07 Phazer would rev to 3000RPM, then cut out.

[vanderrules]

I ended up selling my 07 FX as the girlfriend didn't want to snowmobile anymore. This sled has never given me any issues. The gentleman I sold it to brought it back to me the next day with the following snag:

-Would rev to 2800 - 3200 RPM, then the engine would stumble and headlight/taillight would cut out when it stumbled. Engine would drop back down to idle and run fine, but kept hitting a wall between 2800-3200 RPM when accelerating. Problem got worse the warmer the sled got. Problem would not throw a code.

So I am sharing this as it was a real head scratcher.

-First changed the fuel out and plugs. Problem remained.
-Looked into TORS system, even bypassed it. Problem remained.
-TPS was checked and within spec. Problem remained.
-Next swapped out the fuel pump thinking lack of pressure. Problem remained.
-Next swapped coils thinking they were breaking down under heat. Problem remained.
-Next swapped injectors and fuel pressure regulator. Problem remained.
-Next swapped out the ECU. Problem remained.
-Next went diving into the wiring harness. Everything checked out fine and problem remained.

Keep in mind, this snag did not throw a code the entire time.

So now I am really scratching my head/drinking heavily at this point.

I pulled off the relay bracket and swapped out the reverse relays thinking the reverse system might be activating a governor of some sort. Problem remained.

With the relay bracket off, and me having a cold beer, I stared at the only RED upgraded solid state relay I put on the sled three years ago when i bought it. The RED relay I intentionally put on the EFI circuit as a preventative measure 3 years ago so it would never give me a problem. Bingo! My should never fail super expensive solid state relay was breaking down internally when warmed up and causing this gremlin. The regular electro/mechanical relay would have failed in the off position and I would have looked there first.

I swapped the RED relay with old faithful BLACK and the problem went away immediately.

 

[Mooseman]

That's good to know. That red electronic relay was developed specifically for the fuel pump, a purely electrical mechanical device. They might not like working with electronic systems or vice-versa.