Fuel Sender

[billhatter]

My last trip out I noticed my fuel gage bouncing back & forth.  Before I returned to the marina it just went to sleep.  I've checked the wiring and it all appears to be intact.  I suspect I may have to replace my sender.  Is this something I must order from Catalina or are there other sources.  It appears to be straight forward in terms of removing and replacing.  BUT, any advice would be greatly appreciated.    Incidentally Stu, I found my fan belt at a automotive supply, but did not have success at Napa. 

Thanks for any suggestions.
Bill Hatter
Proud Mary
Hull #5459

[Ron Hill]

Bill : You can buy a replacement fuel sender from Defender or West Marine. 
I ONLY get Gates belts from an automotive store.  Gates is a great brand and hold up longer than the bargens.  A few thoughts.

[billhatter]

Ron

I purchased a Gates fan belt as a matter of fact.  I'm pleased with it.  Thanks for the advice on the Sender.  I'll look through my Defender & West Marine Catalogs.

Bill

[RV61]

Bill,
When I replaced my sender bought at WM I remember needing to be sure the float did not get hung up on the baffle inside the tank.
Something to think about

[DougP]

I replaced the sender just a couple weeks ago.

Took the bulkhead panel (port) off in the aft cabin. Had the old sending unit out and the new one installed and working in no time. The sender itself was a generic 12" sender from WM.

After it was all over I walked away with thee two observations:
1. Was one of the easiest & cheapest boat jobs I've had to do for a long time.
2. There is no way that the gauge could be accurate enough  for anything more than casual information. Started adding engine hours to my log.

[Mike Vaccaro]

Fix the easiest thing first.  If you replace the sender without testing it or shooting the wiring (first the ground from the sender itself, then the wiring at the engine control panel in the cockpit), you may end up replacing a sender needlessly.  Faulty grounds are the number one culprit with inoperative gauges. 

It's also entirely possible that the sender has failed.  If the ground is good, then the sender can be removed and tested with an ohm meter.  To do this, you set the meter up to read resistance, and connect the positive lead to the gauge output and negative lead to the ground. Different manufacturers use different logic (e.g., low ohms at empty, high ohms at full OR visa versa).  But if you move the float arm and resistance changes as the arm moves, the sender is probably O.K.

Some specific examples for different sender manufacturers are: 

Stewart Warner fuel senders are: Empty - 220 to 260 ohms; 1/2 tank - 80 to 120 ohms; full tank -20 to 50 ohms. This is normally noted as 240 ohms at empty and 33 ohms at full.

GMAC fuel tank sender will read in the opposite direction. At empty, it will read zero ohms and at full it will read 90 ohms.

Ford/Chrysler fuel tank sender will read zero ohms at empty and 73 ohms at full.

Cheers,

Mike

[Stu Jackson]

Bill, this is one of the most discussed issues about our boats.  The fuel senders "go" because they're moving in small increments from boats at docks and wearing out the senders themselves.  Doug's hit the nail on the head.  We do this:  http://c34.org/bbs/index.php/topic,3841.0.html

And if you're in there already, if you haven't, it's time to change the fuel hoses.

[Ron Hill]

Guys : Just remember that you are the owner of an asymmetrical tank.  The tank is wider at the top than it is at the bottom. 
SO, when the float arm is horizontal (which should be half way) you really are down about 2/3rds! 
I wrote a Mainsheet Tech article on Replacing the Fuel Sending Unit.  A thought. 

[Chris Martinson]

Doug P -I think we have the same tank arrangement....how did you get the sender out and back in?  I don't have much room between the tank and the bottom of the lazarette. 

Regarding checking the wiring....how can you tell if it is the gauge or sender....I've had to replace gauges so I'm not so sure it automatically is the sender but the bouncing theory seems to make sense.

Chris

[DougP]

Chris,

I was able to determine it was the sender by grounding out the terminals. Put the key in and turned it on. One at a time grounded the two sender terminals. Don't remember which one, but grounding one made the gauge jump, so I assumed it was the sender.

My boat has a Beckson inspection port (4" hole) in the lazerette floor above the sending unit. Didn't matter though, the send angled out of the hole just fine.