Conversion to Mechanical Fuel Pump

[tartan18]

When I bought my Spider this past February I thought it was a 1975 model. I now know the engine is a 1977 while the rest of the car is a 1975. The car had an after market electric (Facet) fuel pump. Because of a head gasket leak I've cleared out a lot of the original smog stuff, had the cylinder head re-built, and I bought a new 32/36 DFEV carb. I am now ready to begin putting everything back together. Because my engine block will accommodate a mechanical fuel pump, I have decided to go that route vs. trying to make an electric fuel pump work in my situation -- less noise and more reliability.

Questions ...

1. Do I need a "one way fuel valve?" I would think the answer would be NO because I have read that I do not need a fuel return line with the DFEV carb.
2. Do I need a pressure regulator?
3. Are there any other issues I need to be aware of when installing the new mechanical fuel pump? I have dry fitted it and it feels like the auxiliary drive shaft does engage the foot of the fuel pump correctly -- any way to test this?

Thanks for your help.

Jim ...

[So Cal Mark]

you do need the phenolic spacer behind the fuel pump

[vandor]

Jim,

>1. Do I need a "one way fuel valve?"

My old Spider was fine without it.

>2. Do I need a pressure regulator?

No.

>3. Are there any other issues I need to be aware of when installing the new mechanical fuel pump?

As Mark said, you need the stock bakelite fuel pump isolator. It's ~5/8" thick and goes between the fuel pump and the block. You will need a gasket on either side of it. New ones are $11.80. I'm pretty sure I have a used one if you want to go that route.

>I have dry fitted it and it feels like the auxiliary drive shaft does engage the foot of the fuel pump correctly -- any way to >test this?

If it feels like it engages then it should be fine. I tried this once only to find that the fuel pump lobe had been cut off the aux shaft!

I am sure you will replace the old fuel hoses too, right? Buy fuel injection rated hose, as it stands up better to the ethanol in the gasoline.

[tartan18]

Thanks gentlemen! I have the phenolic spacer (learned a new word/term) and I have both inside and outside gaskets. New FI style hoses and connectors.

I really appreciate your expert advice.

[bradartigue]

The DFEV has no fuel return while your car is designed with a fuel return line. While not necessary from an operational perspective there are some positives to fuel return:

- Reduces the smell of gasoline
- The needle/seat has less pressure exerted on it
- The pump does not work as hard
- Fuel is continuously (well, almost continuously) circulated

To create a return buy a fuel filter - Auto Zone has them - that has a check valve return circuit. I don't recall the part number but they are on the big wall of filters, they are silver and have two large connections for the fuel in/out and a smaller connection for another fuel out. When pressure builds up in the filter excess fuel is returned through the smaller orifice.

Pretty simple to hook up, you run the main line through it to the carb and the return line to the return plumbing (small pipe) near the brake booster.

[So Cal Mark]

that fuel filter with a return port was used on many Chrysler products in the 70s

[WYSpider]

This is my setup with an electric pump in the trunk.

Return Fuel Line & DFEV


Inline Components Reused from Factory Return Line

[tartan18]

Outstanding advice. Thank you gentlemen very much.