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The truck runs great, starts with a bump all day, but in the morning I have to pump the gas pedal 20 times. edelbrock 600 cfm, fresh rebuild, el. choke works well.
The truck starts right up with a very small squirt of starter spray. Also has a new fuel pump, the fuel hose to the carb is rubber,it is run up beside the breather to keep it cool.
Is there a bad check valve somewhere?
thanks in advance
It may be leaking back to the tank through the fuel pump.. one of the valves inside could have a defect and leak..
Other question I have is, have you looked in the throat of the card first thing in the morning and moved the accelerator linkage? Did the accelerator pump push gas out the nozzles?
Curious if it really is a lack of fuel and / or a choke failure to operate?!?!
there is no check valve unless you put one in..You could put a clear fuel filter up at the carb and see if its empty in the AM..My thought would be carb. accelerator pump?? Floats not set right.
I have a clear fuel filter befor the carb, and since I repositioned the fuel hose it stays pretty full. The fuel used to bubble out of the filter,
so I thought I solved the problem. I also put a clear filter before the fuel pump, and it is pretty empty in the morning. The accelerator pump
seems to work, I need to check it again with my glasses on. Thanks for the help, I'll check the acc pump AGAIN.
I wonder if you were to put a " hump " in the rubber line in front of the carb a few inches high, would that prevent the bowl from draining back?
thing is the gas in the carb can't get pulled back out if nothing else the float valve would prevent all the fuel being pulled back Carb should have enough to restart the engine then the fuel pump would fill it back up quickly.
It used to be very common on quadrabogs to drain the carb back into the tank. They solved it by adding a rubber check on the fuel filter.
There are 2 check valves in the stock fuel pump, the first lets fuel into the pump chamber and as the diaphragm pushes down the first valve closes and the second valve lifts and allows the fuel to exit the pump going to the carb. It is possible that these valves are damaged and allowing the fuel to drain. But if the carb is full in the morning as evidenced by looking into the throat and pumping the accelerator lever and seeing fuel sprayed into the carb then that rules out the pump valves.
Also my memory tells me the the fuel filter on that ford is high enough to prevent the carb from going dry.. but don't forget I CRS... (can't remember S _ _ _)
Sounds to me like you've got a problem in the carb, not in the supply system. Like Mike & Charlie said, the engine starts from the fuel in the bowl, and then the bowl is refilled quickly by the pump as the engine cranks & starts. Something is letting your fuel drain from the bowl. Assuming the casting is good I'd wonder about a high float level getting a siphon started through the jets, and that draining your bowl. If you go out and look into the carb throat after it's been sitting for a few hours you might see fuel dripping into the intake from the accelerator pump nozzles or from the primary/secondary nozzle in the venturi? Worth a look.
take the top off the carb and look before starting----
Old truck, probably no cranking vacume and empty carb
Thanks all, the fuel filter before the carb was full this morning, and I pumped the acc. linkage and saw no fuel squirting int othe carb.
I could here the rubber diaphram rubbing though. the fuel filter I have before the fuel pump was almost empty.
I will tak the top of the carb off in the morning and see what is or is not there.
As an aside, this truck runs strong, it is still pulling hard @ 90MPH, it has a 4 spd NP435 i think.
Put a 1/2" phenolic carb spacer under the carb and it should cure your problem.
I was wondering about that, I hope I have one lying around, thank you!
If the fuel line / filter is full, but no gas was being pumped in when working the throttle, I'd say the accelerator pump has failed. Let's see what you find when you remove the top. There is a small port that keeps the accellerator pump reservoir full, maybe theres debris over that and the pump is being starved?!?!Quote:
Originally Posted by 662doorgalaxie
I'll be sure to check that as well, the weather is nasty, unless you are a duck here, it may be monday or tuesday before i get a chance.
thanks again for all the help.
The fuel can't "drain back" into the tank. The needle and seat are above the fuel level, it would have to jump up to the seat to get back in the line. Your gas is percolating out of the carb from engine heat. A spacer will help. So will an electric fuel pump, it will refill the carb before you try starting the engine.