1957 - starting issues carburetor or fuel pump? | Ford Thunderbird forum club group 1955-2005 models

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1957 - starting issues carburetor or fuel pump?

  • Thread starter Thread starter goffs
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goffs

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1957
I have a Holley 4160 4 barrel carb. My car has trouble starting. The only way I can get it to start is to pour a small amount of gas down the throat of the carb. After starting it runs fine. I am starting to think it could be a weak fuel pump. I do see fuel being pushed into the fuel filter bowl when running. However I've been told that when cranking the pump might not be able to deliver enough pressure (works great when car is running). I did take off the bolt on bowl after sitting for a couple of days and bowl was empty. I then cranked the car for about 10 seconds and then checked the bowl again. It was still empty. I started to think it was the needle and seat. I took off the fuel line and the needle was open (I could blow air into the bowl through the fuel line. So now I'm back to lack of fuel pressure. The carb was recently rebuild (by me) and I followed instructions as close as I could. I'm I thinking correctly or I'm I missing any troubleshooting steps? Would a electric fuel pump possibly correct my issue?

Thanks for any help

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The carburator should hold some gas in the bowl, enough for pumping a squirt into the admission manifold and starting the vehicle to allow your mechanical pump to operate, hoping it is USA manufactured pump and NOT a Chinese copy which are junk.
As you rebuit the carburator, did you adjust the float so it operates "just before overflowing the scew inspection hole"? If not, your carb won't hold gas for the next start session.
 
Even if your carb bowls were bone dry, the car should start in 4-6 seconds if the fuel pump is good.
Ger a vacuum gauge and a clear glass jar and perform a fuel pump pressure AND volume test. Do both as they are two different things. The second page of the attachment describes the tests...
 

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I did adjust the float so gas was just at the inspection hole. I did fill the bowl with gas through the inspection hole and it still did not start. I'm thinking when you press pedal it does not squirt any gas to the carb. I might have two problems - the fuel pump and something in the carb.

Frankie - I totally agree the bowls should fill even if empty after a few seconds.
I will do the above test.
 
Yoir pump is probably goid as utvruns well once on the road.
Please chec the carburator inyector diafragm. Either it is bad or you forgot to install the check (steel) ball, which is tiny.
 
Check your accelerator pump. It's on the bottom of the front bowl, left side. It has a little arm sticking out. That arm is operated by a cam and lever from the primary throttle shaft. Make sure you didn't tighten up the adjusting bolt with the spring. When you open the throttle the cam and lever push the arm down. Test by pushing the arm down. It should squirt fuel.
 
74 Harley said:
Check your accelerator pump. It's on the bottom of the front bowl, left side. It has a little arm sticking out. That arm is operated by a cam and lever from the primary throttle shaft. Make sure you didn't tighten up the adjusting bolt with the spring. When you open the throttle the cam and lever push the arm down. Test by pushing the arm down. It should squirt fuel.
Click to expand...
My accelerator pump is definitely not working. I plan to get a new (american made) rebuild kit. Is there a way to check the pump with the carb off the car. I plan to follow a video rebuild of carb as closely as possible. Should I use compressed air on both holes of the accelerator pump to make sure they are not plugged with anything?

The fuel pump is pumping gas like crazy - not the problem. It's the carb.
 
You can put some gas down the front vent with the carb off the car and work the throttle, just hold it over a pan to catch the gas. You can remove the squirters easily, a small torch tip cleaner will usually clear any blockage. There should also be a spring a check ball in there, make sure it's assembled correctly.
 
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With the diaphragm inverted, install the accelerator pump diaphragm spring into the recess. When installed, the diaphragm must be oriented with the center button facing away from the fuel bowl. This is the contact point for the pump lever. The side of the diaphragm with the shallow rivet head must face toward the recess in the fuel bowl.

Before replacing the pump diaphragm cover, check for warpage by laying the cover on a sheet of emery paper which should be on a smooth surface. Remove the sealing bead, if any is present.
Place the diaphragm assembly on the cover, holding the pump lever arm against the diaphragm so that the diaphragm is flat. Don’t forget to install the spring into the bowl first. Install the cover and diaphragm on the fuel bowl and insert the screws finger tight.

Release the lever, making certain the diaphragm is loose enough to flex without wrinkling at the edges, also the diaphragm must be able to be raised so that the flange of the steel diaphragm washer touches the inner surface of the cover. These two checks will assure maximum diaphragm travel.

Tighten the four screws in two stages, 1/2 torque the first time and full torque on the final stage (5-8 in-lb. torque).

doug7740
1955 Thunderbird Blue
 
I had same problem with my 312 Holley and put a electric fuel pump in line back where not as visible and wired to key side of solenoid. No priming needed, fired right up every time.
 
Two issues with an electric fuel pump: 1) in a severe crash, even if the motor cuts off an electric pump will keep fuel moving to the carb and is a major fire hazard - an inertial switch may suffice but an oil pressure sensing switch is better.
2) if you run an electric pump so it operates through the old mechanical pump (e.g. make it a booster pump) you can fill your crankcase with gas if the old pump's oil seal fails and you won't know because the car will run just fine.
 
goffs said:
I'm actually thinking of a momentary switch to get car started and then off
Click to expand...
That'll work.....I put one on my vintage Corvette to turn on briefly if I suffered from fuel percolation in the Orlando summers and for start up after the car sat for a prolonged period.
 

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Frankie the Fink said:
Two issues with an electric fuel pump: 1) in a severe crash, even if the motor cuts off an electric pump will keep fuel moving to the carb and is a major fire hazard - an inertial switch may suffice but an oil pressure sensing switch is better.
2) if you run an electric pump so it operates through the old mechanical pump (e.g. make it a booster pump) you can fill your crankcase with gas if the old pump's oil seal fails and you won't know because the car will run just fine.
Click to expand...
True. l have mine on a switch under the dash as well as the inertial cutout. With a working mechanical pump I almost never even run it. Just a few seconds from time to time to make sure it still works. Its there in case of vapor lock or if the mechanical craps out again.
 
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