Can the Fuel Gauge be calibrated on a 42DS?

[Trevor]

Hello all,

I know the Scheiber electrical panels have been discussed at length but has anyone calibrated the tank readings? I have shown a picture of the fuel tank reading just before filling the tank.

It has a capacity of 130 litres and the tank accepted 90 litres when filled. The gauge indicates it has just over half left in the tank.

As long as I know this it is not such a big deal but it would be better if at half a tank of fuel it read half.

Just wondering of any calibration function exists? I guess it is possible the tank does not sit level in the yacht and that may be the cause.

Happy sailing,
Trevor

[Mistroma]

I've never managed to find any technical documentation for the Scheiber panel. My gauge always used to sit at full until less than 1/2 full and then dropped rapidly to almost empty.

I finally tried to "adjust" the reading by removing the sender when tank was about 1/2 full. I bent the arm into a curve in small steps until it read 100% on panel when float in full position (i.e. Float held up manually close to top of the fitting).

This seemed to work well for a while and readings seemed correct from 25% - 100% (based on readings before refilling).

It is difficult to get a linear readout due to the shape of the tank (very wide at front top, narrow at rear & bottom). It would be nice to think that the meter had some function to program for tank profile but I doubt it exists.

However, it has started sticking at 100% recently so I'm going to remove it next time the tank is ~50%. I can also take the opportunity to pump out any sediment from bottom of the tank.

[j]

this is the sender in the 36i: whitworths.com.au/main_itemdetail.asp?cat=114&item=34122&intAbsolutePage=1
(or very similar)

I dare say it's the same sender on the 42DS
If I remember correctly you can adjust the the length of the rod by adjusting a screw clamp at the top.
You could also try bending it as mistroma suggests.

[Trevor]

Many thanks Mistroma and J,

I hadn't contemplated removing the sensor from the tank as that is something I would normally shy away from. I thought that perhaps the electronic reading may be able to be programmed so it could track the sensor resistance in a manner relating to the tank volume and not just simply as a linear representation.

Fuel gauges on boats are a worry. Cars seem to be able to get them quite accurate but for some reason yachts seem difficult to have the gauge track the volume of the tank.

Many thanks for your advice.

Trevor

[Mistroma]

Yes, sensor does look like the one shown in J's link.

I think that car tanks tend to be quite a regular shape. A cube that's half or quarter full will have the liquid level at 50% and 25%. I imagine that link between fuel level and fuel remaining will be pretty linear.

Unfortunately, Jeanneau use odd shaped tanks to maximise capacity for a given space. The 42DS tank is narrow at top near stern and becomes much wider at the front. Not a problem, but it also becomes deeper front to back and side to side.

A 50% drop in level might equate to 70% of fuel used (just a random guess). Relationship between level and fuel left is nowhere near linear.

I must admit that I don't rely on the guauge and have data on fuel used in a variety of conditions. This allows me to make a good guess about fuel used/remaining.

I've found that 2.8 -2.9 litres per hour is a good starting point for general running about. That's moderate weather with revs. at 2,200 with some time at 2,400 and occ. wide open throttle runs for a few minutes every couple of hours (2009 42DS, 4JH4AE, 54HP, 3 blade prop.).

[Trevor]

Thanks Mistroma,

That is really good information and our yacht is the 2008 version of yours so the same specifications.

Regards and happy sailing,

Trevor

[Xantia]

Hi Everyone,

Our fuel gauge sort of works, too, so i won't comment on that. However, our fuel tank had diesel leaks from the seals around the sender and the tube feedthroughs from new. Just make sure you get a suitable sealant for the flanges as you put it all back together or you'll have diesel fumes to lull you to sleep.

Bye

Ian

[j]

When I reinstalled all of the tank fittings after cleaning it out and installing a heater I sealed it with nitrile rubber gaskets (homemade) and a non hardening/ setting sealant.

The key is the sealant, because of the different materials(metal/plastic/rubber) if you use a sealant that sets it won't adhere properly, so use one that stays tacky.
I think this is what I used: www.supercheapauto.com.au/online-store/products/Permatex-Form-A-Gasket-Sealant-No-2-85G.aspx?pid=114973#Cross

The original sealant was a setting silicon type, and there were signs of minor leaks before I replaced it.

[Mistroma]

I've removed my sensor about 6-7 times, mostly to pump out the small trap. I use a fuel biocide but usually still get a tiny amount of gunge. I worried about leaks when doing it for the first time. I had some RTV neutral cure sealant from Maplins to hand (used to seal some electrical connections).

I tried that and it didn't leak so have stuck with that and still have some left. It seems to have a decent shelf life but must be getting past its best. This has prompted me to buy another tube.

I always fill the tank brim full and it hasn't leaked yet. I'm paranoid about not over-tightening the screws as the plastic is quite soft. That's my main worry and I want to avoid having to bond a back plate with embedded nuts.

Perhaps someone else has a cheaper alternative.

www.maplin.co.uk/silicone-adhesive-sealant-46001

[dough]

Another bit of data for you.
2007 model, 42i same engine etc 1500rpm 5knts 1.4 litres per hour.
A clean bottom makes a big deffernce.

[Mistroma]

Yes, consumption improves greatly at very low rpm. However, I prefer not to run like that for very long. I tend to run at 2,200-2,400 varying the rpm a bit and sometimes running at Wide Open Throttle for a few minutes as suggested by Yanmar.

I do run at low rpm just before switching off and then give 5 short blips of high rpm in neutral just before stopping the engine.

However, I've always been very careful with engines and only rarely run one just to charge batteries.

Hopefully mine will last quite a long time. We did over 2,000 nm last year and a fair proportion was under engine. The hull & prop were beautifully clean when we hauled out. So I suppose the barnacles and weed couldn't move fast enough to keep up with us.

[ladauphine]

We purchased our 42 DS in 2007 and have encountered all of the problems discussed in the other posts. We replaced the fuel gauge with one that is set in the deepest part of the tank and disconnected the schreiber. The new one is about 80 percent accurate. However , we keep our log book updated with running time and rpm's as a backup. We also use about the same fuel burn at 2,200 -2,400 rpm's. We also had fuel leaks coming from the top of the tank after about two years. The diesel ate through the original sealant and the fuel leaked into the bilge under the aft berth. Every time we filled the tank up full, the sealant would eat through whatever sealant we used. Now, we never fill the tank to the top and check for leaks whenever we're on the boat