I'm hoping someone alot smarter than me can help me with this. I have a 2001 Evinrude 200 Ficht. When I nudge the throttle into idle or slow trolling position, the engine will rev from below 1000 rpms quickly up past 3500 rpms or until I back down off the throttle. If I don't back off, the rpms will want to keep climbing. It only does this when I try to throttle it at idle or trolling speeds. And this problem seems more prevalent when the boat is out of the water and I'm running the engine hooked to a garden hose. To keep the rpms from revving too high too quickly, I have to constantly adjust the throttle. Does this sound like an engine problem to you or could I just be having throttle cable issues? Anyone have any experience with this type of problem? Thanks.
Engine revving too quickly at idle speed
- Thread starter yokecrew
- Start date
Dave LeGear
Contributing Member
- City
- What's left of Pine Island
- State
- Florida
Hard to say other than you need to get it to the dealer to have inspected before you throw a rod. Let us know what you find...
BarryB
Contributing Member
- City
- Pembroke Pines
Ditto to what PS said.
I will assume you have carburetors instead of fuel injection. If not, then disregard the statement below.
Could be the carbs. may be causing the problem. When you transistion from idle, the fuel circuit changes from the idle jets to main jets. Something is causing that transistion not to happen smoothly.
But, have a mechanic check it out and keep us informed.
I will assume you have carburetors instead of fuel injection. If not, then disregard the statement below.
Could be the carbs. may be causing the problem. When you transistion from idle, the fuel circuit changes from the idle jets to main jets. Something is causing that transistion not to happen smoothly.
But, have a mechanic check it out and keep us informed.
BarryB
Contributing Member
- City
- Pembroke Pines
Mmmm...
Well, that's a horse of a different color.
I know automobiles have throttle sensors that tell the computer the position of the throttle. It's is nothing more than an expensive rheostat. If the throttle sensor wears down in one part, false information will be relayed to the computer.
Perhaps, your outboard has the same type of system?
Well, that's a horse of a different color.
I know automobiles have throttle sensors that tell the computer the position of the throttle. It's is nothing more than an expensive rheostat. If the throttle sensor wears down in one part, false information will be relayed to the computer.
Perhaps, your outboard has the same type of system?
I've been able to get my hands on an Evinrude shop manual. It says the throttle sensor provides a voltage signal to the engine control unit which in turn computes the appropriate throttle valve opening. It can be tested using a digital multimeter. It sounds simple enough to test to see if the sensor is faulty. Replacing it if need be might be something different. This might be as good a place as any to start.
BarryB
Contributing Member
- City
- Pembroke Pines
Correct
The voltage signal varies with the resistence in the throttle sensor.
You should be able to measure (with power off) the resistence of the throttle sensor and the resistence should change with the position of the throttle. As you move the throttle smoothly from idle to WOT, your ohm meter should change resistence smoothly. If the resistence changes suddenly or goes up and down then up again (or in vice versa), that may be your problem.
You will need a helper to control the throttle.
Remember, measure with the engine off and no power. Any power will destroy the ohm meter.
The voltage signal varies with the resistence in the throttle sensor.
You should be able to measure (with power off) the resistence of the throttle sensor and the resistence should change with the position of the throttle. As you move the throttle smoothly from idle to WOT, your ohm meter should change resistence smoothly. If the resistence changes suddenly or goes up and down then up again (or in vice versa), that may be your problem.
You will need a helper to control the throttle.
Remember, measure with the engine off and no power. Any power will destroy the ohm meter.
For a variety of reasons, I have gotten distracted from my boating duties over the last month or so. I finally got around to testing the throttle sensor and if I'm interpreting the results correctly, the sensor seems okay. Using a digital multimeter set on Ohms range of 20K (the ranges on my multimeter start with ranges 200, 2000 and then 20K), the reading with the engine off and throttle in neutral is 6.3 (isn't that number the same as 6300 since the meter is set on 20K?). My Evinrude manual says the Ohms should exceed 3000. As I move the throttle forward and in reverse the Ohms readings increase/decrease steadily. There is no erratic pattern to the Ohms readings as I move the throttle. This data leads me to believe the throttle sensor is okay- if I'm off base or reading these number incorrectly, someone let me know.
If its not the throttle sensor, then what else could be be causing the engine to rev like this? Could it have anything to do with the throttle cables? Could they wear out and cause inaccurate responsiveness in the engine?
If its not the throttle sensor, then what else could be be causing the engine to rev like this? Could it have anything to do with the throttle cables? Could they wear out and cause inaccurate responsiveness in the engine?
BarryB
Contributing Member
- City
- Pembroke Pines
6.3 is 6,300 ohms...
Your assumption is correct about the ohms reading. When the manual says "over 3,000 ohms", does it mean at wide open throttle or idle?
I think the throttle sensor is okay.
In order for a motor to increase rpm, it needs more fuel and more air. If the throttle plates are not moving, but the rpm runs up and down, something else is letting in air. Is there a throttle bypass valve that opens when the motor is cold? I would look at that next.
Your assumption is correct about the ohms reading. When the manual says "over 3,000 ohms", does it mean at wide open throttle or idle?
I think the throttle sensor is okay.
In order for a motor to increase rpm, it needs more fuel and more air. If the throttle plates are not moving, but the rpm runs up and down, something else is letting in air. Is there a throttle bypass valve that opens when the motor is cold?
I would look at that next.
Dave LeGear
Contributing Member
- City
- What's left of Pine Island
- State
- Florida
Time to get it to a dealer who has the correct testing equipment to interpret "all" of the sensors feeding data to this ECU. Actual sensor failure is rare (why many are changed when not needed) but trying to use a meter to take readings and then try to figure out if it correct or not? Not logical, and all the readings in the world can be off the mark if there is a loose ground or weak power supply issue to the ECU or even a simple vacuum leak in the engine that is now present. Then you have a condition that the ECU cannot interpret all the data points feeding into it as needed much less make all the needed engine adjustments which can cause a whole range of strange running conditions.
I have seen simple weak batteries cause engines to run poor and smoke quite a bit (running on limp in mode) since the power input was below the 10.5 VDC most engine ECU's need to operate correctly and make the changes to the air / fuel ratio's at the rate of up to 10 times a second as they are designed to make.
The average end user even armed with a repair manual, is not equipped nor really trained to understand most of those readings Much easier and most times cheaper in the long run... To just get it into the hands of the people who have the training and the tools to see the big picture with these very expensive, computer controlled, fuel the now oil injected engines then try and make repairs on your own These engines are not the carb equipped big chain saws of years past, so much safer to know when to fold the cards and move onto the next project at hand and let the expert call you with their findings and then proceed from that point
I have seen simple weak batteries cause engines to run poor and smoke quite a bit (running on limp in mode) since the power input was below the 10.5 VDC most engine ECU's need to operate correctly and make the changes to the air / fuel ratio's at the rate of up to 10 times a second as they are designed to make.
The average end user even armed with a repair manual, is not equipped nor really trained to understand most of those readings
Much easier and most times cheaper in the long run... To just get it into the hands of the people who have the training and the tools to see the big picture with these very expensive, computer controlled, fuel the now oil injected engines then try and make repairs on your own These engines are not the carb equipped big chain saws of years past, so much safer to know when to fold the cards and move onto the next project at hand and let the expert call you with their findings and then proceed from that point 
