Fuel Tank Pressure Sensor Solutions (And Fuel Level Sensor)?
Thread Starter
On The Tree
Joined: Apr 2010
Posts: 174
Likes: 0
Fuel Tank Pressure Sensor Solutions (And Fuel Level Sensor)? I need to run one of these to pass emissions and Im wondering how I can setup a working solution on my 94 Jeep YJ. How have those who need them, been setting this up? My YJ has a charcoal canister from the original setup.
Along those same lines, is the Fuel Level sensor part of the EVAP system?
Along those same lines, is the Fuel Level sensor part of the EVAP system?
Last edited by jeepnut24; Apr 11, 2010 at 10:04 PM.
I am interested in knowing this as well since I have to make it work as well.
Here is what I intend to do so far. For the fuel level, the ECU needs to see a tank at least 15% full to run the emissions check. I will use a resistor to fool the ECU into thinking the tank is 50 % full.
For the fuel tank pressure, I will integrate the actual pressure sensor somewhere onto the tank.
then run the usual 2 valves.
thats my plan so far.
Here is what I intend to do so far. For the fuel level, the ECU needs to see a tank at least 15% full to run the emissions check. I will use a resistor to fool the ECU into thinking the tank is 50 % full.
For the fuel tank pressure, I will integrate the actual pressure sensor somewhere onto the tank.
then run the usual 2 valves.
thats my plan so far.
TECH Regular
Joined: Sep 2007
Posts: 443
Likes: 3
From: Kansas City, MO
I am interested in knowing this as well since I have to make it work as well.
Here is what I intend to do so far. For the fuel level, the ECU needs to see a tank at least 15% full to run the emissions check. I will use a resistor to fool the ECU into thinking the tank is 50 % full.
For the fuel tank pressure, I will integrate the actual pressure sensor somewhere onto the tank.
then run the usual 2 valves.
thats my plan so far.
Here is what I intend to do so far. For the fuel level, the ECU needs to see a tank at least 15% full to run the emissions check. I will use a resistor to fool the ECU into thinking the tank is 50 % full.
For the fuel tank pressure, I will integrate the actual pressure sensor somewhere onto the tank.
then run the usual 2 valves.
thats my plan so far.
Thread Starter
On The Tree
Joined: Apr 2010
Posts: 174
Likes: 0
Any suggestions on the fuel level sensor? What resistor value do you plan to use? Im going to have to find that sensor as well. I found the pressure sensor part number for my app, but haven't found the level sensor?
Is there anyway to run the pressure sensor up under the hood? I have read at least one thread where they set it up this way.
Anyone else running these sensors? Pictures would be awesome.
Is there anyway to run the pressure sensor up under the hood? I have read at least one thread where they set it up this way.
Anyone else running these sensors? Pictures would be awesome.
i believe the stock Fbody fuel level sensor provide 270 ohms when full, 33 ohms when empty. I intend to use a resistor between 100 and 200 ohms.
here is some more info
GENERAL - The Evaporative Emission (EVAP) Control system used on all vehicles is the charcoal canister storage method. This method transfers fuel vapor from the fuel tank to an activated carbon (charcoal) storage device (canister) to hold the vapors when the vehicle is not operating.
When the engine is operating, the fuel vapor is purged from the carbon element by intake air flow and consumed in the normal combustion process.
MORE IN DEPTH - The EVAP purge solenoid valve allows manifold vacuum to purge the canister. The Powertrain Control Module (PCM) supplies a ground to energize the EVAP purge solenoid valve (purge on). The EVAP purge solenoid control is Pulse Width Modulated (PWM) or turned on and off several times a second .
The EVAP canister purge PWM duty cycle varies according to the operating conditions determined by the mass air flow, the fuel trim, the engine coolant temperature, and the intake air temperature. For certain EVAP tests, the diagnostic will be disabled if the TP angle increases to above 75 percent . The evaporative leak detection diagnostic strategy is based on applying vacuum to the EVAP system and monitoring for vacuum decay.
The fuel level sensor input to the PCM is used to determine if the fuel level in the tank is correct to run the EVAP diagnostic tests. To ensure sufficient volume in the tank to begin the various diagnostic tests, the fuel level must be between 15 and 85 percent .
The PCM monitors the fuel tank pressure/vacuum level via the fuel tank pressure sensor input.
here is some more info
GENERAL - The Evaporative Emission (EVAP) Control system used on all vehicles is the charcoal canister storage method. This method transfers fuel vapor from the fuel tank to an activated carbon (charcoal) storage device (canister) to hold the vapors when the vehicle is not operating.
When the engine is operating, the fuel vapor is purged from the carbon element by intake air flow and consumed in the normal combustion process.
MORE IN DEPTH - The EVAP purge solenoid valve allows manifold vacuum to purge the canister. The Powertrain Control Module (PCM) supplies a ground to energize the EVAP purge solenoid valve (purge on). The EVAP purge solenoid control is Pulse Width Modulated (PWM) or turned on and off several times a second .
The EVAP canister purge PWM duty cycle varies according to the operating conditions determined by the mass air flow, the fuel trim, the engine coolant temperature, and the intake air temperature. For certain EVAP tests, the diagnostic will be disabled if the TP angle increases to above 75 percent . The evaporative leak detection diagnostic strategy is based on applying vacuum to the EVAP system and monitoring for vacuum decay.
The fuel level sensor input to the PCM is used to determine if the fuel level in the tank is correct to run the EVAP diagnostic tests. To ensure sufficient volume in the tank to begin the various diagnostic tests, the fuel level must be between 15 and 85 percent .
The PCM monitors the fuel tank pressure/vacuum level via the fuel tank pressure sensor input.
Trending Topics
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine
Verdad Gallardo
7 Most Reliable High-Performance Engines GM Has Ever Built
Verdad Gallardo
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin
Verdad Gallardo
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
You could mount the gauge sender to your orignial unit and have it feed into the pcm and keep the stock one there to run your gauge.
Are you going to add the charcoal canister also? Because I know other car lines monitor the O2 sensor to verify the increase of HC in the exhaust (mixture will go slightly rich when the extra fuel is allowed into the intake)
Mark
Mark
Can you just install the pressure sensor into the evap line using a tee fitting rather than having to modify the tank or tank's fuel level sender? It'll still read the tank pressure just less modfication required.
On The Tree
Joined: Jan 2010
Posts: 181
Likes: 3
I am running a LM7 in a 79 truck. I had to run a 87 blazer tank for the efi which has 4 ports on the sending unit. I used three to the motor and for the fourth on i clamped a piece of rubber hose on it and then clamped the FTPS on the other end of that. So far no issues although i am currently diagnosing an idle problem so i havent looked to far into how well it worked. Here in cali i was going to just run some dummy wires from it for inspection and tune it out but i think that i might just leave it hooked up. I know a guy who is running with it just mocked up and tuned out and he passed smog just fine.
Thread Starter
On The Tree
Joined: Apr 2010
Posts: 174
Likes: 0
My stock level sensor is 1ohm empty and 88ohms full.
DTC P0461
This diagnostic tests for a stuck fuel level sensor signal. The PCM sets this DTC if the fuel level sensor signal appears to be stuck based on a lack of signal variation expected during normal operation.
Conditions for Running the DTC: Ignition is ON
Conditions for Setting the DTC: The PCM does not detect a change in fuel level of at least .79 gal over a distance of 200 miles.
Action Taken When the DTC Sets: 1. Fuel gage defaults to empty. 2. Low fuel indicator illuminates. 3. PCM records freeze frame data.
Not sure that PCM will continue testing eVAP system if this sets. I had this issue with a customer who was trying to do a emissions legal swap in CA. He had used a resistor on the fuel level circuit.
This diagnostic tests for a stuck fuel level sensor signal. The PCM sets this DTC if the fuel level sensor signal appears to be stuck based on a lack of signal variation expected during normal operation.
Conditions for Running the DTC: Ignition is ON
Conditions for Setting the DTC: The PCM does not detect a change in fuel level of at least .79 gal over a distance of 200 miles.
Action Taken When the DTC Sets: 1. Fuel gage defaults to empty. 2. Low fuel indicator illuminates. 3. PCM records freeze frame data.
Not sure that PCM will continue testing eVAP system if this sets. I had this issue with a customer who was trying to do a emissions legal swap in CA. He had used a resistor on the fuel level circuit.
Thread Starter
On The Tree
Joined: Apr 2010
Posts: 174
Likes: 0
Wow, thats a lot of good information. I think Im going to have to use a resistor in my fuel level system as well. The stock level sender is almost exactly 1/3 the ohms of the GM system.
DTC P0461
This diagnostic tests for a stuck fuel level sensor signal. The PCM sets this DTC if the fuel level sensor signal appears to be stuck based on a lack of signal variation expected during normal operation.
Conditions for Running the DTC: Ignition is ON
Conditions for Setting the DTC: The PCM does not detect a change in fuel level of at least .79 gal over a distance of 200 miles.
Action Taken When the DTC Sets: 1. Fuel gage defaults to empty. 2. Low fuel indicator illuminates. 3. PCM records freeze frame data.
Not sure that PCM will continue testing eVAP system if this sets. I had this issue with a customer who was trying to do a emissions legal swap in CA. He had used a resistor on the fuel level circuit.
This diagnostic tests for a stuck fuel level sensor signal. The PCM sets this DTC if the fuel level sensor signal appears to be stuck based on a lack of signal variation expected during normal operation.
Conditions for Running the DTC: Ignition is ON
Conditions for Setting the DTC: The PCM does not detect a change in fuel level of at least .79 gal over a distance of 200 miles.
Action Taken When the DTC Sets: 1. Fuel gage defaults to empty. 2. Low fuel indicator illuminates. 3. PCM records freeze frame data.
Not sure that PCM will continue testing eVAP system if this sets. I had this issue with a customer who was trying to do a emissions legal swap in CA. He had used a resistor on the fuel level circuit.
Teching In
Joined: Nov 2007
Posts: 18
Likes: 0
You could go about this a couple different ways. I haven't personally done this, didn't need to maintain emissions when I did my swap.
#1 - The stock fuel pump in you YJ doesn't supply enough PSI for a LSx motor, so you'll need a new fuel pump no matter what. I changed my tank out so I could stretch my wheelbase, my original sender wasn't working, and when ordering the tank had a choice of fuel sender rings. I personally chose one from a '05+ TJ Wrangler as it supplies the right PSI and maintained the Jeep PCM resistance. In '05 they bumped up the PSI.
#2 - I assume you want to run your factory gauge cluster, therefore your going to need to run and supply both with the correct resistance, the Jeep PCM (0-90ohms) and the GM PCM (33-270ohms).
Mechanical Solution: Modify the tank to run both sending units, use the pump from the GM. (Painful IMO)
Electrical Solution: Run YJ sending unit (that way you don't have to modify the tank). Change the pump on the sending unit to any one of the aftermarket in-tank fuel pumps that push 60 PSI, (seriously not difficult). This will get the right signals to your Jeep PCM and the right fuel pressure. Only one last peice of the puzzle, scaling the resistance of the YJ sender to what the GM PCM is expecting. Using a "voltage controlled resistor" or "resistance multiplier" in a simple circuit you can apply the multiplier scale.
Hope this helps...
#1 - The stock fuel pump in you YJ doesn't supply enough PSI for a LSx motor, so you'll need a new fuel pump no matter what. I changed my tank out so I could stretch my wheelbase, my original sender wasn't working, and when ordering the tank had a choice of fuel sender rings. I personally chose one from a '05+ TJ Wrangler as it supplies the right PSI and maintained the Jeep PCM resistance. In '05 they bumped up the PSI.
#2 - I assume you want to run your factory gauge cluster, therefore your going to need to run and supply both with the correct resistance, the Jeep PCM (0-90ohms) and the GM PCM (33-270ohms).
Mechanical Solution: Modify the tank to run both sending units, use the pump from the GM. (Painful IMO)
Electrical Solution: Run YJ sending unit (that way you don't have to modify the tank). Change the pump on the sending unit to any one of the aftermarket in-tank fuel pumps that push 60 PSI, (seriously not difficult). This will get the right signals to your Jeep PCM and the right fuel pressure. Only one last peice of the puzzle, scaling the resistance of the YJ sender to what the GM PCM is expecting. Using a "voltage controlled resistor" or "resistance multiplier" in a simple circuit you can apply the multiplier scale.
Hope this helps...
Thread Starter
On The Tree
Joined: Apr 2010
Posts: 174
Likes: 0
You could go about this a couple different ways. I haven't personally done this, didn't need to maintain emissions when I did my swap.
#1 - The stock fuel pump in you YJ doesn't supply enough PSI for a LSx motor, so you'll need a new fuel pump no matter what. I changed my tank out so I could stretch my wheelbase, my original sender wasn't working, and when ordering the tank had a choice of fuel sender rings. I personally chose one from a '05+ TJ Wrangler as it supplies the right PSI and maintained the Jeep PCM resistance. In '05 they bumped up the PSI.
#2 - I assume you want to run your factory gauge cluster, therefore your going to need to run and supply both with the correct resistance, the Jeep PCM (0-90ohms) and the GM PCM (33-270ohms).
Mechanical Solution: Modify the tank to run both sending units, use the pump from the GM. (Painful IMO)
Electrical Solution: Run YJ sending unit (that way you don't have to modify the tank). Change the pump on the sending unit to any one of the aftermarket in-tank fuel pumps that push 60 PSI, (seriously not difficult). This will get the right signals to your Jeep PCM and the right fuel pressure. Only one last peice of the puzzle, scaling the resistance of the YJ sender to what the GM PCM is expecting. Using a "voltage controlled resistor" or "resistance multiplier" in a simple circuit you can apply the multiplier scale.
Hope this helps...
#1 - The stock fuel pump in you YJ doesn't supply enough PSI for a LSx motor, so you'll need a new fuel pump no matter what. I changed my tank out so I could stretch my wheelbase, my original sender wasn't working, and when ordering the tank had a choice of fuel sender rings. I personally chose one from a '05+ TJ Wrangler as it supplies the right PSI and maintained the Jeep PCM resistance. In '05 they bumped up the PSI.
#2 - I assume you want to run your factory gauge cluster, therefore your going to need to run and supply both with the correct resistance, the Jeep PCM (0-90ohms) and the GM PCM (33-270ohms).
Mechanical Solution: Modify the tank to run both sending units, use the pump from the GM. (Painful IMO)
Electrical Solution: Run YJ sending unit (that way you don't have to modify the tank). Change the pump on the sending unit to any one of the aftermarket in-tank fuel pumps that push 60 PSI, (seriously not difficult). This will get the right signals to your Jeep PCM and the right fuel pressure. Only one last peice of the puzzle, scaling the resistance of the YJ sender to what the GM PCM is expecting. Using a "voltage controlled resistor" or "resistance multiplier" in a simple circuit you can apply the multiplier scale.
Hope this helps...
Thanks, that does help. I hadn't planned on changing the internal pump, but that may be a better option in the long run.
Im also looking at the possibility of swapping out the gauges for aftermarket.
You should be more concerned with the volume that the pump can put out than the pressure. Most pumps are capable of 2X the PSI that it runs at. Doesn't matter how much PSI you have if it can't supply the volume.