601 won't run without choke

jimiller5

New User
I have a 601 that won't run after it warms up without the choke pulled. Even then, it does not have much power. I've replaced the carb, fuel filter, fuel line, coil, points, condenser, intake manifold gasket, carb gasket, plugs, and plug wires. I've owned it 15 years and gotten real good service out of it up to now.
 
That's lotsa replacing.

What's spark look like?

Goodflow to carb?

Any ice on carb?

Running on all 4?



With ethanol based gas, minor ester in fuel shouldn't be a problem as it should solvate.

Post back
 
Always trouble shoot then parts never the other way around or you can add to the problem.
You say fuel filter as in in line?? If yes get rid of it it will cause more problems then it will fix and could well be the problem. Next check spark. It needs to be a good blue/white and jump a 1/4 inch gap or more. Next make sure you have a good steady flow of gas out of the carb drain plug for say 3 plus minutes. Also try carefully removing the gas cap when it does that could well be a clogged up vent or gas boiling
 
(reply to post at 14:46:06 11/28/14)

wont run with out the choke pulled....

probably the main jets are stopped up with gunked up gas.

however.. could also be a vacuum leak at carburetor mounting or intake manifold to head mounting. but... almost always due the the new gas crudding up your carb jets. Do you have the carb with the adjustable main jet?
 
I've got good spark and gas. I don't think it is a vacuum leak since I've replaced the carb and intake gaskets. It is an inline filter but I'm getting a good flow of fuel going into the carb. I am getting some ice on the carb when trying to start. I'll check the carb drain plug.
 
Throw that stupid in line filter away and never put it back it is not needed and will cause you all sorts of odd problems
 
I have a Jubilee and an IH C. Both marvel carbs I think. In winter, I turn the main jet screw 2 full turns out on the Jubilee and 2 full turns in on the IH C. Both need more fuel in winter or I would have to run with the choke half on and they would die when put under load. That's how mine are. They work just fine.

I'm guessing that computers make similar adjustments in winter too.

I have a 3rd engine with no carb adjustments. Yesterday, I had to apply a little choke for it to run right.
 
(quoted from post at 21:38:04 11/28/14) Throw that stupid in line filter away and never put it back it is not needed and will cause you all sorts of odd problems

I'll try it w/o the filter.
 
I have fixed in line filter problem very often. They tend to clog up easy since most are made for systems with a fuel pump and gravity feed does not put out the 7 plus PSI needed
 
I removed the filter and it still won't run without starter fluid sprayed into the carb. I've got good gas flow out of the drain plug. I'm thinking about getting a carb rebuild kit.
 
With the air cleaner tube off try holding your hand over the air intake of the carb. You should feel a good suction and if all is right with the carb get gas on your hand. By the way it may even try to start when you do that. Some times that is enough to pull a clog out of the carb and some times fixes the problem
 
It will just about suck the skin off my hand but no gas on hand. Any thoughts on the ice on the intake? This happens when I spray starting fluid in it to get it going. I don't do it for more than a few seconds and ice forms on the intake.
 
Since cfc have been banned, lots of starting fluid uses propane as a propellant. It has a natural tendency to create ice as it flows out of the can.


sounds like the main jet is plugged up. Just take the bowl off, and unplug it, it should be fine after that.
 
If you are anywhere near Pittsburgh, PA; bring it to me. I'll give you a second opinion.

If the carb will suck the skin off your hand, it sounds like you have good engine compression and no vacuum leak.

If you have an unrestricted flow of fuel into the bowl of the carb, and there is nothing keeping the fuel from entering the bowl, then the only thing left, really, is a partially plugged main jet.
 
I'm in East TN, so a trip to PA isn't feasible. I do appreciate the offer, though. I've got the carb off again (for the 5th or 6th time) and I'm going to blow it out once again. If that doesn't do it, I'll do a rebuild.
 

When you take it apart, take the main jet out, and look down the hole. it should be spotlessly clean.
 
How far east are you? I am in Nashville and have rebuilt several carbs for 9N/Jubilee/600/800. I agree w other posters that you sound fuel starved. If you really do have great flow when you yank the bowl plug - and I mean great flow on and on and on for a few minutes - then I agree w the others that you likely have a clogged main jet.

You say you replaced the carb?! Wheres the old one? They are easy to rebuild. Really not hard at all to do and no reason to take it to anyone. There are several excellent rebuild guides on line and here. If you are really stumped I can try to help, but I don't know how far away you really are. If you want to mail me the old carb I am happy to look at it for you.
 
I took the carb apart, blew everything out real good, ran a small wire through all the holes, and adjusted the float. I put it back together and now it will start but still must have the choke pulled all the way out to get it to run.

I should add that the neighbor's son put diesel in it last fall and tried to start it. I drained the tank and line and replaced the filter. It ran good all winter and spring. It started not running right this summer and I've been working on it since then.

I appreciated the offer to come look at it but I'm 300 miles east of Nashville near Johnson City. I sent the old carb back to the supplier for the core charge. I'd be glad to pay to have someone look at the new carb.
 
I spent a lot of time and money on fuel problems too so don't feel bad. I was working on an old IH 1600 five yard dump truck. It would run great until you hit fourth gear for a short period of time then it would start to sputter and die. I had to pull the gas tank twice, I rebuilt carb and distributor, complete tuneup. All that to find that it was a spruce twig in the tiny 3/16 fuel line. That would get sucked up into the 90* turn as it came out of the tank. After the truck set for a few minutes it would start back up and run fine until you hit fourth gear.
 

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