72 Cutlass 350. Need to use starter fluid if car hasn't been started for a week or longer. Starts fine if it's been driven regularly. Been told fuel pump gasket leaks and allows fuel to drain out of carb. Any answers? Thx, Tomc5

 

It could be a number of things (I think I covered the most common problems):

1) Fuel pump diaphragm
2) Rotten hoses from your fuel tank to your lines
3) Fuel evaporation
4) Fuel leaking out of your fuel bowl

Have you rebuilt the carburetor recently? Don't forget to check those fuel lines, if they are rotten then your pump will suck air when you crank the engine.

 

You actually left off the most likely cause, which is the check valves in the fuel pump (not the diaphragm) are bad. The fuel definitely evaporates out of the float bowl over the course of a week. A good fuel pump should refill that after only a short time cranking. If the check valves in the pump leak instead of sealing properly, the pump will take a lot longer to fill the carb.

The fuel leaking out of the float bowl is the most-often cited cause and is the least likely, yet people spend a lot of time putting epoxy on those carb plugs for no good reason. If you really lose sleep over that one, simply prop your carb over a piece of paper on the workbench, fill the float bowl, and leave it overnight. If the paper isn't wet with fuel in the morning, the plugs aren't leaking.

 

After it sits, remove the air cleaner and while looking down into the carb operate the throttle linkage and see if there are 2 streams of fuel spraying in there.

 

You left out:

5) Normal operation.

After a week, they all lose a certain amount of fuel from the float bowl, and require additional cranking time to fill the float bowl and start.

The OP did not tell us how long he has to crank to start the car without starting fluid.
Considering starting fluid's volatility, and consequent lack of "staying power," though, it will not run the engine alone for more than a second or two, so it can't be pumping that much gas into the carburetor.

By the way, repeated used of starting ether is bad for your engine, as it breaks down the film of lubricating oil along the cylinder walls and increases wear.

- Eric

 

Eric is correct. People who are used to fuel injection don't know the idiosyncrasies of carbs, especially ones that are driven infrequently. And as Eric also points out, the starting fluid should be used sparingly. I have this problem on my 62 that is driven infrequently. After sitting for a week or more, I'll fill the float bowls with gasoline through the vents using a turkey baster or dispensing squeeze bottle. This solves the problem without washing down the cylinder walls and also avoids long cranking times.

Here's another way to do it:

 

The big question is how long you have to crank it. This comes up a lot and some people are more familiar to fuel injected cars with electric pumps that require no priming. Yes, you can have the above problems listed, but a long crank time is not odd on a carb. car that sits. On mine, with a correctly set choke, I hit gas to floor, let off and crank for 20-30 seconds. Sometimes it stalls right away and requires a second but short crank without touching gas pedal, and then it fires and idles fine.

 

Gee, you guys type faster then I.

 

This is compounded if you have an engine that sucks to get to, like my van, so I leave the cowl off and drive around with a roaring V8 next to me until I fix the issue.

The checkball thing is interesting though. Might mean the difference between a 7 second crank and a 20 second one.

 

A friend of mine did this when his van's fuel pump quit. He attempted to slowly pour gas into the carb as he was driving. Yes, he started a fire. Yes, he's a dumb-a$$.

 

They aren't really check *****, they are rubber one-way valves. Yet another part that deteriorated due to ethanol in the gas and any rust or crud that gets sucked through the sock in the tank. It's not a bad idea to put a fuel filter BEFORE the pump.

 

Like this idea.