Fuel Gauge Problem

R

rkersh409

Petty Officer 2nd Class
Joined
Aug 19, 2006
Messages
100
I have a 95 Evinrude 175hp motor. Today I went to do the monthly engine run and noticed when I turned on the key the fuel gauge went down past E. I pulled the gauge out and made sure I had +12 on purple and +12 on blue when I turned on my light and have +10 on the red. I put a short between ground and the red sender lead and it shot up to full. I then killed the power and checked the red lead and got 423 ohms. I then went to the fuel tank and put the short between the red and ground and the needle shot up to full again. I can't figure this out, could anyone give me some ideas?

Thank You,
Robert
 
HighTrim

HighTrim

Supreme Mariner
Joined
Jun 21, 2007
Messages
10,486
Re: Fuel Gauge Problem

The voltage - “I” to “G” terminal should be 10 to 16 volts.

Test the gauge’s operation by doing the following: Connect a “hot” wire to the “I” terminal and ground wire to “G” terminal. Take the sender (usually pink) wire off back of gauge. The gauge should now read below empty. Next, add a short wire from the gauge’s “S” (sender) terminal to ground. Gauge should now read above full. If the pointer sweeps back and forth, the gauge is OK.

The sender can be tested by checking its resistance with a volt/ohm test meter. Remove sender (usually pink) wire from sender . Then connect two test meter wires to two sender terminals (or center terminal & flange if sender has only one terminal).
Move float arm by hand. Approximate values:
Empty = 240 ohms, 1/2 = 103 ohms, Full = 33 ohms.

(Not all Fuel Senders have the same resistance range. Marine units, either boat-builder installed or purchased at marine stores, are 240-33 ohms. Non-marine units may be 0-90 ohms, 73-10 ohms or some other value.)
 
Silvertip

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,771
Re: Fuel Gauge Problem

The sender resistance should measure between 30 and 240 ohms (give or take a tad). Disconnect the sender wire when making the reading. If you know roughly how much fuel is in the tank you should get a feel whether the sender is right. 1/2 tank of fuel would read about 130 ohms, etc. Don't know why you would read 423 ohms unless there is a high resistance connection somewhere between the sender terminal and the sender itself. Did the boat get rocked severely during a storm or by a passing wake when docked perhaps that may have shook something loose?
 
E

ezeke

Supreme Mariner
Joined
Sep 19, 2003
Messages
12,532
Re: Fuel Gauge Problem

Remember that the the sender is sitting in the fuel tank full of gas while you run your tests.

The sender is a variable resistor controlled by a float and arm. When the old floats lose their float because of the the newer fuels, the only safe option is to replace the unit.

BTW, I believe that the only color that is legal for the sender wiring is pink.
 
R

rkersh409

Petty Officer 2nd Class
Joined
Aug 19, 2006
Messages
100
Re: Fuel Gauge Problem

Sorry guys I was reading the gauge resistance. When I took all the wires off of the sending unit I was reading nothing, like it was open. My gauge done like you said High Trim. So it sounds like my sending unit is bad. Are sending units standard for OMC or do I have to buy one specific to my fuel tank. Also where can I find one and about how much do they cost?

Thanks again guys!
Robert
 
F

flabum

Chief Petty Officer
Joined
Feb 17, 2007
Messages
567
Re: Fuel Gauge Problem

Before you condem the sender, do this quick test. With the gauge hooked up normally, go to the tank where the sender is, cross the sender wire to the ground wire at the tank. look at the gauge, it should read full. If it does not, you have a problem with either the wiring leading to the dash, the ground or the gauge. If it does read full, time for a new sender.
 
R

rkersh409

Petty Officer 2nd Class
Joined
Aug 19, 2006
Messages
100
Re: Fuel Gauge Problem

Thanks flabum, I did that and it did peg out at full. The only other question I have is the opening. None of the sending units say what size opening on the tank I need to have. Are they all a standard size?

Thanks,
Robert
 
Bondo

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
71,148
Re: Fuel Gauge Problem

Are they all a standard size?
Click to expand...

Ayuh,......

In my experince,.... They're All the Same.......
 
R

rkersh409

Petty Officer 2nd Class
Joined
Aug 19, 2006
Messages
100
Re: Fuel Gauge Problem

Thanks for the help guys. One other thing, I want to take my check valve out of my tank to check it. I think it keeps letting gas back into the tank. But what kind of sealing compound should I use when I put it back on? Both the check valve and connector are made of medal. And I know not to use Teflon tape.

Thanks again!
Robert
 
HighTrim

HighTrim

Supreme Mariner
Joined
Jun 21, 2007
Messages
10,486
Re: Fuel Gauge Problem

Alot of guys simply remove the anti syphon valves, since they are notorious for sticking in a semi closed position. Usually the valves in the primer bulb will prevent any fuel from running back down to the tank, although if it does, simply replace the valve.
 
You must log in or register to reply here.
Top