1)Your sensor is not at the right distance from the tach wheel

2)Tach wheel tape is no longer there

3)Tach reader is defective
It more than likely one of the above.

Scott Smith

What he said.

Classic failure to see the tach signal.  In addition to what he said, check the tether wiring.

Does it have smoke at idle?  If so tether orange or blue wire broke in tether or....  PCB pins have cracked solder joint.  G

smoke is wirking fine all sounds are working abd lights.  i swapped out the harnesses in both the engine and tender and it didnt improve.  even changed the tach strip just in case.  still no improvement.  any chance the sound file i copied from the other J could be causing the problem?

tjus may be a dangerous idea, but coukd i swsp the tenders from the Js to see if it affects things?  or coukd i damage the 611 by doimg thst?

If you're not sure of the internal configuration of the two engines, swapping tenders is a very bad idea!

@scott.smith posted:

1)Your sensor is not at the right distance from the tach wheel

2)Tach wheel tape is no longer there

3)Tach reader is defective
It more than likely one of the above.

Scott Smith

These possibilities or a damaged wire in the harness are what is causing your issue. Swapping boards or tenders won't solve the problem. If the tach sensor is the correct distance and the senor itself is fine start checking wiring.

Other than all of the above, it could also be a board failure, there are several components on the board set that can fail and cause the issue.  I suspect usually they fail because something gets shorted to the frame, but it's hard to say.

When you say "all sounds are working" does that mean you can hear the chuffing sounds when moving distinct from the idle sounds when stopped.  I realize at 60 sMPH you don't hear distinct chuffing...and at that speed it can be hard to even hear the engine sounds.  If you have a variable transformer you can lower the track voltage to 10V or so and the TIU should still work fine for the purposes of this experiment.  The idea is a lower track voltage will starve the engine so it can't zoom to 60 or whatever.  This would allow you to hear (or not) distinct chuffing...and perhaps even see if there are 4 chuffs per rev, if the chuffing sounds are uniform, and perhaps other observations that will help diagnose.  If you hear absolutely no chuffing sounds whatsoever and the engine sound while moving is still the idle engine sound, then the tach is not reporting any pulses at all; that would be a good clue.

Another thing to try since obviously you have taken the shell off the engine.  With power applied and the engine at idle, turn the flywheel by hand (wash hands first or wear gloves if touching tape/stripes!).  It's been a while but I'm fairly certain (someone will correct me if I'm wrong) that even at idle, if the tach reports motion the engine will chuff 4 times per revolution (or whatever it is programmed to).  It may take a few dozen turns of the flywheel and may seem like a tedious experiment, but the idea is to rotate the driver wheel at least one full revolution.  The engine will only move an inch or so down the track...

I got the 603 running again, paired with the 611!

I went through all of the suggestions one by one, and it turned out to the the Tach sensor was too close to the flywheel.  I think the wire harness was pressing on it when I put the shell back on.  As soon as I got it back to speck everything worked great!

I owe a big THANK YOU to thank all of you for your help with this engine.  OGR forum never lets me down!   

Glad to hear of a success story, and especially since it didn't cost anything to fix!

@stan2004 posted:

... but the idea is to rotate the driver wheel at least one full revolution.  The engine will only move an inch or so down the track...

Diameter is at least an inch, so I hope it moves at least three inches.