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I have a 2001 70hp 4 stroke Suzuki with 800+ hours. Problem is: From neutral to forward, or reverse, rpm decrease from 650 + or - to 450 or so & when you apply more throttle, it stalls. Does not do it everytime but enough times to make it a bother. Local dealer has had it on computer, injectors et all check out fine. We have replaced spark plugs, both fuel filters, primer ball, checked the tank vent, ran double dose of injector cleaner & a tank of high test. Everything checks out fine but the problem does exist. Any suggestions?? Thanks in advance.
 

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I would if I were in the area but too long a drive from Cudjoe Key. Thanks though.
 

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sparse grey said:
I have a 2001 70hp 4 stroke Suzuki with 800+ hours. Problem is: From neutral to forward, or reverse, rpm decrease from 650 + or - to 450 or so & when you apply more throttle, it stalls. Does not do it everytime but enough times to make it a bother. Local dealer has had it on computer, injectors et all check out fine. We have replaced spark plugs, both fuel filters, primer ball, checked the tank vent, ran double dose of injector cleaner & a tank of high test. Everything checks out fine but the problem does exist. Any suggestions?? Thanks in advance.
I don't know crap about the finer details of Zukes, but I wonder if that 4 stroke has a shift interupter switch and shuts down a couple of cylinders when you shift it? Mercruisers do/did that. They do it to reduce the rolling mass of the engine so it doesn't slam the gearcase everytime you shift it. OMC V6's have one also to shut down 3 cylinders. If that switch is out of adjustment and holding a pair of cylinders out she would fall on her face when bringing the throttle upto quick. I'm just guessing here, but if you've got a manual look for a shift interupter switch or something like that mentioned.. The switch itself will/should be on/in/or near the shift linkage on the engine..possibly the throttle linkages, but they are all close together.

If you find something like this it won't hurt to disconnect it especially if you can dial the idle down some. You'll be looking at the throttle linkages. Look for the idle stop screw, back it out, but the throttle cable throw still controls the idle rpm. You might need to adjust it to lower the idle. I know you are in trouble for a decent Zuke dealer in the Key's, but this could hold you over till you get it back up here without hurting the gearcase.
 

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You may want to have some one perform a cylinder leak down test to check the condition of the valves in the engine. Make sure the engine is coming up to temperature and the thermostat is not stuck open. Also they may want to take a look at the Idle Air Control valve if it is fuel injected. You also may want to test for a leaking fuel injector and verify fuel pressure. Before you have any one do anything don't forget about the basics they are often over looked.
 

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Discussion Starter · #6 ·
Thanks guys for your well thought out replies.
 

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My 2000 25 suzuki was doing the same thing....All it needed was the carbs cleaned and the idle adjusted. Theres a screw underneath the carbs and it adjusts the throttle, occasionally it will loosen.
 
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