Ford 8 N Marvel Schebler carb floods

[gwakenhut]

I am a novice when it comes to engines. I have worked with a local mechanic who has worked on 8 Ns, but he has been unable to solve the following problem. He has rebuilt the carb, and we also changed the plugs. They were in need of change, but that failed to improve the following starting problem.

When I try to start my 8 N, it will almost start on the first roll over. However, when it fires, it sounds like it is getting too much gas, and the firing will continue for 15 sec. and then firing ceases while the engine continues to roll over. If I try to roll it over again, it will fire less frequently and gas will run out where the air filter tube connects to the carb.

If I let it set for 15 min. and try again, it will come closer to starting, but again, it sounds like it is receiving too much fuel. Sometimes I can keep it in this half started state for 15 to 30 sec. by jiggling the choke until it finally quits firing.

I have succeeded in starting it by almost closing the needle valve. When it begins to run with the needle valve alomost closed down, it again sounds like it is receiving too much fuel but better than before. It will also run longer before stalling. However, if I don't quickly reach down and open the valve, it stalls.

Once it starts, and i open the valve, it runs like a brand new tractor.

If you have any suggestions, I will pass them on to my mechanic.

Thanks for your time.
Gary

 

[Soundguy]

the ms carb is pretty basic.. if it's flooding out, check the needle seats.. ..


also.. check spark.. weak spark can cause starting problems...

soundguy

 

[gwakenhut]

I will check these out. Thanks, Gary

 

[Will_Lou]

check the float in the carb. 8n are notorious for bad floats. The float is not part of the normal rebuild kit an could have easily have been ignored when the carb was rebuilt.

 

[Soundguy]

it's doubtfull it is the float. as it runs fine when started he said. a heavy or rubbing float will cause problems the entire time.

soundguy

 

[gwakenhut]

What am I looking for in the needle seats? Gary

 

[Soundguy]

usually a bit of grit lodges there preventing hte needle from seating in the set.

id remove the fuel line and drain plug and shoot a few blasts of carb cleaner in there with a can with a straw.. ( shield eyes ).. then re hook fuel and allow some to flow.. then reinstall plug and remove air hose to see if it overflows into the air hose side.

post back

soundguy

 

[gwakenhut]

Used the carb cleaner, and it started fairly well. I will have to start it again tomorrow to see if we solved the problem.

I couldn't find the drain plug on the bottom, so I took the carb off to have a better look for the drain plug on the under side . Discovered that it is not an M S carb but Zenith was visable on the back side of the carb.

I sprayed the carb cleaner in everything I could reach (it would not run through in any noticeable quantity when I sprayed it in the gas line hole). Hooked the carb back up, opened the gas, but it failed to run out the air hose connection. Hooked the hose back up and hit the starter, and while it did not immediately start, it did so after 2 or 3 tries. Usually it would flood if I didn't make it on the first attempt.

One thing I did notice is that the rt. angle fitting that hooks the gas line to the carb used to have a screen on it between it an the carb (I know because many years ago, I couldn't start it and discovered that the screen was clogged). Shouldn't there be one, and if it is not there, could this be the source of my problem?

Gary

 

[Soundguy]

yes.. a zenith looks a bit different and has different anatomy.. and yes if the inlet screen is gone a bit of trash could have lodged under the needle between it and the seat causing the flooding. sounds like you blew it free.

tsc sells the elbow with screen

soundguy