Need to relax fuel pump spring

[schwim]

Hi there, everyone,

I rebuilt my fuel pump before I read somewhere that the springs in the rebuild kit(I got my from WW) are too strong and threw away the old spring. Unfortunately, now I've got fuel overflowing the bowl due to high pressure.

How does the community relax this spring? Pull it out and bend it a little on either side of the spring? Flatten it under some weight for a time? Clip a little bit off and bend to restore the end profile?

Suggestions and insight would be most welcome.

Thanks for your time!
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Zippy the Wonderbug's achingly slow meandering toward roadworthiness

[OldSchoolVW's]

Fuel pressure is affected by the travel of the push rod within the pump. Determine what the fuel pressure is now with a fuel pressure gauge so you have a baseline. Remove the rod and check the length to be sure it is to spec. If so, and the pressure is too high, start adding gaskets under the pump body to shorten the push rod travel in the pump and reduce the pressure. Pressure should be 2.8 - 3.5 psi. BTW ... aftermarket pumps often put out 5+ psi. If buying a new pump, it is best to invest in a rebuilt Pierburg. Bill at SparxWerks offers excellent restorations.
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Tom

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[rcooled]

Well, you can go to a well-equipped hardware store and buy a similar spring of thinner gauge wire and/or shorter length, but that'll be a trial & error effort to find the right one.

You may also be able to buy an original spring from someone who rebuilds the OEM pumps, like Bill at Sparxwerks > Sparxwerks

Wolfsburg West sells new ethanol-compatible diaphragms w/springs > Fuel pump diaphragm

Or, as some would suggest, you can just stack additional gaskets under the pump as a temporary fix.

More info in this thread > Adjusting fuel pump pressure
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[my3bugs]

i have rebuilt 3 square top pumps in the last month or so , in one i used the WW spring and it seems to be working fine ..............what i would wonder about is your needle n seat valve not closing in your carb and letting in too much gas and flooding your motor .

[my3bugs]

now i still have the spring i didnt use and a new one of WW springs i didnt use ......to me they both feel the same just by my fingers squeezing em ......they look n feel pretty identical .

i think early on they WW had issues with the diaphragm not so much the spring ?

[schwim]

Thank you guys very much for your help. I should have clarified more but was in the garage fingerphone typing and it's hard for me.

Parked the VW for a very long time, was in running condition. I put it back together to test run with gravity feed and that went fine. I plumbed in the tank and fuel pump and that also ran fine but I worried that the fuel pump sitting for years would put me at risk of filling the crankcase with fuel so I bought a rebuild kit and opened it up to replace the diaghram and put the new spring in as well.

It no longer ran fine. It would eventually put fuel into the throat from the breather on the bowl. I put a new needle and seat in from a rebuild kit I bought at the same time. Same issue.

To clarify, this is the same carb, fuel pump, fuel pump spacer and fuel pump pushrod that was working fine prior to me putting the new diaphragm and spring in.

I took the pump apart a second time just to make sure I didn't fumble something but everything looks as it should.

I bought this kit.

I'm not going to modify the pushrod, as that was a working length before this rebuild and I've only changed the diaghram and spring. I don't mind doing a ghetto extra couple gaskets just to get by but when searching this issue, the most common reason I found for this problem after a rebuild was the spring in the rebuild kits. That's why I asked about it. For all I know, that's not the issue but that was what I was reading.

Thank you all for your time.

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Zippy the Wonderbug's achingly slow meandering toward roadworthiness

[wcfvw69]

OP- did you figure this out? I have tons of good original springs for 36hp pumps. Let me know if you need one-

Email me at [email protected]

Bill
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Contact me at [email protected]
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40+ years of VW repair, and VW parts and vehicle restoration experience.
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**Now rebuilding throttle bodies for VW's and Porsche's**
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[schwim]

[ashman40]

Have you measured the fuel pressure at the carb inlet?

You mentioned using a new inlet valve out of a carb rebuild kit. These are notorious for being low quality and not properly controlling the fuel flow.
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AshMan40
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'67 Beetle #2 {2019 project car - Wish me luck!}

[schwim]