8N stops suddenly

[Steve Y]

I have a 1948 8N, 12 volt front distributer. It ran ok, but as I have just recently purchased it I did a few tune-up things to it and now it runs, but only for 5 to 15 minutes and then stops. It stops really quick too, not like it's slowly running out of gas or something. After it sits for 5-10 minutes it will re-start, sometimes it needs to be choked and sometimes it doesn't.

What I did for the tune-up:
- drained and replaced engine and hydraulic oils
- replaced inline fuel filter
- installed a new air breather hose (was non-existent)
- flushed radiator and installed 160* tstat (was non-existent)
- I did nothing with the spark plugs, distrubuter, etc. because that was recently done by the previous owner

I am leaning towards this being a fuel supply issue for 2 reasons:

1. The new inline fuel filter is clear and I can only see a small amount of gas in it- should this be full or am I wrong? (I do have it installed in the proper direction).
2. When the tractor stops I have removed the plug from the bottom of the carb and either get nothing or just a few drips. Definintly not a steady flow though.

I am a beginner at this and am wondering if anyone has any suggestions as to what this could be. Like I said, I am leaning towards fuel related, but I guess I can't rule out electrical either, the wiring is sketchy at best. Thanks for the help!

 

[Mike OH]

I suspect you are using a wrong type of gas filter. Try removing it and see if you get gas flow. I would not use a fuel filter but some like to use them, but be sure you are using the kind that doesn't require a fuel pump to push the gas thru. Also check to be sure you have the gas turned on at least two turns at the fuel bowl and at least two or more gallons in the tank.

 

[R Geiger]

I would say you found the problem with the lack of fuel flow from the bottom of the carb. The PO probably added the in line filter because of junk in the tank. You should have three factory installed filters in the system,. One in the tank atop of the sediment bowl. The screen there does not do much but the stand pipe into the tank gets plugged. another screen in the inside of the sediment bowl above the glass. the third one is part of the elbow that goes into the carb.
I would start by removing line from the sediment bowl and checking for flow there. If ok move down stream until you find the problem. The float needle valve could also be sticking not allowing fuel flow. Might try some light tapping on bowl with wood handle while checking for flow.

Good luck

 

[souNdguy]

sounds like fuel to me.. check needle and seat.

soundguy

 

[Bruce (VA)]

If it does not have gas coming out of the carb at a steady stream w/ the bolt out, you have a fuel problem. First, remove the gas cap. Your vent could be clogged & it vacuum locked. If that doesn’t work, tap the carb bowl w/ a hammer handle in case the float is sticking closed. (don’t whack it w/ the head of the hammer; you can crack the bowl). If you still don’t see gas flowing, the N has three fuel screens; one in the brass elbow, one in the top of the sediment bowl & one on the stem of the sediment bowl in the gas tank. Check the screen in the elbow & the screen in the top of the sediment bowl. (don’t worry about the one in the tank) Both probably need to be cleaned. If you have the fuel knob turned on all the way, it may be trying to feed off of the reserve inlet which is probably clogged. Only open it 2 full turns. Put at least 2 gallons in the tank.

Regarding the elbow, don't honk down on it; it's brass. First, use a flare wrench to remove the fitting. (as in the picture) Next, if you do not have another fitting to screw into the elbow (as in the picture) then use a crescent wrench on the top & bottom (NOT the sides) of the elbow to remove it. Otherwise, you will distort it & you will never get the fuel line fitting back into it.

The in-line fuel filter might be the problem. Remove it & see what happens. This is a gravity flow fuel system; many in-line filters are designed for fuel pumps. If you really think the in-line filter is needed, make sure you have one made for lawn mowers.

Personally, I'd get rid of it & fix the problem that caused some PO to install it.

50 Tips

 

[trac]

Steve i think R Geiger is on the money with your problem. Check the brass elbow on the carb. to fuel line take it off look inside & out. (The secret screen)

 

[trac]

Bruce beat me to the punch he types with two hands not one finger and one good eye like me.

 

[Bruce (VA)]

I have doubled my typing speed by using two fingers.....not hands!

 

[Dell (WA)]

Steve........you ask......"The new inline fuel filter is clear and I can only see a small amount of gas in it- should this be full or am I wrong?".......start to worry when you start seeing half-full of gas in the filter as it is gittin' CLOGGED and needs replacing.

You write........"now it runs, but only for 5 to 15 minutes and then stops. It stops really quick too, not like it's slowly running out of gas or something. After it sits for 5-10 minutes it will re-start".......typical CLOGGED in-tank filter. You haffta remove the IN-TANK valve with the glass bowl for access to the filter. Often times it "MELTS" and there is NO replacement except a NEW tank valve. tip: EMPTY tank by draining it, or be quick with yer thumb .......HTH, Dell

 

[Ultradog MN]

15 minutes of run time could be your weak sister ignition switch and your sparks are bad.
Always, always, always check your spark First.
Pull a plug wire and see if you are getting a bright bluish white spark that will jump at least 3/8". Yellowish wont do. Requires no tools and eliminates one of the 3 requirements it takes to make an engine run.
If you have spark then break out your handy dandy tweekum tools and go after your fuel system.

 

[trac]

Didn t mean to offend you.You have more knowledge than i with these machines.

 

[Bruce (VA)]

No, not at all! I'm just LOL because I honestly do type w/ 2 fingers!

 

[R Geiger]

I figure that you got all the asnwers typed up and all you have to do is copy and paste!!! At any rate always good answers!!

 

[Bruce (VA)]

Tnx! Yea, about 90% of them are cut & paste!

 

[36 Coupe]

Lawn mower gas filters are designed for a 12 cubic inch engine.They may not be able to flow enough gas for a 120 cubic inch engine.A plastic filter near a hot manifold sounds bad.