just changed Fuel Sending Unit (Screws ?)

[SkiDad]

Hi Guys, 1985 Bayliner Capri in very good condition - fuel gauge has been suspect since I got the boat 3 years ago b/c readings were very odd - I generally gas up before I go. Last winter i left what I thought was 3-4 gallons in the tank (gauge was on 1/8th) So I was curious and siphoned 14 gallons out of my 28 gallon tank last week - WOW. When I pulled out the sender the arm would stick and not move freely as it should, so I'm pretty sure the float was not moving up enough.

So i changed the sender and put 12 fresh gallons in now the gauge show approx 1/2 fuel (close enough for me) but now I'm thinking about the 5 screws - i put them all in the same holes as before but I didn't put any rubber washers or anything - the new unit had 5 screws with some plastic at the top. I didn't use them because the threads were thicker and i thought it best to re-use the old ones - i think they might had some residual permatex on them (not much) and probably 20 years old

do have some viton o-rings that should fit. Do I need worry about it ?

 

[gm280]

SkiDad, Personally I would remove the sensor and fix all the problems so you read the correct amount at the gauge. But that is just how I do things. I like things to work and work properly. Otherwise, why even put a new sensors in, in the first place? And I would use all the new hardware and the rubber gaskets because otherwise you can get fuel slosh around the mount. Not a good thing with any possible ignition spark or such. So my suggestion is to take it all out again and install it correctly and make certain the gauge reads correctly and use the proper rubber gaskets too... Safety has to be top priority always! Just remember, if things go bad out on the water, your can't simply run away... JMHO!

 

[Silvertip]

You can adjust the sender for accurate reading when empty, one half or full but not all three. Adjust for empty with boat in the water. Do not adjust for full as you know when that is because you fille d the tank. He can't use the new screws because they are not apparently the same size. Sealant on the screws would prevent seepage through the threads.

 

[Tnstratofam]

You can adjust the sender for accurate reading when empty, one half or full but not all three. Adjust for empty with boat in the water. Do not adjust for full as you know when that is because you fille d the tank.

That is awesome advice. Adjusting for empty in the water versus when the tank is supposedly full is such a better idea. If I would have done that to our ski boat two years ago I wouldn't have sucked all that trash out of my tank throughout my fuel system causing me to loose out on a good month of skiing.:facepalm:

 

[smokeonthewater]

Actually many sending units can be adjusted for empty, and full....

By changing the length of the float arm and the height of the pivot point.

IF it's a quality unit half SHOULD be right in the middle

 

[SkiDad]

sorry i wasn't too clear on my post - I was just trying to give more details that might help someone else. i did replace the sending unit

I actually emptied the tank before doing it. it read empty with an empty tank - i put 4 gallons in and it read just above E - then I put another 8 gallons in and it read just over 1/2 - i feel good about the 4 gallons just moving it past E so I think that gives me a little reserve.

I guess my main question was about sealing the 5 screws - i re-used the old ones. It's probably nothing to worry about vapor wise I'm assuming ? Used new gasket that came with it.

 

[SkiDad]

PS - i'm pretty sure my tank is angled on bottom. the sender unit hole is not in the center of the rear but actually about 1/3 from side. I measured 5 1/4" tank depth but I believe my tank is about 7" deep in the center (guessing) - so I don't think my gauge will be perfect b/c of this design. I cut the replacement sender to match the swing of the old unit.

I guess I'll just pick up some permatex and coat all the scews and call it a day

 

[Fed]

I'd be concerned about raw fuel coming up the threads and out under the screw heads.
The whole sender will be below the fuel level with a full or near full tank when the boat is underway.

I have been in your exact position and to make matters worse the underside of the old screw heads weren't quite flat and a little small to sit nicely on the fiber washers supplied with the new sender.

I ended up using the supplied washers and added ss flat washers to stop the old screws from damaging the new washers then used sealant on the threads and either side of the ss flat washers to stop any leaks.

I remember thinking at he time what a lot of drama over a lousy fuel sender but it was either that or tapping new threads in the top of the tank (yuk) or trying to find a sender with screws that suited the existing threads in the tank.

To make things even worse I suffered a Euro American sender mismatch at the same time (full read empty & empty read full) caused by the PO and my lack of knowledge.
Now it's got me wondering if the Euro senders use smaller screws? Or bigger?

15 Years down track & still no leaks.

 

[Grub54891]

That is awesome advice. Adjusting for empty in the water versus when the tank is supposedly full is such a better idea. If I would have done that to our ski boat two years ago I wouldn't have sucked all that trash out of my tank throughout my fuel system causing me to loose out on a good month of skiing.:facepalm:

It might be me,or maby not. On any fuel tank,be it automotive,boat,dirt bike,,,they all pull fuel from the bottom. Any dirt,moisture,or contaminants will get sucked through the system wether full or empty.

 

[smokeonthewater]

It might be me,or maby not. On any fuel tank,be it automotive,boat,dirt bike,,,they all pull fuel from the bottom. Any dirt,moisture,or contaminants will get sucked through the system wether full or empty.

You're absolutely right

 

[Fed]

I had a tank with junk in it that would only clog when the level was low.
Put it down to floaters, semi floaters or sinkers that got stirred up by fuel sloshing around more when the level was down.

 

[Grub54891]

I had a tank with junk in it that would only clog when the level was low.
Put it down to floaters, semi floaters or sinkers that got stirred up by fuel sloshing around more when the level was down.

I'm sure that could happen,if it does,I'd be cleaning the tank after the first time.