| len47merc | -- 03-18-2016 @ 7:49 AM |
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Tom - sometime back you replied with the following excerpt to another discussion as a means to check the output of a fuel pump: "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." Would this apply to the glass bowl type pumps for a '46-'48 59AB motor? And for the same pump, is the proper fuel pressure 1.5# minimum to 3.5# maximum? Lastly, is fuel draining overnight out of the fuel line and clear filter back into the tank an indication of a fuel pump on its last legs? Thanks Tom - Steve
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| TomO | -- 03-18-2016 @ 8:04 AM |
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Steve, Yes the fuel delivery test is appropriate for all 32-53 Ford and Mercury cars. Yes to the fuel pump pressure. I doubt that the fuel line is completely draining back into the tank. It would defy the laws of physics that a liquid will seek to maintain a level. The fuel in the tank is higher than most of the line until just before the line reaches the clamp on the firewall. If it is taking a long time to prime the carburetor, check the flex line and the gasket for the sediment bowl for leaks. These can leak air and not fuel when the pump creates a vacuum. I will send you a copy of the article that I wrote for the V-8 Times a few years ago. Tom
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| 1932BB | -- 03-18-2016 @ 8:48 AM |
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Steve, You mention a "clear fuel filter". I have had trouble when using them between the tank and pump. They work best between the pump and carb, needing pressure to push adequate fuel flow. Something to try
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| len47merc | -- 03-18-2016 @ 9:46 AM |
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Thanks Tom and 1932BB. One last question - what is the best way to diagnose whether the flex hose between the firewall and fuel pump is collapsing at speed (55 mph)? By the time one stops and gets out of the car the vacuum will have dissipated and the hose returned to its original shape - ? Steve
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| TomO | -- 03-20-2016 @ 8:37 AM |
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I don't know a good way to diagnose a collapsing flex line other than removing and examining it. If the inner lining is going to restrict flue flow, it will also do it at idle, it just won't be noticeable in performance. The fuel delivery test will usually show any impediment to fuel flow. Tom
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| len47merc | -- 03-20-2016 @ 10:04 AM |
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Thanks Tom - Steve
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| rsh1950 | -- 03-21-2016 @ 5:21 PM |
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Interesting subject...I have a 50 Custom and when I first crank it (often after priming it) it will sit and idle for about a minute and just go dead. I keep priming and starting until it will sit and idle (now this might be normal). However when I drive it for a mile or two it just wants to die, so I put it in second and restart the motor and it will do it again in about 1 mile or so. I saw a leak at the glass bowl @ the fuel pump so I have a new gasket coming tomorrow. Another question: I watch the glass (fuel pump) bowl while the car is idling and I can see the pump discharging fuel into the top of the bowl about 15 seconds. Is the normal? I will install the new gasket tomorrow and test drive however, I am not convinced that the leak a the bowl is the problem. I will keep reading your threads. thanks.......rsh1950
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| ken ct. | -- 03-21-2016 @ 5:31 PM |
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You must have a VENTED gas cap on these models. Also you must use the available cork ones (not rubber one). On the glass bowl , make sure you have NO nicks or chips on the glass edge. omo ken ct. This is ment for rsh 1950 /// my mistake Steve sorry. This message was edited by ken ct. on 3-21-16 @ 6:21 PM
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| TomO | -- 03-22-2016 @ 8:34 AM |
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rsh1950, If the sediment bowl gasket does not fix your problem, check the glass bowl for chips as Ken ct recommended and also check the fuel pump for distortion where the glass bowl mounts. If the bowl mounting screw was over tightened, the mounting surface could be bent, preventing a good seal. If so replace the pump. The flex line can look good on the outside, but the inside could be mush, blocking fuel flow. The crimps on the flex line can also fail, allowing the pump to suck air instead of gas. You could also have an obstruction in the fuel line or the tank pickup. The tank could be rusting due to the ethanol in the fuel, and the flakes could be plugging the fuel line. A noisy pump is a good indication of this problem. I would do the fuel delivery test and if the pump is not delivering enough fuel, try clearing the line and pickup with some compressed air and recheck. If the recheck show good delivery, have your tank cleaned and coated with an ethanol resistant coating. Tom
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| rsh1950 | -- 03-22-2016 @ 4:35 PM |
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Thanks to Ken ct and TomO for your input. So, I got the new glass bowl gasket today and installed it. I primed the carb. and the fuel bowl filled as it should. I drove the car for about five miles and everything was good. Before the new gasket was installed the bowl was filling to about 80 or 90% and I could see the fuel pumping in about every 10 to 15 sec. Now with the new gasket, it fills to the top and I don't see the fuel dumping in as before. So I think it is fixed (fingers crossed) until the next thing pops up. Thanks for all the input. rsh1950
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| len47merc | -- 04-01-2016 @ 11:21 AM |
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Quick follow-up on this and endorsement of TomO's process - followed Tom's process for fuel pumping testing and was not only surprised but also quite impressed by how quickly the root cause was identified. Long story short the glass bowl seal was leaking vacuum but not fuel. Pump initially would pull 8-9 lbs of vacuum and quickly (less than 2 secs) fall back to zero after each stroke - even with a firm additional tightening of the thumb wheel underneath. After removing the bowl, cleaning both it and the rubberized cork seal, reinstalling both (flipped the seal) and tightening the thumb screw securely the pump now produces 15 lbs of vacuum with 5-6 strokes and holds above 11 lbs for over 5 minutes. Problem solved. Thanks Tom for the article and process you published in the V8 Times - huge time saver and very effective for me. Learned quite a bit in the process as well. Really appreciate it. Suggest everyone find the article if you can and keep it in your library archives for future use. Steve
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