| Author |
Message |
    
Brae
Member
Username: bman410
Post Number: 9
Registered: 05-2008
| | Posted on Friday, May 30, 2008 - 08:50 pm: | 
|
i have a 1987 75hp mariner two stroke 3 cylinder motor. I checked the compression(i think) and all 3 read at 7 psi.This doesnt seem correct,is this too low? I must have done something wrong. Also while I had the hood cowl off I was looking around and found that the white/black wire from the switch box wasnt hooked up to anything. When I checked the wire diagram it says that it is supposed to be hooked up to the trigger assy.Will this be the cause of it starting but cutting back off? |
JB
Senior Member
Username: beckerjs
Post Number: 1011
Registered: 11-2005
| | Posted on Saturday, May 31, 2008 - 09:23 am: |
|
might want to borrow a compression tester and try it again. simply screw it in the plug hole and spin engine over with ign off. You don't need to worry about the wire if you only have 7psi |
Brae
Member
Username: bman410
Post Number: 10
Registered: 05-2008
| | Posted on Saturday, May 31, 2008 - 01:20 pm: |
|
well how do you turn ignition off. I thought you had to unplug the spark plug wire. Is that correct? If not did I damage the ignition or something else |
JB
Senior Member
Username: beckerjs
Post Number: 1012
Registered: 11-2005
| | Posted on Saturday, May 31, 2008 - 02:54 pm: |
|
pull the safety switch (man overboard switch) to kill ign. Or, ground the black/yellow wire at the switch box, this will kill the spark when using the key. Or, with key off jump the starter relay with a push button style switch.
You do not want the switchbox loaded without a chance to discharge properly, damage may occur. At $250 each it can get expensive. Compression vidio
http://www.themarinedoctor.com/CandS.wmv |
Brae
Member
Username: bman410
Post Number: 11
Registered: 05-2008
| | Posted on Saturday, May 31, 2008 - 10:21 pm: |
|
how do i ground the black /yellow wire at the switch box? |
JB
Senior Member
Username: beckerjs
Post Number: 1013
Registered: 11-2005
| | Posted on Tuesday, June 03, 2008 - 08:58 am: |
|
take a wire and connect it to grd(engine case), take the other end and hook it on to the blk/yl wire. |
Benjamin Jones
Member
Username: benjamin_jones
Post Number: 40
Registered: 04-2008
| | Posted on Saturday, June 21, 2008 - 04:36 am: |
|
Hi there!
Always remember to never attempt starting the motor if plug leads are not grounded. This will cause reverse discharge back to coils and potentially cook the electronics... $$$$$$$$$
Find a suitable device, available at most boat dealers, or make one yourself. Re-post a question as how to make one, the Vet's will respond quickly.
Good luck!
From a cold, wet and wintery Johannesburg in South Africa,
Regards!
Benjamin. |
