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Discussion Starter · #1 ·
I posted a few weeks ago asking about pistons for my 580 EFI. Someone said stick with Suzuki parts and thats what I did. Anyways my sled is still doing the same thing it did before I burned a hole through the top of the piston. I'm sure its just a matter of time before I hole another piston. The sled leans out the PTO side cylinder under prolonged full throttle. Years ago when I was shopping for a 580 EFI I had a guy tell me that his sled was doing this. After spending a small fortune at the cat dealer rebuilding and resealing the entire motor, they finally replaced the ECU and the problem went away. I really don't think the sled is sucking air as it starts, runs, idles perfectly. From what I have seen engines that are sucking air have erratic idle. There is a lot of oil residue on the front of the motor below the exhaust manifold. I'm assuming this is leaking past the exhaust manifold gaskets? I see used ECU units on ebay for $100-$300 - they are $1700 cdn from the cat dealer. A person can also replace just the EPROM chip. Not sure if this will fix my problem though.
 

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I used to blow holes thru both pistons on my zr580 efi. I put on a D&D fuel pressure regulator with a gauge. At WOT the fuel pressure would drop from 36+ psi right down to zero and boom!!!!! @ more holes! Replaced the fuel pump for $300, put it in at the dealer's, started it up and ran great. Went to load it and the gauge went to zero. Took it all apart and found a small chunk of rubber in the fuel pump impeller. The fuel line was rotting out and running chunks thru the pump. Your best bet would be to get a gauge and tee it into the fuel line and watch your pressure. Might see your problem. I put a small fuel filter inline before the pump and never had another problem.
 

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so u started in the right direction: motor burned holes in pistons! is it the pistons fault that the motor is running lean?? u need to look in side the workings of the motor what does the piston wash look like? what about the spark plug? white or brown? where in the throttle did it lean out at? bottom , mid, wot?
if u can answer those ? for us, than its possiable we can help.
it took me adding an egt to my efi to get the answers that i was looking for . it told me that at 5400 rpms (holding throttle in that position)my motor went lean as the temp spiked about 400 deg.(i wont do that again)!!
but at 7200 rpm the motor went way fat i dropped 300 deg. thats how i learned what was happening to the motor as it was running. once i knew these things
this was on a 2003 800 mtn cat efi this sled now has a boondocker control box, adj.fuel regulator and i left the egt on it there is a fuel gage that i watch as i go thru the throttle making sure that the pressure does not drop, some of the things i use might be to much for the average rider it has kept my sled running for the past 4 years with out a problem. even after i installed the turbo. than all those things and info i had gathered made setting up the sled alot easier. and alot less of a headache.
in short; get all the info on your sled that u can it will only help
good luck
anthony
 

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Discussion Starter · #4 ·
Not sure you read my post as I explained all those things you asked. The sled runs lean on the PTO cylinder on WOT only. After a prolonged full throttle run the plug is white. It will run all day at part throttle. If you hold it wide open then it starts to bog out as cyl. temps climb. I assume this is the ECU trying to save the motor. I am going to spray starting fluid around the seal behind the clutch while it is running to see if there is a leak there. I don't think its a fuel pressure problem as then I would hole both pistons as Shelfrost explained. I think its either sucking air or a bad ECU. The ECU flashes once when the key is turned as its supposed to when things are normal.
 

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Could be a dirty injector that won't allow it to flow enough fuel. My guess would be that the ecu is fine. The ECU is typically an all or nothing deal. If is a Check your injector wiring too and see if it is grounding anywhere.
 

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Discussion Starter · #6 ·
I have a chance to pick up some spare parts for a good price. I can get the ECU and throttle body assembly with injectors from a 95 ZR 580 for cheap. My sled is a 96 EXT and has the yellow dot ECU and injectors just like this ZR. My ECU is a 604 and the ZR is a 603. Will these parts work in my sled? Thanks.
 

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The injectors and the whole throttle body assembly are the same part number for the 1995 ZR 580 as well as the 1996 EXT. It should work fine. $895 is what the assembly retails for new.
 
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