Volvo diesel: Wiring into ignition for fuel gauge?

piperca

Petty Officer 2nd Class
Joined
Sep 4, 2010
Messages
151
I installed new Volvo gauges in my boat for my gas to diesel repower; older 31 series engines. The fuel gauges need to be wired into the ignition. Is there a way to do this without having to cut into the ignition wiring with a three way butt connector? Same for the instrument lighting for the compass and fuel gauges. I'm guessing not, but thought I'd ask. Thanks in advance!
 

wrench 3

Commander
Joined
Aug 12, 2012
Messages
2,108
What are you using for a key switch. You could normally attach to a screw terminal on the back of the switch. But don't forget to install fuses.
 

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
40,581
The fuel gauge works the same on a diesel as it does on a gas motor
 

piperca

Petty Officer 2nd Class
Joined
Sep 4, 2010
Messages
151
What are you using for a key switch.

The ignition switch is the one that is supplied with the Volvo diesel panel. There are no screws on the back of the switch. It has a pre-wired black connector that snaps onto the back. I was hoping not to cut into the wiring, but will if I have to. I just don't like those three-way butt connectors with the exposed center where they connect. The original ignition switch was a Cole Hersee, which had screws and was easy to deal with.
 

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
40,581
Don't use the connector, you can daisy chain from one to another, solder the wires, or get a terminal buss.
 

wrench 3

Commander
Joined
Aug 12, 2012
Messages
2,108
What I use for a three way splice is a but connector one size larger than the wiring being used. I twist two of the stripped wires together and put them into one end of the connector and fold the exposed wire double on the third wire before putting it into the opposite end. I use either an un-insulated connector and double wall shrink tube, or a self sealing connector.
 

piperca

Petty Officer 2nd Class
Joined
Sep 4, 2010
Messages
151
Thanks for your input. I think the terminal buss might be the way to go. I have noticed there are butt connectors that accommodate two wires in one end and one in the other. Not sure if I like that idea, since the glue might not get around the two wires and be susceptible to moisture and corrosion.
 

wrench 3

Commander
Joined
Aug 12, 2012
Messages
2,108
An ignition buss sounds like a good way to go, especially if you're adding more than one feed.
If I'm putting more than one wire in the same end of a butt connector I'll put a bit of silicone sealer between them when assembling.
 

piperca

Petty Officer 2nd Class
Joined
Sep 4, 2010
Messages
151
After doing a bit of research, I found that the Volvo ignition switch has an unused terminal that provides switched power; 15a. I intend to run the wires from this terminal to the busbar with an inline fuse and then from the busbar to the fuel gauge. Does anyone know what size fuse I should use between the ignition source and the gauge?
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Since you probably have other gauges, the nagging question remains -- why not tap into the +12 volt connection on any one of those gauges. Gauges draw so little current a 3 amp fuse would be fine but since 16 gauge wire can carry up to 10 amps you can use any fuse up to that size.
 

piperca

Petty Officer 2nd Class
Joined
Sep 4, 2010
Messages
151
All of the other gauges are the Volvo Penta gauges that came with the panel. I am adding the two fuel gauges, since I replaced the original fuel tank with two tanks. I was going to run each of the fuel gauges off each of the ignitions (port/starboard). The switched power is off terminal 15b of the ignition, which feeds all the Volvo gauges. I thought it would be prudent to leave the wiring intact and use the 15a terminal - which is also switched power - to feed the fuel gauges, since it's not being used for anything else. Does this make sense? Please let me know if I'm missing something.
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
This just leads me further into the discussion. Are you using one tank per engine or are you using a fuel selector valve. If you are using a fuel selector valve, wouldn't you want to know the fuel level in both tanks even if one engine is off? Therefore, I'm back to having a single common feed for the fuel gauges. If the tanks are indeed dedicated to each engine it doesn't matter.
 

piperca

Petty Officer 2nd Class
Joined
Sep 4, 2010
Messages
151
I'm using a dedicated tank for each engine, so the fuel gauges are on their respective ignition.
 
Top