Kelly W
Posts: 863
Joined: 1/21/2002
From: Delta,
BC, CANADA
Status: offline
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Hi Ragz, thanks for asking.
You're correct in that both engines come with the exact same setup, aside from a different model of pump and different software parameters.
1. Simplicity and Cost... I'll admit there is a potential for a hot-ish' start if someone forgets to close the ball valve while fuelling up, but typically this isn't a problem. I've only done it once and the flames were minimal. Pouring any residual out the back end should expel enough to avoid major damage to an internal setup. Performing a false start also helps to clear the motor. (false start = activating the start sequence without giving it butane / propane mix) Following that, you could initiate a proper start with the fuel valve close, burning of any excess that's still in the motor casing. I honestly don't hear many comments about it; none that I can recall in the last year for sure... I do make a habit of manually closing the ball valve as soon as the engine is shut down for that reason though, and I also teach the same habits in the ground schools I've done. As for shut down, the ECU simply cuts power to the pump with a stick-down and trim-down command.
2. Unlike some ECU's, the PST ECU is actually powered by the ECU pack and draws and extremely small amount of current from the RX pack. The 1st advantage of the fuse is when a customer makes up his own pack and accidentally reverses the polarity. Once plugged in and switched on, the fuse will blow and likely save the system from a great deal of damage. I've seen some ECU's saved by the fuse, and yet some are cooked just before the fuse blows. Its not a be-all end-all fix, but it does help. The other main reason is in the event of a short, the ECU will also likely be saved. Such shorts could be modified cables, a seized starter motor, seized pump, or a glow plug harness that's damaged and shorted directly to the plug base. Simply put, there's always a potential for something unforeseen to go wrong, which is why you have so many fuses in your car's fuse box. Putting a fuse in the ECU power cable is just common sense basically, and the additional cost incurred in the fuse and fuse holder is cheap insurance.
3. As stated in #2, the ECU is powered by the ECU pack, and not the RX pack. For this reason, we include a switch to allow the ECU to be shut down without disconnecting the ECU battery. If someone were to get creative (although this would void the warrantee) they could theoretically solder a +ve charge receptacle onto the other set of poles in the switch and splice a charge lead into the system... That's not an officially supported modification from PST, just something I've been meaning to try one of these days. I run Duralites, which already have their own charge post, but next time I run a system on a Ni-Cad or Ni-Mh pack, I'll try it. I don't know that there's much of an advantage to not drawing a current off the RX system to power the ECU, but with the current requirements of several digital servos every bit helps.
I hope that answers all your questions. 
Kelly
quote:
ORIGINAL: Ragz
I recently saw a PST 1300 engine. Very impressive performance indeed. I have a few questions about the engine though.
1. What is the advantage of NOT having a fuel solenoid valve like other engines?
2. What is the advantage of having a FUSE inline with the TEMS ECU?
3. What is the advantage of having a switch between ECU battery and ECU?
I believe even the PST 600R has a similar setup. I am considering getting either of these engines and would like to understand the advantages of the current setup.
< Message edited by Kelly W -- 12/23/2005 9:23:35 AM >
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Kelly Williams, GTBA #1969
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Few questions about PST engines - 
