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Subject: No gas getting to the cylinders

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Mike Myers    Posted 05-07-2020 at 19:00:16 [URL] [DELETE]        [Reply] [Email]  
  • No gas getting to the cylinders
  • I have an 8N circa 1951 I think. Bought it at sale couple of years ago and it was a grease bucket but it ran like a champ. Have been slowly fixing it up. It started becoming hard to start and now it won't start. It turns over, but its not even trying to fire. Pulled a plug and its pretty obvious no gas is getting in the cylinders. The old carb was pretty beat up so I bought a new one, identical to the one that was on it. Still nothing. I open the gas cock and after awhile gas starts dripping from the carb (just like the old one did). I know this is an updraft carb so I did a compression check. Spec says min 90. I'm getting 110, 87, 95 and 80. I know I'm in for a valve job, but my question is are these readings low enough to cause a vacuum problem at the carb? Any thoughts appreciated.

    Jack - Iowa    Posted 05-09-2020 at 07:03:00 [URL] [DELETE]        [Reply] [Email]  
  • Re: No gas getting to the cylinders
  • Sounds like you may have two problems.

    Gas should not drip from the carb! When the gas level reaches the set point the float and needle valve should shut the flow off. That is the first thing to fix.

    When operating properly you will not see a wet plug. As JMOR said, gasoline vapor looks dry and is not visible.

    I would look for a vacuum leak around the intake manifold or carb mounting gasket. Spray around those with your starting fluid or other flammable spray.

    I do not see your compression readings as being your problem in starting.

    Tim Daley(MI)    Posted 05-08-2020 at 07:23:51 [URL] [DELETE]        [Reply] [Email]  
  • Re: No gas getting to the cylinders
  • Welcome aboard Mike. First, model year is unimportant unless you are trying for an original restoration. What helps us to better help you is to tell us if you have the front mount or side mount distributor and if it is the OEM 6V/POS GRN electrical setup or a 12V switch over job. Have you a copy of "75 TIPS FOR N-OWNERS" by Bruce(VA)? It's in our HOW-TO's forum along with a ton of other useful self-help and DIY projects. Three things are need to start and run a tractor: Fuel, Spark, and Compression. The latter readings you stated are adequate so concentrate on the first two. Did you do the fuel flow test first before pulling the OEM carb? New carbs may look alike but the OEM was the Marvel-Schebler TSX-241 Model and they are no longer in business, so I doubt if you found an exact new one. New, aftermarket units are made in Cheena and don't assume anything is tested and tweaked (There's no QC) out of the box. If you want, send me your old unit and I will rebuild it. As the others said, fuel flow test needs to be performed. 3 screens in the fuel systems. Two are in the Sediment Bulb Assembly and one is in the fuel inlet brass elbow on the carb. Check and clean those first. Another culprit is a plugged gas tank vent located on the top dome of tank. You can't get to it unless you pull the hood and yank it off - a time consuming job. In my opinion, if you are going to go that far, may as well do it right and get the gas tank cleaned and possibly coated. Start with the basics; baby steps. Avoid the temptation to just start buying new parts and replacing until old ones are verified to be defective. All Ford components were designed to be rebuilt over and over. For any solution, you must perform true root cause problem solving method. Verify fuel flow passes the test. Next step will be the electrical system/spark. Get The Essential Manuals and copies of Bruce's 75 Tips and a copy of WIRING PICTOGRAMS by JMOR to download free.

    Probable NO-GO fuel issue causes are: plugged vent, plugged screens, plugged sediment bulb, dirty gas tank, dirty carb, and more. There are three OEM screens in the fuel system. Two are on the Sediment Bulb Assembly; the 3rd is on the brass elbow inside the carb where the fuel line connects to. SEE PICTURES. I wouldn’t be shoving anything, wires especially, up into the sediment bulb assembly. You have a vertical fine mesh screen on the inlet port inside the tank that you can damage. Best solution is to remove the tank and thoroughly clean. Fuel Flow Test first: One pint in two minutes via drain plug and fuel line at inlet elbow.


    The ESSENTIAL MANUALS are your friend. PM is so important to maintain any piece of machinery.


    Tim *PloughNman* Daley(MI)

    Bruce(OR)    Posted 05-07-2020 at 23:11:18 [URL] [DELETE]        [Reply] [No Email]  
  • Re: No gas getting to the cylinders
  • My 2 cents for what it is worth.
    You have 3 filters on the tractor. Check all those? Gas flows out the bottom of the carb how fast?
    Tried starting fluid yet? High comp engine of about 6:1.
    That should make wet plugs.

    JMOR    Posted 05-07-2020 at 22:31:10 [URL] [DELETE]        [Reply] [No Email]  
  • Re: No gas getting to the cylinders
  • no. if plugs are wet with gasoline, then that is a problem! vapor looks dry.

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