[Peter]

I thought I'd repost here (original thread http://www.alfabb.com/bb/forums/showthread.php?t=45395)

Bottom line, I have just installed a brand new mechanical fuel pump in my GTV.
If I connect just the line from the tank, fuel will come out when cranking. When I attach the filter (which is elevated about 5 inches higher), or even just the line to the fuel filter, not a drop comes out....so it looks as if the pump kinda works, but does not have enough power.....When I suck on the fuel line, fuel comes out easily, so it does not seem blocked. When I drop a fuel line in a container of gas sitting next to the car, the pump does not suck it up. I am inclined to just go out and buy an electric pump, but I an stumped why this mechanical setup would not work......Any clues?

 

[papajam]

To answer a question from the other thread, there is no replaceable filter between the tank and the fuelpump although some fuel sending units in the tank have a filter sock (a very fine mesh screen) on the pickup tube which can be cleaned after the sending unit is removed.
The filter/regulator assembly is always placed between the fuelpump and carb(s) so it can regulate the fuel pressure on the pressure side of the pump. There are also cleanable mesh screens on the carb inputs.

I'd check the fuelpump drive. The fuelpump on the 2l is driven by a single pushrod off the eccentric on the top of the oilpump shaft. I've seen pushrods stick in the bore resulting in the symptoms you describe. You'll need to pull the distributor to observe the eccentric and pushrod operation.

 

[mubezzi]

SPICA cars have a fuel filter between the petrol tank and the electric pump as the fuel needs to be super clean to prevent unnecessary wear to both the electrical fuel pump and the SPICA pump, as well as an additional filter before the SPICA pump itself. Non SPICA cars only have the fuel filter and pressure regulater between the pump (electric or mechanical) and the carburetors, as Papajam mentioned. But I also wanted to mention that the "eccentric (lobe) on the top of the oil pump shaft" is sometimes removed on after market distributors or by race shops because the slight vibration generated by this off-set at high RPM.
Also, make sure you are using adequate fuel lines as carburetors require more fuel volume versus higher fuel PSI in the case of SPICA cars.
SPICA cars run about 30-35 PSI for fuel delivery up to the SPICA pump.
Carburetor cars run about 4-8 PSI in the fuel lines to the fuel filter/pressure regulator...

 

[Peter]

thanks Papajam...I did check that there is no fuel filter. The mesh in the fuel tank that you describe is clean, I checked that yesterday. As far as driving the fuel pump, I did notice a rod, about 3 or 4 inches long, as it fell out when removing the old pump, so if this is the one that you are referring to, it is not stuck. I did not notice any significant wear on it, but that's about all I can think if, maybe it's gotten too short

 

[robtechno]

Peter make sure that it's the right type of pump. When it's an aftermarket brand, nothing wrong with that, you might use the gasket supplied with the pump. See that the lever in the new pump sits at the same distance from the mounting flange as the lever in the old pump. With no resistance from fuel line bends or filter you can have fuel but when the movement of the lever is to little than you will have no fuel due to resistance in the line or filter. It's mechanical so you have to think logic. To much resistance or to little movement will give you no fuel.
Good luck.

 

[Peter]

it IS an aftermarket pump....maybe try it without the bakelite filler between the gaskets? I think I may just put in an electric pump, until I bring this car back to original

 

[robtechno]

No don't try with out the gasket, it will do more damage because the rod will be too long. Measure the distance from the outside pump flange till the point where the rod will push against the lever inside the pump both in the old pump and the new pump. That distance must be about the same. Check the valves in the top half of the pump. you can do this by sucking onto the fuel exit tube or blowing into the fuel in tube. there are two valves and they will overcome that fuel will run back to the tank.

My guess is that the valve body is not okay. Don't fumble around and just get another pump. What's the brand on the pump!, I just wanna know.
Thanks

 

[144]

I'd like to correct what Mubezzi said about the pressure in the SPICA fuel supply system. It is not 30-35 psi, but rather 7-17psi. The pressure relief valve is set at 17 and the low pressure warning light illuminates at 7psi. Normal pressure should be about 10-15psi.

 

[mubezzi]

Ahhhhh, we have a Spider owner...

 

[Peter]

Thanks for all the comments. Just for your reference, this is a carbed car, it's a Euro version. My guess too is that the pump is bad. I need to get it out to see what brand it is, but I think I did not see a brand. I looked for the original Fispa brand, but definitely did not find that written anywhere What I should probably do is try and see what the electric fuel pump from my Duetto (I know, not original) does if I put it in the GTV....just don't feel like messing with the Spider

 

[180OUT]

Thanks for all the comments. Just for your reference, this is a carbed car, it's a Euro version. My guess too is that the pump is bad.

Suggestion: take the new and old pumps apart and compare the diaphragm
gaskets. If they are the same, swap the new into the old housing and the
pump will probably work. That worked for me once.

 

[Peter]

Suggestion: take the new and old pumps apart and compare the diaphragm
gaskets. If they are the same, swap the new into the old housing and the
pump will probably work. That worked for me once.

thanks for the suggestion, but they are very different. I decided to install an electric fuel pump for now, and she started right up....I can't believe how a brand new mechanical pump can fail though. I am afraid it's probably got something to do with the rod that activates it, or rather what activates the rod. Oh well, we're back on the road for now.....I think....I need to go for a test drive