1995 Mercruiser 4.3 wiring nightmare

[1970PM1700]

Hi folks.

I am working on a 1995 Century bowrider with a 4.3 carbureted Merc I/O. It has a brand new motor in it, but the problem is that the guy who installed the motor quit at bolting it in. There are wires everywhere and nothing is labeled. So far I've managed to figure out the slave solenoid, starter solenoid, main circuit breaker and alternator wiring... but I can't get the fuel pump to come on when the key is turned on, and none of the gauges are working as they should. The engine will turn over when the key is turned to start... sometimes. The trim pump, bilge pump, lights and blower are working.

Can anyone hook me up with some wiring diagrams or tell me where to find them?

Thank you!

 

[Bt Doctur]

Re: 1995 Mercruiser 4.3 wiring nightmare

Try this link and if it`s not correct there are other manuals in the Adults Section
http://www.boatfix.com/merc/Servmanl/18/18covr2.pdf

 

[1970PM1700]

Re: 1995 Mercruiser 4.3 wiring nightmare

Try this link and if it`s not correct there are other manuals in the Adults Section
http://www.boatfix.com/merc/Servmanl/18/18covr2.pdf

That's the correct manual alright, but there's only 5 pages of it!

 

[Don S]

Re: 1995 Mercruiser 4.3 wiring nightmare

Here is the manual in a single download.
http://www.4shared.com/file/137828160/8c09b96d/Service_Manual_18.html

You can go here for a manual for your drive also
http://forums.iboats.com/showthread.php?t=251571

 

[180shabah]

Re: 1995 Mercruiser 4.3 wiring nightmare

You should now have the diagrams, but the fuel pump does NOT run with the key in the on position. It is powered in the start position, and after the engine starts it gets power from the oil pressure switch.

 

[zbnutcase]

Re: 1995 Mercruiser 4.3 wiring nightmare

And make sure you DO have an oil pressure switch in the pump circut! It will be screwed in the block just above oil filter. 'nutcase

 

[1970PM1700]

Re: 1995 Mercruiser 4.3 wiring nightmare

Is it possible to find a replacement to the original oil pressure switch? This one has been replaced with a unit that only has one connection point on it.

 

[180shabah]

Re: 1995 Mercruiser 4.3 wiring nightmare

You can gat a new switch at any auto parts store - pretty cheap too.

 

[Don S]

Re: 1995 Mercruiser 4.3 wiring nightmare

Is it possible to find a replacement to the original oil pressure switch? This one has been replaced with a unit that only has one connection point on it.

You could also be looking at the alarm sender, it only has one wire. Many engines have 2 switches and 1 gauge sender. So you have to be able to determine which one you are looking at.