Hi Guys, I just got a Ram 750f from a guy on Ebay. I have a few questions from the Ram experts here.

The Egt probe registers 0 WITH the glo plug connector hooked up, as soon as the rubber plug boot is removed from the glo plug the EGT works like it should. Basically if I remove the EGT probe from the engine it {EGT probe}works, when it touches the engine case with the plug ignition on it reads zero. ???

Second I am only getting 715 or so millibars at max throttle. The engine is in great shape with only 18 cycles, so maybe the owner had the ECU turned down to 10# or so?

Other than that I love it. This is my second engine, the first being the GWM fd/3. Both neat engines.

Oh yeah, also The engine was setup with an oil tank, but the instructions say nothing about this tank. So I filled the oil tank and mixed the right ratio of oil in the fuel as well. ???

Thanks for the help.

It is shorted out replace the EGT

Thankd WD, thats what I figured but wanted to hear it before I start buying new parts.

I had the same thing happen to one of my RAM'S I would like to find a good old Ram 750f now.

Yeah, the 750F is where it's at. Overbuilt and simple to operate. I love the air start too, you cant replace that sound with a speed 300!!!
After all I'm not out there for something that is easy to do. The auditory of listening to an air start turbo is what it's all about for me.

But the CP output thing is what I need to know now. 715 or so millibars at max is what I get now...

WD40 is right about the Temp Probe! I had the same problem from mine when I bought it used. If you bend the end of the probe at a sharp angle where it goes into the exhuast it will short. The max CP should be around 1200mb or so. The only way that this could have been turned down is by the factory. How are the bearings? If they are binding then it could cause this problem. If in doubt call Carlos at RTI and ask him. I love my Ram 750F! I was able to get my first flights on it last weekend thanks to WD40 and also to the people at the Maury county airport ( Site of the Tennessee Jet meet!) What a great place to fly! ( June 11 -13 this year).



Good Luck!

Gene

Hi Gene when do you want to fly that reaper again you did a great job on her makes me want to build a new one.

The max CP, stock, on all 750s and 750Fs (that I am aware of) should have been 1300 mb. With later version ECUs (and you might also need the later start box to set this), the CP was settable to values lower than 1300, in increments of 100. There is always a possibility to have a bast_rdized one that was set at the higher 1400 mb power level (I ran one that way for a season, good power but shorter bearing life). Never heard of anyone running one higher for any time period.

If I remember correctly, the serial number of the 750Fs had an !QUOT!F!QUOT! in it. If it does, that means that it has the !QUOT!fuel in the oil!QUOT! mod and you do not require the additional oil tank. Might be best to double check with Carlos before running without a separate oil tank.

As for the low CP, my first guess would be a weak pump (or some sort of fuel restriction that is causing the output of fuel to the engine to be low), then weak battery. If you want this ironed out with little hassle, send it to Carlos at RTI. If you like to tinker, try swapping pumps or check to be sure the NiCads are up to snuff.

Do not send the ECU to Carlos. He does engines, not ECUs. Andy Low at Electrodynamics designed this ECU, and the start box. He will repair it for you at a reasonable price. He just recently repaired my start box and the cost was reasonable.

Good point Brian. Andy (Electrodynamics) was the designer and manufacturer of the ECUs, so no one is more qualified. I just assumed that Carlos had replacement ECUs and if the whole engine has to go to him anyway, it might save some hassle.

RPMTECH your max power is low. Change your pump to the newer style pump and setup your max cp to 1200mb the newer pump will give you max power thats if your not running a six burner or vs the 12 burner. If you want to remover the oil tank use a Y festo connector between the fuel and the oil line. And change the ECU. And as time goes on in stall a starting motor RPM sensor and a AUTO START ecu .

Max power stock was 1300 mb, NOT 1200. DO NOT under any circumstances attempt to simply merge th oil into the fuel line on a pre-"F" 750. The "F" oil in the fuel mod is more than simply the re-done plumbing on the outside. In the old pre-"F" engines, the oil line goes straight to the bearings. With the "F" mod, a small amount of the fuel goes through an orifice to the bearings. If you do not have the internal portions of the "F" mod, and you tee off of the fuel line to the bearings, you WILL FRY THEM!

PS. You DO NOT need a "new style pump". If your pump is not pumping up to snuff, all you need is a pump that works, be it old, new, or pink with purple poka-dots.

Woketman you have some understanding about the engine and we never see eye to eye on some of these topic. I did all what i post to some of the RAM and Sophia turbines with no problem. I will post picture of the mod so you can understand what i'm talking about. The same pipe setup use to lube the bearing on RAM 750 f is the same on the autostart engines. The older engines may have two pipe line for top and bottom bearing but still works. or call the pro ( RTI)

Last year I had to remove my 750 from my exocet, previously to removing it I was getting 1285mb easily, after I put it back in (all I unhooked was the glow plug and the EGT from the engine only)
After I put it all back into the jet, on the next run up I only got 715mb. I did an ECU set again and everything was normal. 1285 consistently again. I don't know if unhooking any of that stuff changes anything, and I don't know why it would, but that was what happened on my 750f.

Jeremy Ferguson if the engine is running and sounds ok but not getting the full CP pressure or RPM. Its the pump remember thats how the ECU control the engine power.

Yeah, that I realize as well, but like I say, all I did was an ECU reset and it was fine, the pump has worked flawlessly since day one, all batteries were charged, it was just weird, it was fine before I took the engine out, and then after I put it back in I had to reset the ECU. maybe it was just one of those gremlins that seem to follow me around.

Sounds like some weird thingy happened to Jeremy's ECU and it forgot it's max CP set-point. If it happened to Jeremy, it could happen again. RPMTech, try it first. Reset all (set max CP back to 1300, if yours has a later model, settable ECU, and re-do the throttle calibration) and try it again. Be certain your batteries have a good charge and see if that does anything!

RPMTech, the problem is that the engine is not getting enough Jet A to make it to 1300 mb CP, as it should. The reason is what is in question. Either the ECU is not commanding enough voltage to the pump, or the battery is not capable of supplying it, or the pump is old and worn out and can not supply enough, or there is a fuel restriction that is preventing enough to get through, or so on and so on.

There is no bizarre bearing noise (bearings?) at max throttle and sustained external burning of fuel in the exhaust, is there?

Thanks guys, your the best.

Wocketman, Mechanically it is great, so I know that it is either one of the things you said. I will check the nicads too, could be in my haste that I dident have a good full charge on them.

If I was able to set the pressure on the ECU on this version I have how would I do it?

The guy I got this from flew it on a control line!!! Those wires must have been a mile long
So maybe he set it down.

I like the oil tank, so it stays but I dont have to mix oil in the fuel also right?

Control line!!!!! Wow With a jet ???. I love to see that. I think he tie the line to the transmitter. He must get real dizzy after two flight . Make my head spin thinking about it[sm=bananahead.gif]

rpm
my 750p autostart was doing the same thing the first
i tryed to start it euc battery was discharing at 450ma
cycled it with my alpha 4 battery went to 1300 works
great now
vinny

That is correct, if it is a pre "F" mod 750, then you DO NOT need to add oil in the fuel. But be certain that it is an "F" or not an "F"!