if one installs a 1800 fuel pump on a 2.0 engine the stroke differences on the aux shaft will not pump as much fuel, but it will pump enough to run, just not keep up with volume when full throttle is used.... dont ask how i figured this out

Tell me more...

At first I bought an electric pump, temporarily hooked it up, and viola, engine ran fine.

But being picky, I didn't like having to mount it, buy a blockoff plate, running wires, etc. And I saw that Vick's was having a sale on the mechanical pump for $29.99. So I bought one. It was advertised as 77-80.

Same issue. Works great if I move lever by hand, but in engine it does nothing. Seems like the pump arm doesn't hit the lobe on the aux shaft. Stick my finger in the block and I can feel that I have the small lobe design, consistent with the 2000's.

So what the heck is going on here? the lobe IS there, not cut. All the hoses on the car were original with OEM clamps, so it's not like someone modified for electric along the way. Obviously (I think) the cam is spinning, as the car runs with an electric pump.

Any thoughts? I hate to just ditch the mech pump if there's a logical explanation.

Maybe I wasn't installing it correctly. I read through loads of threads today. I'll try making sure the lobe spins, and make sure I have the pump arm above the lobe.

Update: (not sure if anybody is even reading this...)

Called the retailer of the pump. They insist that this "spoon" style pump will fit on my 2000, or any other fiat 124 motor.

I had my son crank the engine while I looked into the block. I saw the lobe rotate, looks perfect. Not scored, just shiny. So then I held the new pump in position, spacers gaskets and all, and had him crank. The lobe never contacts the pump (or I would have felt the pump try to move). Next, I did the same thing with my old pump, this one has the thin arm lever. I felt it contact and move. I heard it pumping air (actually its not shot, just really old)

I then compared the two pumps side by side. The arm on the new pump is about 1/4 " shorter than the old one. I can see the wear pattern on the old one's arm... it extends into that last 1/4".

So what gives? I would think the new one will work if I had a thinner phenolic spacer. I think I just have to send this pump back, and order the exact replacement pump elsewhere.

In the meantime, I rebuilt all calipers, bought new cupernickel brake lines, new master cylinder, new rotors, derusted and painted the backing plates. Once this fuel pump is finished I'll put all that in. Much easier to get at it with the master cylinder out of the way.

it is probably a 1800 pump, would be my guess, because they are definatly different. i will take a picture monday of a 2000 pump, i just pulled one from the engine im rebuilding to sell

sorry, just re read what you wrote, you do have a 1800 pump

So Vick's is telling me they are all the same. I think you're right. Certainly looks different, measures different... and doesn't work!

i promise you they are not the same. i used to think they were until i had a pressure issue. the one i had worked, but barely.