Fuel delivery problem?

[Doug&Deb]

Lately my Coronet has been acting like it’s not getting fuel. It doesn’t stall it just loses power. Turning on the electric pump gets it going again. The problem only occurs after the engine is at operating temperature. The mechanical pump is less than 2 years old and the pivot pin hasn’t moved. I’m due for my annual spring maintenance which includes a new filter. Any suggestions where to start?

[vintage6t]

Are you using the electric pump to start it, or turning it on while driving to over come the loss of power? If only to start, I would suspect possibly a clogged fuel filter or more likely a intermittent clog at the tank pickup. I say intermittent b/c when starting the pickup may flow freely. However, when driving the increased fuel flow in the system may suck debris like rust in the tank and clog the pickup, resulting in a loss of power or even a complete stall. Then when you shut the engine off the debris releases from the end of the pickup and falls back into the tank unclogging the pickup. This cycle just repeats when you drive the car maybe giving the impression it's operating temp related.

 

Could be other things as well but that's where I would start.

[JerseyHarold]

The fuel pump may be sucking air instead of gas.  Check to see that your fuel line clamps are tight and that there are no leaks from the line itself.  

[Los_Control]

Pay close attention to the filter when you change it .... is it restricted from old crud coming loose in the tank?

[Dave72dt]

You might as well check the tank vent too.  Did you put a filter in front of the electric pump?

[Doug&Deb]

Filter in front of the pump. I use the pump for priming and hot starting problems. I do think the tank may be a problem. There’s a leak on top but not around the sending unit. I may have to drop the tank soon.

[DonaldSmith]

When you say "in front of the pump", I think you mean at the inlet, which could be at the rear of the pump, as it is on my car.  

[keithb7]

Winter grade modern ethanol fuel with a lower flash/boil point? Hot engine causing vapor lock. Mechanical fuel pump cannot push through vapor lock.  Electric fuel pump can.

Cold engine, no problem. No vapor lock. Hot engine, yes. When engine is fully hot, I mean hot, then turned off for 15 mins do you notice it is a little harder to start?

 

As discussed here:

 

 

Edited April 15, 2023 by keithb7

[Doug&Deb]

Filter on the inlet side. Keith, yes it may be vapor lock. Our temperature went from the 40’s to the 80’s in about a week. I may try the wooden clothespin trick. That always worked on my D24 I had.

[Sniper]

I do not know how your dual pump setup is configured but if you have your mechanical pump sucking through your electric pump that might be an issue. Some electric pumps don't allow very much in the way of flow through them when they are not running.

[Doug&Deb]

It’s supposed to be a flow through pump but that’s not saying it’s not the problem. Yes the mechanical pump is pulling through the electric pump. I ran this setup since last summer and the problem just started last week. I’ll keep plugging away until I get it. Everyone’s advice is appreciated.

[Sniper]

I suspect you could use the FSM fuel flow test to see if fuel delivery is your problem.