Fuel pump

[Early126]

I have a 650cc engine with Abarth parts including cam and a del FZD. The car has an electric fuel pump but I think this will be pushing too much pressure and flow for the single carb so I want to convert back to the mechanical  pump.

I've bought a pump, pushrod and spacer but the pushrod is like it's too long and stops me bolting the pump down.

Are there issues with a race cam and the drive for the pump? Or do I need a different pushrod? This one is 188mm long. 

[Gadge]

You know a fuel regulator would solve any over pressure you may be experiencing 

[Pete126]

As Gadge said keep the electric pump as long as its output is between 3 to 4 PSI, if its over that you need a fuel regulator. as Gadge mentioned

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[Early126]

Yes a regulator will do the job. Though on this size engine and carb it's really over kill.

Any clues on the mechanical pump set up?

[Pete126]

 Most old cars using carburetors work with 2.5 to 4.0 psi if your having problems with over fueling that could be due to the carburetor not being set up correctly.
TBH a lot of us have changed over to an electric pump because they start a lot easier especially in hot weather as the petrol evaporates out of the carb being at the top of the engine

[1973/126]

 If you really want to revert to the mechanical pump there shouldn`t be a reason why it doesn`t fit.
 You`ll get some resistance when you bolting it down as the rod will be pressing down on the pump drive. You can try to turn the engine in a position where the fuel pump rod will be sticking out the least to make things easier.

[Early126]

Most old cars using carburetors work with 2.5 to 4.0 psi if your having problems with over fueling that could be due to the carburetor not being set up correctly.
TBH a lot of us have changed over to an electric pump because they start a lot easier especially in hot weather as the petrol evaporates out of the carb being at the top of the engine

Hi, I have seen a few with electric pumps. Do you put in an additional switch, one of my worries is to have fuel continually pumping, as soon as the ignition is on, or if the engine stalls etc.
Makes sense about the evaporation. To overcome this I assume you have to crank it a few times to prime the carb before it fires and that may flatten the battery.

Im keeping the electric pump in the tool box so I can revert back if there are any issues, but I was rather hoping to make a simple switch back to the standard set up and see how I get on.
But its just not fitting correctly.

[Rusty's Uncle]

Off the top of my head the push rod for the fuel pump should protrude outside the spacer and gaskets by 1.5 to 4 mms depending upon the position of the cam. If it is way off that then something is not right. The 500 spacer for instance is much thinner than the 126.

[Early126]

Fixed.
The rod measured up to that approx guide so I figured it must be the pump that's whacky.
Disassembled it and it was all stiff as it's new so freed it up and a spot of lube ...
Still seems very stiff to actuate the pump plunger but it's all fitted. I suppose I was hoping it wouldn't sap most of the 26 bhp just to actuate the pump 

[Xylaquin]

I just bought a new mechanical pump and the bit on it that is in contact with the rod not only seems stiff but also doesn't travel more than 1 mm I'd say.

Sometimes when I press it its sticking in the "pushed" position too.

Surely that's not normal?

[Da Londo]

Clearly off topic but do you have any idea of the jet sizes on your FZD?