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dooger
12-11-2008, 10:02 AM
I winterized my boat this week. I hooked a hose up to the fake a lake and started the engine. The engine immediately jumped to 3.5 to 4K RPMs. Woops. I must have pinched a wire while while working on installing the backing plates. I had removed the throttle lever while working on the drivers side of the boat. I also was working under the "dash" area when installing the backing plate for the front leg of the tower on the starboard side, perhaps i pinched a wire when re-installing the kick panel? I checked the linkage and the "butterflies" are closed in the throttle bodies. THere is mucho fuel being sprayed though! I tried removing one of the electric injector clips to see if this would slow the revs down, no joy. Still enough fuel spraying through the other injector to keep the engine revving.

What would cause the engine to rev like this? Any ideas where to look. I couldn't see any loose wires. The throttle linkage is mechanical and i feel the fuel problem is electric.
Thanks for any help.

JimN
12-11-2008, 10:40 AM
Well, you could remove the plate to inspect what may be pinched. Do you have Perfect Pass or another system like it?

The MAP sensor tube could be kinked/pinched and that may be causing the ECM to increase fuel delivery but even if it thinks the vacuum is at 0 KPa, the TPS is in charge at idle and just dumping fuel will flood the engine if it doesn't get more air. The IAC (Idle Air Controller) could be open too much and this would do the same thing as opening the throttle. However, all of the engine control is on the motor and other than the tach wire, I don't think anything is directly connected to the ECM, other than the MDC box for the gauges.

You'll need to remove any panels that were out when you were working on it. You said that you removed the throttle lever- look under the gunwale and see if the lever(s) have been catching the wires and make sure ir's range of motion is the same as before.

dooger
12-11-2008, 11:56 AM
Hello Jim, OK, thanks for the tips. I had to adjust the throttle linkage and perhaps i messed something up there. When i re-installed the cables the throttle linkage was keeping the butterflies open and i adjusted it to shut them... Could this be causing the trouble? Should the butterflies be open a smidge? Hope this makes sense. But now that i think about it, the butterflies being closed could act like a choke on a motorcycle carb and increase the revs. Oh well i now know where to look starting with the throttle linkage first and the IAC second.
Thanks Again.

JimN
12-11-2008, 12:11 PM
Hello Jim, OK, thanks for the tips. I had to adjust the throttle linkage and perhaps i messed something up there. When i re-installed the cables the throttle linkage was keeping the butterflies open and i adjusted it to shut them... Could this be causing the trouble? Should the butterflies be open a smidge? Hope this makes sense. But now that i think about it, the butterflies being closed could act like a choke on a motorcycle carb and increase the revs. Oh well i now know where to look starting with the throttle linkage first and the IAC second.
Thanks Again.

There is no reason for you to adjust the linkage unless the cable stretched. If it worked before you pulled it apart, it should have worked after, without adjustment. The throttle body has a fixed stop that shouldn't be changed. It's set at Rochester, for a specific amount of air flow and the ECM program is based on how much it flows. Closing the throttle plates decreases intake and decreases RPM. There's no mechanical choke on an injected engine, only the IAC and throttle plate(s). There's a collar that keeps the throttle cable on the TBI's throttle lever- slide it back and remove the throttle cable. Start the motor- it should isle at about 600 RPM. If it's higher, the adjustments you made need to be reversed so it's the way it was before. If you adjusted anything on the throttle body, change it so your idle speed is where it was- use the paint lines to see where the throttle stop needs to be, if you adjusted that. There's nothing else that you can change (without breaking something) that will affect the idle speed.

This is not a motorcycle and it doesn't have a simple carb. A choke is only for cold temperature startup and serves no other purpose. On your motor, that's all controlled electronically.