| Dustbowl | -- 02-04-2021 @ 4:10 PM |
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My 1936 Cabriolet has been running very well. Then on a trip home, it lost power going up a steep hill and I barely made it home. The next day, it seemed to start and run well going downhill and on the level to my nearby destination. But coming home uphill it lost power again to the extent I had to be towed home. Something also must have discharged the battery as it would not turn the starter motor. Today it is the same problem going uphill out of the drive way, after I recharged the battery. It will start and idle but loose power as I try to pull away. While the engine was idling, I check and found a strong spark at one plug - spark jumps about one centimeter. I also tried temporarily to by pass the ignition resistor but that made no difference. I suspect several different issues could be causing my problem. Would you please suggest things I can look for. Thanks
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| carcrazy | -- 02-04-2021 @ 5:11 PM |
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Losing power while climbing a hill is a classic symptom of lack of fuel. I suspect either your fuel pump is going bad or you are experiencing vapor lock. Is the engine running too hot when you experience these problems? Your battery may be at the end of its life, have it checked and replace it if required.
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| TomO | -- 02-05-2021 @ 7:30 AM |
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A quick check for insufficient fuel is to pull out the choke half way. If the engine runs better, then do a fuel delivery test. Insufficient fuel delivery can be caused by vacuum leak on the fuel supply to the fuel pump (leaking flex hose, sediment bowl gasket or loose connection are the most common causes of this condition), plugged fuel line (internal rust, collapsed flex line, debris in the tank), weak fuel pump or incorrect gas cap. 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. If you are getting the correct amount of fuel, then you should perform a cylinder balance test by shorting out one plug at a time and notice if there is a change in RPM. If you find cylinders that do not change the RPM, they are your problem. Remove the plugs from those cylinders to see why they are not firing. http://www.verrill.com/moto/sellingguide/sparkplugs/plugcolorchart.htm Good luck and please come back with the results. Tom
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| MG | -- 02-05-2021 @ 12:02 PM |
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"lost power going up a steep hill" ...."coming home uphill it lost power again"...."Today it is the same problem going uphill".... Consider it might be Clutch Slippage....
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| Dustbowl | -- 02-05-2021 @ 1:19 PM |
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Well, I thought I had a simple fix with help from both of you. First , with Tom's suggestion, I pulled out the choke (a!! the way) and found that engine went from a little rough (and no power) to smooth and faster. So a gas problem I assumed.. Then I tested fuel flow and found it at least as fast as Tom suggested. Then I took oil the top section of the carb and found the gas level in the carb reservoir to be low when it should have been full. The float adjustment seemed to be correct so I guessed the intake valve was sticking and I replaced it. Expecting success, I then found the engine running rough with no power!!! When the carb was opened, it looked to be clean inside but, of course, I could have a passage blocked. Before I rebuilt the carb, I want to ask you if you can think of anything other than the carb which could be causing my problem I stiil.have a strong spark and the battery is fully charged. I have speculated that ignition timing may have gone bad but that doesn't explain the choke test results. I hate to mess with timing unless I am confident that is source of problem Any suggestions very welcome.
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| 37RAGTOPMAN | -- 02-05-2021 @ 2:54 PM |
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HI Dustbowl this a long shot, do you have a electric fuel pump ? I assume the gas cap is vented, you could blow out your fuel lines to make sure there is no blockage, front to rear, how old is the front to rear fuel line, has it been replaced when car was restored, and check the fuel pump. remove the top cover to see if you have a build up of dirt I would suspect a fuel problem how is the flex line ? is it fairly new,? this new gas could cause problems with the old flex lines, swelling it up on the inside or maybe it is breaking up leaving particles of small rubber in the fuel lines, this is also true with the fuel pump diaphragm, these also break up , if you have a fuel pump tester see what it tell you, and idf you do not have one, I would take the fuel pump off holding it in my hand with the fuel line attached and work the pump and see if it pumps a steady stream of fuel into a container, maybe you can add some more description let us know so we can solve your problem 37Ragtopman hope this helps check the line from the fuel pump to carb,
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| Dustbowl | -- 02-05-2021 @ 3:28 PM |
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As I explained in my most recent post, I tested flow rate that pump puts out and found it as good or better than Tom suggests. So I don't thing enough fuel getting to my carb is the problem.
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| Dustbowl | -- 02-05-2021 @ 3:30 PM |
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But I will now go out and double check fuel pump out put pressure. I think it should be 5 psi or more.
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| 51woodie | -- 02-05-2021 @ 3:50 PM |
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Could be wrong, but I believe that the fuel pressure should be 2-3 psi.
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| TomO | -- 02-06-2021 @ 7:45 AM |
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Do you have the stromberg cab on the car? If you do, explain your problem to Uncle Max. He specializes in the Stromberg carbs. http://97-express.com/contact/ Did you run the engine and then take off the top of the carb to check the level? You need to do this to find out if your carb is leaking down or the float level is incorrect. Fuel pump pressure should 2-3psi. Any higher will overcome the float and you will have flooding. You will have to disassemble the fuel pump if the pressure is too high and adjust the return spring pressure. If it is too low, I suggest that you have your fuel pump rebuilt. Tom
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| 37RAGTOPMAN | -- 02-06-2021 @ 10:16 AM |
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HI dustbowl HOW old is the gas ? and does it have any water in it ? try a sample in a glass container, just pulling on straws, trying to help. what model carburetor are you using, MODEL 48 ? I assume you have the original ignition system on the car, I assume you checked the needle valve for any dirt, or being some what clogged, did you try running the engine with out air cleaner ? and with a mirror look in the carb and see if you see anything that could cause it running poorly hope this helps, 37Ragtopman This message was edited by 37RAGTOPMAN on 2-6-21 @ 10:58 AM
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| Mr Rogers | -- 02-06-2021 @ 6:20 PM |
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Hmmmmm, going up hill? Wonder it there's sufficient gas in the tank?
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| Dustbowl | -- 02-07-2021 @ 11:34 AM |
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Tom, Max said look for a little debris in the carb, which I found, removed and fixed the problem. Many thanks
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| 37RAGTOPMAN | -- 02-07-2021 @ 11:53 AM |
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HI dustbowl I see you found dirt in the bowl of the carburetor, glad you found the problem,. now where did the dirt come from ? what did it look like, you might want to find out, before you have more problems I installed a fuel filter on LS just before the fuel line comes up from the chassis , used a steel fuel filter and made a heat shield , cause I am running duals, this might be a good idea, since you rebuilt the carburetor, to keep it clean my 2 cents 37Ragtopman This message was edited by 37RAGTOPMAN on 2-9-21 @ 9:15 AM
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