to block, then line back to carb instead of fighting with getting it tightened down with the pump on the block.

Only other tip, strange as it sounds, not every mechanical rwd buick 3.8 fuel pump is created the same. When switching the pump on my Canadian assembled 1987 cutlass with the 231 the normal parts house fuel pump had a much shorter arm than what came out of the engine. I sourced one based on my own research instead and while the arm was still yet another slightly different shape, the length was sufficient for it to actuate properly and it was good to go.

So. Check the old one against the new and don't get alarmed if it doesn't match exactly - just look for functionality. To this day I can't explain if it was a year difference and certain brands were trying to make one part for both odd and even fire engines, of if it was a Canadian thing, or what the deal was. Only that it happened.
Every one of these tips was true and useful, and contributes to the tribal knowledge, now searchable, on this site. Thanks!
 
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