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View Full Version : Kohler CH26 w/ EFI


Bill L
07-03-2006, 09:35 AM
I'm converting from a pulse pump system, a Kokler CH25 on an Exmark. The new engine with all Harnesses,Electric fuel pump, pressure regulator, ECU etc no wiring diagram? The Kohler service manual from on-line is all number coded and the actual Harness I have is all color coded? Need cross reference.

tallimeca
07-03-2006, 09:06 PM
this would be easy. First your going to have to do alot of custom wiring. They , the EFI has a return line, so you'll have to change/modify the tank.

Good luck.

fixer67
07-03-2006, 10:31 PM
You may want to get some one to do this for you. One wrong wire and you will be out a $500 ECU. I have replaced 4 ECUs this year because of wiring mishaps or from jump starting. On an EFI unit every thing has to have the best ground. Just a bit of rust or paint and you can lost enough signal to cause problems. After you install the engine and ECU you will need to reset the TPS as well. I have found that almost any time you go into the wiring on a EFI you have to do a TPS reset. It is no big deal and the book tells how to do it. Once every thing is in place start the engine and run it for 20 to 30 minutes and then shut the engine down and check the ECU codes. If it is all fine you will get a code 61 and no other codes. Have fun and good luck.

PS. There is no cross reference for color codes that I know of. You need to find out which ECU you have. There are 3 different ones in use and all 3 are wired different. The on line manual will help you find out which one you have and will have the pin-out data you need. The harness plugs should make it a bit easier seeing as they will only hook up one way for the most part. You may want to get some help on this one.

Bill L
07-04-2006, 10:25 AM
Fixer, appreciate the info, I figured out the fuel piping, however I still had five wires not sure where they go. I do have the service manual and I have the metal 35 pin ECU, but I can't believe KOHLER puts out one product as I have a color coded wire harness and it's wiring diagram is all numbers?? This kills me when the right hand doesn't know what the left hand is doing. I figure I'm smarter than the average Bear, I'll figure it out (even if I have to undo the harness and trace the individual wires back to the pin connections). If you find any more info, be glad to listen, Thanks, Bill L.

Bill L
07-04-2006, 03:12 PM
Fixer 67, by the way, the post you put up, or reposted on the dual solinoid for the Exmark and rewire of the Delco starter was perfect timing, Thanks. Well as I put it the Bear is back, I figured out all the wiring with out any help from Kohler. Just have a few questions for those who Know. 1. I assume the MIL light for the fault codes is simply a 12 volt LED? 2. The oil sentry safety at the top of the engine is nothing more than a fault to ground, thus grounding ignition on a conventional system. My question is that the Electronic Fuel Ignition system wire harness brings it back to a field installed pin connection and I see that according to the service manual their is no fault code for this failure. Thus should I wire into ignition system to ground ignition or should I wire in either a buzzer or indicator light? So I'm having a wonderful 4th getting educated on EFI's the old fashion way, hopefully one LED away and I'll have this baby running. Thanks, Bill L.

Jman
07-05-2006, 09:19 AM
You do not want an LED, a plain old volt indicator light will work the best. The oil pressure switch should ONLY be hooked to a light or buzzer when installed in a mobile (self-powered) application. The metal case computer does not have a ground to kill system for the ignition, later plastic case ECU's do.

Bill L
07-05-2006, 09:43 AM
Jman, I'm ok with going with the buzzer for the Oil Sentry safety, question on the regular 12 volt lamp for the Fault indicator (MIL), you say don't use the LED, wouldn't that be more durable and more reliable, or is the resistance too low for the ECU?

Jman
07-05-2006, 01:35 PM
Some ecu's, when using an LED, will cause the light to be on dimly all of the time. The regular 12 volt bulb is still the best for this application.

fixer67
07-06-2006, 01:42 AM
Fixer, appreciate the info, I figured out the fuel piping, however I still had five wires not sure where they go. I do have the service manual and I have the metal 35 pin ECU, but I can't believe KOHLER puts out one product as I have a color coded wire harness and it's wiring diagram is all numbers?? This kills me when the right hand doesn't know what the left hand is doing. I figure I'm smarter than the average Bear, I'll figure it out (even if I have to undo the harness and trace the individual wires back to the pin connections). If you find any more info, be glad to listen, Thanks, Bill L.

Well the 35 pin ECU was not even made by Kohler or ever ment to be used on a small engine. It was made by the car maker Volvo for their cars. Kohler did not have a working ECU at the time and to get the EFI engine to market on time they remapped a Volvo ECU. Not sure who makes the plastic ECUs. BE sure you ground the case of that metal cased ECU to both the engine block and the battery ground or you will be sorry. Be sure you run a ground wire from the muffler to the engine block or you will get an O2 senor fault. It was never realy ment for any one to go cutting into the wiring harness is the reason there is no color code. The harness has plugs on each end that makes the placement of them a given.

I know this is not a Walker but go to the Walkler web site and download the owner's manual for the EFI units. A wiring diagram is in the back of the book. I will check to see which one has the 35 pin ECU in it for you

fixer67
07-06-2006, 01:56 AM
Ok, if I have doen this right it should take you to the parts manual for the Walker that had the metal cased 35 pin ECU.

http://www.walkermowers.com/Manuals/model_t/8000-4_pub.pdf

This may be of some help. Good luck

Jman
07-06-2006, 09:30 AM
The metal cased computer wasn't made by Volvo, it and the current plastic cased computers are made by Bosch. The first generation metal cased was used for automotive purposes, that is true, but Bosch is the manufacturer.

Bill L
07-06-2006, 10:46 AM
Fixer, appreciate the additional info. I will add the additional grounds, I have all wiring pretty much figured out and totally tied in. Just lacking the installation of the fault light (MIL), horn for oil sentry switch and I was suggested to add a Diode for the electric clutch. Should be doing a test run Saturday, I'll post my results. Thanks.

fixer67
07-09-2006, 12:58 AM
The metal cased computer wasn't made by Volvo, it and the current plastic cased computers are made by Bosch. The first generation metal cased was used for automotive purposes, that is true, but Bosch is the manufacturer.

Well maybe it was made for a Volvo by Bosch. I was just repeating what the Kohler factory rep told us at the update school a few years back. He said that Kohler did not have a working ECU and was behind and needed to get the EFI to market ASAP and a ECU for a Volvo was used to get the EFI to market on time. He said that is why so many of the pins on the 35 pin metal cased ECU is not used.

fixer67
07-09-2006, 01:48 AM
Fixer, appreciate the additional info. I will add the additional grounds, I have all wiring pretty much figured out and totally tied in. Just lacking the installation of the fault light (MIL), horn for oil sentry switch and I was suggested to add a Diode for the electric clutch. Should be doing a test run Saturday, I'll post my results. Thanks.

Yes, if you are using a electric PTO you had better use a diode set up. If not the backflow and surge from the PTO switching on and off could spike the ECU. Below is how it should be wired up. I have had to do this before. It is easy to hook up and cheap, less than $5 and it can save a $500 ECU.