No fuel

[ggenovez]

Hi all.

I'm having an odd problem. I have no fuel. I recently replaced the fuel pump and I can see it pressurizing to 4 PSI but no fuel is coming out. I can disconnect the fuel lines and put some air in the carb return line and get fuel to come out the return carburetor.

That will get me started but if the car runs for a little bit she'll stall and run out of fuel. Disconnecting the fuel line after the pump shows no more fuel coming in. I just put in 5 gallons of fuel.

Any idea where I should even start to look? I'm guessing there is an obstruction somewhere.

Thanks

G

[Frank Reiner]

Originally Posted by ggenovez

Hi all.

I'm having an odd problem. I have no fuel. I recently replaced the fuel pump and I can see it pressurizing to 4 PSI but no fuel is coming out. I can disconnect the fuel lines and put some air in the carb return line and get fuel to come out the return carburetor.

That will get me started but if the car runs for a little bit she'll stall and run out of fuel. Disconnecting the fuel line after the pump shows no more fuel coming in. I just put in 5 gallons of fuel.

Any idea where I should even start to look? I'm guessing there is an obstruction somewhere.

Thanks

G

I'm a bit confused by the writing, but let me see if I have understood some of it.
First highlight: Is the pressure gauge connected to the fuel line between the pump and the carbs via a tee fitting? And does "coming out" mean that no fuel is entering the carbs?
Second highlight: What is a "return carburetor"?
Third highlight: Does "coming in" mean that no fuel is coming out of the fuel pump, even when the discharge fuel line from the pump is disconnected from the pump, and the engine is spun over with the starter motor? If that is the case, it would suggest that a blockage exists between the tank and the pump, or there is an air leak between the tank and the pump, and that the gauge pressure is simply air pressure. Hence, the pump is working, but pumping air.

[ggenovez]

Frank, My apologies. The text above barely qualifies as English. Maybe that will teach me to post something when I'm exhausted, Frustrated, and 2 hours late for bed.

So to clarify,

Highlight 1, I disconnected the fuel line to the carburetor. Cranked the engine and no fuel came out. I then put a pressure gauge on that line, disconnected from the carburetor, and the pressure climbed to 4 PSI. So we know the pump is working. Correct?

Highlight 2: Then, I removed the return line from the carburetor, this is the overflow line that connects back to the tank from the carburetor. and I pressurized it with some shop air. (return carb should read return fuel line from carburetor)

Highlight 3: Yes. there is no more fuel coming out after the line was pressurized. even though the pressure gauge, disconnected from the carburetor shows 4PSI

Probably would have been easier to re-write the whole thing.


I hope that helps.

I appreciate any assistance.

[Frank Reiner]

Here is what we know:

That the pump, when deadheaded into the pressure gauge, will show pressure (4psi) when the engine is spun. Conclusion: the pump diaphragm is probably intact.

When you applied air to the return line, the tank was, at least temporarily, pressurized, which resulted in flow of fuel through the delivery (suction) line, and through the pump, to the carbs. Do I have this sequence correct?

[ggenovez]

Outstanding. Yes that is correct

[Frank Reiner]

Originally Posted by Frank Reiner

Here is what we know:

That the pump, when deadheaded into the pressure gauge, will show pressure (4psi) when the engine is spun. Conclusion: the pump diaphragm is probably intact.

When you applied air to the return line, the tank was, at least temporarily, pressurized, which resulted in flow of fuel through the delivery (suction) line, and through the pump, to the carbs. Do I have this sequence correct?

If the highlight is indeed the correct sequence/scenario, then we may conclude, for the moment, that the fuel supply line from the tank to pump is not blocked.

The next step is to find a possible air leak in that line from the tank to the pump, including the flexible hose connection between the chassis and the pump. Follow the chassis line from front to back, looking for any clamped on hose connections/splices. Those, and the flex hose at the pump, are the most likely point of an air leak.

[ggenovez]

Thank you Frank.

There wouldn't be a diagram somewhere of all the fuel lines would there?

I think replacing all the rubber lines is in order.

[ejboyd5]

Have the in and out fuel lines on the pump been reversed?

[bsharp8256]

Have you checked the in-tank strainer?

[ScooterABC]

I can suggest a number of things that I went through in resurrecting the fuel system and tank on my 1963 220S.

1. Run a fuel line from a gas can that is HIGHER than the fuel pump sitting next to the fender and going to the fuel pump.

2. Run a fuel line from the return line to the gas can.

Q1: Does everything work? It should.

Next:

1. Blow compressed air into the fuel supply line (towards the tank). NOT MUCH AIR. You should hear bubbling at the tank. Do you?

2. Do the same thing with the return line. Again, bubbling?

I think your pump generating 4 psi is irrelevant if there is no VOLUME of fuel pumped. If I understand you, you are saying you can crank the engine with the output from the fuel pump going to a pressure gauge and it says 4 psi but if you disconnect the gauge you don't get gas spurting out of the hose. Is that correct? To me that means blockage on the supply line.

[ggenovez]

Thank you all for your help.

I have replaced the fuel line at the tank and I now have a constant supply of fuel. On to the next problem.