gas gauge

[lakeerieboater26]

what does replacing a gas gauge entail ? I have a 18' mariah diable with mercruiser 3.0 alpha 1. Is this an easy at home fix or a pain in the ***** ? Looking to do spedometer too.

 

[rebars1]

Re: gas gauge

The wiring part is easy. The POA part depends on how accessable it is. Have you determined why it does not work? If not, you should test the wiring and the sender first. Maybe the guage itself is OK.

I don't know about the speedometer. There is usually an air line to the pitot tube at the stern.

 

[Mischief Managed]

Re: gas gauge

You might want to consider a Lowrance LMF-200 with an fuel flow sender and an EP90 water pressure sender. It'll take the place of the speedometer and fuel gauge while also offering you GPH and MPG. It will be vastly more accurate than a regular fuel gauge too. They are very easy to install and reasonably priced. You can also add other senders to it to read things like water temp, air temp, oil pressure, engine temp, etc. Once the wiring is installed, adding senders is extremely simple.

 

[Silvertip]

Re: gas gauge

Agreed that replacing the gauge is a mistake unless you are absolutely sure it is the gauge that is causing the problem and not the sender or related wiring. To remove it, disconnect the wires and remove the two nuts that secure the "U-shaped" bracket. Pull the gauge out the front of the panel. Reverse the procedure to install the new one. DO NOT overtighten the two nuts. Speedometer mounts the same way. The only wires involved on a speeo are the for the internal light. The pitot tube just pulls off the back of the gauge. Again, if the speedo doesn't work, the tube may be pinched or the pitot is simply plugged with debris.

 

[Utahboatnut]

Re: gas gauge

I agree with the above, also I have never had problems with the actual guage typically(atleast for me) its been the sending unit in the gas tank. If there is access to the top of the tank via a hatch in the floor its a pretty easy fix if not it gets rather time consuming. It is possible to cut a hole and fix the problem then install a hatch in said hole. Test the guage first then go from there. The speedo is generally the pitot tube that is either pinched, punctured, or disconnected. Sometimes its the pickup that is damaged but on a merc it is in the drive so it getting damaged is a lesser possibility. They can get clogged pretty easy go to the manual for your drive and find the pickup location so you can look there first. When mine goes south I can generally get it going again if I stop and back up 20 or so feet then proceed again and it comes back to life. They have never been known to be super accurate so a gps might be money better spent if you want a true reading of your speed. The speedo you can do without the gas guage needs to be addressed or carry 10 gals with you on the swim deck.

 

[lakeerieboater26]

Re: gas gauge

pilot tube ? whats it look like and where might it be ?

 

[littlebookworm]

Re: gas gauge

It's called a pitot tube. It's mounted at the bottom of the transom. It's usually cream-colored and looks like a little pendant or flag aimed downwards. If you grab its "tail," you can move the tail upwards slightly. This pressure while moving sends air pressure up the thin hose to the speedometer. It's not a very accurate system. A speedometer attached to a GPS is much more accurate. By the way, before you disconnect the wires from the fuel guage, make a little sketch of the connections and the various colored wires so you know where to connect each of the near connections. As was said, it's usually not the gas guage which goes bad; it's usually the float mechanism in the tank. Sometimes that's easy to change and sometimes that's a PITA, especially when you need to move the tank to get to the mounting plate. You'll need the old float mechanism to match it to a new one. There are numerous variations on the float and swing arm. Test the guage before you bother pulling the float. Good luck. Hy