280ss wiring question

[Kerry Cordy]

I have a 2005 280ss. When you turn the key on, the fuel pump does not run? I checked the relay before the pump and everything is great. I ran a jumper to the pump and it runs. I traced the problem to the factory solid red wire with purple stripe harness that Mercury provides for the fuel pump. On the block are two factory relays that the red/purple wire comes out of. I thought I found my problem. I replaced the 2 relays with new Mercury factory parts. The red/purple wire is still cold. Why do I not get 12 volts to the red/purple wire when the key is on? Bass fishing is on fire here in California. I'm on the sidelines and not making 90mph passes, Bummer.

Thank you for your thoughts and helping a fellow Allison owner, Allen

 

[tomoad]

Are you getting power from key switch wires to the relays?

 

[Bobalouie]

I think I have heard that the driver that energizes that wire is a common failure point in the ECU. You can either get the ECU fixed which may be pricey, or bypass it for about $30. On my 280, I bypassed it. Ran a dedicated relay to the pump and put a switch on the dash that way I could turn the pump on anytime I wanted. Its pretty easy to do, just wire up a new relay and connect key on 12v from somewhere on your dash to a switch at the dash and use that as the signal to turn on the new relay. Wire the relay direct to the battery thru a 15Amp breaker or fuse(I used a breaker), and then to the pump and you are back in biz.

 

[tomoad]

Sorry I misread, I now see we're you stated there was power before the pump

 

[tomoad]

I knew this could be done with a 260, 280, or a Drag with the digital EFI boxes. But honestly didn't know that this set up would work with the stock 280 set up. Motorola stuff. My brothers Drag motor fuel driver did this and he wired it up like this of course it has a A13 digital box

 

[Kerry Cordy]

I really appreciate the suggestions. I will run a switch off the key and run a wire back to the relay before the pump. I'm curious about the other wires that come off the 2 factory relays? If the red/purple is not hot, I'm sure the others are dead also. I have the factory manual. I will try to trace these other wires to check and see if some other key on accessories are dead now also. I will go to the local Marine store and locate a suitable dash switch that is water proof. I would sure hate to have that pump go off while on the pad at 90. I will post my results.

Thanks Allen

 

[Dave Hensley]

I feel your pain. Spent the better part of last summer hunting electrical issues on a 225x. This probably will not help you but y 2002 280 has the red w/blue tracer and a black ground with waterproof bullet connectors coming out of the harness bundle just below the starter. When the key switch is on there is 12v across them. The red w/blue tracer does terminate at the aft most relay of the two located below the ECM. Check your ground???

 

[Kerry Cordy]

I think I have heard that the driver that energizes that wire is a common failure point in the ECU. You can either get the ECU fixed which may be pricey, or bypass it for about $30. On my 280, I bypassed it. Ran a dedicated relay to the pump and put a switch on the dash that way I could turn the pump on anytime I wanted. Its pretty easy to do, just wire up a new relay and connect key on 12v from somewhere on your dash to a switch at the dash and use that as the signal to turn on the new relay. Wire the relay direct to the battery thru a 15Amp breaker or fuse(I used a breaker), and then to the pump and you are back in biz.

Can you recommend a water proof switch? I'm concerned about a switch vibrating off while screaming across the lake. A fuel pump switch vibrating off at 90 does not sound like a very nice boat ride?

Thanks, Allen

 

[Kerry Cordy]

I feel your pain. Spent the better part of last summer hunting electrical issues on a 225x. This probably will not help you but y 2002 280 has the red w/blue tracer and a black ground with waterproof bullet connectors coming out of the harness bundle just below the starter. When the key switch is on there is 12v across them. The red w/blue tracer does terminate at the aft most relay of the two located below the ECM. Check your ground???

Dave, I will check the ground.

 

[Dave Hensley]

I hate extra switches in the boat. Just means another hole. You could pick up 12v when the key is turned on from the ignition harness or go to your accessory toggles from the factory. Most of the time there is an open side on one of them. Just remember the wire going to your fuel pump relay can be very small, 16 ga, as it is carrying very little load.

 

[Kerry Cordy]

You guys are not going to believe this. Today I went to start my research on the boat again. I went to the front of the boat to put the boat in neutral, looked down and the kill switch was in the off position. Flicked it on and the pump comes on when the key is in the on position. I feel like a dumb ass, but very excited and relieved I'm back in business. As an interesting note I started checking everything and the big spring that goes from the head forward to the big aluminum arm was broken and just hanging there. Kinda Bizzare. Where is a good source for such a strange part?

Thanks again for all the help, Allen

 

[silverbullet02]

Glad you're back running! You aren't the first one to be had by the kill switch, lol!

 

[Bobalouie]

www.boats.net has everything

 

[Kerry Cordy]

Thanks Bob