Lazer Z only starts with assist of battery charger

[GrassBarber]

I mentioned the starter and I thought the OP tested it

 

[bertsmobile1]

The starter is turning, what is happening is the fuel pump is not priming the system.
It is a fuel injected engine.

The last cheap item would be the fuel pressure gauge but from memory it is a just a spring loaded bypass.
If there is a wire hanging out of it then that piece of kit could be faulty and registering full pressure when there is none but as before it is another clutching at straws job.
I do not have the error codes for your engine which would be the next step to see if the system is registering a sensor fault.
Will have a dig around the hard drive latter to see what comes up.

 

[mowerman556]

You've taken a good first step to solve this issue. To respond to your comment about the relay, let me add info about my recent experience with the starter relay on the motorcycle I mentioned in my other post. Starter relays is nothing more than a switch that 'relays' high current to the starter motor. Sounds to that the high current contacts inside the relay have finally either corroded or have worn out to the point that the relay won't send enough current to spin the starter motor to start the engine. My motorcycle is a '06 Suzuki that due to age, is beginning to have issues. Along with making my own grounds, I also changed the starter relay. It was the original relay. The high current contacts DO corrode and wear out. By you using the high amp charger, that forces high current across those contacts that you are not getting form the battery and you can start the engine. Once it is running and you release the ignition key, the starter relay breaks current across the contacts to the starter motor and has zero effect on whether the engine runs or not. My recommendation is to test the starter relay or just replace it. These relays are more expensive than a run of the mill relay. These are specialized. The starter relay for my Suzuki was nearly $80. I changed the relay on my Exmark last year and if my memory is correct, it was under $40.

Thanks for the additional info, Boit4852. For $40, I'll get a starter relay from the local dealer and see what if that helps. I agree with the high resistance relay contacts. I'm thinking about the ECU along those lines... The silicon barriers in IC chips (known as P-N junctions) can break down without being a hard failure. I saw a description decades ago which showed the PN junction as a brick wall, and over time, some of the bricks loosening and falling out, either allowing leakage or not passing current at proper times. In that vein, the higher current "forces" the signal through the P-N junction, completing the circuit. Should this be the case, the IC will completely fail at some point, at which time no amount of current would allow a signal to pass. (Back in the early days I used to do component level circuit board repair... with an oscilloscope.)

I'll report back after I get a relay in install it. I assume it's externally mounted? Or is it?

 

[mowerman556]

The starter is turning, what is happening is the fuel pump is not priming the system.
It is a fuel injected engine.

The last cheap item would be the fuel pressure gauge but from memory it is a just a spring loaded bypass.
If there is a wire hanging out of it then that piece of kit could be faulty and registering full pressure when there is none but as before it is another clutching at straws job.
I do not have the error codes for your engine which would be the next step to see if the system is registering a sensor fault.
Will have a dig around the hard drive latter to see what comes up.

Thanks Bertsmobile1. I saw your note here after I responded to boit4852. Am I to assume from your comment that because the starter is turning I can safely ignore the starter relay replacement?

Regarding the fuel pressure gauge... I don't have one? There are no gauges on my Exmark whatsoever, unless we consider the hour meter to be a gauge (of sorts). Where would I find this wire hanging out of a fuel pressure device to check for a wire hanging from it?

Back to the earlier train of thought, I looked online for a replacement ECU and nearly fell out of my chair.... two sources, and $1,003 USD at each. Holy cats. Is there an Exmark salvage yard or used parts emporium online that I haven't found from my poking around yet?

Thanks,

mowerman556

 

[shiftsuper175607]

It could still be the starter (as was mentioned, to replace)...is the lug where the battery connects getting hot when you try to start it?
Does it turn normal speed or very slow?

A bad starter can pull a lot of amps.

 

[mowerman556]

It could still be the starter (as was mentioned, to replace)...is the lug where the battery connects getting hot when you try to start it?
Does it turn normal speed or very slow?

A bad starter can pull a lot of amps.

I will temp test the battery lug on the engine after attempting to start it a few times. Everything sounds correct, including cranking speed, only the mower won't start. The mower does not have the fuel pump prime when the key is turned to "on" position". When I add the battery charger (on 55A setting), the fuel pump primes and the mower starts, and runs normally after that (for hours). If I shut it off, however, it will not fire again unless the charger is connected again. It will however, crank and crank and crank (sounding normal), just no fire. Battery is new. Wiring and connections have been tested half a dozen times.

 

[mowerman556]

It could still be the starter (as was mentioned, to replace)...is the lug where the battery connects getting hot when you try to start it?
Does it turn normal speed or very slow?

A bad starter can pull a lot of amps.

Hi shiftsuper175607 The battery lead on the engine lug does not get hot whatsoever when cranking. As soon as I connect the battery charger, the engine fires immediately, like on the first revolution or two.

Would a bad starter pulling a lot of amps prevent the fuel pump from priming the system? That's the root problem... no fuel prime for the six seconds when the key is turned to "on". When I connect the charger, the engine fires right now.

For what its worth, the mower is always stored indoors, and only used by me for residential mowing of four acres. It never gets wet except for the times I wash it, which hasn't been since earlier this summer and well before this problem started. The mower is a 2003 model, and has about 825 hours on it. 28hp Kohler EFI.

Thanks.

 

[shiftsuper175607]

Hi shiftsuper175607 The battery lead on the engine lug does not get hot whatsoever when cranking. As soon as I connect the battery charger, the engine fires immediately, like on the first revolution or two.

Would a bad starter pulling a lot of amps prevent the fuel pump from priming the system? That's the root problem... no fuel prime for the six seconds when the key is turned to "on". When I connect the charger, the engine fires right now.

For what its worth, the mower is always stored indoors, and only used by me for residential mowing of four acres. It never gets wet except for the times I wash it, which hasn't been since earlier this summer and well before this problem started. The mower is a 2003 model, and has about 825 hours on it. 28hp Kohler EFI.

Thanks.

You have an unusual and interesting problem.
I considered the starter problem because something seems to bedrawing the voltage down low enough that is preventing the fuel pump/relay fromoperating as it should.
Keep working at it and hopefully you will get this solvedwith a lot of help. Please let us know how it turns out. This is quite a headscratcher.

 

[Boit4852]

As Supershift mentioned, something is causing a large enough voltage drop when trying to start the enjoy with only the battery. One easy test is to hook up a meter at the battery and see what voltage reads at rest. Should be ~12.4 to 12.8 range. While keeping the meter hooked up, crank the engine while reading the meter and see how low the voltage drops. Write that down if your memory is as bad as mine. As was mentioned, if the voltage is too low while cranking, the fuel pump relay probably won’t operate and the fuel pump won’t run thusly, the engine won’t start. If you see voltage much below 10v, there is excessive draw while cranking and that certainly could be the starter motor along as the battery is good. Most auto parts stores will test your battery and starter for free if you are willing to remove the starter yourself. I’ve had my starter off a few times and can do it now quickly. Yours might more difficult. Makes it easier if you jack it up on that side and remove the wheel.

 

[bertsmobile1]

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.