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Fuel Sender

Change the fuel sender to one that is more accurate.

DISCLAIMER: TheMalibuCrew.com and the author of this article offer these instructions simply as a guide and hereby relinquish all liability and responsibility for the results of said instructions. By following any instructions set forth in this article, you agree that you are doing so at your own risk, and accept the consequences of your own actions. Again, we will not be held responsible should any undesired outcome result from following the instructions below.

The fuel gauges on Malibu boats are notoriously inaccurate. The good news is that it is an easy job to install a new fuel sender to correct the problem for less than $50.

Tools and Supplies Needed:
  • SAE standard 5-hole fuel sender. I used a Teleflex fuel sender from the local West Marine. Discount Inboard Marine sells the same sender for around $28.
  • socket wrench
  • heavy duty wire cutters and potentially…
  • 16 gauge wire
  • 2 butt-end splicers
  • 2 ring terminals
  • electrical tape
Estimated Time to Complete: 1 hour
Difficulty Rating: Low


Before the real work, you need to gain access to the top of your gas tank where the existing fuel sender is. On some models this will require no work at all. On others it could require some effort. On my 2004 RLXi it meant removing the trunk floor.

STEP 1: Removing the old fuel sender

This picture shows the existing fuel sender installed in the gas tank.

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Existing fuel sender installed in tank

The fuel sender is held in place by 5 machine screws and has two wires going to it. The two wires will probably be pink and black and may be enclosed in an insulated wire jacket. Depending on the type of the existing fuel sender you have the wires will be either held in place by nuts or spliced into the wires that go directly to the fuel gauge. If they are held in place with nuts, just unscrew the nuts and remove the wires. If they are spliced in place, you will need to determine the best place to cut the wires that you will be able to splice into. In my case, two 8 gauge wires ran from the existing fuel sender and then spliced into the wires running to the fuel gauge.

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Existing connection between fuel sender and gauge wires

After removing the wires you can simply unscrew the machine screws and carefully remove the fuel sender from the tank.

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Existing fuel sender removed from tank

STEP 2: Preparing the new fuel sender

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New sender

Most fuel senders are pretty universal and will fit tanks of varying depths. The fuel sender I installed, for example, fits tanks anywhere from 4 to 24 inches in depth. This means that we need to adjust both the support channel and float arm that are part of the fuel sender in order for it to fit properly.

The first thing that we need to do is measure the depth of the inside of the fuel tank. The directions that come with your new fuel sender will have a table that will then tell you how short to cut the support channel and float arm of the new fuel sender in order to fit properly.

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Measuring inside depth of fuel tank

Using the inside depth of the tank, determine from the new fuel sender's instructions how long the support channel and float arm need to be and cut them to the appropriate length. The support channel will usually be cut an inch or so longer than half the depth of the tank. In my case the tank's depth is around 6 inches and I cut the support channel to 4 inches. You may want to consider initially leaving them just a bit long and cutting them again later on after you are sure you have the correct lengths.

You can now attach the float arm to the support channel. The instructions will document where the float arm should be attached. It will usually be just a little bit deeper than half the depth of the tank. Again, in my case the tank's depth is around 6 inches and I attached the float arm to the support channel 3 1/4 inches from the top of the fuel sender.

Finally, you need to make sure the float arm will not be obstructed when inside the fuel tank. The support channel is attached to the top of the fuel sender with a couple of screws and can be rotated on the top of the fuel sender in 90 degree increments if necessary. In my case, I needed to rotate it so that the float arm would come off the support channel towards the front of the tank. At first it may appear that this would not be necessary because you can just rotate the fuel sender on the tank. However, the 5 holes for the fuel sender are NOT spaced evenly.

Now it’s time to attach the wires to the new fuel sender. If you cut the wires to remove the old fuel sender you will need to splice new wire in between the wires coming from the fuel gauge and the new fuel sender. Make sure you attach the black wire to the “-“ terminal on the new fuel sender and the pink wire to the “S” terminal on the new fuel sender.

Finally we can make sure the new fuel sender is working as expected. Turn the key to the on position (do not start the engine) and make sure the fuel gauge moves when you move the float arm up and down.

STEP 3: Adjusting the new fuel sender

At this point the new fuel sender could just be put right into the tank, but if you want more accurate readings you will want to make sure the lengths of the support channel and float arm are correct and possibly make some adjustments.

The easiest way I could think of to do this was to build an open-ended box that was as high as my tank is deep. You can then cut a hole in the top and place the new fuel sender into the box to mock up a fuel tank.

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New fuel sender inside box in order to adjust easily

With the new fuel sender inside the box, turn the key to the on position again (do not start the engine) and move the float all the way up to the top of the box. The fuel gauge should go to “F”. Then move the float all the way down to the bottom of the box. The fuel gauge should go to “E”.

If they go all the way to both “F” and “E” you are all set. If they don’t, you need to adjust either the length of the float arm or where the float arm attaches to the support channel accordingly.

STEP 4: Installing the new fuel sender

Before putting the new fuel sender back into the tank there is one thing we need to do. The wires going from the fuel sender’s wire terminals down to the float arm need to be tie-wrapped to the support channel to keep them from obstructing the float arm. Make sure you keep them wrapped cleanly and you won’t have to bother with a stuck float arm later on.

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New fuel sender adjusted and wires tie-wrapped to support channel

AAt last we can put the new fuel sender into the tank. Do not forget to use the gasket that came with your new fuel sender – I forgot. Then carefully place the new fuel sender into the tank and screw it all down. You should be able to use the screws from your old fuel sender. It may be easier to disconnect the wires from the terminals if they are in the way and reattach them afterwards.

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New fuel sender installed

Wrap Up

It is unfortunate that Malibu doesn't use a more accurate fuel sender. The old fuel sender was very well built but was obviously inadequate and I can't believe there would be in additional cost in switching to another fuel sender that would work better.

While you are doing this, I would strongly suggest installing a fuel/air separator such as the one described in this article to help avoid spewing fuel out the vent whenever filling up. It will only take an additional 15 minutes and this is a good time to do it since you already have the tank exposed.
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