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View Full Version : Kawasaki 29 DFI Power Loss


Choppa Jon
05-05-2010, 07:55 AM
Hi everyone I am new to the forum and I really could use some help. I bought a 08 Scag Turf Tiger (STT61v29DFISS) with a 29 Kawasaki DFI Liquid Cooled (FD791D-CS04) and a 61 Velocity Deck with collection system 740 hours. I have owned a Wildcat 61 with a 27 Kohler and a 48 Tiger Cub with a 19 Kawasaki. I had no problems mowing with the the other two but this Turf Tiger is causing me problems. The mower starts and idles fine and the rps sound good too. The problem is I lose power when I engage the PTO for deck. The mower does well on hills and will climb them with little or no issue without the deck on. When I turn the deck on the mower will drop RPM's significantly and almost stall. I then have to back off the wheel motors and let the rpm's catch up. I took the bagging system off and I had the same issue. I just pick this mower up two weeks ago and the previous owner said that there were no issues with the unit. When I got the mower I changed all the filters, oil and hydraulics. At first I thought I had air in the hydraulic system but I don't believe that is the case since the mower clibs hills well without the mower deck on. I tried calling my local dealer who can't pffer too much help because he is not too familier with the DFI. I called Scag and they said it could be a coil but they are not sure. If anyone can help me diagnose the problem that would be great because I really need to get this thing mowing again. Thank you all in advance for any help you can offer.:confused:

pugs
05-05-2010, 12:42 PM
Probably running on one cylinder. Check spark on each side. Check compression and leakdown on each side.

Choppa Jon
05-05-2010, 01:02 PM
Really? It sure does not sound like it is only running on one cyclinder because it starts easy and the RPMs only drop when the deck is on. I thought it would run much worse on 1 cylinder. I will look into it. Thanks for the advice. How could I tell if the coil is bad?

pugs
05-05-2010, 02:43 PM
Kawasaki's run really well on 1 cylinder. Once you see enough of them you kinda know what to listen for...otherwise only time you will notice is the huge loss of power when engaging the deck.

I dont know for sure on the LC stuff but have seen many 15-25 air cooled twins that run well, start well but are only running on one cylinder.

Easy thing to do is with it running and some type of insulated tool pull 1 spark plug wire. If it keeps running and doesnt change much, put it back on and try the other side. If pulling 1 wire kills the engine, you know it was only running on that side. We use plastic fuse removal/installation pliers for this.

Choppa Jon
05-05-2010, 09:00 PM
Thanks Pugs. I went to the dealer and he told me to take off the one plug wire and try and start the unit. If the unit starts then put that wire back on and then then remove the other wire. It started both times. I am assuming your method is different? I looked at both plugs and they both had some carbon on them. He also told me totake the harness out of the computer and check for green oxidation which there was none.

Choppa Jon
05-05-2010, 09:25 PM
One more thing I did a compression test and each cylinder came up 80- psi

pugs
05-06-2010, 10:21 AM
Thanks Pugs. I went to the dealer and he told me to take off the one plug wire and try and start the unit. If the unit starts then put that wire back on and then then remove the other wire. It started both times. I am assuming your method is different? I looked at both plugs and they both had some carbon on them. He also told me totake the harness out of the computer and check for green oxidation which there was none.

This would do the same thing just slower and safer. Basically checking to see which cylinder the engine is running on. If you dont have a tool that can safely pull the wires off while running this would be another way to do it.

Did you try doing this at all? Was it running on 1 cylinder or both?

Choppa Jon
05-06-2010, 11:20 AM
I tried it your way and when I pulled the wire the motor started to hesitate and then was able to idle up. When I tried the second wire it did the same thing. Neither side when pulled made the motor stall. I did this at a lower RPM. I just took it to the dealer and he only had a few minutes to look at it while I was there and he said that the RPM is 3900 and that the governor sounded like it was woking right. He was not able to turn on the deck to see the power loss. He is stumped too.