Engine shuts down when i tap gauges

Chrisvr6

The previous owner installed new gauges in my 236 captiva with 454 mag. I tapped on the water temp gauge (diagnosing different issue)  while running the motor on muffs and it shut down. It won't restart until i tap the right spot on the dash. Which gauge would shut down the motor like that? I did have a mysterious shut down problem last season while underway. Could this be it? 

212rowboat

I'd be pulling the dash panels off and looking closely at wiring harnesses... the only thing, in my mind, it could be is an exposed wire on your key switch, and another exposed wire allowing a ground to happen. 

i bet it would be fun trying to operate at speed with that issue.

Chrisvr6

i just don't get how a gauge would make the motor shut down. Crazy. 

212rowboat

i doubt it is... I'm thinking an exposed ground is tapping an exposed lead on your ignition switch, interrupting it, and powz, engine dies.

Chrisvr6

Thanks. Will check. That vhf radio is making the depth finder do crazy stuff when its running too. First thing will be to disconnect vhf radio. 

craigswardmtb

I had a similar issue where I ran some wiring to the ignition switch for the bow thruster I installed.  A single strand from the hot wire was outside the ring terminal I installed and found its way over to the other power on hot wire/lead.  So when I turned the key to the on position, not the start position, it cranked the starter continuously.  I wouldn't be surprised that when they installed the gauges, a wire was run to one of the ignition switches, and you have a stray wire making contact with a lead on your ignition switch, as Drew mentioned.

MarkB

Yeah, the only thing that will do that up at the helm is interference with the ignition. The bad news is that doesn't sound too good, that a tap can cut the engine. But the good news is that it should be easy to fix.

Chrisvr6

It was the craziest thing. Tapped the water temp gauge with just two fingers. Then it was intermittent and hitting different places on the dash. 

Chrisvr6

So, did some digging behind the gauges. Purple wire on the oil gauge was loose and almost off the post. Seems ok now.

aero3113

That's a nice and easy fix!

Chrisvr6

is there a feature that kills motor if oil psi is zero?? 

raybo3

Glad you had a nice easy fix..

MarkB

Chris, the gauge only provides feedback on what the engine is doing, it does not serve any function to keep the engine running. There has to be some kind of short to the ignition, or even a loose wire. If you have things open, I would dig further.

Chrisvr6

My mechanic said "yup, that'll do it". He said the purple wire is daisy chained throughout and that's the ignition circuit. 

JC290

Your mechanic is correct

212rowboat

I thought the purple wire was the ignition monitor, as in the RPM gauge... But anyway, if something interrupts the ignition continuity, it ain't gonna run no matter what that is... You're just lucky it was at the terminal rather than in the pulls... That would be a monstor to track down.  

Chrisvr6

but the purple wire goes through each gauge and the ignition. 

Chrisvr6

and to think i tapped the water temp gauge with two fingers,  one time, diagnosing my low water temp. 

Chrisvr6

it is. 

MarkB

So the live on the ignition runs through the gauges. I guess if you think about it, the gauge lights only run when the ignition is on, kind of makes sense.

JC290

That is the way it was on my old 242fv

frodo13056

My guess is that your issue is at the tach. The tach simply reads the "pulses" from the distributor ( or brain box that controls spark) and if you ground the hot wire from the tach, you ground out your spark circuit. Emergency kill switches ground the distributor hot circuit so you have no spark. Many alarm systems use a relay that grounds the spark circuit if the alarm is actuated to prevent someone from hot wiring and starting the engine.