Lazer Z only starts with assist of battery charger

bertsmobile1 said:

What both you & Super are missing is the fuel pump should pump up the system when the switch is turned ON way before he hits the Start Position
If you own a fuel injected car you have the same system.
When the key gets turned to the on position the fuel pump kicks in to pressurise the system.
This is what is not happening.
The pump relay is not firing up the pump unless the battery charger is on a very high setting and would be over voltage.

Depending upon which system he has either the ECU is duff, or the fuel pressure sensor ( if it has one ) is not sending a low pressure signal to the ECU so it fires up the pump.

So from here on Mowerman556 will have to go to the Kohler web site & download the service manual for his mower.
As he mentioned a "plug with about 40 pins" I will assume he has the 32 pin Bosch controller on his mower.
We have gone through all the easy stuff, now it will be a case of running the fuel pump control circuit diagnostics,
AS he has not mentioned an error code this would tend towards a problem with the ECU itself .

We do not know which engine & which injection system Mowerman has and even if he did there is very little I can do from here on.
The pump is in fact working and at some point the controls for the pump are working but the start up cycle is not unless the system gets an overwhelming voltage.

This normally would suggest a bad connection somewhere but he has done all of the jumping from the battery that he can so now we are left with the ECU & the pump relay, if the later is not part of the ECU or possibly the Fuel pressure sensor ( should it have one ).
According to how I interpret the manuals I have the unit should be showing a service warning if the pump , relay or pressure controller are bad and he is not getting one.
All that can be done now is to see if the ECU is putting out an error signal by hooking up a test lamp or reader to it.

The problem with all this stuff is the sensors used put out very low voltage signals and in many cases it is only a fraction of 1 V so any corrosion on any wire can cause a fault as could any terminal where all but a few wires have broken.
Mowerman does not have the gear to read the outputs ( neither do I ) .
I keep some old dial voltmeters for making these readings ( best I can ) and bought a way too expensive LED test light that has never proved to be reliable.

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Good observations and info. This is an a very interesting problem and troubleshooting thread. My experience with similar issues are with my '06 motorcycle that is fuel injected. While it is these are different machines, they shar a general design. The issues with my bike were traced to the main ground from the battery to the first connector(badly corroded). Adding extra grounds can be a big help, in my opinion, but doesn't help in this case. As you mentioned about a bad connection, that's worth exploring. It will take a patient and determined troubleshooter to track this problem down. It wouldn't surprise me that the root of the problem is very simple. I hope the OP will share the final solution.

Boit4852 said:

Good observations and info. This is an a very interesting problem and troubleshooting thread. My experience with similar issues are with my '06 motorcycle that is fuel injected. While it is these are different machines, they shar a general design. The issues with my bike were traced to the main ground from the battery to the first connector(badly corroded). Adding extra grounds can be a big help, in my opinion, but doesn't help in this case. As you mentioned about a bad connection, that's worth exploring. It will take a patient and determined troubleshooter to track this problem down. It wouldn't surprise me that the root of the problem is very simple. I hope the OP will share the final solution.

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Thanks to all of you for the assistance and measured response, as well as bearing with me as I sometimes take days to get back to the mower issue. Between near drought conditions here (outside of Detroit, MI) and the never ending to-do list, I don't work on the problem as diligently as I should. Again, appreciate all the inputs to date.

I'll also share that forward of the starter there are three black plastic relays. All of them have the same number on them. I can hear one of these relays "pick", as we used to say in the tech world, that is, the relay coil gets energized and the contact(s) are opening or closing (depending on configuration (NO or NC). I have NOT switched those relays around as yet. I will do that and see if it creates a change in symptoms, and report those findings back here.

Thank you for the tip on metering the battery voltage (it is brand new, one month old). When I turned in the core, the battery store tested and it registered 218 or so CCA. The new battery, tested before I left the store with it, registered 320 CCA. Note, it's the same brand and size of battery I have been using for years, this being the third or fourth in 5 years. The old one was installed in 2014.

Below are some photos of the external of the ECU box, or at least what I think is the ECU. It has what I referred to as a roughly 40 pin connector, which may be the Bosch 32 pin as mentioned. Interestingly, the serial number shown for the Engine on the Bosch box is NOT the same serial number as shown elsewhere. Back in the memory banks I seem to recall I had to have the dealer effect a repair, which involved a replacement ECU. I think that it was still under warranty its been so long ago. I have records in a file if this is important to look into.

There's also been some discussion of codes. I assume this is done with a reader of sorts, or by some sort of codes (blinks?) generated by the LED next to the start switch? This mower does not have any other gauges or readouts, no fuel gauges or anything, just the hour meter, so not sure how to accomplish any code diagnostics.

Thanks everyone, for the attention, and spurring me on to find this problem. Hopefully with all your help WE will solve this one together, before someone else has the same problem!!

ps... see the connector and module in the first photo. It's located on the right side of the engine, down low. What is it? Secondly I was surprised to see the insulation pulled back well over one inch (2.54 cm) on the middle conductor. Been like that since day one, unless there's been shrinkage on one insulation and not the others. I'll fix that as well.

As stated befoe, you will have to go to the Kohler web site & download the service manual for your engine.
The injected ones have E in front of the model name so are ECV ??? or ECH ???
The manual does have diagnosis methods both using the Kohler reader and just a test lamp counting blinks.
If you have a single bare wire on the plug, good chance that is the signal wire which some one pulled the insulation back so they can read it.
Individual sensors are generally tested disconnected but the ECU itself has to be powered up to be checked.

bertsmobile1 said:

As stated befoe, you will have to go to the Kohler web site & download the service manual for your engine.
The injected ones have E in front of the model name so are ECV ??? or ECH ???
The manual does have diagnosis methods both using the Kohler reader and just a test lamp counting blinks.
If you have a single bare wire on the plug, good chance that is the signal wire which some one pulled the insulation back so they can read it.
Individual sensors are generally tested disconnected but the ECU itself has to be powered up to be checked.

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@bertsmobile1 The mower is fuel injected, it is the Kohler CH745. I did get the Kohler engine manual, document number 24_690-01-EN.pdf online and downloaded it. I'll be going through the wiring and fuel prime operation, thanks!

@boit4852

thanks for the tip on the voltage check across the battery terminals. The battery is new this year, btw.

I'm using an analog VOM. On the 50 volt scale the meter pointed to 12VDC. Being a rather small meter I could not get any more accuracy. When I cranked the engine, the VOM reading did drop to 10VDC as you said it might. I thought that was interesting, and a step in the right direction toward resolution. I will check with local auto parts stores to see if they can test the starter motor for the mower, and go from there, as well as check more of the wiring, clean the connections again and etc.

mowerman556 said:

@boit4852

thanks for the tip on the voltage check across the battery terminals. The battery is new this year, btw.

I'm using an analog VOM. On the 50 volt scale the meter pointed to 12VDC. Being a rather small meter I could not get any more accuracy. When I cranked the engine, the VOM reading did drop to 10VDC as you said it might. I thought that was interesting, and a step in the right direction toward resolution. I will check with local auto parts stores to see if they can test the starter motor for the mower, and go from there, as well as check more of the wiring, clean the connections again and etc.

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take the battery and have it checked also

mowerman556 said:

@boit4852

thanks for the tip on the voltage check across the battery terminals. The battery is new this year, btw.

I'm using an analog VOM. On the 50 volt scale the meter pointed to 12VDC. Being a rather small meter I could not get any more accuracy. When I cranked the engine, the VOM reading did drop to 10VDC as you said it might. I thought that was interesting, and a step in the right direction toward resolution. I will check with local auto parts stores to see if they can test the starter motor for the mower, and go from there, as well as check more of the wiring, clean the connections again and etc.

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It comes back to people not having a proper understanding of basic electricity.
A battery stores ENERGY not volts not amps.
Volts & amps is how we measure the energy that a battery can provide so when you have a heavy Amps draw, the Volts will always go down.
I used to run a fleet of Rolls Royces hire cars and the voltage drop was so high the engine would not fire while it was cranking on the Electronic ignition models and these cars had massive batteries.
We had to retrain all the drivers how to start the cars and once they got it pat, no more flat batteries & burned starter motors.

However your problem appears to be a timing one as you previously mentioned the pump should prime when the ignition is turned on, BEFORE the engine cranks & the voltage drops.
SO the appropriate check would be voltage at battery ignition off vs ignition on
If there is a voltage drop of 0.5 V or more that points to a fault in the wiring applying an excessive load ( potential short )

Simular issue here. Mowed with it until I was done then had to use the bathroom. Pulled up to the front door and when I came back out no power to starting circuit. No fuel pump and no starter. I do not really carry all my tools with me so did the basic test that I could. My electrical tester indicated no power through the ignition. Went to store and picked up new ignition switch. Replaced it and still nothing. Searched more checking all relays and safety switches. Nothing I could find. Then thought maybe the solenoid on the starter. I jumped the starter with jumper cables and I got starter spinning but no gears to the flywheel. Tada found the problem. Called around and no one stocked the starter and it was priced at an astronomical price. $485.00 plus shipping. Went online and found one for $48.00 OE replacement. Ordered it and when it came in I installed it. I now have power to everything for a split second before the fuse blows. No what? Totally at a loss for what it could be. Then I remember I replaced the ignition switch. I reinstalled the switch and started right up. I bench tested the old starter and it was bad. So it turned out to be a bad solenoid that was causing all the power to not go to the other parts.

@BlazNT thanks for sharing your experience. I've not been on the forum for a while due to any number of more pressing personal and family matters. So, I've been starting the mower with the aid of the battery charger all summer and fall. I'll dig in to the starter solenoid being the problem. Out of curiosity... did you attempt to start the mower with a battery charger like I've been doing, and did it start in that situation? Thanks!

mowerman556 said:

@BlazNT thanks for sharing your experience. I've not been on the forum for a while due to any number of more pressing personal and family matters. So, I've been starting the mower with the aid of the battery charger all summer and fall. I'll dig in to the starter solenoid being the problem. Out of curiosity... did you attempt to start the mower with a battery charger like I've been doing, and did it start in that situation? Thanks!

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I did not have a battery charger with me at the time. When I was finally around one I had already figured out the problem. So I never got to test it that way. While you are down there tighten the ground bolt.