1955 Fuel Pump Operation - Is this Normal?

[KAD36]

Guys - had a wierd thing happen with a fuel pump today and I've low confidence I have a good fix - need some folks to weigh in here

Last year the car died in an intersection - hot day (100 deg and humid outside). Ran great till I came to idle, then stumbled and died. Figured it was vapor lock. Wouldn't re-fire. It would run an a squirt of starting fluid and that was it. Pulled the outlet pipe and cranked it and no fuel came out. Went home and pulled a spare pump off the shelf (same one I put on in 1982 when I got the car going). Put on the replacement pump. After some stumbling and missing, it fired up and ran fine. It was also cooled off pretty good. Bottom line- I never got to root cause - bad fuel pump, vapor lock, or bad gas ( the gas inthe tank was 2 years old, I was down to 1/4 tank at the time, maybe a little less and had Stabil and lead additive in it, probably a bit of overdose over the years). The fuel in the glass strainer bowl was kinda slimy feeling and opaque. Tank by the way was flushed out and Bill Hirsch liner put into it back in 1995. Fuel lines by the way are all original.

When I got the car home, I drained the tank completely, rinsed it out with fresh gas best I could (tank still in car), and then refilled it with 93 octane, and added nothing. Car has been running fine.

So now, fast forward to this weekend. Not wanting to drive the family around with a 22 year old fuel pump on the car, I pull it off and put the old one back on (it was only 3 year old) because I never got to root cause to condemn the pump. Car then wouldn't start - no fuel. Pulled the outlet pipe, no fuel. Pull the pump back off the car and put it on the bench. Couldn't believe it was the pump - didn't made sense - it was too new and evey time I had a pump go it squirted fuel all over the place. I don't have a pressure meter, but I did run a hose into a glass jar and vigourously worked the lever by hand. After about 15 pumps, the gas started shooting out of the outlet pipe. Even held a slight pressure if I put my finger over it and pumped. Put it back on the car, and bingo, she starts right up on the fifth crank over. One thing I did notice is that when the car first started alot of air bubbles were bubbling into the glass fule strainer jar. At high idle (1500 - 2000 rpm) that stopped - and now it seems pretty steady with no air bubbles.

So what gives? My thoughts -

1) Is it possible I didn't get the fuel pump arm on the cam eccentric - If I didn't I wouldn think it would mate clean to the side of the block - can this mistake be made?

2) Since when do you have to prime a fuel pump to get it to work on the car?

3) Can something have been stuck inside there that I freed up when I beat on the arm?

4) Is the fuel pump supposed to pump some bubbles into the line like I saw or should it always be steady with no air ever - independent of fuel bowl level?

5) If the diaphram is ruptured or has an integrity issue would the pump still work at all?

Bottom line - I don't have confidence in this pump - will probably send the 22 year old one in for a new one so I have a spare - but for the time being while this thing is working - what do you guys think - is this pump marginal or has someone else come across the same nuiances and I shouldn't be concerned?

Any advice/experience appreciated and thanks in advance for your replies

[old-tank]

Hey Ken

Glad to hear that you are playing in the street again. Rebuild your old pump and then rebuild the one on the car for a spare. You have already given that pump too many chances to perform.

But if you want to be stubborn and trouble shoot it here are some suggestions: check for fuel in the oil or at the vent hole in the body of the pump; then check that there no leaks (air or gas) in the line from the tank to the pump. A small leak in the diaphragm will make it inefficient or leak into the oil or vent (not all pumps leak at the diapnragm), and no pump will work well if there is an air leak on the suction side.

I rebuild all my own pumps and have not had the failures that I had when others did the job...not that hard, just pay attention to instructions/details

Willie

[KAD36]

Hey Willie - good to hear from you again.

I tried rebuilding a pump once and got about as far as taking the top cover off - then there was a diaphram on top that I couldn't get disconnected from some stud in the middle. When I looked into the service manual, it looked like there were special tools I needed to get it apart and put it together- so at the time I was rushed and threw it in a box and got a new one. I'll have to study the manual again this weekend and see if I want to take another charge at it. If I do, I'll have lots of questions. That 22 year old pump is history.

An update - no more bubbles coming into the fuel bowl - I took it for a 15 mile drive, ran it in Low for a while - stomped on it a few times - seems okay. I also tightened up the clamps on the rubber fuel line that connects the feed pipes - maybe some air was getting in there. The flexible pipe is long gone and I plumbed in some barb ends and jut run a piece of fuel line up there.

Hows your electric pump install going? What pump did you decide on? Do you need a pressure regulator or is it built into the pump?

On another note - after I returned home from my drive - I noticed both backup lights stopped working. Anyone ever had their reverse switch apart? Can it be cleaned?

[old-tank]

Hey Ken

Driving at night with a questionable fuel pump? Anyhow there is a fuse for the backup lights and yes the switch can be disassembled to clean the contacts even though it was not designed to be opened. The adjustment of the switch is tricky especially if there is wear on the linkage...on mine I have to sometimes jiggle the shift lever while in Low to get the lights to work. One of those things that you have to live with...kind of like the glove compartment light and latch.

The fuel pump is installed and hidden on the frame by the gas tank. No regulator since I plan on using it only for filling the carb before starting and during vapor lock episodes. It is too noisy for constant operation.

On rebuilding the pump the only special tool that I needed I made from a nail...grind the point off, flatten the lower 1/2", bend the lower 1/4" at 90*. If you do get a rebuilt pump loosen the cover at the diaphram and while pushing up on the lever retighten the cover, that way the diaphram will not stretch during operation and fail early.

Willie

[KAD36]

Willie - Driving around with an iffy fuel pump at night - hey everyone is allowed a lapse in judgement - one can never take too many rides in their 55 Buick! Besides, with my tool box and a spare pump in back and all the fittings loosened up I can swap em in and out in under 30 min!

I just let my 20 yr old nephew take it around the block (with me in it) - wish you could have seen the smile on his face when he laid into it a little - "Ain't nothin like my Chevy Prizm!" Indeed!

I think what I will do is send the 22 yr old pump in and get a rebuilt one from Bobs Automobilia(any one people prefer over Bobs - last one I got was from Buick Specialists?). Looking through the manual again and your post, I think after I get that one back I will take your advice, put it on the car, and rebuild the one on the car now - except take my time with it. I may be sending you some e-mails fot help when I get there. Good tip on relieving the stress on the diaphram.

I did the tape measurement per the manual instuctions on the reverse light switch - it was on the edge of starting at the 1/8 inch mark, and sure enough, getting that switch just right was tricky. Basically, I have it adjusted now so that the backup lights work again, but the car has to be in Park to start it - switch timing is off in Neutral. I will have to disassemble the switch and clean it up - hopefully thats do-able without disintegrating anything - will tackle that tomorrow.

End of the month I have to pull the steering gear again and get it rebuilt by a pro to stop the leaks. At least I'm back on the road - 200 miles this summer so far!

On your electric fuel pump - does the standard mechanical fuel pump have any trouble pulling fuel through the electric pump when it is off? Is there a special design of pump to get that allows this and if so whats it called? How much PSI does the electric pump push - how do you know when to kill it?

Keep in touch

Ken

[old-tank]

Ken

The stock pump pulls thru the new electric fine. It is a cylindrical pump bought from CarQuest with fitings at both ends, an integral filter and is supposed to put out 15psi. I have a switch hidden at the lower left of my dash and use it as needed such as before starting to fill the carb and during a vapor lock episode (no vapor locks recently now that "summer" gas is available). It could be used constantly but it makes a lot of noise.

Hope this helps.

Willie

[JohnD1956]

Can you explain how to use that homemade tool? I tried to rebuild my pump once but the instructions for that tool seemed to apply to the vacuum side of the pump, and I never did feel I had gotten that right. I think that was shown by decent fuel delivery but my wipers were very unreliable.

[Guest imported_NikeAjax]

On my '56 Century I put an electric pump in just in front of the fuel tank, and ran a wire to power it up from the coil. Sorry I can't remember what kind it is, but I believe it was off of a Corvette?!?!?!(yikes!) It's round, can-shaped, and puts out 7 1/2 psi, so I put a regulator in just before the carburetor, and set it to 5 psi so as not to cause flooding of the bowls. The better the pump, the less you'll hear it, if you have it on all the time, like I do. Some of them like the square-shaped "Perculators" need to be bolted down to something VERY firmly like the chassis, not sheet-metal, to keep from causing too much noise.

Just a thought,

Jaybird

[old-tank]

JohnD1956

I use the tool to hold the levers in place while installing the diaphrams. Hard to explain any better than the service manual. The vacuum boost bottom of the pump will barely work the wipers if engine vacuum is not attached. Engine vacuum directly to the wipers will give adequate function at idle and slow speeds, but will slow or stop on acceleration...this is what you would have if the diaphram was not attached to the levers. If the performance of the wipers is slow always check the wiper motor and the vacuum connections. the vacuum line form the engine came loose last week, resulting is rough idle...tried the wipers and they were slow. Hooked to back up and I had smooth idle and good wipers. Of course there are other things is the pump like the valves that can give problems...I have installed the valves wrong and got to do it over.

Willie

[JohnD1956]

Thanks for the reply. As it was I bought a pump for the old girl last summer when I thought mine was the root cause of a knock. Of course it wasn't but it's too late to do anything about that now.