View Full Version : Kawasaki fh451 15hp twin cyl.coil question

09-05-2010, 02:37 PM
Having an intermitant run problem with my kaw fh451 twin cyl. and I started a csi investigation on the cause. While I had the top cover off engine I found the flywheel very rusty as well as the coils so I removed them and hit them with some emery cloth and figure while they were off I would test them per factory service manual. I was using the factory A B C flow chart to check the ohms readings using my simpson 260 and also a fluke 73III to verify and both meters gave the same readings and both coils tested with the same ohms readings but they were not within factory specs for half the readings as per the chart.The engine runs strong up until it starts acting up. Is there something I could possibly be overlooking on these coils. I was going through the fuel system originaly thinking it was the possible culprit and it still very well may be but the coil readings being off has thrown up the red flag.Anyone that can lend some opinions would be much appreciated

09-05-2010, 08:04 PM
Well, If both coils test out of specified range on two different meters I'd tend to think the coils are faulty. That still doesn't mean you couldn't have two issues causing your problem.

09-05-2010, 09:58 PM
Well, If both coils test out of specified range on two different meters I'd tend to think the coils are faulty. That still doesn't mean you couldn't have two issues causing your problem.

Hey Restrorob thanks for the response .The thing that confuses me is they failed the resistance tests on half of the checks then how could they possibly run the engine .When I say fail I mean they weren't just a little off spec where there was supposed to be 2-18k they were reading open loop

09-06-2010, 04:51 PM
Restro will likely have a more intelligent and critical anwer than what I have to offer, but here goes. When a coil fails during operation, it is most likely a result of heat causing the coil to expand which in turn leads to a separation which causes a loss of continuity. When the coil cools it will contract enough to allow for continuity, permitting the coil to provide output. Needless to say, I haven't taken the time to tear down a coil to check where the loss of continuity may have occurred.

Anyone who is old enough will remember replacing ignition wires on the older automotive distributor ignition systems due to excessive resistance in the wires. This could be another possible cause.

09-06-2010, 05:24 PM
Thanks Dutch I understand about heat and expansion causing issues with coils.I just don't get how they tested bad but I put those coils right back on the engine and fired it right back up .

09-06-2010, 09:06 PM
That frequently happens with ignition coils--some more than others. Lawn Boy probably has the worst record for coil failures, at least with most of the old two strokes. I've been away from the Toro/Lawn Boy shop for 8 years now and I don't see many of them anymore but for a period of 7 or 8 years, I would replace from 30-50 per season.

09-06-2010, 09:17 PM
you normally wont see a problem with a coil till it heats up, they are really hard to troubleshoot due to this reason.

it might help if you describe your problem a little more so people can help decide if it could be the coil causing it.

09-06-2010, 10:23 PM
Was cutting one of my customers lawns and the engine was running fine about 15 mins in it started sputtering like it was running out of fuel .I reached down an switched to the other fuel tank on my gravely 34z and before it completely stalled out it recovered and ran for another 5 min then started to sputter out again.I took off both fuel caps and there was fuel in both tanks finished lawn and loaded back up on the trailer.The following morning I started unit pulled it off the trailer and parked it in the garage .Pulled off the fuel filter placed a mighty vac and pulled vacuum on both tanks and had fuel delivery from both tanks replaced fuel filter .Was going to pull carb off and clean it and while I was that far I pulled the top cover off to clean the fins and found the coils and flywheel really rusty.I pulled off the coils to clean with emery cloth and tested coils knowing that they could have been the cause of the sputtering.Both coils failed the factory specs chart but after installing them back on the engine the engine fired right back up.I was just surprised that coils that far from factory specs would even light the engine off.

The Lawn Ranger CT.
09-07-2010, 12:18 AM
Restrorob and Dutch1 have hit it on the head for you,... I have a 17hp Kawasaki fh500v and it would start up great and out of the clear blue it would start to skip or run on 1 cyl. , once it was warmed up , it would act up, but cold she would start and run great , those Coils can be tricky~!

09-07-2010, 11:21 PM
Well I picked up 2 new oem coils today took them home and tested them with the same meters simpson 260 and a fluke 73III .SAME READINGS as the old ones .Somethings not right with the testing procedure.I know for fact my meters are good .Has anyone else ever used the abc test chart supplied in the Kawasaki service manual for testing coils and have accurate readings?I tried to talk to someone at Kawasaki they referred me to the local dealers. Two different dealers basically told me they test them by unplugging them while the engine is running to see if they were bad or not.I know it works for them most of the time but I like to bench test items due to getting (bad) brand new parts in the past. I guess I'm just anal.

12-15-2013, 02:55 PM
My kawasaki 15 hp on my gravely 34z if it gets wet, rained on etc it will only run on 1 cylinder once it warms up it start running on two cyl, it has been missing more lately I'm guessing 1 coil is going bad
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12-15-2013, 04:46 PM
I would replace both coils for good measure . They are known for intermittent failures. Also on the 34z keep an eye on the fuel tubing that sits inside the gas tanks as it deteriorates and starts sucking air as the tank empty's as this can give an intermittent run problem as well. You will have to pull the grommet out of the side of the tank to check where the hose connects to the barb right there at the grommet. If the hose looks swelled replace it with Tygon (yellow)tubing.

12-15-2013, 04:52 PM
z50, your engine is likely missing after a rain due to a loose plug boot(s). If they aren't tight around the plug wire and the porcelain, they will retain water allowing the spark to track through the water to the plug base. Next time it happens, blow out the plug boot with air and give it a try. Use small zip ties to tighten those areas up or better yet, replace the boots--they are available at most autoparts outlets. While you're there, check for corrosion on the plug wire ends or broken wire where it's retained to the plug connector.

This is not to say that you don't have ignition coil problem but that problem can be checked out with inline spark testers while the engine is running.

In addition, Kaw recommends a valve lash adjustment every 300 hours.

08-09-2014, 12:21 AM
By chance did you ever come up with a solution to your problem? I've been fighting this on a Kawasaki FD731V 26HP machine (Country Clipper Boss). Same symptoms you gave. I checked the coils this eve using the manual and my coil readings on the primary were way off. I used a Fluke 179. Ohms were supposed to read 16-24ohms and I was getting 301Kohm on #1 coil and #2 coil read 308Kohm. It's also supposed to read open when you switch pos and neg leads, and mine did that. I suppose that checks the diode? Mine checked fine on the secondaries. I would love to get a new coil and check resistance on it with my meter before buying to make sure I actually have a failed part. The manual says using a different meter than they recommend may give you a different reading than they get with theirs.