Fuel gauge reads the wrong way round

Tim M · 13 June 2006, 09:05

I've just wired up a new fuel gauge on my boat. The tank already had a sender in it which I have connected the new gauge to. However, the gauge reads the wrong way round - when the tank is full the gauge says it is empty and visa-versa. I'm pretty sure the gauge is OK - only just bought it.

Is the solution as simple as swapping the two wires that connect to the sender round? I may well have wired it wrong - on the sender is the "sender" terminal likely to be the pin sticking up on the middle? (I assumed it was and the screws at the side were ground)

Cookee · 13 June 2006, 09:10

There are two types of sender - US and European, you'll need a US one on a Mercury! Wema do them to order.

craig_c · 13 June 2006, 17:14

We had the exact same problem on a previous boat, we did try swapping the wires round on the guage but it did not work... easiest way to look at it is if sum1 nicks your boat, they think they have got a full tank!!!

jyasaki · 13 June 2006, 18:24

FWIW, the difference (I think) between the US and European senders is the resistance range. Shouldn't have anything to do with guage polarity.

jky

Matt · 13 June 2006, 22:16

There's 3:
10-180 ohms
240-33 ohms
90-0 ohms

For obvious reasons, the gauge and sender have to match

Tim M · 13 June 2006, 22:19

Right....It seems odd then that it should give me a correct reading albeit the wrong way round. I'll have to find out what range the sender is.

Matt · 13 June 2006, 22:23

Not really.
90-0 is specifically for the vdo range of tube senders.
The other 2 are close enough to the inverse of each other for government work.

Tim M · 13 June 2006, 22:39

It's not a Mercury gauge btw. Can't remember the make without checking but from memory it begins with F.....

The old gauge was also made by them (replaced cos it was rusty and horrible)...weird

Matt · 13 June 2006, 22:50

Faria. Can be bought from asap supplies who usually have stock.
http://www.asap-supplies.com/
They sell both european and us resistance ranges
Link to one of the gauge ranges:
http://www.asap-supplies.com/toc.php...BY_STYLE&prod=

jyasaki · 14 June 2006, 00:54

Try looking here:

http://www.teleflexmarine.com/cgi-bi...=us&link2=1047

and select Fuel Systems from the menu below the really bad drawing.

This thing is not rocket science; shouldn't be all that hard to troubleshoot.

jky

jyasaki · 20 June 2006, 19:38

Hmmm. More info:

[From a different boating forum here in the US; response to someone whose gauge was reading somewhat wacko]:

What type of Gauge do you have? If you have a Yamaha multifunction spedo you may have your dip switches set incorrectly. There are three settings; Yamaha, USA, and Europe. If they were set to Europe your fuel gauge would work in reverse (show full when empty and vice versa) but if they are set to Yamaha then your fuel level may indicate as you have said. The USA setting is used for most fuel senders. This is something that the dealer should have checked before delivery.

This implies that the Euro standard is opposite the US (decreasing resistance as the tank empties, or vice versa; don't ask me...) In either case, sounds like your problem.

jky

RAS · 21 June 2006, 19:43

Hi Tim
I had the same problem on my fast fisher, the cause is that the float on the sender has been mounted the wrong way round. The cure is to remove the sender and slide the arm out and refit the opposite way round. What should happen is the resistance should decrease as the float raises, but by fitting the float arm the wrong way round the resistance is at minimum with the float down and increases as the float rises as you add fuel.
Hope this helps.

jyasaki · 22 June 2006, 00:07

Or, you could move to Australia, where everything is upside-down anyway.

jky

Nick Hearne · 22 June 2006, 09:19

So can some one tell me if a 240-33 Ohm is US or Euro

Just found out it is US, thanks to Steven at A.S.A.P. Supplies Ltd

fast fred · 23 June 2006, 11:00

"the cause is that the float on the sender has been mounted the wrong way round. The cure is to remove the sender and slide the arm out and refit the opposite way round."

this is the problem,

Tim M · 23 June 2006, 12:13

THanks for all the replies. The arm being the wrong way round sounds the most likley as the gauge is very accurate, but the wrong way round. I wuold have thought that if the resistance was wrong for this gauge then it woulnd't be as accurate.

fast fred · 23 June 2006, 12:26

it's just held on by two screws, flip it and check it be for you put it back in,
seal it backup good,

NO power goes to the gas tank at any time, ground and Send only,
power never.