1971 Mercruiser 3.0L Wiring Diagram or Service Manual

[Reelsea]

I know that these are available at boatfix.com but i havent been able to find them on that site. I was wondering if anyone had a diagram or service manual. I just go the boat and it has been sitting for a while and im trying to get it running. Thanks

 

[jeff13601]

Re: 1971 Mercruiser 3.0L Wiring Diagram or Service Manual

If you go back through all of the posts you will see all kinds of links. Look for the topics that you feel cover some of your questions and you will find all kinds of info or just ask away.

 

[Reelsea]

Re: 1971 Mercruiser 3.0L Wiring Diagram or Service Manual

i have been going through them, i just havent found what i need

 

[Don S]

Re: 1971 Mercruiser 3.0L Wiring Diagram or Service Manual

Your not going to find a wiring diagram or manual from boatfix, there are a couple of newer engines they have manuals for, but nothing even close to that old. Most of their online manuals are for drives.<br />The color codeing was also different back then, what are you trying to figure out?

 

[Reelsea]

Re: 1971 Mercruiser 3.0L Wiring Diagram or Service Manual

Im having a problem with the ignition shorting out, im not getting any spark, now keep in mind the boat has sat for a few years, but im nearly positive something is shorting, i did a continuity check from the ground wire for the engine, on both the hot and ground sides of the ignition coil, and picked up continuity with the key in both the on and off position. The solenoid on the motor is locked up and needs to be replaced but that wouldnt cause the short i dont think. Im going to be taking the engine out of the boat at some point and that is another reason i am looking for it. Also there are a few wires that are unconnected that should be but im not sure where they connect to, they could be for the motor itself or for another accessory on board, im not sure yet, they were not attached when i bought the boat.

 

[leetbeef9999]

Re: 1971 Mercruiser 3.0L Wiring Diagram or Service Manual

Don S<br /><br />Please check out leetbeef9999 question on May 24<br /><br />Thanks<br /><br />Need your help...<br /><br />P.S. Will send plane to pick you up : -))

 

[Dunaruna]

Re: 1971 Mercruiser 3.0L Wiring Diagram or Service Manual

Reelsea, I can't help you with the diagram but I may be able to help with the short. First you will need to make a very simple tool. You'll need a headlight globe (halogen) and some wire, wire it up like this - <br /><br />

<br /><br />Disconnect the negative battery cable, connect the wires from the globe between the negative battery post and the disconnected cable. At this stage your electrical system is disconnected and you cannot do any damage.<br /><br />If there is a short anywhere, the globe will illuminate - the more intense the light the less resistance in the short. In other words, if it's mega bright - it's a major short, if the light is dim then it's a minor short.<br /><br />Now the fun starts, start probing and wriggling wires/looms/connections etc. Disconnect plugs and reconnect again. Turn ignition on and off - you get the picture. When the light goes out you've found your short. For instance: If you disconnect the starter solenoid terminal and the light goes out - you've got a faulty solenoid.<br /><br />You CANNOT cause any damage testing this way.<br /><br />Aldo

 

[Reelsea]

Re: 1971 Mercruiser 3.0L Wiring Diagram or Service Manual

does the bulb have to be a halogen? Also i have a multimeter if there is a way to use that to my benefit testing this

 

[Dunaruna]

Re: 1971 Mercruiser 3.0L Wiring Diagram or Service Manual

I have worked alone for 20 years and sometimes I need to get creative. If I'm 20ft away from the multi-meter I can't see it, but I can see the light intensity of a halogen globe.<br /><br />Also a halogen globe won't blow with a dead short, a normal incandecent will.<br /><br />Once you have found the circuit that is the cause of the short you can then start probing specific areas with a mult-meter (OHMs).<br /><br />Aldo

 

[tommays]

Re: 1971 Mercruiser 3.0L Wiring Diagram or Service Manual

dunaruna<br /><br />that is brilliant no more trying to see the meter<br /><br />tommays

 

[Reelsea]

Re: 1971 Mercruiser 3.0L Wiring Diagram or Service Manual

ahh cool thanks yea i know getting to see those multimeters can be tough, i had some business to take care of today but i will try and pickup a bulb tomorrow and test it to see what happens..<br />Thanks for your help i really do appreciate it

 

[Dunaruna]

Re: 1971 Mercruiser 3.0L Wiring Diagram or Service Manual

Use heavy wire, 10 guage or heavier.<br /><br />It is a very cheap way to point you in the right direction - and you CAN'T fry anything in the process!<br /><br />Oh, and one final thing - don't stare at the light

 

[Reelsea]

Re: 1971 Mercruiser 3.0L Wiring Diagram or Service Manual

lol, i thought that was how i was supposed to tell how bright it was =)

 

[Reelsea]

Re: 1971 Mercruiser 3.0L Wiring Diagram or Service Manual

soooo yea, i decided to do a compression test the other night......<br />cylinder 1 - 140psi (great)<br />cylinder 2 - 125psi (good)<br />cylinder 3 - 30psi (holy ****)<br />cylinder 4 - 30psi (wheres my beer?!?!?!)

 

[Dunaruna]

Re: 1971 Mercruiser 3.0L Wiring Diagram or Service Manual

So you fixed the starter motor? Was that the short problem?<br /><br />It would seem that a short is the least of your problems. Time to tear it down?

 

[Reelsea]

Re: 1971 Mercruiser 3.0L Wiring Diagram or Service Manual

you know i started kicking it over, and i think the switch just needed some use, i still have a problem getting spark on the ignition coil, but i threw some marvel mystery oil into the cylinder tonight, im gonna see if i can get that down in the piston rings, see if it will free them up if that is the problem, but as far as the spark goes, im not sure yet, im going to be re-wiring the motor and the whole boat actually in the somewhat near future(im in college so i have to save up some money), i have to put a new floor in the boat as well, but that shouldn't be too big of an issue, i have done it before, the thing i havent done is pull an i/o motor, has anyone pulled one, specifically a 3.0L, that has any helpful hints, i know there are 3 motor mounts, but im not sure as to the transmission yet, havent had a chance to get a real good look at it.

 

[jeff13601]

Re: 1971 Mercruiser 3.0L Wiring Diagram or Service Manual

You need to pull the outdrive first. Then unhook the motor mounts, gas line, wires etc and lift her out

 

[Reelsea]

Re: 1971 Mercruiser 3.0L Wiring Diagram or Service Manual

I was hoping i could get away without having to pull the outdrive, is that feasbile, maybe a harder to do but feasible?

 

[Don S]

Re: 1971 Mercruiser 3.0L Wiring Diagram or Service Manual

You may be able to get the engine out with the drive still on, but you can't put it back in without pulling the drive or you will end up damaging the coupler while trying to get all the parts back under the rear motor mounts. Plus after R&Ring and engine you MUST check the alignment or you will again damage your coupler.<br />And they require an engine pull to replace.

 

[Reelsea]

Re: 1971 Mercruiser 3.0L Wiring Diagram or Service Manual

lol, sooo looks like im in for some serious fun then huh?