Fuse? for '68 911 Fuel Pump

[Allen Henderson]

SWB guys,

Does the '68 have a fuse for the fuel pump and, if so, where is it located. My pump seems to cut out from time to time and I'm thinking, perhaps, the fuse connection to the fuse holder is not good.

Or, is there a relay and, if so, is it on a fuse. Or? Thanks.

Allen-

[304065]

Allen,

The fuel pump circuit is unfused. Power flows through a red wire from the hot side of fuse #1 back to the engine electrical console where it goes into a clear plastic three way wye connector, the other terminal of which is a black wire to the fuel pump (and the third connector is a feed to the ballast resistor). As you have probably observed, the fuel pump gets its ground from the aluminum panel to which it is screwed, and there's a braided copper ground strap with some NLA funny looking ring connectors that completes the path to ground where the panel bolts to the side of the car. It is this ground path that is most susceptible to oxidation and I suspect the source of your intermittent operation.

Be sure to disconnect the battery when working around the fuel pump, gasoline is the most hazardous common substance I can think of.

If you wouldn't mind, could you kindly post a picture of your original '68 fuel pump setup? Either here or over where I am collecting data on these setups,
http://forums.pelicanparts.com/showt...=swb+fuel+pump

[Allen Henderson]

Thanks for the response and I will post a picture of the factory set-up this evening.

Does the pump sense when the fuel line to the carbs is full and shut off?

-Allen-

[Allen Henderson]

Here is a photo from a '68 we I recently sold on eBay. One can take the pump all apart and fix things. I this case the point contacts were dirty but I ended up taking most all of the pump apart. Now it is working fine. It is IMHO a silly old design. A rotating pump makes much more sense.


-Allen-

[304065]

Allen,

Thank you for the photo. That is a "hardi" pump which is a roller cell type, not the piston type that the Bendix is. I think these have also gone solid state and I know they are available new.

Here's how it works: the pump has a built-in pressure limiting circuit, so when you turn it on, it pumps fast to build pressure, then once it hits the pressure limit, will pump slowly to maintain it. What holds the flow back is, in fact, the needle valves in the carburetors, which is why having the right fuel pressure is vitally important: too high a pressure will damage the needle valves and will make the float level too high for correct carburetor operation. I use 3.5 pounds for my Webers which works fine, although the unregulated output of the bendix pump is around 4.5 or so.