Fuel pump question for the Pontiac guys.

[JACK M]

 

My neighbor is trying to start this old street rod that has been parked for a long long time and we have no history.

He thinks its a 400 from the 60s or 70s.

It will fire with a prime but doesn't pump fuel.

I get fuel when I put a little pressure in the gas tank. (the pump has three nipples, I think one might go back to the tank as a vent).

We have the pump off and I can feel up in there and can feel what I presume is the eccentric (along with a kind of loose timing chain.)

My question has to do with the eccentric. It feels like I can turn it with my finger tip, Is there a bearing on a sleeve that the pump shaft rides on? If so then maybe it just needs a new fuel pump and be done with it.

I suggested maybe stick a long dowel or the likes up in there to see if the eccentric does indeed push the dowel up and down when cranking the engine.

Am I on the right track?

 

I forgot to mention, when we took the pump off it is so stiff that we can't move the arm, I would think that would mean that it is compressed already, but that didn't dawn on me right at the moment.

We put the project off so that I could bring in all my knowledgeable friends on this fantastic site for some more educated opinions.

Thanks in advance.

[joe_padavano]

The third line on the pump is fuel return to the tank, not a vent. Replacement pumps are cheap.

[JACK M]

1 hour ago, joe_padavano said:

The third line on the pump is fuel return to the tank, not a vent. Replacement pumps are cheap.

Makes sense, if it were a vent it would only vent back to the tank because I could pressurize the fuel fill.

He has a new pump, we just want to do some testing of the eccentric before we put it on.

Not being a Pontiac guy I am curious about whether it should feel loose (spin) on the front of the camshaft.

The best look is in my Motors manual, but cant tell from the picture in there.

[joe_padavano]

The eccentric on a Pontiac actually has a separate ring that goes over the outside of it. This is likely what you feel spinning. The eccentric itself has a tab that keys it to the cam gear.

 

[JACK M]

4 hours ago, joe_padavano said:

The eccentric on a Pontiac actually has a separate ring that goes over the outside of it. This is likely what you feel spinning. The eccentric itself has a tab that keys it to the cam gear.

 

Perfect, this is what I was thinking.

Thanks.