Fuel Gauge

[dooma_Flatchy]

I just bough a bass boat, The fuel gauge works but it works backwards, Full is empty and empty is full.The guy I bought it from used a marker and put an E and F on the gauge.:facepalm:
He said it's wired up backwards. I have not had time to fool with that because of snow,rain and cold, and working on the steering cables. I have to get under the dash this weekend to finish the steering cable work. I'm not exactly sure what type/kind the gauge is. But do I swap the wires around on the gauge or do I do it at the sending unit, Or is there something else that needs to be done?

P.S. The battery cables are not hooked up backwards. That's the first thing I looked at.

 

[jtexas]

Re: Fuel Gauge

I don't think reversing the wires will have any effect -- I think the gauge & sender are mismatched. I could be wrong though..........

 

[Fed]

Re: Fuel Gauge

jtexas+1, NO amount of swapping cables can fix this. You need a matching gauge.

 

[dooma_Flatchy]

Re: Fuel Gauge

Thanks jtexas and Fed, Now I have to figure out what type of gauge I need since I don't have the old one to go by.

 

[Don S]

Re: Fuel Gauge

Being backward could mean the sender in the tank was installed upside down. Many senders have to be cut and assembled for specific tank depths, if the part of the sender that the float hooks to is installed upside down, it will read backwards.

 

[Silvertip]

Re: Fuel Gauge

I really doubt there is a mismatch between the gauge and the sender. Fuel senders are typically measure 33 - 240 ohms with 1/2 being about 109 ohms. As Don mentions, if the sender had been replaced at one time, it may have been installed upside down which makes the resistive element work backwards. If that's the case and you can't turn the element around, a new sender is in order. As long as it is a 33 - 240 unit and matches the tank bolt pattern you are good to go.

 

[dooma_Flatchy]

Re: Fuel Gauge

Ahhh, That makes a little more sense to me. Thanks..

 

[Don S]

Re: Fuel Gauge

If that's the case and you can't turn the element around,

Have to disagree with that statement, there are a few of the most popular senders on the market that can be turned over. The element is just held on by screws.

 

[dooma_Flatchy]

Re: Fuel Gauge

Ill check that out. Thanks Don S

 

[Silvertip]

Re: Fuel Gauge

Have to disagree with that statement, there are a few of the most popular senders on the market that can be turned over. The element is just held on by screws.

I don't disagree with that but my response indicated "IF" it can't be reversed you have no choice but to replace the sender. Here is one that cannot be reversed. I repaired this one and keep it as a spare. The plastic housing was originally riveted to the mount but is now secured with a bolt. The top of the sender is secured with plastic hooks through square holes on the back side as shown in the second picture. In this picture you can see that electrical connection coming off the top of the sender. That would not reach the sender terminal if reversed. If one wanted to spend the time to re-manufacture the thing it could be turned around. But it is definitely not a remove, reverse, and secure operation. But if your point was if this type of sender was used then the reversed sender would not be the problem in the first place -- then I would agree with that as well as this sender cannot be installed incorrectly. Well -- it can but it would not cause a reverse reading.

 

[Fed]

Re: Fuel Gauge

jtexas+1, NO amount of swapping cables can fix this. You need a matching gauge.

I'm going to retract that at least for the moment.
I believe I'm thinking the difference between the OMC style & Merc style trim gauges & senders.

 

[jtexas]

Re: Fuel Gauge

I'm going to retract that at least for the moment.
I believe I'm thinking the difference between the OMC style & Merc style trim gauges & senders.

well, I stand by my original statement: "I could be wrong..."

 

[Silvertip]

Re: Fuel Gauge

The most logical of the causes is indeed a reverse reading sender. Many of the universal units have a mount that must be cut to the proper length to match the tank depth. In the process of doing that the sender may have been installed upside down. So instead of reading 33 ohms when full, it provides a 240 ohm reading when the float arm is all the way up. Thus the gauge reads backwards. If the +12 volt and ground connections were reversed at the gauge you would have sparks and a blown fuse because you would be putting 12 volts on a ground terminal. Since all of the gauges are generally daisy chained one to the other you have +12 volts to ground. Fuel gauges and senders are not "engine" related so you cannot compare motors here. VDO for example offers gauges with 0-90 ohms 10 - xx ohms (don't remember off hand the high end) but those are not the typical senders found on U.S. built boats.

 

[dooma_Flatchy]

Re: Fuel Gauge

Yup, The sender was installed upside down. I pulled it out and swapped it around and it reads correctly now. Thanks for the help.