Another fuel gauge issue.

[DavesSV6Tonner]

I've had a read of a few of the faulty fuel gauge threads but couldn't find any issues similar to mine.
Since the Injectronics refurbished ECU was installed to my 2004 S V6 Cab & Chassis in late March 2019 the fuel gauge readings are totally screwed. Since filling the tank to the first click I've done 225km (all city driving) and the gauge is reading just under 3/4 of a tank and the distance to empty is 310km which I know from experience is BS. At 225km traveled from full, the gauge needle would normally be around the last white line and the distance to go would be around 120km. The low level warning used to sound at around 60km to empty now it is at 19kms to empty and the gauge needle is on the last red line. Took 55 litres to fill the 60 litre tank.
Does anyone know which computer controls the fuel gauge? I'm betting it is the ECU not the BCM.

Dave.

 

[scaredyet]

I have the low fuel warning issue as well. Mine started happening after using the Body Diagnostic software from Envious Customs. I did reach out to Jason but he didn't help much.

I was thinking about sending my stuff over to Injectronics to have a look at.

How much did it cost you? I have a 2005 VZ Wagon

 

[BIG_JV]

I remember when I had my ECU replaced at holdens (I was more foolish back then), the auto-elec explained that after he plugged in the ECU, he needed to program something with the Tech-2 otherwise the fuel gauge would end up reading backwards. So Dave, I think the Ecu definitely plays some sort of role with the fuel gauge.

 

[figjam]

I've read your post a few times, and can't work out what your problem is. Or am I not understanding ?
If the gauge shows empty, and you put 55 litres in, that seems logical to me. And the range of 500+km showing seems right when full.
I wish mine was as good as that, when mine shows empty and 60km remaining, I can only get 45 litres into a 68 litre tank.

 

[DavesSV6Tonner]

The problem is I normally get around 300km out of a tank around town (less if traffic is gridlocked and/or I have the air con running) before the low level warning comes on at 60km to empty.
At that point it would take 47 litres to fill the 60 litre tank (correction 68 litre tank).
I have believed all this time that it was a 60 litre tank and 60 - 47 meant I had 13 litres left at the low level warning.
Thinking about it now, after just learning the tank is 68 litres, the gauge was never that accurate before, even after the fuel gauge software update was done in 2005. If my calcs are correct 68 litres at avg 14.7 litre per 100 I should get approx 530 km per tank.

Anyways, the point of my post is the gauge would normally show half a tank at 150km traveled on the trip meter. Currently the gauge is showing just under 3/4 tank and the trip meter shows 225km traveled. As this is the first full tank since the ECU was replaced I'm keeping a close eye on the gauge however I'm betting the gauge is going to drop very quickly from Half tank to Empty over the next 100km.

The other thing that has always concerned me is the design of the fuel tank. How do you scavenge all the fuel out of a tank that spans either side of the prop shaft and there is no connecting pipe between lowest points of the two reservoirs? I'm pretty sure there is only one fuel pump inside the tank.

 

[figjam]

Good point about the low areas of the fuel tank. Dunno. Others on here have done fuel filters and pumps in these and they may be able to answer how the fuel gets from one side to the pump pick up.
Tonner Matt is a bit of a guru on these.
I think your gauge is working OK, but the discrepancy in accuracy is annoying, and anxiety producing if you are travelling in remote country areas.
So now you have to re-calibrate your brain to recognise the new readings.

 

[Tonner Matt]

Tonner Matt is a bit of a guru on these

Thank you for the mention/vote of confidence there sir
I've just been fortunate (or unfortunate maybe) to have worked on a few over the years
Besides that I've owned my VZ One Tonner for just over 6 years now so that probably explains my familiarity with them

 

[Tonner Matt]

The other thing that has always concerned me is the design of the fuel tank. How do you scavenge all the fuel out of a tank that spans either side of the prop shaft and there is no connecting pipe between lowest points of the two reservoirs? I'm pretty sure there is only one fuel pump inside the tank.

You are correct, there is definitely only one fuel pump in the tank

I had similar thoughts to you when I noticed the shape of the fuel tank.....That was until I changed the fuel filter
The pick up of the fuel is all to do with the design of the fuel pump module assembly
The picture below will explain it better:
That black plastic fuel line goes from the module and into the low point in left hand side of the tank (fuel pump is on right of tank)

 

[Fu Manchu]

I've had a read of a few of the faulty fuel gauge threads but couldn't find any issues similar to mine.
Since the Injectronics refurbished ECU was installed to my 2004 S V6 Cab & Chassis in late March 2019 the fuel gauge readings are totally screwed. Since filling the tank to the first click I've done 225km (all city driving) and the gauge is reading just under 3/4 of a tank and the distance to empty is 310km which I know from experience is BS. At 225km traveled from full, the gauge needle would normally be around the last white line and the distance to go would be around 120km. The low level warning used to sound at around 60km to empty now it is at 19kms to empty and the gauge needle is on the last red line. Took 55 litres to fill the 60 litre tank.
Does anyone know which computer controls the fuel gauge? I'm betting it is the ECU not the BCM.

Dave.

Mine does almost the same thing.
Only I used a ECU BCM PIM Key set from a wagon in my Crewman. The wagons have a bigger tank than the crewman and, with experience, ¾ tank is half-ish. The last ½ goes at an exponential rate and low fuel comes on at almost situation critical.

Maybe the ECU they did hasn't been set up correctly.

 

[DavesSV6Tonner]

You are correct, there is definitely only one fuel pump in the tank

I had similar thoughts to you when I noticed the shape of the fuel tank.....That was until I changed the fuel filter
The pick up of the fuel is all to do with the design of the fuel pump module assembly
The picture below will explain it better:
That black plastic fuel line goes from the module and into the low point in left hand side of the tank (fuel pump is on right of tank)

View attachment 204662

Thanks Matt

I thought there would have to be some engineering trick to it. Unfortunately that leads me to another thought.
So the pump directly pumps fuel from the right hand side of tank and the hose & clunk scavenge the left hand side.
I wonder if hard cornering could cause fuel transfer from one side of the tank to the other at low fuel levels and lead to air being sucked into the fuel system at extremely low levels?