Fuel Pump Push Rod Protrusion

[Dwayne1m]

Just for kicks and giggles I checked the push rod for my fuel pump on my 74SB. It's the proper length at 3 15/16", but what has me confused is that the orange Bentley says that with the push rod at its highest point it should be protruding 1/2" above the flange. I have only 3/16". Is the Bentley wrong, or is that the measurement for generator equipped engines? I did numerous complete revolutions to make sure that's the highest point, and this is with no gaskets under the flange. Looking at the underside of the pump, 1/2" seems like a lot.

[Multi69s]

The 1/2" measurement is for the generator style fuel pump only.
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[Dwayne1m]

The Bentley says to add/remove gaskets to get the proper push rod protrusion. So then for alternator engines there is no measurement or adjustment other then replacing the push rod if worn? If that's the case I'm curious as to what the difference is between generator pumps and alternator pumps if one needs 1/2" travel while the other only needs 3/16" travel.

[vernonc]

Dwayne, Bill (wcf69vw) will probably chime in later but, if not, contact him directly....He'll know for sure.

mort
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"Those who don't read newspapers are un-informed. Those who do read newspapers are mis-informed." Will Rogers

'69 sedan, low mileage, all original.....currently being 'freshened-up' for road trips and daily driving...just not every day

Freshening-up link http://www.thesamba.com/vw/forum/viewtopic.php?t=617386

[ricaroo]

This is how Cusser explained it to me...

Jan. 2017 Hot VWs p. 40. had an article about fuel pump pressure checking,
Spec 2.8 – 3.5 psi at 3400 rpm Check with a fuel pump pressure gauge. Add gaskets under fuel pump or reduce pushrod length to lower fuel pressure.

The article stated: "At highest point of engine revolution, from top of base gasket to top of steel pushrod should be 13.0mm". However, I believe that this article was focused on fuel pumps with the 108mm pushrod. Since the shorter 100mm pushrod rides on the same place as the 108mm one, I calculate that the shorter pushrod should extend 5.0mm beyond the flange at its highest point. Agree?

Hope this helps, it sure worked for me

Rick
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1971 Standard Beetle 2 dr Sedan 1600dp

[bhartwell59]

[Q-Dog]

A 5 second search in theSamba photo gallery found this.

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Brian

'69 Dune Buggy
'69 Beetle Convertible
'70 Beetle

[74 Thing]

Pushrod lengths are approx 4" for alt and 4.25 for generator, but that is assuming you are using the correct fuel pump.

The throw-the amount of movement for the pushrod is approx 1/4" for each.

The photos above are correct to show that if the lever sticks out of beneath the base then most likely you need to use the shorter alt pushrod.

It is true that the alt pump is also angled at the top to clear the alternator, but that does not necessarily mean it is the smaller pushrod-once again it is determined if the lever sticks out past the base. Another way to check is look at the side of the fuel pump and where the pin goes through the body that holds the lever. If it is closer to the base then you use the shorter pushrod, and if higher away from the base you use the longer pushrod. Take a look at some fuel pump photos and it should be obvious.

You should tee in a fuel pressure gauge and verify your pressure whatever you use. Stacking gaskets is ok, but it does reduce pressure but also volume which is another discussion all together.

[Dwayne1m]

I should have mentioned but I do have the correct fuel pump. It just threw me off when the Bentley said the length of the push rod above the flange should be 1/2" and mine is nowhere near that.