fuel pump rebuild

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michaelbalk330
Posts: 130
Joined: Fri Feb 06, 2015 8:28 am

fuel pump rebuild

Post by michaelbalk330 »

does anyone make the 3 layer red diaphragm ?
my pump was getting a bit leaky so I pulled it to rebuild.
I cant remember which car of mine had a 3 layer diaphragm but think its better than that single black one.
my "one way valves" seem fine but i need gaskets and the diaphragm

Michael
Michael
1967 330GT #9693
1960 190SL
1967 Ducati 350 Sebring #04783
1959 Moto Guzzi Galletto #GNR93
1973 450SL
1988 Mercedes 300CE 5 spd
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tyang
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Location: New York
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Re: fuel pump rebuild

Post by tyang »

HI Michael,

I've seen a three layer diaphragm that looked like a modern replacement, but have not found the source yet. The single layer black nitrile ones seem to be working fine. The usual sources, Parts Source, GT Car Parts, and T Rutlands all should supply just the diaphragm, and check valve seals to rebuild the pump. Make sure the face of the diaphragm mating surfaces are flat. I have a rig that can bench test the pump before installing, but in your case, you can install the pump, disconnect the front line on the fuel rail and direct the fuel into a container. plug up the fuel rail and start the car with with the electric pump. While the engine in running, you'll see the mechanical pump pulsing fuel into the container. That will confirm it's pumping fuel.

Good luck.

Tom
'63 330 America #5053
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michaelbalk330
Posts: 130
Joined: Fri Feb 06, 2015 8:28 am

Re: fuel pump rebuild

Post by michaelbalk330 »

ok will try . I am making progress.. My metal cam lever thing is worn and I am replacing it, and did some math/engineering so I can make the phenolic spacer the correct thickness for maximal pumping. The new fittings I purchased for 10mm fuel line ( fuel pump inlet) had a 14mm banjo and mine are 12 mm. it was quicker to just fix it than to send it back etc!
So i torched it, removed the old 14mm and brazed a new 12mmx10mm banjo.. Came out good. attached pics.
I figured while I had the pump out, I should replace the old ( and likely original ( italian hose as it was wearing from rubbing against car.
M
Attachments
IMG_3049.jpeg
IMG_3043.jpeg
IMG_3040.jpeg
IMG_3039.jpeg
fuel.jpeg
fuel (1).jpeg
Michael
1967 330GT #9693
1960 190SL
1967 Ducati 350 Sebring #04783
1959 Moto Guzzi Galletto #GNR93
1973 450SL
1988 Mercedes 300CE 5 spd
User avatar
michaelbalk330
Posts: 130
Joined: Fri Feb 06, 2015 8:28 am

Re: fuel pump rebuild

Post by michaelbalk330 »

tom
why couldn't I just put it back together, and watch it fill an emptied Fispa fuel regulator/filter bowl?
m
Michael
1967 330GT #9693
1960 190SL
1967 Ducati 350 Sebring #04783
1959 Moto Guzzi Galletto #GNR93
1973 450SL
1988 Mercedes 300CE 5 spd
User avatar
tyang
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Joined: Wed Nov 27, 2002 10:28 pm
Location: New York
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Re: fuel pump rebuild

Post by tyang »

michaelbalk330 wrote: Mon Sep 06, 2021 8:00 am tom
why couldn't I just put it back together, and watch it fill an emptied Fispa fuel regulator/filter bowl?
m
It's hard to judge exactly how much fuel is being pumped into the glass bowl and at what rate. seeing how fast it's filling a container can confirm if it's providing enough fuel at idle.

Nice work BTW.

Tom
'63 330 America #5053
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michaelbalk330
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Re: fuel pump rebuild- with helpful hints

Post by michaelbalk330 »

DONE
330GT Fuel pump rebuild Step by step. ( FISPA 150)

1. Remove fuel pump
2. While there, check fuel hoses to ensure they don’t also need replacing.
3. Measure “throw” of the plunger coming out of the mounting area by turning engine over by hand. Mine was about 2.7mm
4. Rebuild fuel pump. Use good washer seals for the one-way valves so that flow is unidirectional from the inlet all the way through the pump to the outlet if your valves don’t have built in gaskets like the OEM. Make sure all surfaces are “plane” and clean. Test the valves before installing ( just blow.. they should be “one way”) to ensure they are fine.
5. Each of the mechanical movements inside the pump (basically everything the hammer is attached to) needs to have as little slop as possible. Remember with 2-3mm of throw, any movement lost to sloppy linkage will limit the diaphragm movement in and out.


6. Ensure all gaskets are good and there is no “weak point” in the seal. I used rubber type (UK vendor has premade, but you can cut your own out of appropriate thickness Buna-N type sheets), not cork, as my last cork ones only lasted 5 years. I hear if you seal the cork with “gasket shellac” you get better results but haven’t tried.
7. The lightweight spring on bottom allows the hammer to move only, but not the diaphragm. It takes a lot of force to move the hammer the 2-3 mm in to then displace the diaphragm “in and out”. However, using a bench set up like Tom’s or a simple one like I did will make the diaphragm move in and out and you can actually hear the suction/seal working. All I did was place the pump on a socket that was resting vertically on my bench, and push hard on the pump up and down. (Formal testing will be done once its installed as I didn’t want to build a testing machine).

8. Now you have to determine the thickness of the mounting phenolic spacer. It’s just math/physics and there are a number of ways to do it. Use common sense. My original spacer was measuring 10mm and the plunger was barely touching the original hammer at maximum excursion; one reason it didn’t work. I retracted the plunger all the way in and I placed pump on the mounting studs until the hammer was pushed in but not yet moving the diaphragm. I measured the space/distance left in between the mount and the pump. Since plunger moves 2.7 mm in and out on my car, I now can determine how thick that spacer needs to be… the goal is when plunger is in, the diaphragm is relaxed and when the plunger extends the 2.7mm, the diaphragm is pushed outwards. If you make the spacer distance too small then you might exceed the mechanical movement limit of the fuel pump diaphragm. If it’s too thick, the plunger doesn’t move the hammer enough. That’s the common sense part. You could even mount the pump and remove the bottom cover as in the pic below and crank the engine to see how much movement there is.
9.
10.
11. Installed pump and new inlet hose (which I wrapped with heat shield as it runs adjacent to oil pan)…. NO leaks (anywhere….and trust me I had everything apart) ; works great. Interestingly, as car idles, I can see the Fispa filter-regulator get filled with fuel in a “lub dub” fashion (as low RPM that plunger moves infrequently) , but its enough to keep the bowl ½-3/4 filled and perfusing the carbs. When I accelerate, the pump fills it completely.. no electric pump needed!
12. Of note, the elbow banjo bolt @ inlet is in tight quarters… I removed the 2 mounting bolts for the pump and pulled pump out so I had better access and could get the banjo bolt threads started and tighter and then remounted the pump. It was a lot easier than repeatedly dropping a washer and cutting my hands up.
13. Very happy with the results. Runs as intended on manual pump , new hoses, and no leaks.


14. Lastly, I found an original FISPA rebuild kit in Greece with 2 diaphragms, gaskets, and valves and have attached pics. It was stored very well- all rubber soft and pliable. Valves are perfect! Price was reasonable and the material is definitely great condition and useable. Just including this for memorialization. Note how thick the top gasket is:

15. I have this as a file with all pics embedded.. but cant attached PDFs or Doc files here.. if you want it, just email me
Michael
1967 330GT #9693
1960 190SL
1967 Ducati 350 Sebring #04783
1959 Moto Guzzi Galletto #GNR93
1973 450SL
1988 Mercedes 300CE 5 spd
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michaelbalk330
Posts: 130
Joined: Fri Feb 06, 2015 8:28 am

Re: fuel pump rebuild

Post by michaelbalk330 »

pics
Attachments
installed pump and outlet.jpeg
fuel pump top.jpeg
fuel pump inlet.jpeg
330gt fuel pump spacer.jpeg
Michael
1967 330GT #9693
1960 190SL
1967 Ducati 350 Sebring #04783
1959 Moto Guzzi Galletto #GNR93
1973 450SL
1988 Mercedes 300CE 5 spd
User avatar
michaelbalk330
Posts: 130
Joined: Fri Feb 06, 2015 8:28 am

Re: fuel pump rebuild

Post by michaelbalk330 »

more
Attachments
fuel pump  330 (3).jpeg
fuel pump  330 (2).jpeg
fuel pump  330 (1).jpeg
fispa OEM fuel pump.jpeg
fispa OEM fuel pump (1).jpeg
Michael
1967 330GT #9693
1960 190SL
1967 Ducati 350 Sebring #04783
1959 Moto Guzzi Galletto #GNR93
1973 450SL
1988 Mercedes 300CE 5 spd
User avatar
michaelbalk330
Posts: 130
Joined: Fri Feb 06, 2015 8:28 am

Re: fuel pump rebuild

Post by michaelbalk330 »

more
Attachments
fuel pump  330.jpeg
fuel pump  330 (5).jpeg
fuel pump  330 (4).jpeg
Michael
1967 330GT #9693
1960 190SL
1967 Ducati 350 Sebring #04783
1959 Moto Guzzi Galletto #GNR93
1973 450SL
1988 Mercedes 300CE 5 spd
User avatar
michaelbalk330
Posts: 130
Joined: Fri Feb 06, 2015 8:28 am

Re: fuel pump rebuild

Post by michaelbalk330 »

schematic
Attachments
fispa 150 schematic.jpeg
Michael
1967 330GT #9693
1960 190SL
1967 Ducati 350 Sebring #04783
1959 Moto Guzzi Galletto #GNR93
1973 450SL
1988 Mercedes 300CE 5 spd
User avatar
michaelbalk330
Posts: 130
Joined: Fri Feb 06, 2015 8:28 am

Re: fuel pump rebuild

Post by michaelbalk330 »

oem Rebild kit
Attachments
fispa 150 fuel pump rebuild.jpeg
fispa 150 fuel pump rebuild (4).jpeg
fispa 150 fuel pump rebuild (3).jpeg
fispa 150 fuel pump rebuild (2).jpeg
fispa 150 fuel pump rebuild (1).jpeg
Michael
1967 330GT #9693
1960 190SL
1967 Ducati 350 Sebring #04783
1959 Moto Guzzi Galletto #GNR93
1973 450SL
1988 Mercedes 300CE 5 spd
chris
Posts: 219
Joined: Sat Mar 02, 2013 7:52 am

Re: fuel pump rebuild

Post by chris »

Good description. Did it the same way some time ago. Mine even started only on mechanical pump after rebuild without running electrical pump. I build a small teststand to adapt the phenolic spacer for maximum stroke, to test the pump out of the car and measure fuel presure. See picture. It has the same mechanical mimic as the plunger of the engine.
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15EBBB29-42D8-4EBE-A316-D196B00C5BC7.jpeg
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michaelbalk330
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Joined: Fri Feb 06, 2015 8:28 am

Re: fuel pump rebuild

Post by michaelbalk330 »

chris
I love that set up! great work. thanks for posting.. I wish I had thought of that.
M
Michael
1967 330GT #9693
1960 190SL
1967 Ducati 350 Sebring #04783
1959 Moto Guzzi Galletto #GNR93
1973 450SL
1988 Mercedes 300CE 5 spd
John Vardanian
Posts: 1906
Joined: Wed Sep 04, 2002 12:13 am
Location: San Francisco Area

Re: fuel pump rebuild

Post by John Vardanian »

Great work, Chris. Thanks for sharing.

john
PF Coupe
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