Fuel Pressure Sensor suggestions

[Cameron]

Hi,

I am unfortunately still chasing my tail on my EFI install and the piece of data I do not have is a reading for fuel pressure.  (the rv still randomly dies and I am not sure if it is fuel going away or something else - but I need to eliminate the fuel going away).

I have tried twice to install a FPS and both failed.  the first one was undoubtedly my fault.  I tried to run 12v power to a 5v sensor which obviously didnt work well.  the second time I bought a 5v step down and a similar sensor to the one I had before.  I started the RV, seemed like it was working correctly then the pressure eventually went to 0 and it never reported again.

both times I just bought a 30psi sensor off amazon that were really fairly reasonable in price (want to say under $20).

at this point, I would love someone to just suggest a combo of stepdown and sensor that should be a 'known good' and take my decision making out of the mix.

suggestions greatly appreciated.

Cameron

[Bruce Hislop]

I have an Auto meter fuel pressure sensor which I installed over 10 years ago.  I used the 5 volt source from the EBL ECM which also powers the MAP and TPS sensors.  I think it was a lot more than $20, more like $100 back then.

Bruce Hislop

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[Bill Van Vlack]

I bought one from Ebay, but this one from Amazon should work:  I bought this 5v supply, also from Amazon.

I bought a separate power supply because I wanted to add more analog points and didn't want to risk hosing the EBL ECM.

You should be able to test the FP sensor by piping it to a regulated air supply, connecting to your 5V supply, and measuring the output voltage.

Fuel Pressure Sensor Specifications:
Material: Stainless Steel
Voltage: 5V
Pressure: 30 psi
Thread Type: 1/8" NPT
Input: 0-30 psi
Output: 0.5V~4.5V linear voltage output. 0 psi outputs 0.5V, 15psi outputs 2.5V, 30 psi outputs 4.5V.
Accuracy: within 2% of reading (full scale).
Thread: 1/8"-27 NPT.
Wiring Connector: Water sealed quick disconnect. Mating connector is included.
Wiring: Red for +5V; Black for ground; Blue for signal output.

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[Cameron]

since those items look indistinguishably similar to the ones I purchased, I am going to try and rig up a test before buying again..

my sensor is just on a T in a straight section of the fuel line.  so, just a 3/8, 1/8, 3/8 brass fitting.  is there some other way I was supposed to mount the pressure sensor?

thanks!

Cameron

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[Bruce Hislop]

Mine is just "T'd" in on the high pressure side as well.

Bruce Hislop

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[Cameron]

hey Bruce, thanks.

when you say 'high pressure side', I assume you mean on the 'bottom leg' of the T?

fuel in------T------fuel out

             |

         FPS sensor

(hopefully my ascii art stayed formatted correctly)

Cameron

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[BruceHislop]

I was referring to the high pressure side of the throttle body (TB) (aka, the input side). The return side of the TB has very a low pressure and we don't really care what that pressure is.

Your diagram of the "T" is correct putting the fuel pressure sensor on the side of the T.

Bruce Hislop

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[James Hupy]

I would caution you, if you are going th make this installation permanent to NOT USE FLEXIBLE HOSE for your commections. I use armoured lines myself. Or, all metal fittings with Gates ethanol resistant lined hose barb fittings with clamps intended for fuel injection high pressure lines. Just what I do.
Jim Hupy
Salem, Oregon

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[BruceHislop]

Jim,
What do you suggest for flexible fuel line jumper hoses between the frame, body and engine (throttle body).

I'm currently using Gates barrier hose (some 30R9 and some 30R14).  I would like to use something more heat resistant where it gets closer to the exhaust and engine heat.

Bruce Hislop

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[Jon Roche]

I would like to see a photo.  

On my install the fuel ports on the tbi pointed downward toward intake.  Was going to be very difficult to use anything but flexible rubber fuel lines.     I have seen some use AN fittings but I am not a big fan of those because they are not easy obtained locally.  

I have metal fuel lines run up to the rear

Firewall.   But then I transition to rubber.  They are ethonal rated EFI rubber fuel line, and if I remember was kinda spendy.   

The good thing is it is all right in your face when ever I open the hatch any issue or deterioration I would see right away.  Hoses are also well away frome exhaust or heat. 

I spent lots of time trying to stay away from rubber lines on this…. But just could not solve the issue of those bends at the tbi and getting things to line up/remove.  

One other reason though for a gm based rochester.  Pressure is only 12psi.    But I guess if it does rupture there would be more flow since it is no longer regulated…

On Jun 18, 2024, at 9:59 AM, James Hupy <james...@gmail.com> wrote:



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[Bill Van Vlack]

I have a fuel pressure sender hard-piped to the Rochester TBI, then this flexible, ss-braided, PFTE kit from there back to the tee that combines pump outputs for each tank.

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[James Hupy]

Gates "BARRICADE" for fuel injection. It is rated for 60psi+. I use the high temperature teflon sleeve material slipped over the hose and secure it in place with metal ty-wraps on each end. I get mine from a friend who has a performance speed shop. Another is Aircraft Spruce in Florida.
Jim Hupy
Salem. Oregon. P.S. also good on speedometer cables near headers.

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[Cameron]

hey Bill,

how important is the amperage of the 12v to 5v stepdown?  the one you have linked above lists a 5 amp output;

DROK® Waterproof Voltage Regulator, 9-35V to 5V 5A DC to DC Buck Converter

but it is out of stock.  any others I am finding look to have a 3A output.

thanks!

Cameron

On Sat, Jun 15, 2024 at 6:34 PM Bill Van Vlack <bill.va...@gmail.com> wrote:

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[bc...@juno.com]

Hope this works, here is my sensor on a carb. EFI similar.
Bruce Roe

[Bill Van Vlack]

Cameron,

 A 3A, 5V power supply should be plenty for any/all sensors you'd ever connect to the EBL ADC inputs.

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[Cameron]

ok, doing some testing.

I have a 30psi sensor that ranges from .5 to 4.5 volts.

I took the sensor off the vehicle and hooked up to a 5v step down and the sensor and saw that it had the expected .5 v current with no pressure.  I then put back on the vehicle and turned on the ignition and still had the .5v.  I then started the engine and on the WUD the pressure went to ~2.1 psi.  I had left the wires exposed on the sensor and tested at the sensor and saw it had .668v.

so, I want to think the sensor is correct and the WUD is correct.  so, the remaining question is - can this thing really run on ~2psi??

thanks!

Cameron

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