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What is underneath fuel pump
Posted: 26 May 2016, 10:15
by Sir Brixalot
I havent been able to run on petrol. I bought a new fuel pump so dismissed that as a cause. But looking back today whatever it is under the fuel pump is all smashed up.The top is plastic attached to a tapering shaft. Can any one tell me what is is
Haynes calls it an insulator but I think in Brickwerks its a fuel pump spacer can anyone confirm. Only £2.35 but four times that in post. Only just had a delivery as well
Re: What is underneath fuel pump
Posted: 26 May 2016, 10:22
by Aidan
pictures would help make sense of the question
the mechanical fuel pump on a wbx is driven by a 100mm pushrod running in the block and there is a metal lever in the base of the pump that is pushed by the pushrod and thus drives the diaphragm pump in the head of the pump
Re: What is underneath fuel pump
Posted: 26 May 2016, 10:26
by Sir Brixalot
Sounds right Aiden. Thanks. Seems to have lots of different names also seen it called the fuel pump flange. My old one had a filter on top does anyone know if these can still be bought
Re: What is underneath fuel pump
Posted: 26 May 2016, 10:47
by CovKid
Its basically a bakelite guide (or was originally). Heaven knows what its made from now. But yes, commonly called a 'flange'. To my knowledge it hasn't changed since Beetle days. Without it, the pushrod would rattle around
Never seen it mentioned on 80-90 but seen a few instances on bugs where the pushrod could bind in the flange when the engine got hot.
https://www.vwheritage.com/shop/type25- ... tartRow=15" onclick="window.open(this.href);return false;
Re: What is underneath fuel pump
Posted: 26 May 2016, 10:52
by DoubleOSeven
...and be very careful not to torque the fuel pump down too hard or it will crack the bakelite flange. Fill it with grease and replace the gaskets too.
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Re: What is underneath fuel pump
Posted: 26 May 2016, 13:48
by Sir Brixalot
Thanks funny enough the new rod sticks in the new flange both from gsf. The old rod moves more easily.
The old rod is flat at the bottom the new one is rounded. Is the old one flat from wear and tear?
Petrol is reaching the pump (brand new from brickwerks) but not coming out even when sucking. When I got the pump I just bolted it on. Should I have done something more?
Re: What is underneath fuel pump
Posted: 26 May 2016, 14:23
by itchyfeet
Rod should be exactly 100mm
99 is not enough
flange is in stock at VWH
https://www.vwheritage.com/shop/type25- ... tartRow=15" onclick="window.open(this.href);return false;
https://www.vwheritage.com/shop/type25- ... tartRow=15" onclick="window.open(this.href);return false;
Re: What is underneath fuel pump
Posted: 26 May 2016, 16:41
by Sir Brixalot
GSF one was too wide. The old one is probably less than 99mm. Cheap flange broke when nuts were slighty more than hand tight while I tested pump. Getting OE from heritage.
Lastly what activates the rod to move up, is it levered or pressure that moves it?
Re: What is underneath fuel pump
Posted: 26 May 2016, 18:46
by Jawin89
The fuel pump rod is mechanically activated from the distributor drive gearing.
Re: What is underneath fuel pump
Posted: 26 May 2016, 19:38
by silverbullet
(The distrubutor drive gear has a ramp on it's diameter. The fuel pump rod operates at an acute angle to the dizzy shaft axis and the fuel pump rod is lifted and lowered by this ramp)
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Re: What is underneath fuel pump
Posted: 26 May 2016, 19:41
by itchyfeet
A picture says it all

Re: What is underneath fuel pump
Posted: 27 May 2016, 15:09
by Sir Brixalot
Thanks it's all coming together in my mind. Now just to wait for the parts to turn up after the bank holiday