G'day Fellas,

Well for the second time a Fuel Pressure problem has raised it's ugly head on me.
I've got the ISSPRO 6 X Guage set and developed a fuel pressure issue soon thereafter install (2 or 3K km later).

The guage was reading 100+psi. I'd done all the normal checks and proved wiring was sound and correct.
Disconnected the fuel pressure sender connection and plugged it into the Boost sender unit and the Fuel Guage read correct Boost pressure proving guage is good.
Couldn't do other way around by connecting Fuel Pressure connector to Boost guage as my Boost guage is only 0 - 30 psi, so couldn't prove fuel pressure sender unit.

I obtained another ISSPRO Fuel Pressure sender unit from Clay and I connected it up and Bingo all good at 60 - 65 psi. So was a faulty sender unit.

This same problem just happened to me again during my last bush run. That is fuel guage going to 100+psi.
However it was a little different this time in that it went to 85-90 psi for a while before going to 100+psi.

It ran at that 85-90 psi for a good 300 km. I suspected stuck poppet valve, incorrectly seated spring (although unlikely as it had been running at 60-65psi for thosands of km).

I done the following:

1. Again I disconnected the fuel pressure sender connection and plugged it into the Boost sender unit and the Fuel Guage read correct Boost pressure proving guage is good.
As mentioned above, I couldn't do other way around by connecting Fuel Pressure connector to Boost guage as my Boost guage is only 0 - 30 psi, so couldn't prove fuel pressure sender unit.

2. I drained fuel bowl and lifted cap and pushed the poppet from inside bowl and it was not stuck and moved easily and freely.
Put cap back on and primed the bowl (KOEO) and it went to 100psi straight away.

3. Opened fuel bowl drain and KOEO to see if the guage would go to 100psi even if no pressure could build in bowl with drain open.
Sure enough it went to 100psi ???

4. In order to eliminate all doubt I then disconnected the return line and carefully removed the RR FRX FPR to ensure the spring is seated correctly as it was. Pulled poppet valve checked for scuffing and seat, all looked good. Cleaned it up with Tooth Paste (finest grade grinding paste I know lol).

5. Connected plastic hose to return line and blew down the line to prove no blockage. No problems could feel air bubbling into fuel tank and hear the bubbling sound. So fuel return line all clear.

6. I had 2nd Gen RR FRX unit fitted with the 'Gold ' Spring. So I changed to the weaker 'Silver' Spring and reassembled. KOEO to prime system and it went to 100psi.

This was not fun to go through out in the bush on a camping trip. But I thought it necessary to do all the above because I had at least 1,500km to go to get back home and didn't fancy driving around with a 100+psi charged fuel system under the hood .
Anyway I convinced myself that it must be another faulty sender unit (but why?) and continued my vacation. The truck run as sweet as a nut pulling 7K lb + caravan on rough outback roads. No fuel leaks etc.

So it looks as though I need another; even better 2, one as spare sender unit.
But is it just bad luck that I would get 2 x Faulty sender units ? Or is there something else that could cause this ?

Have any of you fellas had issues with ISSPRO pressure sender units.
All other 5 guages work perfectly (TFT, EGT, Boost, EOT, COT).

Cheers,
Reg.

 

I had a bad fuel press sending unit also. Isspro sent another, and has been fine since.

 

I talked with Clay yesterday about replacing my sending unit. It lasted 6-8 months and was reading 100+.
It read over 55 psi when the fuel bowl was empty. Isspro is sending out another.

 

Clay also sent me a replacement ISSPro FP sender. When I compared it to the faulty one the part numbers were different. Don't know the old part number but the new one is R89141. This was about 2 years ago. The replacement has been workng properly ever since.

Frank or stinson 108-1,

Do you still have the bad senders? Would be nice to know the part number and date code (right below part number).

Edit: Also the new sender part number.

 

Robin my faulty sender is still on the truck, ill get the numbers and post them in later. It's getting tires installed right now.

 

Thanks Frank.

 

I have the bad one somewhere, I'll try and find it. Doubt I can read the new one with it installed on the fuel bowl. Post filter.

 

Thanks. I would like the part number from the failed sender.

Certainly no hurry.

 

Reg, Im on my third sending unit and it still doesnt read right. Stewart Warner gauges are not cheap either. I have a mechanical under the hood and electronic in cab and the in cab reads about 15psi lower.

There are two ports on the back of the filter (pre and post filter). Buy ya self a $45 mechanical and some line and tap into the spare so you can check ya sender



If you order another one make sure they bench test it before they ship

 

G'day Robin,

I see I'm not the only one with dud sender units and looking at Brian's post below it is not restricted to ISSPRO either .

As I mentioned when the first one failed good Ole Clay sent a replacement out here pretty quick.
That one has now failed and the Part# is R89141 same as the one you have had no issues with for 2+ years. Appears these units are like CPS Units some work some don't even if same Part#. If there were a 'Batch Number' it could be of help, but I guess that's asking too much.

I have kept the failed unit.
I'm at sea at present but will contact the missus to see if she can get a Part# off the old unit.
I'll get back on that asap.

Cheers,
Reg.

 

G'day Brian,

I have been considering this for a while now.
It's a good indication of a Filter getting choked up if the differential increases. So if you note the differential pressure with new Bowl filter and pre-pump filter fitted then you have a good starting point to properly monitor the health of the fuel delivery system .
If post filter pressure gets lower and pre-filter is not affected then I guess it's an indication that the bowl filter is getting choked up (higher differential). If pre-filter is dropping it could be an indication of a choking pre-pump filter or weakening pump?
If pre-filter only is dropping and post filter pressure is not affected (same) then it would indicate that the Electronic sender unit is again faulty.

With the chances of getting a gut full of ****ty fuel in the outback, it is a good mod to do Brian.

Cheers,
Reg.

 

Robin, I don't see any numbers on my sender, unless they are very small and on the bottom.... The sender is still attached to my fuel bowl.
As soon as I get my new one from Isspro I will get back to you with that number.

 

All that is true Reg. But I was referring to checking the accuracy of your electronic sender. The mechanical gauges are more accurate than electronic. Switch the mechanical over to both sides and if the read the same then your electronic sender is faulty.

 

I'm sorry to hear about your FP sensor issues. They had a bad batch a few months/year ago. I thought most of them had been pulled out...

I'll shoot this thread to Michael as well.

Joe

 

Know anyone over at Stewart Warner Joe ?? Cause it seems to be a common problem