blento

My '55 Rocket 88 has a 1976 455 from a Cutlass. I have no idea how many miles on it, it runs great no noise, no smoke and good compression. I replaced the fuel pump 3 times because there was very little fuel getting to the Quad Jet. I have a clear filter and it just barley sputtered gas into the filter, at any RPM. I thought I had a tank or line problem, but putting a hose direct from the pump to a 5 gallon can was the same. As the tank is the original '55 it does not have a vent line returning to the tank, that outlet on the pump was plugged.
Well I gave up and got an Airtex electric (E8090) installed it at the tank, barley enough room and no room for a filter. That works great, I tested it before I connected it to the gas line and it pumps great. Now I discovered it never shuts off. I guess if you spend $150 instead of $40 you could get one that shuts off at full pressure. So I found a 2-7 pound switch at Pegasis Auto Racing (#1064) it has a single connection that I connected to the ground side of the pump. If the pressure is below the set point, the contacts close and the pump runs. If the pressure is at or above the set point the contacts open and the pump stops. Seems kinda silly for the pump to run all the time..
Am I the only one that has had problems with a 455 mechanical pump??????

oldcutlass

The ethynol fuels tend to eat them if the rubber parts are not compatible I hear, as I have not run into this issue. I would take/cut the old pump apart and see what kind of stuff is in there.

Ozzie

I've always used a mechanical pump without ill effects from the ethanol (up to 10%) laced fuel. If you want to do a non-destructive inspection of one, get one from a 1964 330. They used the bolt together type. Also some aftermarkets for 1965 were bolt together.

blento

I only had the pumps for less than 50 miles, I really hate the crummy corn gas they force use to use, but I think that whatever on the engine that actuates the pump is the problem. It looks like the pump does not get enough stroke, because if I worked the arm off the motor I got a good stream of fuel. Guess it will not matter now, the electric works great, but I did have to add a check valve to prevent the pressure from going back to the tank when the pressure switch did turn off the pump. Works great now, when it sits and idles, the pump will be off quite awhile.

MDchanic

I haven't noticed you mention how your car ran during those fifty miles that you had each fuel pump.

All you mention is that you had a visual problem:
You didn't like the way that the fuel looked inside the clear fuel filter, but you don't mention any actual symptoms of fuel starvation.

And why do you feel that the electric fuel pump should shut off? The original mechanical pump doesn't shut off.
In fact (though I may be naïve), I have never heard of a fuel pump shutting off, other than modern ones that turn off if the engine stalls or the car crashes. The fact that you had to create a workaround for a problem that didn't exist before (installing a check valve) indicates that all you did was create work for yourself.

- Eric

Octania

"whatever on the engine that actuates the pump is the problem."

not likely
inside the engine is an eccentric on the cam which actuates the FP arm.

When the arm moves, it pivots and draws back a spring loaded diaphragm within the pump, drawing in fuel from the line from the tank. Think of it as cocking the hammer on a gun. When the arm is released by the eccentric in the engine, the diaphragm is allowed to move as dictated by its spring, pumping the fuel out to the carb. How much it moves depends on the fuel use demand at the time. If the carb says "no more" then the pump will supply no more.

One assumes that both inlet and output ports on the FP have a check valve to ensure that each flows only in the desired direction.

That is as much study as I have done on the mechanical fuel pumps.

Indy_68_S

Odd that 3 pumps had same symptoms...

They weren't on upside down, were they ?

AFAIK, mechanical pumps are good to well north of 400 HP...I know the standard mech FP on my 350 will fill a gal jug in a few mins.....so I wonder if somehow you're getting some odd part number or odd cfg pump with a weird arm...or if somehow your eccentric is wrong/damaged.

Octania

We are back to "there isn't really a problem" -

"...1976 455. It runs great.... I replaced the fuel pump 3 times because there was very little fuel getting to the Quad Jet. I have a clear filter and it just barley sputtered gas into the filter, at any RPM."
==========================
OP is confusing observed fuel flow with "a problem"

If it runs great, then by definition, you do not have a fuel flow problem.

Replace the visible filter with solid steel line and you won't see the "poor flow" and you will now have no problem. Right?

blento

I guess I left out the reasons, it would not run well after about 40-45, it would stumble and act like all kinds of problems. I tried a lot of things and a lot of suggestions about what was causing it before installing the clear filter, including a new fuel pump, then finding there was very little fuel flow.
I just felt that unlike the mechanical pump, there is really no need for the pump to use battery when at idle or if the ignition is on without the engine running. And most of the new cars the pump shuts off if there is no oil pressure, but goes back on when the starter is engaged. And that requires either electronic logic or a relay to accomplish.
As a side note my '55 has all it's power back and gets about 10-12 MPG again but goes like hell!