| jeff holland | -- 06-10-2010 @ 2:16 PM |
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Hi Folks again! Wrote to you last that my Merc is hard to start after engine warm-up and attempts to restart. I also had quite a bit of work done on the carb and fuel system since I was having a constant fading problem when driving down the road when I got the car. That was the original problem and why I had my mechanic look at it. I thought the mechanic had taken care of the problem, but it appears to be back after having the car back for only a few days. I had the carb. rebuilt, put in a 6v. fuel pump,tune-up, distributor, coil, plugs, new battery, plug wires,fuel pressure regulator, new gas tank, fuel lines checked. After I wrote last about the hard starting problem I also replaced the cables to the battery ( as suggested), and made sure the wire from the solenoid was clean and good. I made sure the fuel tank was full. When it faded on the road again today I tried to restart. The fuel pump was running,starter engaged, but engine seemed o have no fuel. I pumped throttle, no start. I did note a small amount of fuel leaking from the bottom of the carb intake. I let the engine set about 5 minutes and with several restarts the engine started up. I am running out of ideas as to the engine fading problem. I had a compression check done and everything was fine. The engine runs strong, but I think the fading and hard start after warm-up may be somhow linked. Your thoughts? Jeff Holland
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| ford38v8 | -- 06-10-2010 @ 3:26 PM |
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Jeff, When we try to diagnose problems, all we have to go on is the exact wording of the question. If my previous diagnosis was inaccurate, I apologize, but at least now you know that your electrical system is up to snuff. From what you describe today, it does sound like a fuel delivery problem. I know, you have a new gas tank, pump, and carburetor rebuild. The fuel leak under the carburetor is not right, so it's a given that there's a problem with the rebuild. Your gaskets are not seating properly, and/or your economizer valve is not seated properly. Gasket seating requires flat carb surfaces, as the old castings can become warped. The gaskets must also be fuel resistant to today's gasoline. The newer economizer valves don't fit the old carburetors properly, and must have its mating surface machined to match the flat on the carburetor, or as an alternative, the use of a garden hose gasket to make a seal. Look at the valve to see the radius between the threads and the gasket surface, as this radius is the mismatch. In addition to the rework of the carburetor which seems at this time to be mandatory, you may check the output of the pump. Disconnect the line to the carb and direct that line to a container while you crank over the engine with ignition off. If the stream of gas flowing from the pump is not strong with each stroke, you'll know that in addition to the carb problem, you have a delivery problem behind the carb. With all new parts behind except the line itself, there may be an air leak somewhere, which would not show up other than low fuel delivery. Check and tighten all connections from tank to pump, and including the pump itself. There are other things to check, of course, but one step at a time so as to not confuse the issue. Alan
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| jeff holland | -- 06-10-2010 @ 3:54 PM |
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Alan- The garage that did my work sent the carb. to a builder in Florida ( don't have the name). I have heard he is the best so hopefully the leaking fuel problem is not too big an issue. I will be sure to discuss with the mechanic. Thanks Jeff
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| 37RAGTOPMAN | -- 06-10-2010 @ 4:57 PM |
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I am just wondering if the gas cap is vented ? if it is not, the gas will not flow, also make sure the electric fuel pump is not on the same circuit of the IGN COIL,this will make the car loose power,because of voltage drop, it seems the more you items you put on the car, it has more things to go wrong, are you still using the original fuel pump,? the gas leaking out of the carb could be from over choking.but if gas is leaking out I doubt you have a fuel problem, when you get it running,take the air cleaner off and look down the carb with the engine running, and see if gas drips down the venturies. it might have gotten a piece of foreign object in the needle and seat, and is not shutting the fuel off when it reaches the full level in the float bowl hope this helps, 37RAGTOPMAN,,, KEEP ON TRUCKIN,,,.
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| shogun1940 | -- 06-10-2010 @ 5:57 PM |
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when the car dies get out quick and check the spark it should be blue white if it is give the carb ashot of ether to see if you have a fuel or spark problem
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| supereal | -- 06-11-2010 @ 9:16 AM |
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It isn't possible to check the fuel line from the tank to the firewall without removing it, straightening it out, and trying to push a wire thru it. We are seeing lines that seem OK, but are severely reduced in the ability to deliver sufficient fuel. We suspect that the "new" oxygenated gas is promoting rust. Another hot start trick is to install a booster circuit to the coil using a diode. I have it on all my cars.
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| TomO | -- 06-11-2010 @ 9:23 AM |
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Jeff, it helps if you keep the same problem in one thread, instead of opening a new thread every time you post something. Did you have your mechanic perform the voltage drop tests and the other tests that I suggested in your previous post? The Holley carburetor used on the 50 Merc has a history of leaking at the input fitting. The fitting that the fuel line screws into needs a good copper crush washer between it and the carburetor. The threads in the carburetor body must be in good shape. Just because you have a new coil,points and condenser, doesn't mean that you don't have weak spark. You could also have flooding problems. The Holley carburetor is difficult to get set up right. Tom
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| supereal | -- 06-11-2010 @ 2:11 PM |
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The carb that TomO refers to is the one with air intake on the side, rather than the top, and is called a "dual concentric carburetor". It is considerably more complex than the usual Ford carbs, and was also used on some Ford trucks. It has a power valve quite different from the others, and is a real puzzle for anyone who hasn't worked on them before. I have diagrams if they would help. If your car has an automatic choke, check to see if it is closing when your engine is hot. There should be a "poppet" valve in the choke plate, and the plate should be free to move, and stay open when the car is warmed up. It is actually a very good carb, when it is in good condition. They tended to leak if the ball check valve in the bottom of the accelerator pump is leaking or missing. Due to the construction of the carb, it is difficult to impossible to see what is happening by looking into the throat.
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