2004 Gator HPX running erratic, hesitation

[Kyle_in_Tex]

Skip down to post #6 for answer to the original issue in red. I was getting gas overflowing into the crankcase, checking the dipstick, it'd be an inch too high.

This has the Kawasaki FD620D gas motor. It has been running great for years since 2016. My son tells me one day, "Dad, I can't get the gator to run..."

I've been chasing my tail on this gator. Not running correctly, very erratic. Seemed like it is stumbling when you try to give it gas. Sometimes it will idle, sometimes it won't. I've cleaned the carburetor 3 times, replaced fuel pump, cleaned air filter, and I finally watched the spark at night with both plugs laying on the heads and turning it over. It seemed like the rear cylinder's spark is erratic. (but it wasn't, I just didn't have it grounded well).

I have already replaced the ignition module once at a cost of over $300 back in 2016
2004 John Deere HPX 4x4 Gator Will Not Start

Wish I had some service manual information, like how to check the individual coils? A new coil is about $82, new module= $330. So I'm hoping it is a coil.

Anyone know how to test the ignition coils? I'm a decent mechanic. These coils are different. They don't have the usual grounding stacked plates, it has the spark plug wire and 2 spade terminals.

Thanks in advance for any help. My hope is that if I can figure it out, I can help the next guy.

 

[Spanner]

First - Install 2x new sparkplugs.

 

[Kyle_in_Tex]

First - Install 2x new sparkplugs.

Done. That was one of the first things done. I've read threads about opening the gap up from .025 to .034, which I did, but it hasn't helped. These run a relatively cold plug BPR2ES.

One other problem that was occurring was the carb's needle wasn't sealing in the seat. The seat in these carbs in NOT replaceable. I bought a new float and seat from Deere. The reason I know it was flooding, was because the crankcase was filling up with gas. It was flooding with the previous Chinese fuel pump too. I changed the oil when I first noticed it, then I changed the oil after installing the new float and needle, and it was still flooding. I took the carb off again, and using my stereoscope, I inspected the seat. It appears to be made utilizing a pressed powdered brass method. The brass for the seats, and all the jets looked almost porous under magnification. The sealing chamfer of the seat looked "granular" and rough. So I measured the included angle on the rubber tipped needle. It is about 72°, and I made a hard plastic tip with the same angle, put some 400 grit clover compound on it, used a cordless drill and "lapped" the seat until it looked better. Below are some before and after pics of the seat. It does not leak now. The Holley fuel pump (Holley Mighty Mite 12-425) rebadged Facet pump, I bought is only 1.5-2.5 psi. It flows quite well. I'm tired of putting cheap Chinese pumps that fail after 1-6 months on it.

I read threads about valve push rods breaking/bending, so I checked the valves last night. they were all good within .001" of nominal .010"

I've read about the restrictor in the air filter's intake to inhibit air, for whatever reason...Some say to replace it, some say to jet the mains up and remove it.

BTW, I put a new carburetor on it way back, maybe 2007ish?

The seat's through hole is only about 1mm in diameter for perspective. But gasoline's capillary action is strong, and it will leak through if if can.

After lapping photo above. It appears to be sealing well, no gas is getting into the crankcase.

 

[Kyle_in_Tex]

I just tested the suspect ignition coil with my ohm meter. It has 2 spades connections and the plug wire (PW)

spade to spade = 0 ohms
either spade to PW without cap = 7K ohms
Plug cap has 5k ohms
spade to PW with plug cap = 11.9K ohms

Without the service manual, I'm not sure if these are good or bad numbers.

 

[Kyle_in_Tex]

So each cylinder has it's own ignition coil. I switched them, and re-tested spark last night. They were both working fine. Something is intermittent. So I put the plugs back in it, and it is still very hard to cold start. It is like choke is not working. After a lot of cranking, it will start trying to idle, then more cranking and it will eventually idle. I let it warm up, then try to give it some throttle, and it falls on it's face and dies.... Kept trying to feather in more gas and eventually it accepted the throttle and wound up. Still not running right though.

 

[Kyle_in_Tex]

I did buy a new coil, and since I had swapped the original coils, the suspect coil was now in the front. I went ahead and installed it to see if there was any change, but none. Put the old original coil in a zip lock and save it for later if needed.

I am going to run out of hair to pull out. I believed I'd found the problem, but may have over compensated along with the problem....It has good spark, valves are adjusted, compression even at 105psi each. So all things point to the carb. I had purchased a carb rebuild kit, gave it an ultrasonic bath in simple green, and put it together. Still super rich. Blowing gas and dark smoke out the exhaust when it is running, but running poorly. Ok. Next, my buddy came over and we take off carb again (I'm getting where I can do it in about 4 minutes off, 8 minutes back on), he said he believed that the floats (non-adjustable) were not shutting off soon enough, leaving the fuel level high in the bowl. This pointed back to maybe I lapped the chamfer too big. So I went to extremes. I took it to work, with the float bowl off and put in the bridgeport mill on a couple of parallels in the vise. The seat (that the needle seals off) is a pressed in plug. The only way to lower the fuel level is to either move the seat lower, which lowers the contact point, and the floats shut off flow sooner, or make a new one with smaller chamfer. I carefully pressed from the opposite side (on the backside of the seat) and lowered it about .025-.030ish. I used the mill as an accurate press. This lowered the floats about .065 being "out on the limb". I put some alcohol in the fuel line and held the floats up by hand and no leakage. OK HERE'S THE DUMMY ME PART.... there are 2 hoses coming off the top of the carb. One is fuel in, the other is a not so clear breather hose maybe 5mm ID. It is very dirty on the bottom end and you can't actually see through it due to grease/grime/crud and 17 years old. When I was winding it up around the carb to put it all in a zip lock, I noticed some dust came out of it....I bent it around and much more came out. Some insect had built a dirt nest up in it...NO ability to breath was making the engine's vacuum just suck so much fuel into the engine, it would just flood. So with it cleaned out and the breather clear, I put it back on the gator, and it's still not running properly, but I believe it's lean from my float mod. So I'll press the seat all the way back in and see what happens. Might not happen until Sunday as I'm booked up til then.

 

[Zebrafive]

Have you replaced the pulsor coil?
I do not know what spark plug caps should OHM. You might want to try new ones?

 

[Zebrafive]

Does it have a spark arrestor on the muffler? I think it was an option. If so, see if it's carboned up/clogged.

 

[Kyle_in_Tex]

Thanks Zebrafive, no, have not replaced pulsar coil. I've checked 3 or 4 times since initial problem and both plugs have blue spark at night time.

I've had the exhaust off. Yes it has the spark arrestor, and I took it off to check the exhaust for being plugged up. It is clear. Unit only has maybe 500 hours +/- on it.

I have to say it's such a simple engine and I'm embarrassed to admit it's kicking my rear. We have another gator, so it's not got to be fixed right away....

 

[Kyle_in_Tex]

I did buy a new coil, and since I had swapped the original coils, the suspect coil was now in the front. I went ahead and installed it to see if there was any change, but none. Put the old original coil in a zip lock and save it for later if needed.

I am going to run out of hair to pull out. I believed I'd found the problem, but may have over compensated along with the problem....It has good spark, valves are adjusted, compression even at 105psi each. So all things point to the carb. I had purchased a carb rebuild kit, gave it an ultrasonic bath in simple green, and put it together. Still super rich. Blowing gas and dark smoke out the exhaust when it is running, but running poorly. Ok. Next, my buddy came over and we take off carb again (I'm getting where I can do it in about 4 minutes off, 8 minutes back on), he said he believed that the floats (non-adjustable) were not shutting off soon enough, leaving the fuel level high in the bowl. This pointed back to maybe I lapped the chamfer too big. So I went to extremes. I took it to work, with the float bowl off and put in the bridgeport mill on a couple of parallels in the vise. The seat (that the needle seals off) is a pressed in plug. The only way to lower the fuel level is to either move the seat lower, which lowers the contact point, and the floats shut off flow sooner, or make a new one with smaller chamfer. I carefully pressed from the opposite side (on the backside of the seat) and lowered it about .025-.030ish. I used the mill as an accurate press. This lowered the floats about .065 being "out on the limb". I put some alcohol in the fuel line and held the floats up by hand and no leakage. OK HERE'S THE DUMMY ME PART.... there are 2 hoses coming off the top of the carb. One is fuel in, the other is a not so clear breather hose maybe 5mm ID. It is very dirty on the bottom end and you can't actually see through it due to grease/grime/crud and 17 years old. When I was winding it up around the carb to put it all in a zip lock, I noticed some dust came out of it....I bent it around and much more came out. Some insect had built a dirt nest up in it...NO ability to breath was making the engine's vacuum just suck so much fuel into the engine, it would just flood. So with it cleaned out and the breather clear, I put it back on the gator, and it's still not running properly, but I believe it's lean from my float mod. So I'll press the seat all the way back in and see what happens. Might not happen until Sunday as I'm booked up til then.

FINALLY GOT IT RUNNING!!!
Here's "The rest of the story". So if you read the red text above, I had found the carb's breather tube clogged and cleared it. What I failed to include was that I had bought a cheap chinese rebuild kit on amazon. It had new gaskets, jets, needle (I didn't need it), and the custom molder float bowl rubber o-ring, and a few other things. In hindsight, I'm not even sure why I bought it except that I needed new intake gaskets and the float bowl o-ring. I MADE THE MISTAKE OF INSTALLING THE JETS THAT CAME IN THE KIT WITHOUT MEASURING THEM. Folks, I'm a machinist by day, and I should know better. Anyway today, I took the carb and all the old parts to work. At lunch I dis-assembled the carb and used a small gage pin set to check the jet orifice hole sizes. It has 2 main jets, and 2 pilot jets.

OEM main jet size = .028"
chinese main size = .053" (ALMOST DOUBLE IN SIZE)

OEM pilot jet size = .014"
chinese pilot size = .028" (DOUBLE IN SIZE)

the chinese sized would flow more than double the amount of fuel needed.

So I changed the oil again (it had gas in it from the excess). I bet I have the cleanest engine internals around.

But it started, and ran great. So all along, it was a clogged breather tube on the carb caused by a mud dauber/fly. The bottom 5" of the hose had been greasy and grimey so that I couldn't tell it was clogged internally. What a run around to find a small problem. ARGH.

I honestly thought that, if this didn't get it right and running, I was going to have to buy a $400 carb, so thank God I got it figured out.