PDA

View Full Version : Intermittant Loss of power...out of ideas! Please help!


Mark Pappas
05-28-2009, 07:21 PM
We've got an Exmark Lazer Z HP mower with a Kawasaki 18hp motor that has been giving us a lot of trouble lately. We've put a lot of time and parts into it and have had little success. Description of the problem/ time line:

Last summer: VERY rarely (as in maybe once every 2-3 hours) the mower would fall flat on it's face, and run very rough. It would miss and sputter, and would die if I turn the blades off. Sometimes it would come back after a few seconds, other times it required the mower to cool down and then it was fine again. It happened so rarely that it was basically impossible to troubleshoot.

Replaced: Fuel Filter

This spring: First startup, it cranked immediately and ran great until it warmed up. After that it runs like the throttle was pulled out, but doesn't miss at all. The engine is consistent in rpm, however it sits at a lower rpm then normal. It has a lot less power, and is barely usable. Then seemingly randomly, it will rev back up to normal rpm and run fine for a few minutes. If we let it cool down, it runs fine.

What we've done so far: 2 new fuel filters, drained tanks/ new fuel 2 times, blown out all fuel lines, replaced fuel pump, plugs, voltage regulator, and ignition coils, removed and cleaned carb twice, cleaned fuel bowl a number of times, performed both hot and cold compression tests (< 10% variance from cylinder to cylinder)


After replacing the voltage regulator, it began to do what it did last summer with missing and running rough every now and then, but it seemed to prolong the period before losing power (possibly coincidence?). Most recently we replaced the coils and after running it today, it made it MUCH longer then normal before losing power. When it started having problems, it was MUCH better, and only lasted a few seconds most of the time. However a new symptom popped up: When turning the key to off, the mower continued to run. I had to turn off the fuel to kill the engine.

We're extremely frustrated at this point! Does anyone have any ideas? I can't help but think it's electrical related after most major changes coming from the voltage reg & coils combined with the new symptom of the mower not shutting off.

Any help would be greatly appreciated! If you've made it this far, thanks for reading...

DT Lawn Care
05-28-2009, 07:41 PM
Well the fact that it won't turn off brings the Ignition Switch to mind. Could be solenoid? but I don't think that it would even run. You might have some loose connections somewhere to correct your main problems, but if you've done all of that other crap, I would assume that you've checked all obvious locations.

That is a very weird problem, considering all of the stuff that you've replaced.

When I was reading the start, I was thinking ignition coils, but looks like you've got those covered. Could be the flywheel that actually works the magneto? The flywheel is what will power the coils. That is about the only other thing that I can think of.

Good Luck

Mark Pappas
05-28-2009, 08:37 PM
Thanks for the response...hadn't really considered the magneto thing, I will take a look at it and maybe consider a new part there depending on the price.

We have looked at most of the obvious connections, but I'm wondering if maybe this could be a grounding issue, or just a lose connection that hasn't been found yet (or multiple). I should probably also note that fuel shutoff solenoid doesn't seem to be working properly, as it has been backfiring after shutoff. I'm tempted to make a new harness, because it almost seems like there could be a number of electrical connection problems. I'm just not convinced that that's what it is given the sequence of events.

Any other ideas?

Restrorob
05-28-2009, 09:10 PM
I'd like to see some unit model AND serial numbers along with engine model AND spec numbers ?

viper00085
05-28-2009, 09:33 PM
when it drops power, any type of smoke from the exhaust at all? When it drops power, can you pull the choke out 1/2 or more and it regains power?

From your symptoms I dont think it is a carb/fuel supply issue, but if you see any type of black smoke from the exhaust it may be running rich or flooding everynow and then, or if the additonal choke helps it, it may be running lean on fuel for some reason.

It def sounds electrical related. Grounds, ign switch and connections to start for sure with the engine not shutting down properly. I would get this situation fixed first, so it does not affect the rest of your troubleshooting, and who knows it may take care of all the issues.

Also had one just like this earlier this year on a lazer hp. Customer complained of losing power, sometimes stalling, but very, very intermittent. It ended up being the seat delay module (safety module). Quick test on one side of the module is with the brake off and steering handles in, lift up off the seat. there should be a 3-5 second delay before the motor dies. If it shuts off right away, then the module is bad, if it does not shut off at all, check your grounds and wiring first. Now there are other tests on the module too, but they are more serial number specific.

Mark Pappas
05-29-2009, 12:41 AM
Thanks for the tips viper, It doesn't smoke at all, and I've tried playing with the throttle/choke when it's rough and it doesn't seem to make a difference. My thought was that it was flooding also, but there doesn't seem to be any indication of that. One time I pulled the plugs after it was acting up and one had some unburnt fuel on it, but the other did not. I'm guessing that was because of the ignition system not working properly, not because of a fuel delivery issue.

I'm pretty sure the motor will die the instant our seat goes up, so perhaps that's the problem. I always thought that it was supposed to be instantaneous for safety reasons. Are you sure there is supposed to be a delay?

Sounds like I should probably be looking for a repair manual with some more detailed electrical info. Any suggestions as to where to pick on of them up? I will get the serial/ model #'s tomorrow later in the day.

viper00085
05-29-2009, 07:12 AM
yep, there should def be a delay before it shuts off when the operator comes off the seat, a few seconds or so. Its there so on bumps, and with lighter operators,etc the unit does not constantly try to shut off and die.

I dont believe exmark offers any serv amnuals, but they do offer good electrical troubleshooting guides for the units and components to us dealers thru there dealer websites. I dont know if they have the tech sheets avail to the public though. May want to call exmark tech help directly and see if they will give them to you or speak to your dealer.

DT Lawn Care
05-29-2009, 09:25 AM
yep, there should def be a delay before it shuts off when the operator comes off the seat, a few seconds or so. Its there so on bumps, and with lighter operators,etc the unit does not constantly try to shut off and die.

This must be only on an Exmark ZTR, because every other walk behind, riding mower, or ZTR I've used has no delay at all.

Mark Pappas
05-29-2009, 04:59 PM
Checked the manual and it does mention that the seat saftey switch is a time delay system.

But anyway, here are the #'s:

Engine sticker read:

CODE: FHV500V-A510
[Barcode]
E/NO FH500VA06289

Mower:
Model #: LHP4417KA
S/N: 175793

Ruben Rocha
05-29-2009, 07:11 PM
Not knowing hours on the machine.
How long has it been since the valves have been adjusted?
Should be like every 300-400 hours.

viper00085
05-29-2009, 07:36 PM
you got an older unit there, shes been around a while! on yours its number 1-543316 safety interlock module that controls everything. Back then, they did not call them delay control modules and you know I cant remember if there is supossed to be a delay on that old of a unit. I will try to find out and let you know.

From about sn# 260,000+ they started using the delay control modules (eg: part#100-6186,etc) on all exmark/toro ztrs.

Mark Pappas
05-29-2009, 09:51 PM
Thanks! Yeah, the manual says there is a delay to prevent accidental shut offs over bumpers or for lighter riders, so I think you might be right there.

It's only got 422 hours on it! It doesn't seem like a valve issue given the randomness and other symptoms

Mark Pappas
06-09-2009, 07:42 PM
Ok, have some new information for you guys....

I an effort to fix the issue of the engine not shutting off, we replaced the ignition switch today. It continues to remain running after being switched to off. However the blades won't turn on, so it seems that it's shutting off the other systems as it should (Fuel Valve, Clutch Switch, Hourmeter, Saftey Module). The most noticeable is that when the switch is turned to off, the engine drops in RPM like it does when it loses power.

In response to the seat safety switch suggestion, we bypassed the switch and it seems to have no effect.

Any ideas? On the wiring diagram, it seems like the only other thing that could be malfunctioning could be the time delay module since it connects to both the IGN switch and the Solenoid.

Ruben Rocha
06-09-2009, 08:01 PM
Intermittent loss of power was the original complaint.
I can't believe that Rob did not suggest adjust the valves which I did suggest.
So there it is.
But now there are all other types of problems reported.

Mark Pappas
06-09-2009, 09:17 PM
Ruben,

Thanks for the response, and I did respond to your original comment that I didn't think it seemed like a valve issue. Given the additional symptoms and the fact that it has responded only to electrical components being replaced, that seems to point further away from a mechanical issue. The engine not shutting down is not a valve issue, and the fact that the switch being turned off seems to affect the RPM as though it is losing power leads me to believe that it is electrical. If I am missing something, please elaborate further. I'm not trying to disregard your suggestion, but there wasn't a whole lot of explanation of how it is relevant to the other problems.

jkilov
06-09-2009, 09:37 PM
Ok, have some new information for you guys....

I an effort to fix the issue of the engine not shutting off, we replaced the ignition switch today. It continues to remain running after being switched to off. However the blades won't turn on, so it seems that it's shutting off the other systems as it should (Fuel Valve, Clutch Switch, Hourmeter, Saftey Module). The most noticeable is that when the switch is turned to off, the engine drops in RPM like it does when it loses power.

In response to the seat safety switch suggestion, we bypassed the switch and it seems to have no effect.

Any ideas? On the wiring diagram, it seems like the only other thing that could be malfunctioning could be the time delay module since it connects to both the IGN switch and the Solenoid.

Well, I think you answered your own question. It's either that delay module or a bad connection / grounding somewhere. I would take my time and clean all contacts, but you probably did that already.

I'm guessing it remains running slower because the ignition does'nt turn completely off but the fuel valve does.

DT Lawn Care
06-10-2009, 12:03 AM
The fact that the RPMS drop when you turn it off brings bad ground to mind. Though if you checked your connections, you should be set!

Ruben: I agree with Pappas, it will VERY UNLIKELY be the valves related to this. It would have absolutely no effect on the electrical problems he is experiencing.

Honestly, this has got to be THE MOST puzzling case I've read about so far.

Once you do find it, it will probably be something simple, seems like it always is in my case :laugh:

Good luck, and keep us updated.

Mark Pappas
06-10-2009, 07:31 PM
I suspect you're right about it being something simple! It's just been frustrating throwing parts at it and having little to no change.

Plan right now is to bypass the delay module to the coil and see what the effect is. If that fixes the issue then the module will be replaced. Still haven't checked on the price for the part yet. We have checked the contacts, and they all seem to be in good shape, but it wouldn't hurt to go over that again.

Will definitely keep you updated!

Mark Pappas
06-24-2009, 07:26 PM
Well it seems that we might have finally solved it. We pulled the plastic engine cover off and found that one of the coil wires had been pinched and pulled off of the coil. We've mowed 3 times since then, and the first time it ran a little rough towards the end, but the last two times have been perfect all the way through. Not sure why it still ran rough, but maybe it just coincidentally had some bad gas.

I'll keep you updated if anything else comes up, but I think that solved it! Thanks for the help guys...