RAM 750 Unstart?
 

I'd post this situation/query in the Turbine forum but there isn't a subforum for us remaining RAM users ...

I've got a resurrected 750F as an E-start courtesy of RTI (using Bob Price's latest ECU firmware). The turbine can be commanded just fine using the PMP and AIR buttons on the EDT. When starting (either RCVR or MANUAL) I get a nice soft ignition on gas with an uneventful ramp to RUNNING. EGT and Revs all indicate what you would expect for a nominally running turbine.

Here is where it goes to hell in a handbasket: When commanding the turbine off of idle to a higher power setting using MANUAL or RCVR mode it will instantly unstart with an error message of "RUN-RPM LOW". I know the ECU firmware will shut down the turbine if the detected RPM falls below 20K (but I'm still seeing an appropriate idle RPM of 38-40K being displayed the instant before it unstarts). I've spoken to both Carlos (RTI) and Bob Price about this. In fact, the whole package is with Bob Price and he can't replicate the problem.

The only thing I can think of is interference (from what?) into the RPM sensor leads to the ECU causing it to think the RPM is below 20K or nonexistent. The pump itself hoses out K-1 like I ustacould pee :) so I'm thinking the pump at least pumps but ... ? And I've taken care to ensure the RPM sensor lead is away from the lead going to the starter/glow ignite lead, etc. but is there something else I might be missing?

Thanks for any clues! :D

Mike

RE: RAM 750 Unstart?
 

Are you using a UAT?

I just recently had a RAM 500 that would go to high throttle but would flame out on the way down to idle and show the same RUN-RPM LOW error. It was found that the UAT bag was black from algae. Replacing that cured the problem.

RE: RAM 750 Unstart?
 

Yup, brand new - purged it using the 750's fuel pump commanded by the PMP feature.

Mike

RE: RAM 750 Unstart?
 

I had a simular problem make sure the rpm sensor wiring is not bundled up with the starter wires. They can cross talk and give false feedback reading to the ecu; mine would try and restart the engine all of the time until it ruined the starter. Carlos clued me in on this years ago

RE: RAM 750 Unstart?
 

Understand. Yep, I wracked my brain trying to come up with reasons and, reevaluating my installation, what you describe is most plausible. It would certainly underscore my first post. I know about keeping the RPM sensor wiring separate or isolated and I may have experienced a case of brain fade on this one and routed it too close. I'll get on it as soon as I get the turbine back from Bob Price and shut down the wild goose chase we've been on. :D Thanks for the reply and encouragement.