580 EXT EFI Injectors Going Bonkers
HHEEELLLPPP, please for the love of god someone help. Long time reader and fixer, first time I haven't been able to find any solutions through other peoples pain. I have a 1995 580 EXT EFI that has been giving me more than a run for my money. Short of the long is the injectors are being held open and flooding the engine like crazy. There is 12.62 volts at both injector connectors, battery voltage is 12.82 even with the key and kill switch off. If i disconnect the injectors I can start the sled, plug them back in and ride all day, plugs come out the most delicious mocha tan color, runs perfect, idles great, reaches max RPM, gets decent fuel economy. Shut the sled down, come out the next morning and it's a bear to pull, flooded to the gills and generally takes four grown men 30 min. to get it going. Unplug the injectors, pull the plugs, leave it sit for a few days and it acts like nothing ever happened and laughs at me.
A few details and checks so far:
Battery: brand new, holds charge, even recharges during riding to proper voltage
Injectors: Pulled, cleaned, flowed, bench checked -work great
Stator: Resistance within serviceable limits (almost dead nuts actually)
ECU: No codes, injectors still have voltage with both connectors off
Compression: A cool 120 each cylinder with 2 different gauges (one of which is actually checked and calibrated every 6 months - how's that for legit?!
Drop resistor: each black to white gives 5.9~6.0 ohms, black to black is 12.0. With that disconnected the injector power is finally cut off
Injector and Ignition triggers checked good
TSS circuit bypassed or not makes no difference
Found one loose ground on the back of the ECU - no change.
I tried fiddling a little bit with the throttle position sensor without any luck.
Fuel pressure builds to about 36 PSI and holds when the injectors are unplugged, when they're plugged in it drops quick and fills the engine with fuel.
I couldn't find any obviously damaged wires or harnesses although I have not completely torn the sled down, I tried shooting wires to ground but unfortunately even with Arctic Cat's glorious shop service manual there just isn't a comprehensive wiring diagram for the EFI system which serves to annoy the ever loving christ out of me and I have no idea what should be grounded and what should not.
So I'm at wits end, this is my 10 year old son's first sled that Santa brought him this year (Santa doesn't deal dope so he ain't rich) and so far after getting towed out twice and watching his dear old dad's eye twitch and get his hand caught in the secondary clutch he isn't so impressed with owning a machine.
Sorry to write a novel but that's the way she goes.
Last edited by tadschude; 01-10-2017 at 06:03 PM.