G'day Fellas,
I put in a set of ISSPRO Performax gauges maybe 8 to 10 years ago?
I had an issue with the Fuel Pressure a few years ago and I got another sender unit from Clay and it fixed the problem.
However the same issue popped up again a year or so later, so put in another sender and all good.
Now same issue with spades. That is the Boost is doing the same thing and that is erratic readings, fuel 80 to 100psi+ , Boost 25+ psi at idle or cruising speeds, both gauges going to stops and staying there etc.
The sender units are Fuel R89141 (2151C) and the Boost R8914 (7033A)
I believe the Fuel & Boost both read off a 0-100psi sender so the one sender unit should suit both?
I see the Clay has an ISSPRO Sensor on his site P/N: R89148. Is this an updated version of the R8914 sensors I have? or is it for some different ISSPRO gauges?

My ISSPRO Performax Master Controller (Electronic Signal Processor (ESP)) is P/N: *9607396 S/N: B278.
I cannot find a ISSPRO supplier/agent here in Australia so have to rely on you fellas for solutions.
Cheers & Beers
Reg

 

Clay at Riffraff should be able to help uyo out with this.
I would also try contacting isspro directly.
Sorry I can't be much more help. Here's a bump for you anyway.

 

The senders are both 0-100 PSI at 0-5 volts. I would lower your fuel pressure considerably, I used 55-60 PSI to run my 400 HP mods, and that was plenty. The fuel pressure cannot raise the power at all, but it can lower it if your pressure falls below 45 PSI. The Injector Control Pressure is what makes your REAL fuel pressure when the right foot falls.

If you lower the pressure, and do what you can to keep the sensor from too much heat, your fuel pressure sensors should last much longer. I have known people that put the fuel pressure sensor directly on the head, and the sensor doesn't like that.

As for the boost gauge, make sure you have good electrical connections before buying another sensor. It's easy to fall into the trap of "My fuel sensor has failed before, so that MUST be what's wrong with my boost gauge".

 

G'day Tugly,
I have checked connections and voltages as per ISSPRO instructions and all seems good.
I have Clays FPx and use the 55psi spring and when the sensor or gauge is behaving that is the pressure it reads.
I have disconnected both the fuel and boost when powered up with engine running and when re-connected whilst powered up, they will run fine during that trip.
Fuel pressure in the low to mid 50s and boost doing its thing 0-25psi. Shut down and possibly next start all is good and then they go all over the shop??
I'll do another ISSPRO trouble shoot and see if the is not some intermittent issue.
Clay is on to it for me (what a Guy ). I haven't found an ISSPRO outlet or agent here in Aussie so dealing with them direct is difficult.

Cheers and Beers,
Reg

 

Ah... I misunderstood what your actual fuel pressure was. Sorry. That sounds like a "brain" problem in the Performax, or a bad ground somewhere.

 

G'day Tugly,
Well I've finally had a chance to do a more comprehensive check of the ISSPRO Gauges/Sensors/ESP.
Removed Ground wire (Brown) and put a new connector on and added a jump wire to the battery negative for added grounding.
Turning the ignition on and the gauge needles do not move to the pointer stops and settle to sensor readings?
If this function doesn't show the next step was to check voltage between the Black and Orange wires on the gauge connections.
Voltage checks with ignition on:
Fuel and Boost gauges at the gauge pins: Voltage between Black and Orange = 6.38V and between Blk & White = 4.4V
(I had on one occasion a 7.0V reading between Blk & Or but the reading slipped down to the 6.38V)
Voltage at sensor connection for Fuel and Boost between Blk & Red = 7.03V and between Blk & Green = 0.0V

Next step was to disconnect the Grey Connector from the ESP and with ignition on check the following:
Reading between Brown (Ground) and Pink = 12.03V and between Br & Red = 12.03V.
(read 11.2V in initial key on due to glow plug relay draw I suspect).


Next step: Disconnect Green wires for Fuel & Boost from the Grey connector.
Reconnect to the ESP and power up and take following readings:
Fuel between Green and Ground = 3.48V then dropped to 0.87V. I guess the initial reading is the pressure it sensors as fuel pump builds pressure.
However a reading of 3.48V is indicating 75PSI and has to be false as I do not have a high pressure spring in the FPx.
Boost between Green & Ground showed 0.87V. Also has to be a false reading as that voltage indicates around 10psi boost.

This is what happens on start up with Fuel pressure indicating 75/80 to 100psi and boost at 12psi before even moving.
I then took the truck for a run and about 5km down the road all came good 52psi Fuel pressure and 1-3psi boost. Tramp it Boost to 25psi and settle back to 3-4psi.
About 5km later the same false readings all back again. Stopped turned off and restarted and all false readings again.

I've never had Boost pressure gauge issues before but have had the Fuel pressure issues in the past.
I'm starting to think the ESP is on the fritz and it may have been an intermittent fault for some time

Hope you or others can shed more light on this annoying problem.
Cheers & Beers,
Reg

 

I'm a bit confused here. My understanding is black is ground to the sensor, green is signal back, and red is +5 volts from the signal processor to the sensor. I'm reading a lot of voltages in your text, but nothing that says 5 volts. If you don't have 5 volts on the red wire and ground on the black wire to the sensor, nothing you get on the green wire will make sense.