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Jeremey

09 420 fm issues

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Been a while since I posted on here but seems to be a lot more knowledge on here versus most of the Facebook pages. Here's my issue

 

Just rebuilt my buddies 09 420 4x4 fm with power steering. Motor is solid, timed correctly, valves clearance is correct, my issue is when you hook the plug wire up to the plug is basically stalls the motor out and will only crank over a few times and stall out. Thinking the ecm might be shot because I've checked all the sensors, ohmd out the harness and checked stator and regulator. The only other thing I'm not sure about is they deleted the power steering module 🤦‍♂️why i do not know but that shouldn't cause whats going on should it?  Thanks for any input on the subject it would be appreciated.

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I don't think the power steering has anything to do with it.

 

So as I understand it, the motor will turn over fine with the plug screwed in, wire off, but if you put the spark plug wire on the plug it bogs down the motor turning over?  Is that right?

 

 

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Jeep,  that is correct.  Has backfired once or twice in the last 3 hours of messing with it.  Motor makes 3 or 4 revolutions then stalls and turns over the same amount of times and stalls.

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So an update, I just covered the intake boot inside the air box with my hand and it quit stalling and will turn over constantly until you turn it off. Then begins to stall again🤦now I really need someone else's 2 cents 🤣🤣🤣

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That's a new one for me.  I can understand it spinning over with the plug out, but just putting the plug wire on the plug shouldn't increase the drag on the motor.  That doesn't make any sense at all.

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Jeep, have narrowed another of it down just stuck with limited input on it now. It wasn't just the plug stalling it. If you leave plug hooked up but unhook the fuel pump or injector(stop sending fuel to intake) turns over fine no issues. Send fuel to intake though its like it vapor locks the motor for a sec and then back fires. Pulled the motor back apart just to triple check and everything checks out. Only thing that isn't correct is that it has 150 psi of compression versus the 73 the manual calls for.

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You sure it's timed right?  Any parts been swapped around?  If it's firing at the right time and there's fuel in there it should fire off!

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Yes sir have checked it several times as well as pulled the motor out last night and tore it apart and checked it again. Swapped heads out with a running bikes head and the fuel system just for ! and giggles. Have everything put back together but have a few neighbors that work nights so waiting till at least lunch to try it. 

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Are the leads swapped on the coil? There should be green wire to green colored connector.

i don’t know that it would make a huge diff 

Edited by Goober

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On 11/10/2020 at 3:30 PM, Jeremey said:

Been a while since I posted on here but seems to be a lot more knowledge on here versus most of the Facebook pages. Here's my issue

 

Just rebuilt my buddies 09 420 4x4 fm with power steering. Motor is solid, timed correctly, valves clearance is correct, my issue is when you hook the plug wire up to the plug is basically stalls the motor out and will only crank over a few times and stall out. Thinking the ecm might be shot because I've checked all the sensors, ohmd out the harness and checked stator and regulator. The only other thing I'm not sure about is they deleted the power steering module 🤦‍♂️why i do not know but that shouldn't cause whats going on should it?  Thanks for any input on the subject it would be appreciated.

i see this thread is old, so just gonna make it small and to the point. you say you rebuilt this motor, can you explain in full detail what all you did to the motor in the rebuild process ?. and the plug wire has nothing to do with it not cranking over, unless !!!, you are drawing down the battery some how from a shorted wire somewhere ?, other than this..no other reason to '' bug '' down the engine while cranking it over.

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