Topic: Leaking carburetor, weak fuel pump ?


DDBland    -- 08-15-2020 @ 12:55 PM
  I have a 1951 Mercury in original condition. After it sits unused for a few days I have to prime the carburetor to start it. Does the gas evaporate/leak out of the carburetor? Maybe I need a new fuel pump? New carburetor ?
Thanks!!
Dave


TomO    -- 08-16-2020 @ 7:31 AM
  The fuel bowl should keep enough fuel in it to start the car after sitting a week. I would say that your carburetor is leaking fuel and should be rebuilt.

Tom


DDBland    -- 08-16-2020 @ 1:37 PM
 
These re-builders have been recommended on this forum:

Charlie Schwendler 716-662-9159

Sal. (586) 612-1650
sal_cicala@yahoo.com

Any others or any experience with these guys?
Thanks!
Dave


37RAGTOPMAN    -- 08-18-2020 @ 11:07 AM
  hi DDBland
after you drive the car, and shut it off,
take the air cleaner off and use a flash light and see it is dripping gas,? you can use a mirror,?
do you smell gas in the garage when sitting ?
also try a new flex line, if yours is old,
tighten the fuel line connections, maybe the fuel pump is loosing its prime,?
check fuel pump pressures,
hope this helps 1937 Ragtopman


stanzuser    -- 09-01-2020 @ 3:19 PM
  sometimes if you turn the engine off while it is hot the carburetor will percolate the fuel into the manifold. If everything else fails try putting an insulator under the carb.


DDBland    -- 02-12-2022 @ 11:57 AM
  After a few "life events" I am back to getting my 1951 Merc 4 door sedan going. I drive it about 4 miles one Sunday a month. To start it I prime the carb using a "home-made" priming system (see photo)- a line spliced into the gas line near the carb which I carefully put gas in using a syringe. I understand a "common" problem is gas leaking/evaporating out of the carb after it sits a few days. My car will start quickly after 2 days of rest but not 3.

Works Ok but I would like to get rid of the priming system so my son can start it easier/safer after I'm gone.

The carb and fuel pump were installed in 1990 and the flexible fuel line in 2012.

The glass bowl on the fuel pump stays full and the car runs good after I get it going, so is the fuel pump OK?

Suggestions?
THANKS!


37RAGTOPMAN    -- 02-13-2022 @ 6:27 AM
  leaking carburetor.
by the photos you posted, it looks to me the carb seems to be leaking, but it been on there of 32 years
if you start it everyday do you have the problem,?
I would replace the flex line to start and see if that makes any difference,
this may be the problem it is 30 years old, and is not made for the NEW GAS, same with the FUEL PUMP.
the next would rebuild or have the fuel pump rebuilt, not replaced by a China part,
any car sitting for a month with a carb would have issues,
I had a 1980 Toyota truck and if sat for a week, it took many cranks to ge tit to start,
but used eveyday had no problems,
Hope this helps 37Ragtopman


carcrazy    -- 02-13-2022 @ 9:26 AM
  There are some secrets to getting the Flatheads to start reliably after sitting for several days.

Use an auxiliary electric fuel pump mounted at the fuel tank. Wire this fuel pump through the ignition switch and a dedicated switch for the pump. You can mount this switch beneath the instrument panel. You can use this pump just for priming the fuel system prior to starting if you wish.

Make sure your automatic choke is working properly. If you have a manual choke, apply it fully while cranking the engine to allow the vacuum created below the choke plate to help pull fuel up from the tank.

Carry a can of starter fluid with you at all times to be used if the engine still refuses to start.


TomO    -- 02-13-2022 @ 10:59 AM
  The 1949-1953 Mercury carburetors are different from the Ford carburetors and have different problems. You should be able to start your engine without having to prime it. Your practice of only driving the car 4 miles one Sunday a month does not help your situation. It would be much better if you took it for a 30 mile drive on your Sunday tour. This would allow the oil to reach operating temperatures and exercise all parts in the car.

Your carburetor is leaking and it sounds like you are having problems with priming the carburetor with the fuel pump.

I have had good experience with both carburetor rebuilders that you posted before. Sal seems to have more experience with the Mercury carburetor then Charley, but either of them will do a good job.

You need a good fuel pump, good clean fuel lines from the tank, correct idle speed adjustment and a good operating automatic choke to properly prime the carburetor.

First check if your fuel delivery is sufficient.
To check fuel delivery, you need a graduated 16 ounce or larger container to determine the amount of fuel delivered in a measured time. Disconnect the fuel pump line from the carburetor and direct it into a graduated container. Crank the engine long enough to get 2 ounces of gas in the container and then continue cranking for 15 more strokes of the pump. The pump should have delivered 6 more ounces of gas.

Insufficient fuel delivery can be caused by a vacuum leak ( gasket on sediment bowl leaking air, bad crimp on flex line, pin holes in flex line. leaking connections to an added filter or electric fuel pump or connections not seated properly), plugged flex line, plugged fuel line, plugged tank pick up, worn pivot in the pump arm, stretched diaphragm, plugged tank vent or wrong gas cap or a worn push rod. It should travel about 3/8" from low point to high.

You have the double action fuel pump, so I recommend the it be rebuilt by Charley Schwendler.

The signs of leaking around the carburetor can be from the input fitting, sticking float or excess fuel pump pressure. Be careful when checking the input fitting. Over-tightening of the fitting can lead to carburetor damage. If you have a leak there, I recommend a carburetor rebuild to install new gaskets and set the float correctly.

Your idle should be set to 400-450 with standard or OD transmission and 400-425 with the Merco-Matic. The choke should be set to the center index point. If it does not fully close at that point, operate the engine until it reaches the normal operating temperature. Move the cover on the automatic choke until the choke starts to close, then back off one index mark. Tighten the screws.

I suspect that your main problem is fuel delivery and that the flex line and a new gasket for the sediment bowl on the fuel pump may help you out.

Tom


DDBland    -- 02-14-2022 @ 9:41 AM
  Thanks 37ragtopman -

Your question of do I have the problem if I start it everyday is no. After I drive it I can start it with no problem for the next 2 days.

After I prime it and drive it, on the following 2 days it starts "immediately" - one of the impressive traits of the car!

After it sits a few days I expect it to start immediately again. Am I being too impatient and should I expect it to crank for awhile to get it going? How long should it have to crank to get the fuel back into the carb?

Thanks


TomO    -- 02-15-2022 @ 7:24 AM
  I can let my 40 Mercury sit for 3 or 4 weeks and it starts right up. After sitting all winter, it takes about 30 seconds to prime the carburetor. I suspect that you have a vacuum leak in the lines leading to the fuel pump or that your fuel pump valves are leaking. A fuel delivery test will help determine if this is your problem.

Tom


sarahcecelia    -- 03-14-2022 @ 3:45 PM
  That priming system you are using can be very dangerous!!

You can buy a spray can of primer at the local auto supply. you just remove the air cleaner, give a shot of it and start it! You can also just pour about an ounce or so down the carbs throat and start it!

The bowl on a carburetor has gas in it; some of it will evaporate in about 2 or more weeks. When you want to start the car; after it sits for 4-5 days; take the air cleaner off and stroke the accelerator rod while looking directly down the carbs throat. You should see 2 small streams of gas going into the manifold- if you don't see them; the gas leaked out of the carb. Running a car Less than about a 15-20 mile round trip is very detrimental!! It doesn't get a chance to get to operating temp. or re-charge the battery!

Regards, Steve Lee


sarahcecelia    -- 03-27-2022 @ 6:41 PM
  Electric fuel pumps must be left on all of the time!!
I forgot to turn mine in with the little on/off switch on the lower edge of the dash; well when I was driving down the road the motor started to die several times and I thought "What's wrong now!!" It finally quit!
I then realized the electric pump was OFF! Turned it on, started the car, and went merrily on my way!! When they are in the OFF POSITION they BLOCK THE FUEL FLOW!!!!

Regards, Steve Lee


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