'05 900 RMK diag help request

Rider1958 · Mar 10, 2010

Been trying to find problem, but no luck so far, here asking for ideas....

Buddies sled was starting hard - would run for a second then quit, repeat.
Took it for a ride, at some point during the day it started losing power, would hardly pull itself by end of day.
Now if you finally get it started, it runs like it's in Limp Mode - bogging, backfiring.

Dealership replaced temp sending unit and spark plugs and fuel filter - no change.
Return trip to dealership - now they said pistons were scuffed.
Yet they did compression check - 125 and 130.

We took head, throttle body and reeds, exhaust off and looked at cyls and pistons - everything looks great - not scuffed.

Checked TPS action (with analog gauge) - fine.
Rotated TPS slightly in each direction - made starting worse - put back to original position (I had marked it).
Checked stator exciter coils - fine. (180 ohms each)
Checked fuel pump pressure - fine. (60 psi)
Looked extensively for wire / connector problems - none found.
Examined throttle body, reeds, exhaust valve components - fine.

Any ideas on what to look for next?

We are thinking reassemble and try it again, if no change take it to EXPERIENCED dealership and ask for Digital Wrench diag to help pinpoint.

Willing to do work required to repair, but having trouble finding problem....

BIGGDAWG · Mar 10, 2010

what is fuel pressure?

what is voltage when sled does run?

sounds like a fuel pump or injector issue

Rider1958 · Mar 10, 2010

Hi BigDawg! We too are in Iowa - Sioux City.

Fuel pressure at 60 psi - used a gauge and applied 12 volts to connector.

Do not know output voltage when running - do you mean voltage from charging coils?
I have only checked resistance on exciter coils.
I also looked at flywheel timing mark when MAG piston at TDC - right on the mark.

Also thought fuel, but pump seems to be working normally, and fuel filter was replaced.
Do not know how to check an injector, thought I read that if injector failing, a trouble code would show on MFD.
But if injector(s) clogged / plugged a bit I don't know how that would be indicated if at all on MFD.
Take injectors out and look at pintles for dirt / plugged?
Apply a voltage to injector (when removed) and see if actuating?

guidoxpress · Mar 10, 2010

have you set the TPS per the video?

have you replaced the TPS harness?

Rider1958 · Mar 10, 2010

I have not yet checked / set TPS, will obtain or build a tester and do that.
Nor have I replaced the harness - we examined it - looked fine, and harness had been secured with a zip-tie so wasn't moving.
But still could be bad, likely a good idea to order and replace harness, then check / adjust setting.

This is my buddies sled, my sled is the same exact model and the issue he is having seems strangely like the "Limp Mode" mine went into when I was very low on coolant once and it got hot.
Except that his does it when cold or hot.......

Super Dave3 · Mar 11, 2010

I have seen this issue a few times. You sound like you have covered most of the basics. Try removing the exhaust can and turn it upside down and look into the exit hole to see if a baffle has came loose and is plugging the exit.

Rider1958 · Mar 11, 2010

Thanks for the responses - I am going to try all of the suggestions made - we're pulling the engine and checking the injectors. We'll certainly check the can, I hadn't thought of that.
Ordering a TPS test tool and new pigtail too.

I keep hoping to just "stumble" onto the problem.....

silveradoforever · Mar 13, 2010

Sounds like the TPS harness to me, my sled was doing the same exact thing so i tried reseting the tps that worked for a minute until I hit a bump and it jarred the harness again. I ended up having a broken wire in the TPS harness, I repaced that and havn't had a problem since. :whoo:

GKR · Mar 13, 2010

Sounds like TPS issues to me. You're on the right track with replacing the harness and calibrating the TPS.
Keep in mind the TPS harness issue was a wire breaking inside the insulation so it was not visible or easily found. I believe this was from the zip-tie being too tight.

05900 · Mar 14, 2010

Also are fuel lines in tank in one peice/restricted
Spark in good condition coil/wires
Throttle switches okay?

MacDawg productions · Mar 14, 2010

I'd like to know what kind of voltage is being put out of the tps? Plug your tps setting tool into that.

Super Dave3 · Mar 16, 2010

So, what did you do to fix it?

Rider1958 · Mar 17, 2010

So far - problem has NOT been found.

The only thing out of place we've found so far is 3 wires from hood/speedo cluster cut/broken near front of hood - don't know how they were cut, but doubt they would make engine run poorly (tho I could be wrong).

We pulled the motor out to check or replace the injectors, and to replace the pistons/rings if needed.

I talked my buddy (it's his sled) into taking the motor to Dan at Indy Specialty to balance the primary and look at the pistons/cylinders.
We found nothing wrong so far but welcome an expert taking a look.

So waiting for buddy to take engine in, and for him to order the TPS harness and test tool, in addition to the o-rings and exhaust gaskets (and maybe injectors).

We had hoped that the ECU could be tested out of the sled, but was informed (by dealer) that it has to be in sled to use Digital Wrench program.

I'm taking seriously all of your suggestions, and will post the solution when we find it.

Thanks for all the responses, so far this forum has produced the only answers we've gotten to questions we've had.....

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'05 900 RMK diag help request

Rider1958

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