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View Full Version : Kawasaki FC420V won't run under load


derekmman
02-11-2008, 09:26 PM
First off just wanted to say I am new to this website and I was blown away by everyones quick responses and knowledge on the topics. With that said here is my problem, I have a Lesco Commerical W.B. w/ a Kawasaki FC420V engine on it.

The Problem:
-It will die immediately once a load is applied to it.
-Will die if throttled up too quickly, it must be babied up but once there it will evenually die (within the minute, plus this is also w/ no load).
-But on the good note it will sit there and idle all day long.

What I have done so far:
-Replaced the fuel filter and hose.
-Cleaned the carb, making sure all orfices were clear.
-Checked the spark plug just to knock that off the list.

What I have noticed:
-It will backfire when dying, sometimes.
-The butterfly valve on the carb will be thrown wide open right as it starts to die by the arm in the picture.
http://i220.photobucket.com/albums/dd56/derekmman/100_0224.jpg
Any help would be welcomed.

Thanks in advance,
Derek

MowerMedic77
02-11-2008, 09:58 PM
Hey Derekmman, lets start with easy things to check remove you gas cap and with the mower still, look inside the tank(bright flashlight) for any debris that may be blocking the outlet from the tank into the 90deg. on/off valve fitting.
If this looks clear(reinstall your gas cap) grab a clean jar or empty gas can and shut off the fuel then disconnect the line at the carb and insert the end of the line into the jar/can and reopen the valve and see how your flow looks, should be nice and steady if not check back from this point into the tank for any obstructions.

Post back and let me know what you find, or don't find:laugh:

derekmman
02-11-2008, 10:22 PM
It has a nice steady flow of fuel. I got to playing with the throttly by manually moving it and any sudden movements will result in the engine dying.

lifetree
02-11-2008, 10:32 PM
It has a nice steady flow of fuel. I got to playing with the throttly by manually moving it and any sudden movements will result in the engine dying.

That was a fast response, only 22 minutes after he ex[plained what to check ... or, had you already checked those items ??

MowerMedic77
02-11-2008, 10:34 PM
It has a nice steady flow.

ok good, now you said that you have cleaned the carb. Did you completely remove and tear down or just spray carb spray up the center?

MowerMedic77
02-11-2008, 10:41 PM
I got to playing with the throttly by manually moving it and any sudden movements will result in the engine dying.


This is usually from a blockage or restriction in the transition ports on the carb, when you go from idle to full rpms the carb adds extra fuel from these ports to help with the extra fuel requirements of full rpms or any type of parasitic load. This is why I asked what type of carb cleaning you had performed.

Landrus2
02-11-2008, 10:42 PM
We always over look the governor.

derekmman
02-11-2008, 10:44 PM
Cleaning the carb pretty much consisted of taking it off the engine removing the bowl and spraying up into the holes and watching it come out the other side. I was/am hesitate on taking it completely apart. I have flashbacks of the first time I took apart carb, but mowers carb is alittle less involved, I hope.

Lifetree, I had already checked those things but ran back outside to double check.

derekmman
02-11-2008, 10:49 PM
So what you are saying is those ports, I am guessing the smaller ones to the sides, might be clogged and that I should tear it all the way down and clean it?

MowerMedic77
02-11-2008, 11:04 PM
Cleaning the carb pretty much consisted of taking it off the engine removing the bowl and spraying up into the holes and watching it come out the other side.

I wish it was that easy:laugh:
this is a link to a breakdown of your carb
http://www.buykawpower.com/kmcb2c/Menu?action=CATALOGB2B&prodID=2869404&elementType=2&historyDepth=2

you need to pull out from the carb ref# 11003 and make sure its clear, also you will need to pull out ref#49123/A and ref#49121/A(be careful they are soft brass)and make sure all the small passage ways are all clear and free of debris. You will also need to remove ref# 92009c and pull out ref#92064/A and clean out here also. With all the jets removed you can easily clean with a can of carb spray and compressed air. It may be in your best interest to take the carb to a shop and have it stripped and cold acid dipped and rebuilt. But that is only if you are unsure of the rebuild process.

MowerMedic77
02-11-2008, 11:08 PM
So what you are saying is those ports, I am guessing the smaller ones to the sides, might be clogged and that I should tear it all the way down and clean it?

You are refering to ref#'s 16035 and 16035A clean them also and
clean it completely as much tear down and clean out as you feel comfortable doing. Just take you time on a clean work surface and if you have a digital cam take pics of each step as a reference and you can go back and see where each item removed went if you get lost or confused.

derekmman
02-11-2008, 11:16 PM
I am sure I can rebuild it, I have all the tools to do it also. I will let you know how it goes tomorrow then. And thank you for the incredibly fast responses. I wish I would have gotten on here a few hours earlier to where I wouldn't have wasted my daylight.

MowerMedic77
02-11-2008, 11:26 PM
Real quick, with the air filter cover off and the unit running when you rev it up and the unit starts to die if you give it a spray with carb spray( or quickly cover the air horn with a rag to choke it out or make it run rich) will it pick back up and run or still die? If stays running go through the carb if not let me know I will be on tomorrow.

derekmman
02-11-2008, 11:41 PM
I am going to go ahead and go throw the carb b/c it kept running once a shot starting fluid was given to it. I get the idiot of the evening award for tonight. I had starting fluid there with all the stuff I was working on the mower with and got caught up in other things with the mower and didn't even think to do that.

Thanks again and I will let you know how it goes, though it will probably be later tomorrow night on account of having to go to school.

MowerMedic77
02-11-2008, 11:56 PM
No problem, good luck and let us know how it goes:)

derekmman
02-14-2008, 09:53 PM
Ok, I went through the carb cleaning everything I possibly could. Now, or at least I notice now while trying to start it will either backfire out of the exhaust or a small blue flame will come out of the carb. I made double sure that I put everything back on the exact same way that it come off. Also I haven't been able to get it started as of yet.

MowerMedic77
02-15-2008, 08:31 AM
I notice now while trying to start it will either backfire out of the exhaust or a small blue flame will come out of the carb. Also I haven't been able to get it started as of yet.

Constant backfires(during starting) from the exhaust or the carb will be caused by valves hanging up or not closing during a compression stroke. I can't see how this would have just started happening after a carb rebuild :confused: If some how this unit got out of time(sheared flywheel key) then it would also pop like your describing.

Side note: What spark plug do you have installed and what is the air gap set to? Also this engine has an ACR or automatic compression release but what kind of compression readings are you getting? Kawi states min. 55psi

Stillwater
02-15-2008, 09:57 AM
Constant backfires(during starting) from the exhaust or the carb will be caused by valves hanging up or not closing during a compression stroke. I can't see how this would have just started happening after a carb rebuild :confused: If some how this unit got out of time(sheared flywheel key) then it would also pop like your describing.

Side note: What spark plug do you have installed and what is the air gap set to? Also this engine has an ACR or automatic compression release but what kind of compression readings are you getting? Kawi states min. 55psi

Good point on the timeing, the key can even just be partially sheared and cause a issue

MowerMedic77
02-15-2008, 12:14 PM
Kawi states min. 55psi

Before someone else calls me out on it ,this is the reading for a FB460V, you have a FC420V and it should be 71psi min. My bad:hammerhead:

derekmman
02-16-2008, 12:32 PM
Let me re-phrase what I wrote earlier. It will backfire sometimes, not all the time. I talked to me dad the other day, he is who I bought it from, and he said the guy he took it to to fix it said the carb couldn't be saved. Why I don't know though. When I took apart the carb it looked very clean like someonehad cleaned it recently. I think I am just going to buy a used carb from a guy that has a small engine repair business down the street.

Jason Pallas
02-16-2008, 11:34 PM
Not to throw a wrench into things but, this sounds like it could also be a govenor issue too.

derekmman
02-17-2008, 07:06 PM
How would I go about knowing if it was a governor issue?

Thanks,
Derek

MowerMedic77
02-17-2008, 07:14 PM
When the engine was running was is screaming past 3600 rpms?

derekmman
02-17-2008, 09:20 PM
No, not from what I was told.

MowerMedic77
02-17-2008, 09:41 PM
Then its most likely not a gov. issue Your issue is still fuel related.

derekmman
02-17-2008, 11:18 PM
Will a carb off any fc420v engine work on my engine? The reason I ask is there is a guy on ebay selling one and I is off a John Deere 170 tractor w/ a fc420v engine. It looks a little different from mine.

-Derek

Jason Pallas
02-17-2008, 11:40 PM
I wouldn't rule the govenor out. I've had engines do exactly what you've described and it was a govenor issue. If you manually manipulate the govenor, do you see any change in engine RPM? Do you feel any resistance when you manipulate it?
The fact that your engine doesn't work "under load" makes me think that your govenor is hung up. This is classic sign of a govenor that isn't working right. Given that you've cleaned the carb and can't/didn't find anything of great or obvious concern makes me think that this is not a fuel delivery issue..... but rather govenor issue.

MowerMedic77
02-18-2008, 08:29 AM
Here is his own quote from earlier
it kept running once a shot starting fluid was given to it.

This alone should rule out the gov. beside the fact that the FC420V is not known for gov. issues in all the time I have been fixing engines and all the mowers I have seen with this engine installed I have fixed...................0 gov.
I have adjusted the gov. but his issue is still not related to this.

And I would not get the carb from the John Deere engine.

Landrus2
02-18-2008, 08:40 AM
[QUOTE=MowerMedic77;2160431]



Hello have question for you how do you (fine) tune a carb on a Kawasaki 15hp.:drinkup:

MowerMedic77
02-18-2008, 08:53 AM
[QUOTE=MowerMedic77;2160431]



Hello have question for you how do you (fine) tune a carb on a Kawasaki 15hp.:drinkup:

Are you referring to a fh451v, if so then this is a fixed jet engine. You can only adjust the air pilot screw on the top of the carb (EPA).

derekmman
02-18-2008, 09:13 PM
Well I am sold on it defineitly being a fuel issue. I am going to buy a carb from a guy my father knows that has one. If that doesn't do it then I don't know.

Jason Pallas
02-20-2008, 01:53 PM
Mower Medic - you're right. I must not have seen the "shooting starting fluid into the carb" part of the original description. My bad. Although, while the govenors on those particular models re not known for failure, I have seen a few that have hung up and mimicked his problem - run fine at idle and then die under load. But, given that he can get the engine to maintain under load with some starting fluid, it does appear to be a fuel delivery problem.

Landrus2
02-20-2008, 06:41 PM
Well I am sold on it defineitly being a fuel issue. I am going to buy a carb from a guy my father knows that has one. If that doesn't do it then I don't know.

Have you pin point you problem.:waving:

sawman65
02-21-2008, 03:56 PM
Let me re-phrase what I wrote earlier. It will backfire sometimes, not all the time. I talked to me dad the other day, he is who I bought it from, and he said the guy he took it to to fix it said the carb couldn't be saved. Why I don't know though. When I took apart the carb it looked very clean like someonehad cleaned it recently. I think I am just going to buy a used carb from a guy that has a small engine repair business down the street.


sometimes up here in the cold,water will get into the fuel and freeze. if there is enough water in the carb it will split or distort the emulsion tube.i have cut carbs in half on a band saw because my mind would not let it go.and i seen it with my own eyes. water can do some bad things folks, smash float's flat,distort inlet ports out of round so no needlevalve will ever work. seen carbs busted in two..go get you a new carb just make sure it has the same controlls on the butterflys as yours.