| Author |
Message |
    
Kirk Bawiec
Member
Username: smplsoft
Post Number: 55
Registered: 06-2009
| | Posted on Wednesday, August 12, 2009 - 06:24 pm: | 
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I have a 1982 Mercury 70hp 3 cyl 2 stroke sn 6164457 and I think I have a weak spark on cylinder #1. These are NGK BUHW surface type plugs. What kind of spark should I be seeing? With engine runing I disconect cylinder 1 and engine continues to run but both 2 and 3 die if disconnected. |
JB
Senior Member
Username: beckerjs
Post Number: 1827
Registered: 11-2005
| | Posted on Thursday, August 13, 2009 - 09:07 am: |
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you should see the same spark on all 3, swap coils and see if it moves with the coil. Also is it getting gas to the top plug, clogged carb? |
He
New member
Username: wilplum
Post Number: 1
Registered: 08-2009
| | Posted on Thursday, August 13, 2009 - 09:17 am: |
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can you use a different throttle conrol and key assembly with the 50hp mercury thunderbolt.(control box)serial#4417120 |
JB
Senior Member
Username: beckerjs
Post Number: 1828
Registered: 11-2005
| | Posted on Thursday, August 13, 2009 - 09:36 am: |
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He, on the merc main page you will see START NEW DISCUSSION, you should open a new thread. Yes you can use a different box but it needs to have the right wire configuration for your engine. Yours should plug into the side of the engine, the next style plugs into the engine under the cowl with a different harness end.
edit, I thought you gave us the engine serial number. If your engine is older than 1980 it has the old style plug |
Kirk Bawiec
Member
Username: smplsoft
Post Number: 56
Registered: 06-2009
| | Posted on Thursday, August 13, 2009 - 03:56 pm: |
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JB, the spark that I am seeing is a very very small, ultra thin white spark jump the gap of the plugs. I am thinking that the spark is weak and unable to jump the gap under compresion. Cylinder #1 is wet with gas/oil. Carbs, fuel, fuel pump and reeds are all good. I just rebuilt this engine and I am starting it for the first time. New pistons, bearings, seals and gaskets. This there such a thing as a weak spark? I read somewhere that mercs need a hot wide bright blue spark. What do they mean by this? Hot meaning strong? |
JB
Senior Member
Username: beckerjs
Post Number: 1834
Registered: 11-2005
| | Posted on Thursday, August 13, 2009 - 04:15 pm: |
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here ya go,
http://www.themarinedoctor.com/cgi-bin/YaBB.pl?num=1114482356
or
http://www.themarinedoctor.com/CandS.wmv
download the troubleshooting section and the dva specs here
http://cdielectronics.com/Downloads/tabid/55/language/en-US/Default.aspx |
JB
Senior Member
Username: beckerjs
Post Number: 1835
Registered: 11-2005
| | Posted on Thursday, August 13, 2009 - 04:23 pm: |
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the spark should jump 3/8 to 1/2 inch, bright blue. Try a different plug before tearing into the engine again. |
