AC fuel pump clean and rebuild

[foster461]

This weekend, one of my projects was refurbing a spare fuel pump. I recalled a web site describing how to make a soda blaster using a blow off gun and some tubing so I bought a big box of baking soda from the grocery store ($1.80) and made up a soda blaster following these directions:

 

http://www.aircooledtech.com/tools-on-the-cheap/soda_blaster/

 

The results and my apparatus shown here. No, it did not take 5 tons of soda, that is snow slowly melting after the winter. Actually to blast both halves of the fuel pump used about half the box of soda. What I liked is that while the soda took off all of the oxidation it did not destroy the original patina of the pump.

 

http://s38.photobucket.com/user/foster461/library/TR3A%20restoration%20project/8%20April%202013%20-%20Fuel%20Pump

 

 

Moving on to the pump rebuild.. I bought a kit from Moss which was a Powertune brand, made in Taiwan. I happened to have an original AC Delco rebuild kit for comparison. The main difference is the diaphragm. The AC diaphragm is a multi-layer fabric/rubber material that has some structure to it, a kind of bellows near the center. The diaphragm in the Powertune kit is just a flat piece of rubber.

 

Not sure how the older AC diaphragm will hold up with the local E10 fuel. I imagine the Powertune kit sold here is designed for it. The diaphragms that I took out were original AC and they were pretty rigid.

 

Rebuild was pretty easy, more time spent cleaning than assembling.

 

Stan

[peejay4A]

Thanks for this Stan. I've just unearthed the original pump from my 4A so I'll be making my own soda blaster too.

 

Do you know if the screws are available? Mine are a bit chewed.

Edited April 8, 2013 by peejay4A

[mike3739]

Amazing Stan

 

 

Cheers

 

 

 

Mike

[foster461]

Thanks for this Stan. I've just unearthed the original pump from my 4A so I'll be making my own soda blaster too.

 

Do you know if the screws are available? Mine are a bit chewed.

 

I checked my local hardware store and they had nothing like the original screws. I considered using some #10 allen head bolts which would have probably looked ok but in the end I cleaned up the originals in the blast cabinet and painted them black.

 

This may be obvious but I had to google a bit to figure out that the flat spade end of the shaft has to engage with a slot in the lever and then you rotate the diaphragm 90 degrees to fully engage the shaft with the operating lever. So you insert the shaft into the hole with the flat end in line with the operating levers so it will drop into the slot and then twist it. I marked a couple of lines on the top so I could be sure I got a 90 degree twist. Once the shaft seems to be engaged, work both the operating lever and the manual lever to make sure both move the piston. Dont forget the spring..

 

Stan

[stuart]

I hate to say this Stan but I suspect your NOS AC Delco diaphragm may well last longer than the repro one Ethanol or not.

FWIW did the kit include the small seal for the base of the shaft where it comes into the casing under the diaphragm as most kits dont and you end up getting engine oil into the lower casing.

Stuart.

[foster461]

I hate to say this Stan but I suspect your NOS AC Delco diaphragm may well last longer than the repro one Ethanol or not.

FWIW did the kit include the small seal for the base of the shaft where it comes into the casing under the diaphragm as most kits dont and you end up getting engine oil into the lower casing.

Stuart.

 

I did not see that lower seal in either the AC Delco kit or the Powertune repro kit and to be honest I have no idea how you would install it unless it can just be slipped in down the hole.

The AC Delco kit is superior in every regard. Even the valves and gaskets in the Powertune kit look minimalist compared to the AC Delco parts.

 

Stan

[BlueTR3A-5EKT]

Off at a tangent. The simple soda blaster. I have a paraffin sprayer that works that way.

 

I also made a vacuum cleaner using the same principle years ago with a cloth bag to collect and clear up swarf after drilling inside aircraft structure.

 

Peter W

Edited April 9, 2013 by BlueTR3A-5EKT

[angelfj]

not sure how the older AC diaphragm will hold up with the local E10 fuel. I imagine the Powertune kit sold here is designed for it. The diaphragms that I took out were original AC and they were pretty rigid.

 

The fuel pump in Grey Lady is a NOS AC pump that we rebuilt. However, we did not use the RED diaphragm included in the rebuild kit. First of all the original diaphragm looked OK and the color of the new one wasn't correct. Our assumption turned out to be WRONG. Either the original BLACK diaphragms are incompatible with modern fuels or they just plain fall apart due to age. Ever since last June, when the restoration was finished, I have been plagued with bits of old diaphragm getting under the jet/seat of the float bowl. This results in a very serious and sudden loss of power either by fuel starvation if the jet gets stuck closed or flooding if the jet sticks open,. It's amazing how much **** of significant size ends up in the bottom of the float bowl. Grey Lady is at Brian's shop this week to have a new BLACK diaphragm installed + other minor maintenance issues corrected.

 

Moral of the story: do not install aged fuel pump diaphragm. John S at TRF has rebuild kits with new BLACK diaphragms in stock.

 

Cheers,

 

Frank

[peejay4A]

TRF rebuild kit ordered. Also just out of interest the 6 screws that hold the pump body together are the same as the ones which fix the fuel sender to the tank - at least the ones I recovered from my pile of bits match.