Merry Fisher 805 fuse box

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kareheat

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Hi

Can anyone help? We have recently bought a Merry Fisher 805 and have just noticed that our fuel guage is permanently stuck on full tank!!!! I wish. When we turn off the engine it returns to 0.

This is a problem which has only just occurred. We have been trying to find out where the fuse box is on the boat to see if this problem is associated with this, but we are unable to find it.

Can anyone give us any idea where to look or advice on the fuel guage problem



Ross
 
Stuck fuel gauge

Hi

I need help, can someone answer my query about our fuel gauge?

We need to sort this asap. Can anyone help with advice for our Merry Fisher 805


Karen
 
Uneducated guess is that the fuel sender float is stuck up.

However, as the owner of a Merry Fisher 695, the gauge does read full or almost full until it's only got a 1/4 of a tank left and then it just drops like a stone.

It should only come on by pressing a switch. It's a quirk of some of the Jeanneau models that you need to push a switch to check your fuel quantity.

POssibly not much help, sorry.
 
Hello

Thanks for the reply. Hubby has already checked the float and all okay. Unfortunately the fuel gauge was working when we bought the boat 2 months ago, but last week-end we noticed its reading of a full tank.

Still wonder if it could be something to do with the float, although my husband did remove it from the tank and it seemed to be okay.
 
Had this problem on my old boat and it turned out to be a poor earth.
When hubby checked the float, the gauge should have changed as he moved the float(slowly as the gauge takes time to react). If not sounds like an earthing problem.

Hope this helps
 
The fuse board for the MF805 is located at the back of the helm and is accessed by removing the panel above the sink in the heads (4 screws). The panel consists of two banks of six, mini circuit breakers. These are mini trips, that fit into standard automotive sized blade fuse holders. On mine, the fuel gauge is a 1 amp fuse which i uprated to 3 amp when i fitted the rudder angle gauge.

The fuses are, from left to right :

Navigation & Anchor Lights
Fridge
Fresh Water Pump
Shower Pump
Bilge Pump
Windscreen Wipers, Horn

Demister
Cabin & Exterior Lights, Helm 12v Socket
Windscreen Washers
Radio/CD
VHF Radio, Fishfinder
Fuel Gauge, Rudder Angle Gauge

Some items will be options and may not be fitted to your boat.

I doubt it's the fuse though. The gauge on the 805 works differently to Tom's 695, it doesn't need a switch to be pressed to make it work. When totally full mine reads full and will not move or fluctuate until at least an hour of normal running time. After that, the gauge moves down at a reasonably steady rate, but after about 3/4 of a tank it begins to read low while on the plane. For instance, 3/4 of a tank whilst stationary or at displacement speeds will only read 1/2 a tank when you get up on the plane.

You'll have two wires at the sender. One will be a negative, easily checked with a meter. The other will go to the gauge. Two ways this can work, one is the gauge starts off at full and the sender applies a resistance that lowers the needle. The other is the gauge starts at empty and the sender supplies a variable negative to make the needle rise. As your gauge reads full all the time it means one of two things, you have the first system and the sender isn't sending or you have the second and and it's sending as if the tank is full, or there is a short. Take both wires off of the sender and make sure the contacts are clean, refit them.

If that does not work, remove the panel in the heads to give access to the rear of the gauge. Take the wire off of the "G" terminal, if the gauge drops to empty you have the second system above, put the wire back on and go take it off of the sender. if it drops again, the sender is knackered. If it stays on full, there is a short in the wire from the gauge to the sender (highly unlikely to be the case).

If taking the wire from the "G" terminal didn't make any difference you'll have the first system above. Leave the "G" wire off and short the negative and "G" terminals together with a short piece of wire. The gauge should read empty, if it does, your fault is not the gauge. Refit the "G" wire and take both wires off of the sender and short them together. If the gauge again drops to empty, the sender is knackered. If it stay on full you either have a break in one of the wires or the negative wire isn't connected securely somewhere. Running a wire direct from a known good negative point to the "G" wire at the gauge will rule out the negative wire.

For your information, the batteries on your boat are under the cabin floor, beneath the cabin table. To gain full access to them you need to remove the table top and pedestal then undo the screws in that floor section, plus the front two screws in the pedestal base.
 
Hi Paul

that's great. When we get on her next week-end we will try this out. We are in Portsmouth.
Will let you know if it worked. We have been on her all day long trying to find out the problem with it. Unfortunately we also seem to have a faulty fridge.

Oh well. Thems the breaks!!!

many thanks again


Karen and Ross
 
kareheat said:
Hi Paul

that's great. When we get on her next week-end we will try this out. We are in Portsmouth.
Will let you know if it worked. We have been on her all day long trying to find out the problem with it. Unfortunately we also seem to have a faulty fridge.

Oh well. Thems the breaks!!!

many thanks again


Karen and Ross
Click to expand...

You're welcome, hope you get it sorted. Might be a fuse for the fridge, ours only works from 12v. A couple of other hidden things on the 805, just in case you didn't know, there is a trip for the windlass under the bow cabin steps, next to the battery isolators. There are also some filters for the bilge and potable water pumps hidden in a compartment that is accessed from the lazarette locker. There is a removable panel in the starboard side forward bulkhead, inside the locker. This is where the potable water tank, pump, filter and accumulator lives. The bilge pump filter blocks easily and is a pain to get to and clean, so i fitted another one in the locker.
 
Merry Fisher 805

Hi Paul

Just thought I would let you know my hubby tried all those tests today and it all tracked back to the sender being faulty. My brother has taken it away to solder some wire on it. So thanks again for your help.

The fridge has now found its way to the menders!!! Some place in Fareham, to have a look at it. It wasn't the fuse because we managed to get the light to work (pulled the fridge out to have a look at it, couldn't find anything wrong, put it back in and then miraculously the light came on).

We are thinking of re-naming the boat, currently called Irresistible (spelt wrongly) to Knot His, what do you think?

thanks again.

Karen and Ross
 
When we first bought ours we had a couple of teething problems too, toilet wouldn't flush and some carp in the fuel tank. An electric conversion fixed to toilet and a good clean of the tank and we were away. Other than a leaky raw water pump and a battery, she's been as good as gold <touch wood> and we're very happy with the boat. When you get these little jobs fixed, i'm sure you'll be happy with her current name :)

Oh, one other little tip, when it comes to servicing the engine, if it's fitted with the Nanni engine it's a 3.0 litre Landcruiser based lump. Oil filter, secondary fuel filter etc all available from local motor factors.
 
Hi Paul

Yes our toilet wouldn't work but my hubby took the hand pump to bits and managed to get it working with some Vaseline! Now it seems to be working okay.
Sorry for asking but what is carp in the fuel tank?

On the whole we are pleased with the boat, it is just getting these small jobs sorted.

thanks very much for all your advice though, it is much appreciated.

Can't wait to start going places - it is handy having Southampton within easy reach, Beaulieu and even France maybe one day!!!!


Karen and Ross
 
kareheat said:
Hi Paul

Yes our toilet wouldn't work but my hubby took the hand pump to bits and managed to get it working with some Vaseline! Now it seems to be working okay.
Sorry for asking but what is carp in the fuel tank?

On the whole we are pleased with the boat, it is just getting these small jobs sorted.

thanks very much for all your advice though, it is much appreciated.

Can't wait to start going places - it is handy having Southampton within easy reach, Beaulieu and even France maybe one day!!!!


Karen and Ross
Click to expand...

carp in the tank = c r a p in the tank :)

carp is a commonly used replacement for c r a p as internet forums often tend to filter the latter with **** :)

Here's our toilet with the electric conversion, fit straight onto the existing toilet where the hand pump is.
 
Last edited:
Re: Merry Fisher 805

kareheat said:
Hi Paul

Just thought I would let you know my hubby tried all those tests today and it all tracked back to the sender being faulty. My brother has taken it away to solder some wire on it. So thanks again for your help.

The fridge has now found its way to the menders!!! Some place in Fareham, to have a look at it. It wasn't the fuse because we managed to get the light to work (pulled the fridge out to have a look at it, couldn't find anything wrong, put it back in and then miraculously the light came on).

We are thinking of re-naming the boat, currently called Irresistible (spelt wrongly) to Knot His, what do you think?

thanks again.

Karen and Ross
Click to expand...

Hi theer.
Have a Merry fisher 805 with fridge not cooling.. Light on but no noise or cooling.. any idea whats wrong? how did you sort your one?
 
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