Electrical Guru's needed!

26Scarab502 · 11-07-2009, 04:56 PM

I just replaced all my gauges on my Scarab 26, and now the the motor will not run. It turns over but no spark, possibly no fuel. Is there a wiring schematic available where I can verify my connection? I know that that most of the wires coming form the motor come from the right of the dash over to the left where the ignition is. Does the power for the coil come through the volt or hour meter? Any help would be greatly appreciated.

whoya · 11-07-2009, 06:48 PM

Wiring Colors for MerCruiser
NOTE: Color codes listed below DO NOT apply to fuel injection system harnesses.
BIA COLOR CODE AND ABBREVIATIONS WHERE USED
BLACK (BLK) All Grounds
BROWN (BLU) Reference Electrode - MerCathode
ORANGE (ORN) Anode Electrode-MerCathode
LT. BLUE/WHITE (LT BLU/WHT) Trim - ”Up” Switch
GRAY (GRY) Tachometer Signal
GREEN/WHITE (GRN/WHT) Trim - ”Down” Switch
TAN (TAN) Water Temperature Sender to Gauge
LIGHT BLUE (LIT BLU) Oil Pressure Sender to Gauge
PINK (PNK) Fuel Gauge Sender to Gauge
BROWN/WHITE (BRN/WHT) Trim Sender to Trim Gauge
PURPLE/WHITE (PUR/WHT) Trim - ”Trailer” Switch
RED (RED) Unprotected Wires from Battery
RED/PURPLE (RED/PUR) Protected (Fused) Wires from Battery
RED/PURPLE (RED/PUR) Protected (+12V) to Trim Panel
ORANGE (ORN) Alternator Output
PURPLE/YELLOW (PUR/YEL) Ballast Bypass
PURPLE (PUR) Ignition Switch (+12V)
YELLOW/RED (YEL/RED) Starter Switch to Starter Solenoid to Neutral Start

whoya · 11-07-2009, 07:25 PM

Dash wiring

whoya · 11-07-2009, 07:26 PM

Not sure if its for your year.
I think they stayed the same over the years and models though.

don · 11-07-2009, 09:34 PM

Start off by seeing if you have 12 volts going to the coil and power pack. If you have power for starter check fuel pump is working if it is electrical pump. You should have power if key is on going to coil. You can run a jumper to the coil to see if it starts then trace wires back to ignition to see if you might have crossed a wire on back of ignition.

26Scarab502 · 11-08-2009, 12:02 AM

The boats a 94 with the fuel injected 502. I'll check the Coil power and trace it back good idea. I really wish I would have tagged every wire when i took the dash apart it would have saved the headache. Laziness never pays off.

Audiofn · 11-08-2009, 07:19 AM

Check you kill switch!!!

If that is hooked up correctly and the cap is on then look at your wire that comes from your tach. If you have that going to the wrong location it will not start.

Jon

26Scarab502 · 11-08-2009, 12:35 PM

Will do, Thanks guys for the tips hopefully I can get this done before the decent weather disappears.

GEORGE YURICK · 11-09-2009, 11:17 PM

check to make sure the gray wire (tach signal) is NOT hooked to ground or you will have no spark.....

also check that your kill switch is hooked up properly and not to a ground...

i have seen guys do this before...

26Scarab502 · 11-11-2009, 10:49 PM

Found the problem. It was that there was no power getting to the coil because I used the wrong wire. There were two; purples one went to nothing and the other feeds the coil. swaped wires and fixed a couple of bad grounds to the new gauges and everything work.

Although now when I rev the motor the Tach seems to have a delay where it shows the rpms after I've pulled the throttle back and the oil pressure gauge seems to stick at the last peak pressure and only comes down if I turn the ign. off and back on. If it not one thing its the other, welcome to boating right?

Correction: I took the boat out today before I store it for the winter. The tach problem is that it works fine til I get past 3K then it starts reading completly irradic. Plus its affected by any electrical draw. Example if I'm cruising along at 3K rpms and hit the trim tabs switches the The rpms fluctuate by 1k. It weird I think I had multiple problems and have only address the obvious one. Any one else have this happen to them? I think I might just trace every wire coming from the motor.