Check your compression. If it’s low they can stall going into reverse. You’ll want to see close to 125 or higher

 

115 psi on one cylinder, 100 psi in the other.

 

Thank you for the suggestion, I'll check that when I get home, it doesn't usually stall when going into reverse though, it just doesn't actually spin backwards.

 

That can also happen if there is shortage in electrical power. Disconnect the headlight fuse and try again.

 

Okay, I'll give that a try too.

 

If you are not used to checking compression then do it with a couple of different compression gauges. What altitude are you at? This effects compression readings.

When the reverse is engaged but the engine ends up running in forward, this also could be due to low compression, or from the forward and reverse timing coils being set wrong.

 

Thank you for the info, I'm at roughly 1700ft.

 

OK, not too much effect on compression readings..... maybe 5 psi lower than at sea level. Just wanted to make sure you were not at 5-10K feet of altitude.

 

115 psi in one cylinder, 100 psi in the other.

 

Okay, I'll update you with readings once I get home to test.

 

OK, on the manual start, so there is no battery to help the electrical system in the reversal.

Without further electrical testing, it is hard to say if the electrical system itself is weak, or if the low compression slows the engine speed when trying to reverse, and that causes the electrical output to be too low after the system's attempted restart in reverse.

Regardless, I would take another step to measure the compression again. Maybe someone can comment on how much they think the adapter is lowering compression readings.

 

I'll see what I can do to borrow one from a friend, but im the past I've never had issues with this one

 

I have seen cracked magnets cause a low output when trying to engage in reverse.

Good point on the low compression that can slow down the engine speed. If it had an electric start I could probably tell if this was the case by listening for a change in engine speed. I have never tried with a pull start, but maybe it would work too.

At least now he's got a workaround by switching to low beams.

I can believe the cracked magnets.

The problems with the voltage testing that you ask the OP to do is that the MPEM has to see some minimum voltage to be able to see the triggers and fire the spark while cranking or while reversing. But this minimum voltage in well under 10 volts, and is in the 3-5 volts range per testing in the manual. Plus we care about what is at the MPEM not at the fuses, and any wiring or splice corrosion issues between VR and fuses can throw off the test results.

Fantastic. Locate one of the two 20A fuses and see how much voltage there is with and without the headlights. The top of the fuse should have a test port to place the red test lead, and the black goes anywhere on the chassis.

This test is going to have problems, because it does not say the testing conditions or the test spec.

If you want to advise people to test this, the here is the way to do this:

• Test from red/blue and black wires at the MPEM connector, while cranking. Look for 3 to 5 volts DC. This can be tested with and without the lights on to see if there is a substantial difference; in this situation, that would be expected but it still should stay in spec if all is good.

 

The problems with the voltage testing that you ask the OP to do is that the MPEM has to see some minimum voltage to be able to see the triggers and fire the spark while cranking or while reversing. But this minimum voltage in well under 10 volts, and is in the 3-5 volts range per testing in the manual. Plus we care about what is at the MPEM not at the fuses, and any wiring or splice corrosion issues between VR and fuses can throw off the test results.

I was after the running voltage with an without the headlights, but what you posted would be an interesting test to see how far it drops.

If this were a REV then I would ask to check the configuration harness which is the short piece of harness that configures the wiring for either manual or electric start. I am not familiar with the wiring on a 2002 MXZ other than it being in the ZX chassis. And that multi-page wiring diagram is terrible.

Then again, the most common sled issues are often the same with a short to ground in the wiring under the seat that leads to the tail light, and a short to ground in the grip warmers. I wish that I knew an easy way to isolate those two circuits. Actually, we can simply remove the 20A for all those things! The headlights on high are a sufficient load to determine the stator is outputting enough current.