Hi, I am back again - this time I am looking for a clue as to why my fuel gauge is acting strangely.

In the past two years I have had the gauge act with a mind of its' own, in that when the tank level gets down to just below half-full the gauge will suddenly drop to empty. It will stay like that for perhaps 10 miles, or else if the ignition is turned off, and then it comes back up again.

This morning, when I turned on the ignotion the gauge sat on empty, but for the first time a message came up "Fuel Gauge Fault". This stayed on for about 5 minutes and when I went to drive off I noticed that it had gone and the gauge was back up at its normal position [depending on fuel level].

I asked my local garage guy and he thought that it is a cable issue, he suggested that it could be the connections on the top of the pump or a plug connection a bit further along the cable [wherever that might be].

Perhaps someone can suggest what could be the issue ?

Currently waiting for new brake pads to arrive, although I think that I may replace the discs as well. They look a bit heavily grooved but I was looking in poor light. I will look again tomorrow.

Pierre3.

It sounds like a dead spot on the sender track to me. I've known when that happens (which I've had on other vehicles) that once it reads something it knows is invalid, the gauge will act strangely until its past that point and power cycled. The cars I've had that have had that sort of fault have been gas converted vehicles, and it seems they are more likely to show the issue as they stay at a similar level in the tank for extended periods on gas.

Could be a bad connection, only way to really tell is get into the sender unit and start looking at it. If there is a plug involved, it may be one where it goes through the floor but I wouldn't know which one that might be, Rave would tell you if noone else can on here.

If you can get to the sensor output you could test it with a multimeter and moving the level sensor about.

It may have a fault code logged if you have a Nano to look at it, just in case its the cluster playing up as well, that might give you a better idea where to look. I know the Galaxy I've got logs an invalid fuel level message as its on gas so doesn't drop as the car expects it to when driving.

If its consistant at the same level of fuel in the tank, its more likely going to be the tank sensor than anything else.

I agree with Brian. If it does it at odd times because it can, then a dodgy connection between the tank sender and BeCM. If it always does it when you have roughly the same amount of fuel in it, then it will be a dead spot on the carbon track on the sender. Mine has the same fault when I am just below the 1/4 mark but that is because the tank level has sat around that point for all the time I've owned the car as that is the amount I normally keep in as a reserve in case I run out of LPG. I've actually got a brand new fuel pump in the garage that I bought well over a year ago but haven't got round to fitting yet.

Hi guys, thanks for the advice.

I haven't had a chance to put the Nanocom on, but the gauge seems to drop to "empty" at about half full and below. If the fuel level is below half full then the gauge will drop to "empty" at random opportunities, there isn't a definite point at which it drops. But, usually below half full it will drop down at some point.

The car doesn't have to be stationary, I may be driving along and then notice that the gauge has dropped. And it usually returns to its original [depending on fuel level] position when the ignition is turned off for 10 or 15 minutes, i.e. going into the shop to get a cup of coffee.

It has always done this from the day that I bought it. I remember ringing the garage from where I bought it, to complain that they might have put a couple of gallons of diesel into the tank as they knew that I was driving from the Midlands [where I bought it] to Edinburgh. The gauge said "empty" and the fuel light was on, but the sales guy said that they had put 3 gallons in the tank. Sure enough, when I filled up the tank was nowhere near empty. I had to ring back and apologise !!

So the gauge has always been a bit flaky, and I just fill it at around half full, to be sure to be sure.

I did notice that the carpet has a very clean cut where I think the pump is, under the rear seat. I have never lifted it up but it does look like it is factory made, what is the likely hood that there is an access hatch underneath it ? I can't go out and check as I am not at home where the car is !

Pierre3.

Nanocom just shows a number between 0 and 255 for fuel level so when your problem is there, it will show 0 or very close to that. If the gauge just drops it means the wiper has found a high resistance part of the track but is still seeing something (so the Nano will show a low number), if it comes up with 'fuel gauge fault' it has gone open circuit so would show 0. Turning it off may correct it or even going around a sharp corner so the float is moved will do the same. When mine hits the dead spot, even going over a bump is sometimes enough to wake it up again.

Sounds like you need a new fuel pump as that incorporates the gauge sender. If you have a factory made hatch, then you have some sort of prototype as the P38 never had a hatch. I suspect someone may have been in there before to try to cure the same fault. Or they just cut the carpet in the hope of finding a hatch and when they didn't, ignored it.

Hi Richard, I had a look last evening, and the cut-out in the carpet is for the top of the shock absorber, at least I assume that's what it is. Put it this way, it isn't an opening for the fuel pump.

As it isn't a major problem, at the moment, then I will probably wait until warmer, drier weather comes back, and drop the fuel tank. I can see that doing it that way will also give me a chance to look at the brake lines etc.

As usual, thanks again for your advice.

Pierre3.