About 6 months ago my fuel pressure started reading low. Less than .5 lbs without the boost on. Boost brought the pressure to 5 psi. I replace the sender and got the same results. I added a mechanical gurage and found that the Dynon is reading about 1 lb low. Measueing the resistance across the sender (not hooked up) I read 11.9 ohms. How can I fix the 1 lb offset?
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an alternative browser.
You should upgrade or use an alternative browser.
Fuel Pressure
- Thread starter Larrybia
- Start date
- Joined
- Mar 23, 2005
- Messages
- 13,226
There's no way to calibrate beyond the build-in tables, but we're pretty confident that the EMS fuel pressure calibrations are fairly spot-on. 11.9 ohms is just a hair over over 0psi.
What sensor part number do you have installed, and what sensor type do you have selected in setup?
What sensor part number do you have installed, and what sensor type do you have selected in setup?
- Joined
- Mar 23, 2005
- Messages
- 13,226
Also, did you verify the calibration of the mechanical gauge? A fixed 1lb offset is more an indication of a mechanical gauge offset than an electronic gauge, since the scale of resistance vs. pressure is not linear.
As I stated about 6 months ago I started getting low fuel pressure readings on the Dynon. I replaced the sensor with one I bought from Dynon and still see the same basic results. I have an 0-320 on my RV-9A. The first measurement I provided to this forum was of the old guage and when I did the measurement again after blowing into the sensor and tapping it the 0 PSI resistance value was down to 9.8 ohms.
I just finsihed looking at the pressure sensor on the engine now. The new one. It has a "7.07" and "32/25" stamped into the monting fitting. The Dynon is set to "Type 1" for the sensor. Measuring the resistance versus my mechanical guage gives:
7.2 Ohm for 0 psi
9.5 Ohm for 2 psi
20 Ohm for 3.5 psi
28.8 Ohm for 4.5 psi
I am considering putting a 5 ohm resistor in series with the sensor to bing the 0 psi value to the proper point.
Have you seen this type of problem with the sensors?
I just finsihed looking at the pressure sensor on the engine now. The new one. It has a "7.07" and "32/25" stamped into the monting fitting. The Dynon is set to "Type 1" for the sensor. Measuring the resistance versus my mechanical guage gives:
7.2 Ohm for 0 psi
9.5 Ohm for 2 psi
20 Ohm for 3.5 psi
28.8 Ohm for 4.5 psi
I am considering putting a 5 ohm resistor in series with the sensor to bing the 0 psi value to the proper point.
Have you seen this type of problem with the sensors?
- Joined
- Mar 23, 2005
- Messages
- 13,226
Haven't seen too many problems with these sensors, except in cases where they're subject to excessive vibration (hence our reccomendation to not mount them directly to the engine).
But, if you had ordered the fuel injected fuel pressure sensor (who's output is the same resistance range as the carbureted sensor, but stretches from 0-80psi instead of 0-30psi), you'd end up seeing pressure readings that are order half as much as they should be.
Unfortunately, those stampings are not indicators of which sensor you actually have. Do you happen to have your receipt to confirm which one it is?
But, if you had ordered the fuel injected fuel pressure sensor (who's output is the same resistance range as the carbureted sensor, but stretches from 0-80psi instead of 0-30psi), you'd end up seeing pressure readings that are order half as much as they should be.
Unfortunately, those stampings are not indicators of which sensor you actually have. Do you happen to have your receipt to confirm which one it is?