M7 is dead

fordpickupman · Jan 11, 2017

I've been stumped for quite awhile on this. I pulled my M7 off my sled deck last winter and when I went to move it into the garage it died. I pulled it and the lights quivered a few times but it didn't fire. The more I pulled it the less they would light up until they did nothing.
I ohm checked the stator and it checks out and sends out voltage to the different areas it is supposed to.
I replaced the voltage regulator as it didn't ohm in spec.
No change.
It pumps fuel.
It has spark.
The lights and gauge don't light up.
I bought a harness, ecu, injectors, tps off a running sled and put them on this morning.
No change.
It will puff smoke out the Y pipe, but won't fire. No lights, no gauge.
What is wrong?
I'm at a total loss.
It has spark and fuel. Shouldn't it run?

Rixster · Jan 11, 2017

are you sure that your injectors are firing?

fordpickupman · Jan 11, 2017

Injectors firing

I assume they are.
With the plugs out it will blow some oily gas vapor out the holes.
The injectors are getting voltage.
How else can you check them?
I swapped them out too.

Does the ecu get power from the lighting coil? My lights don't work at all. Before what ever went bad, they would light up when I pulled it.

The fuel pump does pump fuel.

Sledbrain2 · Jan 11, 2017

You can run the or cycle the injectors with a 9 volt battery and some alligator clips,

I have a 06 m7 that just died over the summer a few years ago, Mine did not have lights, fuel or spark. I re-wound the stator and issue was solved. I would check the output of voltage from the stator for all the coils, You will need a repair manual to get the specs. R M has stators for 200.00, There is a timing pick up that can go bad. When that went bad my m7 would run just not very well,

89sandman · Jan 11, 2017

I'd do a compression test first, then squirt a little fuel through the spark plug holes and install new plugs, hold the throttle to the bars and give it a few pulls. Of course if it starts to fire let go of the throttle

If you still get nothing then it is time to check for pulse at the coils.

fordpickupman · Jan 11, 2017

I've ohm tested the stator. It tests ok
It has plenty of compression.
Fuel pump gets 15 volts and pumps fuel.
The spark plugs light up with a strong blue spark.

I will try firing the injectors with a battery. I assume you can hear them click.

I think it must be related to the lights not working. It seems to me that would be a stator thing, but it ohm'd within spec.

I've talked to Blaine Pertler several times over the last year about it, we pretty much ruled out the stator. Pertler rewinds Cat stators and knows his Cat electrical stuff pretty well.

bigjb · Jan 11, 2017

Does it have compression?

89sandman · Jan 11, 2017

If you have good compression and add fuel to the cylinders like I posted and have adequate spark it will fire or try to fire until it burns the fuel you put in the cylinders. If it starts or tries to start you then will know it is fuel related, if it doesn't then it's time to start testing the ignition system. Trouble shooting is the process of elimination, this is the easiest and quickest way to start that process

It will let you know if your problem is fuel or ignition related. I would want brand new plugs when beginning!

fordpickupman · Jan 11, 2017

I'll try the gas in the hole tomorrow morning.
It's got good spark.

swrev · Jan 12, 2017

Not sure if a 7 would be the same as an 8, but had a buddies M8 that would not fire primary injectors from a short in the tail light wiring. His was turbo'd so he was able to mess w/ his box and make it run off the secondary injectors until he could trace the problem. Ended up just unplugging wiring and was back to normal.

fordpickupman · Jan 12, 2017

Gas in the hole

So it fired and ran for 45 seconds or so after dumping some gas in the spark plug holes.
I assume one of the wires going to each injector is a ground. Is this correct? Or do I need to use a chassis ground to fire the injectors with a battery? When I hook up the volt-meter to the injector wires I get around 15 volts while yanking the rope.
Remember the fuel pump does pump fuel and it did always spew some gas out of the spark plug holes.

Interesting about the M8 having primary and secondary injection. Is that what the two leads are to each injector? I assumed one was a ground.

fordpickupman · Jan 12, 2017

Wiring

I got rid of the taillight wiring a few years ago.
I also removed the throttle safety switch as it was worn out and would fail me at the most wrong times. The thumb warmer is gone too. And I replaced the kill switch with a dirt bike spring loaded kill switch. And the high low headlight switch is gone too.

swrev · Jan 12, 2017

Secondary injectors were for the turbo. Not a stock setup. I have no ideas after taillight. Was just hoping that you might be running into a simple problem like his sled had.

89sandman · Jan 12, 2017

Now we wre getting somewhere! The computer grounds the injectors to make them fire hook a test light or voltmeter to one of the wires going to a injector and pull it over if using a test light it should go on and off if using a voltmeter the volts should flux up and down, if it does pulse you have a fuel delivery problem if it doesn't there is a problem in the computer circut.

fordpickupman · Jan 12, 2017

Injector voltage

15 volts at the injectors

Rixster · Jan 12, 2017

check your lighting coil, yellow and brown wires coming of the stator. or find the acc. plug up by your handle bars, same thing, yellow and brown. give the rope a few rips and see if you get 12 AC on that circuit. you may have cooked your computer. on the M series you cant just take lights off with out installing a resistor in line. the m series runs on 12 volts AC except for the fuel pump, its is 12 DC. since it is a AC system you have to use the electricity that is generated. if not it will start cooking expensive parts.

I guess if you swapped the ECU its probably ok but I have seen them get cooked in as little as 10 seconds of running with a bad ground.

fordpickupman · Jan 12, 2017

Ecu & lighting coil

So the ECU needs power from the lighting coil in order to run?
I bet that is the problem since none of the lights work.

I will check one of the accessory plugs for voltage.

fordpickupman · Jan 12, 2017

Lighting circuit

She's not making any voltage on the lighting circuit

89sandman · Jan 12, 2017

Keep trying

fordpickupman · Jan 12, 2017

Injectors

It varies from 14.9 to 15.5 as the crank is spinning.
It ramps up with the pull of the rope and drops off as the crank slows down

M7 is dead

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