I'm trying to run a RAM 750 but I'm not getting CP reading on the Hand held unit ( electric start ), the glow plug is hot, the turbine is rotating, the propane is flowing, I'm getting the engine to start and run on the propane, the temp. reading is counting up but I'm not getting Case Pressure readings, with out it the pump will not start. I blew throug the lines to the ECU and I get CP readings and I blew to the engine and I can hear the air coming in to the engine so there is no restriction in the engine.

This engine run a few months ago just fine, so what the heck is going on here ( miss place the manual [&o] )

Thank you for any help that you may offer.

Sounds like fuel. Make sure the temp is over 200 deg or try priming to test your pump.

How do you make the pump to prime? and is the pump started after the Temp gets around 200 deg?

I have a full auto start 750p and through the data box you just press the button for prime and the pump runs as long as you hold down on the button on the data box and I stop when I see the fuel reach the engine case.
I had the same problem with my 750p but it was a fuel solenoid problem, would only run on propane.
The EGT has to reach 200c b4 the fuel is introduced on my setup.

I use Alberto from Modelbau when I have problems or need service.

I will get in contact with Alberto tomorrow. At the moment I got the engine to run on the propane but it is not getting to 180 or 200 deg. to get the fuel pump to run, it calls for over temp at aroun120 deg.

Casey was talking about a full auto start 750P (that has the Bob Price RPM controlled ECU). You (CARS II) have the older Andy Low Electrodynamic's pressure controlled ECU (hence your reference to CP), correct?

If so, it appears that the ECU is not sensing Compressor Pressure (CP) properly. You said that you blew into the line and the pressure sensor in the ECU detected it. Is there a possibility that you have the CP line hooked up to the wrong port on the engine? Perhaps that port is blocked internally on the engine. Have you tried blowing into the tube again (perhaps the pressure sensor is intermittent)?

Compressor Pressure (CP) will not read ontil ramping starts

Ahhhh! Its been years since I had a RAM. Unknown's revelation is very important indeed. Sounds like the ECU is not starting Fuel Ramp due to some issue. Perhaps it never thinks its hot enough to start. You say it says Over Temp at 120? Sounds like the logic is weird in the ECU. Is there a chance you could borrow another ECU from someone and try it?

I'm in the procces of investigating the how much it will take to covert it to full autostart, there is no need to deal with this if it is avialiable.

Thank you for the help.

Unknown is right, you will not see CP readings until you are into the ramp cycle. Two things to look at: 1) Are you feeding it enough propane to get the temp up quickly? I turn on the gas switch and open the propane bottle till the regulator just starts to make noise. 2) Make sure you've primed the pump. To prime the pump, turn on the RX and TX and move the throttle to cut. Press the red ignition button to run the pump. Be careful not to over prime, the pump moves the fuel pretty quick. Also make sure you have a check valve in the fuel line after the pump so you don't loose the prime. As far as auto start, it won't be worth the money, especially if you have an air start motor. After you buy the new ECU, solenoids, RPM pick up and electric starter you'd be better off selling the engine and buying a used version of a newer, autostart motor. Send me an e-mail at [email protected] and I'll forward you a copy of the manual.

OK lets Toss another "Casey" into this and really confuse everybody,


I helped Carlos this weekend:

First problem (no POP) was no power going to the plug, worked fine with a glow igniter.

The Cp will read on the display if you push the ignite button and blow into (pressurize the CP line) .

Carlos would make a great truppeter as he was able to push it up to read 242.

Problem 2: no CP pressure

It was able to run on the propane but failed to ramp onto the fuel pump,
CP remained at zero during the whole start cycle, It started 3 times on the propane,
(we did relube the bearings after each failed start as running extended duration's on propane toast bearings)

Suspect the somethings plugged the cp outlet on the engine as the ecu was reading the pressure with
the cp line pressurized manually. (bug parts in the engine?, Propane line switched with the CP line inside the cowl?)

Carlos is continuing the troubleshooting of the engine.

John-

As Carlos stated, this engine ran perfectly about 6-8 weeks ago when we were out flying the Roo at WDM. It was brought back from the field to my house where it's hung safely in the garage. Nothing's changed, none of the lines were pulled, etc. The only thing we could think of is that the battery may have lost charge, and the ECU may have lost its "learned" programming.... (dunno about that though.... old tech and all). Carlos said he "re-taught" the ECU and Tx, and that's when it started lighting the plug.

Mark

Hi Carlos,

Try pushing in the egt probe a little deeper in the nozzle. This should raise temp enough so ECU will start "fuel ramping" .
Those guys are right- you wont get CP readings at the low rpms you get with propane/electric motor only.

If I recall, ECU should see >180C before fuel ramp starts.

Jake

Jake

You are correct, I was hoping for you to reply this thread.

This is what I know, I'm getting the engine to fire up on the propane, but I'm running out of time on the glowing og the glow plug or it is over temp. I know now that I will not get CP untill I get it to run on the Kero and that the pump will not come on unless the temp. gets to 175c to 180c. so, I will fallow Jakes recomendation to push the EGT probe alittle into the nozzle.

I will give it another try tomorrow night.

I left out the "other things" we found wrong
as not to embarass a fellow pilot..... let us know what fixes it...

Carlos I had the same problem with mine years ago , I was so frustrated that I took the front cover off and to my surprize the fuel line was bent not alowing the fuel to flow properly to the engine I replaced the fuel line , put the cover on and the it started up perfect again. Just my 2 cents

I thought that I posted my last reply two days ago but it didn't work for some reason.

I run the engine and it run ok. I push the temp. sensor about 1/8" and now it was able to sence the real temp. It started just fine, now all I have to is to adjust the servo travel on the throttle.

At the same time I'm in the process of redoing the instal to get a better balance and to clean up the front, it should be ready to fly this Sunday.

Thank you to all who reply. Jake, you are the man.

I flew the Roo with the Ram 750 last weekend, this new/old tech engine runned just fine, more than enough for this airplane, now days I can start this engine faster the the full auto set ups, so there you have it, if you find one of this engines for a good price, buy it, why not?

Great news. Congratulations!

Thank you to all that helped.