|
|
Chris,
The new settings on the EM2 fuel pressure calibration require the SW sensor and the EM2 update.
Your EM2 FP reading sounds like the sensor is either not connected or the sensor is not grounded (not making connection to block). To test this guess, With power OFF, measure the resistance to engine ground at the sensor output. It should be about 10 ohms. If this is correct, disconnect the sensor from the EC2 (at the sensor) and see if you get the same reading. If so, the connection is probably broken somewhere.
Tracy
On Tue, Dec 28, 2010 at 5:04 PM, Chris Barber <cbarber@texasattorney.net> wrote:
Tracy/Group,
I hate to be the village idiot (somebody's got to do it and Obama is in Washington.....bad Chris...not a political forum....bad bad BAAAAD), but, would I still be able to use the SW sensor with the mods you
mention if I have NOT been updated recently? Well, at least not in the last two months.
I have had fuel readings around 126 psi on the EM2 even though the gauge on the fuel pressure regulator read just a hair under 40psi.
I have been meaning to buy a new VDO pressure sender but hesitated until I verified the wires...which I have now done. Should I use the VDO....or transition to the SW? Is the update needed or does it just adjust the settings
as you described in your post?
Now, on to the EGT reading problem and a desired solution and a few wire run tweaks and I may be ready to call a DAR.....uh, or not ;-)
Chris
Hello Brian,
Here is an excerpt from the updated EM2 installation guide. Note that this assumes that your EM2 has been updated since this change was developed (last 2 months or so).
FUEL PRESSURE SENSOR
The EM2 was originally designed around VDO pressure sensors and the fuel pressure sensor was to be the same type as used for the Oil Pressure sensor.
VDO at some point changed the design of these sensor and they are no longer
safe to use with Fuel (they begin leaking from the terminal end).
The closest substitute is a Stewart Warner
114875. These are available from Summit Racing as PN
SWW-114875. To make it fully compatible with the EM2 you must wire a 562 ohm resistor from the sensor output terminal to ground.
This can be added near the sensor or near the EM2, which ever is most convenient.
You must also set the Channel 13(mixture) Low limit value to 1 instead of 0.
The calibration values for the Fuel pressure channel (12) should then be set to the following values:
Scale factor – 6.922 , LOW END OFFSET – 0, SENSOR OFFSET ~ 963 , LOW ALARM LIMIT - ~28 , HIGH ALARM LIMIT -~55.
Tracy
On Tue, Dec 28, 2010 at 12:10 AM, <bktrub@aol.com> wrote:
Tracy,
did you ever find a suitable replacement fuel pressure sender? What are you using now?
Thanks,
Brian Trubee
Sent: Mon, Dec 27, 2010 4:30 pm
Subject: [FlyRotary] Re: Fuel rail pressure
Just for another data point:
I installed the fuel pressure regulator prior to the fuel rails in my 20B installation so there is no fuel flow to flush vapor from the rails on hot startups. This arrangement is now used on most new cars. Even with this arrangement I have had no trouble
with vapor lock. Even if it should happen, the EC2/3 primer function would be able to vent the vapor from the rails.
This setup allows the use of a Floscan type fuel flow sensor with the EM2/3 since there is no return flow from the fuel rails. No big advantage other than being much easier to calibrate.
Tracy
On Mon, Dec 27, 2010 at 6:53 PM, <bktrub@aol.com> wrote:
It seems to me that the fuel would have to be pretty hot for the vapor pressure to exceed 40 psi and cause vapor lock. Running the fuel pump in such a case would cause coller fuel to flow through the rail and back to the tank.
Brian Trubee
-----Original Message-----
From: Al Gietzen < ALVentures@cox.net>
To: Rotary motors in aircraft < flyrotary@lancaironline.net>
Sent: Mon, Dec 27, 2010 3:49 pm
Subject: [FlyRotary] Fuel rail pressure
Also remember that when you are starting the engine you are starting it under a load. This is different then in a car config where in a car you are starting it with no load attached to the
crankshaft. If the fuel rails are getting so hot that they are vaporizing I would think this would cause an excess pressure in the fuel system and be very dangerous. This is not a problem I have ever had in a car. What is causing this besides poor ventilation?
The pressure in the fuel rail can never exceed the setting of the pressure regulator; which should
bear about 40 psi engine off. That’s true even if you call the e-shaft a crankshaftJ.
Al
|
|