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Fuel pump woes -- '64 Impala

15K views 18 replies 8 participants last post by  Madencali 
#1 ·
Seems as if I am making a career changing fuel pumps. The car is a '64 327/300HP and it is on it's 3rd (original style replacement rebuildable type) fuel pump. The original pump was replaced when I built the engine ....just because it was 47 years old. The (pressed in) pivot pin on that replacement pump eventually started working out so I replaced the pump rather than driving the pin back in since it would only work its way out again. The next fuel pump (number 3) made me call a roll back after the engine shut off 30 miles from home. When I disassembled that pump I found that one of the valves had simply fallen out and was laying on top of the diaphram.
Now, with replacement pump #3 I noticed that oil had accumulated on the bottom of the pump to the point of dripping. There was no oil coming out of the weep hole at the top of the pump. The only oil was at the very bottom. I tightend the two screws on the bottom of the pump and so far after about 150 miles it is still oil tight. The were alreay quite tight. All I managed to accomplish was to tighten them further; less that an eighth of a turn.
I am concerned about two things. First, if the screws weren't tight enough to begin with, they will probably be the source of a leak again.
Second, upon further thought, I do not know if there should be any oil accumulated in the bottom (below the bottom gasket) of the fuel pump in the first place. Is that normal? I don't think so.
These Airtech pumps at about 57 bucks apiece.
Am I the only one to experience this? Any thoughts or knowledge or experience or suggestions from anyone?
Thanks,
Bob
 
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#2 ·
Bob,
Your story is not giving me a good feeling. I still have the original pump that the General Installed at the factory and the last few years I have been thinking about rebuilding or replacing it. Mine is also on a 64 327/300 so I await your solution.
Sorry I can't help but I am interested in any resolution you find.
I think I will just keep a spare with me and rebuild the original when it finally gives up.
 
#5 ·
As to the oil are you referring to oil accumulating in the fuel pump boss. If so this is normal and it will pool there as it has a restrictive return oil path. It shouldn't leak if you used a gasket and your mounting plate is flat (as in not warped). The 1/4-20 bolts torque down to 34 inch pounds, and they have a double star washer to hold them tight so that they do not loosen up over time.

Few replacement parts are made to the same standard of quality demanded by the General back when these cars where new. Part of the problem lies with the policy of your local parts store. That policy is they will cheerfully give you a replacement part if it proves defective. (notice that they don't offer to pay your labor bill to R&R the part or your towing bill)

This is because you are the QC department. Rather than paying someone to verify that they have good parts on the shelf the way GM did it with statistical testing of received parts; they just assume that they will have a limited number of known bad parts that they will sell to you and if you happen get one that is bad it is just your bad luck. They will give you a good one (they think with a 96% assurance of being correct) to replace it. This keeps their cost down and profits high. We accept this policy by buying cheap (it is why Wally World exists; every one knows it is bad for the common man but everyone still shops there hoping someone else will buy elsewhere else to correct the problem).

When I shop I avoid Discount any brand store and look at all of the NAPA parts I buy to see where it is made. If it isn't made in North America (I used to say made in the USA, but I have had to relent recently with NAFTA) I won't buy it. Period. I will do without or rework something else to make it work.

Big Dave
 
#6 ·
Thanks, Dave.
....and Yes, I leaned long ago that unless one enjoys swapping out 'warranteed' parts, one should avoid the discount auto parts stores which is why I usuall only deal with NAPA. Oh, did I mention that my Airtech pumps came from the CarQuest store?
'Shoulda kept and rebuilt my original AC pump. Shame on me.
A-n-y-w-a-y,......
I am not certain about what you refer to as the "fuel pump boss". This oil leak is the gasket that seals the bottom 'cup'(?) to the valve assembly above it and is retained with two slotted screws. Are those the 1/4X20s that you mentioned?
 
#7 ·
Dave,
I was faily sure that that there shouldn't even be any oil below the bottom gasket and accumulating in the cup that is retained to the valve assembly above it with the two (now over thightened) screws. Are we suggesting that I replace this Airtech pump with a genuine AC from say Corvette Central, ....like I should have done in the beginning?
 
#8 ·
I believe so.

I use a Holley high volume (part number 12-327-25 rated at 170 gallons per hour) pump whenever I have to use a mechanical pump (three valve pump with adjustable spring pressure).

I generally rely on an electric pump (Aeromotive A2000) as they are reliable and flow a large volume of fuel that is pressurized from the tank forward (with a matching return line). I do not like a dead head fuel delivery system as it heats the fuel (and if it is a mechanical pump it heats it even more as the engine heat is transfered to the fuel by the aluminum pump body which is an excellent conductor of heat or electricity). You can buy a submersible pump that is quieter that is part of your fuel pump pick up and fuel gage sending unit that just drops into your fuel tank in place of the stock pick-up and fuel gage sending unit. But they are rarely as cheap as a replacement A-C fuel pump.

Big Dave
 
#9 ·
Thanks again. Dave.
I agree and if I wasn't trying to keep my '64 "as delivered" the Aeomotive unit would be the way to go.
This time I will simply call Corvette Central, bite the bullet, pay the $124 for "correct" fuel pump with 'AC' cast on the top and bottom and hope for the best.
 
#10 ·
Some great info & ideas here from all....however I need some specific input from any who've had experience with SBC mechanical fuel pumps that actually last and resist ethanol and methanol blended fuels (specifically the darn diaphram). I, too, am tired of annual or sometimes more frequent pump-swapping...my labor counts for something, right? I prefer to stay mechanical rather than electric.

I've researched the following pumps to determine if manufacturers specifically state or address this issue, could only find some partial details, so anyone with carnal knowlege of any of these being used by yourselves please advise me (and if there are good ones not on my list please advise)- thanks all in advance for your help!

Edelbrock 1721 (states OK for blended fuels on website & tech line).

Carter M4981 (states"functions in the presence of alcohol, stale gasoline & ozone")

Airtex 40987- states "Upgraded seals and laminated pump diaphragms ensure compatibility with modern multi fuel blends" and is $19.00 at AutoZone. Really?

Holley 12-834- states "not for alcohol or methanol", so not a propsect.

NAPA (Echlin & Belknap): Have replaced 2 already, won't use again.
:pout::clonk::wacko::mad:
 
#12 ·
Thanks, Dave- I didn't know about diaphragm color being an indicator of content and chemical compatibility! Will use that tidbit in my search. Some of these pumps are $130.00 list, I'd like to hear from anyone having used/ using them as to their function and reliability. I daily-drive my '68 and try to keep it as stock as possible, with only forced changes of an Edelbrock electric-choke 550 carb and HEI distributor. I still run factory ramshorns with dual exhaust, so PSI volume needs are low for me...otherwise I'd jump on your recommended electric bandwagon!
:)
 
#13 ·
My 1965 Impala with original 396-325 has been through 2 mechanical pumps in the last 15 years. We drive the car in the warmer months and it sits most of the winter with occasional start up. I run only premium fuel, but it does have 10% alcohol in it. So I would say fuel pumps are not a problem here.
 
#15 · (Edited)
Thanks, Larry and Eddie....we drive 4 months yearly here, as the Rocky Mountains of Montana require us to park our classics and drive big bad diesel pickups most of the year to combat the ice, SNOW, and minus 30 degree winter temps. Eddie, how much carnal knowledge do you have of the Carters? I like their info and design specs on their website, and they're around $70.00 vs the other top-shelf name at 120.00+.....
 
#16 ·
I myself think i need to swap my fuel pump, I'm not sure though. I've been fighting with my car, if it sits it just doesn't want to fire up. If you start it everyday or so it's fine. I recently put on a new carb, but I wanted to see what would happen if I let the car sit for a week. Sure enough it wouldn't start as I expected, even though I didn't want to face that music. I have a inline universal fuel filter that's just below the carb. Today I went and bought a new one and a air filter. I put them on and tried to fire it up and still nothing (like I knew would happen). I realized the filter was bone dry, no fuel had entered the filter. I then took the the line off and no fuel spilled out. I then fastened the line back to the filter. My buddy said hey try it again and let me see what's going on. This time the car wanted to start but couldn't. Magically fuel had now entered the filter container.

I really hate using starter fluid but I'm done with trying to figure it out. I decided **** it I'll shoot one more shot and try again. The car fired right up and ran just fine.

Do fuel pumps die a slow death or do they just go out?

It works fine once it gets the initial start up. There no issues stalling or acceleration, and I can almost guarantee it will fire up with no real effort tomorrow when I try again.

I'm not a mechanic but I get how things work. I undertake when the motor cranks it engages the pump which sucks the fuel and feeds it to the carb. The issue seems like there's just not enough initial pressure once it sits for a while. I could be off by a long shot but that's what it seems like to me.

I guess I'll replace the fuel pump and if the problem persists I'll just have to deal with taking it to a mechanic. Taking the car to a mechanic is a blow to my pride, that's really the only reason why I've stalling on the issue for so long. I just want to fix the damn thing on my own.

From reading this thread you guys seem to like the Holley pumps yeah? What about the good ol AC Delco ones, are they **** now?

I'm really trying to stay away from as much Chinese bull**** as I can.
 
#17 ·
Hello again, Ethan!

Classic symptoms of a dying mechanical fuel pump....the diaphragm is failing, has a rupture or pinholes, or is letting go around its perimeter where it meets the metal body. System looses vacuum, fuel doesn't stay in upper line from carb to filter (no "check valve", per se, is in these older systems). Lots of things can cause this, but see our discussions above, most common (other than age, I suppose) is fuel type. The deterioration can also happen from long periods of inactivity, IE winter storage especially if fuel isn't treated.
Please let me know what fuel pump you choose to go with (part number, cost, etc) and good luck! I'll be right behind you doing this same proceedure soon!
:waving:
 
#19 ·
Hello again, Ethan!

Classic symptoms of a dying mechanical fuel pump....the diaphragm is failing, has a rupture or pinholes, or is letting go around its perimeter where it meets the metal body. System looses vacuum, fuel doesn't stay in upper line from carbto filter (no "check valve", per se, is in these older systems). Lots of things can cause this, but see our discussions above, most common (other than age, I suppose) is fuel type. The deterioration can also happen from long periods of inactivity, IE winter storage especially if fuel isn't treated.
Please let me know what fuel pump you choose to go with (part number, cost, etc) and good luck! I'll be right behind you doing this same proceedure soon!
:waving:

Yeah now the car is acting up bad lol. Now it wants to die at idle, idling very low and rough also. The carb is brand new. If you hit the gas it's fine, a bit sluggish but won't die! I am gonna replace the fuel pump I just have no idea which one. Autopart stores keep trying to sell me a 17 dollar airtex or something like that, but it ain't happening. I think I'm going to buy a AC Delco pump. I'll let you know what happens.
 
#18 ·
These cars were not designed to run with alcohol in the gas. The original neoprene hose was resistant to gasoline, but not to alcohol. Rubber and alcohol don't mix because alcohol is an ACIDIC organic solvent. Over time it will dissolve the neoprene hose to the point were it leaks. the rubber crumbs will clog the fuel filter.



You have to replace all of the factory neoprene hose with a PTFE (Teflon plastic) lined fuel line:



The hose should have a green stripe to show that it is resistant to gas and alcohol.

Not only is the hose at risk, but so are the steel fuel lines, the galvanized steel gas tank and the pot metal carburetor are at risk of chemical attack. The pictures I have illustrate what alcohol does to a Holley 4150 carburetor, but your Rochester or Carter carb are equally at risk because they were all made out of di-chromate clad pot metal cast carb parts.









So to counteract the corrosive effects of alcohol Holley has recast these parts (those that are not billet) out of solid aluminum and then has them anodized green to protect the aluminum. With any anodized part the protection lasts only so long as the sacrificial metal remains chemically active. The coating is consumed over time.



Quick Fuel and Barry Grant did the same thing with their Holley clones (Barry Grant is now a wholly owned subsidy of Holley so there isn't the copyright infringement question that makes me wonder why Colt Industries that owned Holley when these carbs first appeared on the market didn't sue them) only anodizing them in red or purple instead of the Holley Green that matches the industry standard for gasohol.

So a new carb that is designed to work with gasohol will not be affected, but your old carb will be adversely affected. The only solution for a museum piece is to run straight gasoline without any alcohol in it such as race gas available in five gallon cans from VP Sunoco, or other sources. Shipping fees and disposal of the hazardous waste (the empty can) drives up the cost, but I do not recommend buying it in 55 gallon drums like I used to do before 9-11 as it decomposes within days (the higher octane additives evaporate quickly once the drum is opened). There are still gas stations in most big towns at least in the South-east that still sell straight high octane lead free gas, but usually only on a Friday from a locked pump as there is no road tax associated with the gas sale. As such it has to go into an empty 55 gallon drum left over from my previous buying race gas, or five gallon gas cans. It is also legal to put it in your trailered race car (a trailered car without a license plate).

Big Dave
 
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