Hi, All,
I'm new to this forum, but belong to several other motorcycle forums which is not helping me solve my current problem.

I have a '07 TRX420FM Rancher with EFI that will not start.
Here is the history.
Ran fine until one day this winter, would not start. Cranked fine, back fired, flooded, etc would not start. Waited for warmer day, and it stated fine. Ran rest of winter up to last storm. Last day it ran it was sluggish.. like it needed a tune up or something. Then a day later I started it. It ran rough went three feet and just died. Could not restart it. So here is what I have done so far:

For each thing I have tried, all the rancher does is turn over, and backfire.

1. Checked for indicator lights flashing - nada, all lit like they should be
2. Checked Air cleaner, no blockage
2. Replaced spark plug, and I do have spark
2. Gas is fine, runs in lawn mower, and I put in seafoam just in case.
3. Fuel pump seems to work fine because I removed the fuel line and cranked it, gas flew out..
4. Charged the battery, tried a new one.
5. Checked the bank angle sensor it seams fine.
5. Checked the fuses, all fine
6. Checked the bank angle sensor, seems fine
7. Replaced the fuel injector
8. Replaced the valve next to the injector (CATV)

So, WTF? I don't have a peak meter so I am not sure how to check some other things. The symptoms seem very similar to when I put my motorcycle back together after replacing the stator and had the stator sensor wires reversed.... Which leads me to think that maybe I have a bad crank sensor ? I checked the parts fische, and I can not find the crank sensor anywhere, it seems you have to buy the whole stator to get it?

So, a few questions..
What might be the problem?

Where can I get a new Crank Sensor (CKP)?

Should I just day F**K it and just ride.. ? Thing is I use it to tow my lawnmower, so I really do need to get this stupid thing running again...
My next option is to figure out a way to tow the lawnmower behind my motorcycle..

Why does such a simple engine need to be so freaking complicated ?

Thanks for any help in advance.

Free drink to the one that solves the problem.

Thanks
Chris

 

Check all the wiring for a bare spot or short. I also would check the switch and safety switches for shorts or if they are going bad (by pass them - reverse, N, brake switches, etc).
Sounds electrical to me but I am not an expert

 

Thanks I will check for bare spots in the wiring. I also ordered an inexpensive multimeter with a data hold capability that might be able to help me do the peak voltage tests.

I doubt any of the switches would be the problem since the ones you mentioned are either not in the ignition circuit,or would prevent the engine from turning over, but I will double check them anyway. Still given that it does backfire and have spark.. still leads me to suspect the CKP..

I'll try one more day to solve this myself then I'll probably end up taking it to the dealer..

Thanks

 

I would think if the crank position sensor went, it would display a trouble code.

I think they are similar to the Rincon, in that they have a sock type filter in the fuel pump sub-tank?

The other thing I would wonder about is the idle air controller. The IAC is a rectangular black piece on the throttle body, with a little metal piece around it, secured with two of the tamper resistant torx screws.

They have been known to gum up on Rincons, and the cure is generally to remove and spray with carb cleaner.

If you remove it, you should be able to see it run through its travel when you turn the key on.

 

I will give that a check tonight. There are no trouble lights and they all light momentarily as they should when I first turn on ignition, so I don't have a blown bulb. I did more testing yesterday with the multimeter I got with hold capability. I did the test for 90 volts on the coil and did not see it. The manual says that I either have an insufficient multimeter or the ckp sensor is bad.. Well I have spark, so I am suspecting the multimeter for this test. The IAV makes sense given the symptoms.. like it is not getting enough air and just backfiring.. I will take that apart and check it tonight. I hope it turns out to be that simple.

Thanks

 

I had a simialr problem on a 4 wheeler I used to have. Backfire, no start. I did almost everything you did except replace the spark plug. I checked and had spark so I didn't replace it. Then I learned that just because a plug sparks out in the open when you ground it, doesn't mean it will jump the gap under compression. I put a brand new plug in and she purred. So, try another new plug.

 

I agree with budedm, change the spark plug first. A friend has a 2009 420 rancher that would die like you had turned the key off but would start right back. His problem was a loose connection back near the battery. It was on a white connector that powered almost everything. Just a thought.