1990 Mercruiser 4.3..... rpm and speed Problem...

[henry7o7]

hello,
I have a 1990 dynasty cuddy cabin.. I got this boat and took it out on a test run.. It runs great.. 40plus MPH @ 4800 RPM...

it has been sitting for about a year so decided to replace some parts...

Replaced impeller... ignition cap... ignition rotor... ignition sensor (located inside cap) ... thermostat ...

Took it out for a test run and when i put it into gear and go.. it doesn't plan fast well not at all.. does about 30mph after about 2 mins of going.. wot and only does about 3000 rpm..

ANY HELP???

 

[90stingray]

Re: 1990 Mercruiser 4.3..... rpm and speed Problem...

You get a plug wire crossed? Double check everything.

 

[henry7o7]

Re: 1990 Mercruiser 4.3..... rpm and speed Problem...

plug wires correct.. with no load (not in gear) the engine runs fine..

 

[fuzzybob]

Re: 1990 Mercruiser 4.3..... rpm and speed Problem...

Henry, At the top of the forum in the "Adults Only" sticky there is a link that lists a bunch of stuff to check if you're having WOT problems.

I'd go with stingray's advice and double check everything you did..... I know with me it's always simple stuff that screws me. Good luck!!

 

[Bondo]

Re: 1990 Mercruiser 4.3..... rpm and speed Problem...

Ayuh,... If it ran Great before ya fixed it,...
And it Don't now,... Ya screwed up somewhere...

 

[Bt Doctur]

Re: 1990 Mercruiser 4.3..... rpm and speed Problem...

no load, it will red line in rpm with 2 dead cylinders. Check the plug wires in relation to the firing order.

 

[Bbeaz425]

Re: 1990 Mercruiser 4.3..... rpm and speed Problem...

I have a 1991 4.3L that is doing the exact same symptoms (only i didn't change parts) it just started occurring. Please respond to this thread if you pin point your problem, it may be the same issue with me. Thanks!

 

[Bt Doctur]

Re: 1990 Mercruiser 4.3..... rpm and speed Problem...

B, you really should start your own thread so your question dosent get lost.
Start by changing parts like a full tune up, check/replace all filters. Inspect prop for bent blades.
Compression test would be next.