wherlehy

1970 Cutlas S 350 rocket - manual fuel pump, four barrel.

When I go to start it, it just goes vroom for a second then dies, over and over again. Looked at the fuel filter and it looks empty.

Broken fuel pump?

Yes the tank is full.

442Harv

Disconnect the line, take a container, and hold it, and have someone turn the key and crank the engine, will tell you right away if it is pumping.

wherlehy

The line from the fuel pump to the fuel filter I presume?

Bill

Olds64

Correct. If you disconnect the line between the fuel pump/filter and the carburetor the fuel pump should gush gas into a coffee can. The OE fuel filter was built into the inlet of the carburetor but you might have one between the fuel pump and the carburetor if you have a rubber hose instead of the OE steel line.

Loaded68W34

Before disconnecting anything, check to see if the carb has fuel in it. If you move the throttle manually, you should be able to see the accelerator pump squirting fuel in the carb. If you see fuel squirting, the fuel pump is working. The fact that you said it does this "over and over" makes me think you may not have a fuel problem. Does it fire while cranking and then die when you stop cranking? You may actually have a problem with the ignition feed to the coil (resistance wire). While cranking, the coil gets power through the yellow wire from the starter. As soon as the key comes off cranking, the yellow wire loses power and the coil needs to get power from the resistance wire. If the resistance wire is not getting power, the motor will fire while cranking and die as soon as you come off of the crank position. If this is the case, you will need to diagnose why the wire is not getting power to the coil.

Vintage Chief

All good suggestions, none-the-less, generally speaking a mechanical fuel pump will begin to develop tell-tale signs of eminent failure - most often fuel begins leaking along the seam between the top & bottom of the fuel pump, it's possible the interior diaphragm has ruptured, as well. Have you noticed any fuel leaking anywhere from the fuel pump? Another possibility is the fuel filter itself has collapsed, become fully clogged (choked) from gum. Remove the carburetor fuel filter inlet housing and examine the fuel filter. Has it collapsed? A little more information would be helpful. Did the engine all of a sudden do this or has this been a slowly developing theme over some period of time?

Vintage Chief

Just read this about the same time I posted - good observation(s) worth pursuing.

Fun71

An inline fuel filter will not fill up with fuel. I have one and it is never full.

joe_padavano

These plastic fuel filters have caused more lost sleep and posts like this than anything else...

BangScreech4-4-2

But first thing: test the fuel pump as suggested in post #2. If the pump tests okay then you might inspect the filter. Report here with your findings.

As Norm mentioned above, the situation is a little iffy because fuel pumps don't usually check out with absolutely no warning. But we might as well start by ruling it in or out. And it's a readily available $40 part, so while I'm usually against "throwing parts at the problem" if you're going to do it this isn't a bad way to go.