Problems at WOT

andy6374

Lieutenant Commander
Joined
Aug 4, 2005
Messages
1,617
Just recently my 88' 200 HP Mercury has not been able to acheive WOT. What it does exactly: It gets to WOT for 1 second and then backs off. I intially tested for spark in all 6 cyclinders. 3 of the ignition coils were not firing. I tested the stator and found that the blue/white and red/white stator leads had no resistance between them and the red and blue stator leads had the wrong resistances between them, so I replaced it. Then I tested for spark once again and found no spark on the same 3 coils, naturally I suspected the switchbox and replaced it. Now I have spark in all six cyclinders. It started up better than it had in a long time, smooth idle. However, when I took it for a ride I still couldn't acheive WOT. I suspected the remote control key harness, so I disconnected it... didn't work. Then I thought the temperature sender might be grounding out and making my engine think it was overheating when it wasn't. I disconnected it...didn't work. I went back to the ignition. I have CDI trigger and didn't know the proper resistances and wasn't able to test it. I know the trigger controls the advance spark....so maybe it is that. So I was just able to get a good OEM trigger and haven't tried it yet. My question is... Do you think it is the trigger causing my problems or a fuel problem. My fuel line, suction ball pump, and inline filter are all good.<br /><br />Thanks for any comments or suggestions<br />Andy
 

KCLOST

Commander
Joined
Jun 22, 2002
Messages
2,095
Re: Problems at WOT

Don't think it is the trigger... If it was you wouldn't see spark at any speed. <br /><br />You do know that you have two switchboxes, and it's recommended to replace both at the same time if they are the original Merc. boxes. But anyway...<br /><br />What are your WOT (or highest) rpm values?<br />Tank venting ok?
 

andy6374

Lieutenant Commander
Joined
Aug 4, 2005
Messages
1,617
Re: Problems at WOT

Just a quick question for KCLOST's reply, so the trigger couldn't be damaged in a way where it works a lower RPM's but doesn't work as well at higher RPM? IF I had spark on all cylinders, why would you think the other switchbox is bad (unless you are saying this because it is recommended).<br /><br />Anyways I agree with it probably not being the trigger, I just tested it to complete the ignition system testing so I could rule it out. But like I said I don't know the specs. for a CDI trigger.<br /><br />Do you think a faulty fuel pump could be to blame? My vent looks unclogged.
 
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