Nice write up - I followed you very well. My gauge also does not read properly. It reads about 1/4 of a tank less than what it should be. This leads to overfilling the tank and the fuel comes out of the vent hole. I now have an adjustment to do. Thanks for the tip.

Thanks, Chuck, for that good info. It so great when members help each other out with that kind of sharing.

Good information. My gauge always shows fuel to be about 1/8th more than is actually in the tank. I try to keep a log of hours used and find that on my M30A (30 hp) I burn .6 gallons per hour. I try to top off when the gauge gets down to around 1/2 gallon.

Chuck - you have an interesting idea - I did not think of the suction cup solution. Since I am so cheap - I used a 1-quart plastic container of auto oil that I had used, I cut the top off then I drilled a 1" hole on one of the flat side so that it fits over the vent hole protruding fixture and I insert over the protrusion. I place a paper towel inside to catch the overflow if any. Then I have the Admiral listen for the fuel. When any noise can be heard I stop pumping. Usually my fuel gauge will show 3/4 of a tank full. I think this means the tank is full.

Interesting discussion. When our gauge reads 2/3 full, I slow down the fill rate and my admiral listens carefully at the vent. If I don't stop at the first 'gurgle' I have a great risk of spilling fuel out the vent within a few seconds.

She holds a small piece of fuel absorbent rag there and we discard it at the fuel dock.

After a short bit (10 seconds or so?), the gauge reads full, so I expect there is a delay in the unit's display.

[url]http://www.tgmmarine.com/nospills/pages/product002.html[/url]

Been Here done it!!

Chuck,
Had a little misprint. I try to top off when the tank gets down to 1/2 full. I worry about enough other things; don't want running out of fuel to be one of them.

That is a worthy piece of info, Chuck.

You would think if you pulled out a tube only X inches long that you might use a thin rod to see where the actual tank bottom was and realize is was 2X!

Someone once said that the worst thing about our beloved Catalina 36's is the Previous Owner! They sometimes do some outlandish things.

Chuck, thanks for that great post. I've added it to our C34 Critical Upgrades topic, since I think it's sooo important.

[url]http://c34.org/bbs/index.php/topic,5078.msg31743.html#msg31743[/url]

I guess all of the fuel sender units vary it telling you how much fuel you have because of the position of the tank float. The cover screws on the sender are offset so it is important to mark the cover and the plate before removing the sender unit. While I did replace my unit over a year ago in La Paz and it works fine, however I still rely on my fuel log and engine hour meter to figure out how much fuel I have left. There are services that will do fuel polishing however the Catalina has no inspection port for a dip stick so to do any fuel polishing you either take the sender unit off so you can circulate the fuel using a fuel polisher in through the fuel filler and out through the now open port where the sender unit was or empty the fuel tank and remove it for a thorough cleaning.
Hilbre

Another option for polishing is to remove the fuel line where it enters into the Racor and attach a line to it to pump out fuel and then just return it through the deck fill fitting.

Also seems to me that the existing fuel pump could be used with the primary (Racor) to do the same.

Has anyone done it this way?

Fuel polishing won't get all the gunk out of a tank. It will clean up the fuel temporarily of some stuff in it like the leftover biosolids from having water in there, but the asphaltenes and other precipitate byproducts of making diesel the modern way will still be there and will still work their way into the fuel system. The only way to get the stuff out that's stuck to the walls and floor of the tank is to take it out and have it cleaned. A lot of rad shops do that work nowadays.

Aside from that issue, when you run the fuel pump and the engine is not running, you should hear fuel going back into the tank from the engine return line. You are running fuel through both primary and secondary filters when you do that. Just jump a hot line to the pump and let 'er run.

Since we're on the general issue, but off the original poster's story, I have a related question:

Every once in awhile my fuel gauge doesn't register at all. A couple of years back, when this first happened, I replaced the entire sending unit and that seemed to clear things up. The other day it happened again. I was motoring through some chop, and I noticed that after a few minutes of the boat bouncing around the gauge was registering. I guess the float was stuck on something, but I'll be darned if I can figure out what, or why this has happened a few times.

Any thoughts?

For a symptom like that, I would suspect a loose electrical connection somewhere.

This happened to me too. I had bought a brand new fuel sender from CatalinaDirect. It worked for a while, but never registered accurately. Then it stopped working altogether. It was expensive, too, as I recall!

I replaced it with a magnetic fuel sender from River Marine Supply here in Miami. It has no swivel rheostat or long float-on-a-stick and all the electrical stuff is fully encapsulated above the fuel tank. In four years, the sales clerk said he has never had anyone return one, so I have high hopes for this one which, by the way, only cost me about $40.

So far so good. Registering accurately.

Ben, did you have any issues with the cover plate screws lining up during your replacement?

Hi, Stu. Yes and no. Two of the holes are a bit farther apart than the other three. That had me stumped for a bit, but then I saw it. Once I lined up the odd two holes correctly, it all lined up perfectly.

It's apparently intentional coz both the 5-hole fuel senders I've bought have that nice little "feature". Not sure why they are designed that way.