420 crawler not getting fuel

[justjd420]

My crawler was flooding so I took apart the carb and cleaned because I believe the float was sticking. I made sure the float had a gap of 1/4 inch and everything seemed to be clean. When I reassembled the engine popped then would from that point. I have excellent spark at plugs and points. Noticed that plugs were dry even after choking for several times. I placed just a little gas in cylinders and it popped right over. The bowl in the carb is also getting gas because I noticed it was full when I disassembled once again to change needle valve that resulted in same problem. Please help.

[Lu47Dan]

Did you clean the jets and passages inside the carburetor body when you had it apart? I had one tractor that I worked on that both jets were plugged with gunk, it would not start even fully choked. I used a fine wire to clear jets. I used Brakleen to clean the carburetor's passages out and then blew them out will air pressure. It cured the problem with that carburetor.
Take the carburetor apart and clean the passages out.
Dan.

[H-D]

+1 with Dan. The time honored lesson was DON"T clean metering orifices with wire; with the ethanol-mixed gas this is out the window. The blends are FAR worse about forming deposits & the deposits they form are more difficult to remove. Also, the blends do NOT have the same btu (energy) by volume or weight as the straight gas had. This means the fuel/air mixture is leaner now. There must be a conversion factor for how much leaner a given blend percentage is, but I am not privy to it. Lawn equipment (mostly air-cooled) is suffering particularly badly from this lean-out. There is a growing advocacy for running gas powered equipment out of gas (using valve to block fuel to carburetor) if there is a chance that it will be idle for more than a month. Conventional wisdom is to pour fuel over a month old into a high use vehicle with a 10+ gallon tank & burn it as quickly as practical. Gott mitt uns?

[Stan Disbrow]

Hi,

My answer to the modern fuel in old machines is to simply not use it at all. I go to the local airport with my gas cans and come home with 100 octane low lead.

Yes, it costs more than the modern road gas does, but it starts right up, doesn't burn out the spark plugs, and - most importantly - does not leave behind deposits when it evaporates.

One can also use 100 octane no-lead racing fuel, but they get quite a bit more money for it than av gas. I just paid $4.44 a gallon for av gas and see where the race gas is $7.69 a gallon at the local oval track.

I find that the extra money paid for the av gas is more than worth it now that I no longer have any fuel-related issues.

later!

stan

[JD440ICD2006]

I find that using fuel stabilizers works pretty well as long as the unit does not sit for a long time. It will keep gas for up to 1 year.
It is so much cheaper than AvGas.
I only pay the over double price for AvGas to run in my ATTEX 400 due to the oil gas mix factor.

[justjd420]

I have cleaned the carb with carb cleaner. Soaked all the parts, cleaned, the jets, replaced seat and needle valve, adjusted the float to 1/4 inche and still no gass seems to be making it to the cylinders. ????????? I am running out of things to try. The carb is getting gas in the float chamber. The tractor fire with a little gas in spark plug holes but that is it. Please help.

[JD440ICD2006]

Did you set the idle and load needles per the service manual to get it started?
If there is gas in the bowl and not gettting to the cylinders, either there is a blockage past that or a leak in the intake between the carb and the manifold.
If gas is there and it draws a vacuum, the gas is going to move to the cylinders.
Most of the time it is just some little something that will drive us crazy until we find it, then it is obvious.

[OneWelder]

Even though you are getting gas to the bowl , it may not be coming in enough volume
either disconnect line or pull plug on bottom of carb , make sure it runs out not just a drip.
I recently had a similar experience and found the line plugged ,but would allow enough fuel to carb to fill bowl - just not enough to start and run

[Paul Buhler]

If you want it, I can send you a .pdf carb manual with schematics and ideas. Send an email to: pbuhler@vermontel.net.

At least tearing down and rebuilding a carb is pretty easy.

Depending on which carb you have, some of the galleries have right hand bends in them that a wire won't clean in one step.

Quote from the manual - I couldn't copy the graphic.

"The Idle System
Fig. 5-14
The idle system controls the flow of fuel at
idle speed and at slow speeds until the throttle
is opened wide enough to allow the power fuel
feed system to function.
When the throttle valve (6) is in the idle position
the edge of the valve is between the primary
idle orifice (7) and the secondary idle orifice
(8 ). With the valve in this position the air pressure
(manifold vacuum) at the primary idle
orifice (7 ) is lower than the air pressure in the
fuel bowl chamber (9 ) and fuel is forced from
the fuel bowl (1) into the idle fuel passage (10) .
As the fuel travels through the idle fuel passage
(10) it passes through the metering orifice of
the idle jet (11) to the point where it is combined
with air entering through the idle adjusting
needle seat (12) . The mixing of air with gasoline
helps to atomize the fuel and this process is
repeated at the secondary idle orifice (8 ) as the
fuel travels through the idle fuel passage (10).
As this rich mixture of fuel and air emerges from
the primary idle orifice (7) it is reduced to correct
proportions by the air which passes around
the throttle valve (6) since
this valve must be slightly
open to permit the engine
to idle. The resultant mixture
is correct for operating
engine at idle speed,
provided the idle adjusting
needle (13) is properly
adjusted.
As the throttle valve (6 )
is slowly opened from the
slow idle position it gradually
subjects the secondary
idle orifice (8 ) to intake
manifold vacuum,
and the secondary idle
orifice (8 ) no longer bleeds
air to the idle fuel passage
(10) but feeds an additional
quantity of fuel into
the engine. This is proper since the throttle valve
is now open wider and will admit a greater
amount of air to blend with this additional fuel
to maintain the correct proportions of fuel and
air for the engine.
As the throttle valve (6) is opened still wider,
the idle fuel delivery begins to fade out, however,
the throttle valve at this point is far enough
open for the power fuel feed system to begin
functioning.
The idle system as described above is the most
positive and satisfactory of idle systems, as it is
working under very high suction and the mixture
flows through the small passages and orifices at
very high velocities. It is necessary to bear in
mind, however, that there are times when these
small holes may become plugged with particles
of dirt or foreign matter and will require cleaning.
At such times the passages, jets, and small
drilled holes should only be cleaned with a
cleaning fluid such as gasoline and air under
pressure. Never use drills or wires as a change
in size of these small openings will change the
entire calibration of the carburetor."

[H-D]

What JD440ICD2006 said about a blockage in the intake manifold reminded me of a Ford 6 that a 75 year old diesel mechanic brought me because he couldn't get it to start. The engine had been overhauled by one of his co-workers & 'pickled'. The old guy bought it & put it in his truck , but it wouldn't start. Culprit was a spray can (WD-40?) lid which the rebuilder had placed in the intake under the carburetor to keep the engine 'fresh'. Had never seen it before & haven't since. It's an easy check, no draw at the carb throat while cranking is the tell-tale.

[hemiracing]

Here are a few steps to try. The first would be as stated earlier, remove the plug at bottom and gas should STREAM out. This would be and open circuit and gas should come out just as if the line from the tank was cut.If it does not here is what I would do. Go to local parts store and get a cheap gas shut off. Cut your fuel line between the tank and filter and place the shut off. Now remove gas cap, and with a small container to catch gas open valve. If there is not a good flow place a rag over the open gas filler and apply compressed air from the valve back into the tank. It is possable to have sedement at the pick ups.Once you have gas flowing there, shut the valve and put the line on from the filter to the shut off. Now remove filter and make sure there is a strong flow there if there is not replace filter. Now go to the carb remove line and open valve, get good flow there. Now go back to carb drain and you should have a good flow if you do not, remove the carb and on some of these there is a screen (filter)behind the fitting where the line conects to the carb body. The new fuels will plug these very easy. So by doing these steps you will have confirmed enough fuel at the carb. After all this if it still will not fire, remove carb and vacum check the intake system. The easyist way I know is take a small piece of lexan cut to fit where carb went screw a vacum fitting into the center of lexan apply grease where gasket would go and turn over engine. The amount of vacum will vary with engine condition and someone else on here might have a better feel for what it should be but it will only take a few lbs to pull enough fuel to start. If this checks bad start looking for cracks in intake or some form of leak or write back and we can go over some things to look for.... I wish this could have been shorter, but I do think this will get you going. Also with the shutoff in place when you are going to not use for a while shut fuel and let idel to stall these new fuels are bad.... Paul

[Lu47Dan]

If the carb was flooding out from a low float then rebuilding the carb and setting the float correctly should cure that problem. Shut off the fuel at the sediment bowl and remove the fuel line, if you have a parts washer use the fluid to test the lines flow. If the fluid flows correctly then check the line to carburetor fitting's screen for trash, clean and re-install the fitting. Attach a piece of vinyl tubing to the fuel line, place the end of the vinyl tubing into a small fuel can, and open the needle valve on the sediment bowl. If the fuel does not flow correctly, siphon the fuel out of the tank and remove the sediment bowl assembly and clean the needle valve and sediment bowl. While the tank is empty check the tank for varnish and gum build up, I had a Wisconsin TJD engine that the gum and varnish build up on top of the tank would break off and plug the needle valve up on it and shut the engine down. I finally had to clean and line the tank with this POR-15 product.
http://www.por15.com/FUEL-TANK-REPAIR-K ... info/FTRK/
It cured the problem and I have since restored several other tanks to usefulness. Read and heed all the instructions.
Dan.

[H-D]

I like stupidly simple tests! Why not shut the fuel off at the sediment bowl, remove the line from the carb, & connect a gravity feed tank (lawnmower?). If it still won't light up, it must still be in the carb. If on the other hand, it runs fine, the problem is up wind.

[justjd420]

Thanks to all of you but once again it was something simple. The type of carb I have is a Marvel type C. I had to open the high power jet more than what it was to allow for the fuel in the bowl to be pushed into the manifold. Once I opened the high jet it started and needed a final carb tuning with the idle jet. I ran the tractor for four hours non stop pulling a off-set disk with absolutly no problems. Also I have found during my rebuild that a small rubber gromet cut in half works great for the rubber O ring for the throttle shaft. I had to open the passage way of the gromet by heating it on a same size rod as the shaft. I just added a little heat to the rod and it formed a perfect opening.

[JD440ICD2006]

Glad you got it going!