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1987 DT115 throttle issue
I have a 1987 DT115 that had been sitting for 2 years. Cleaned tank, carbs, fuel filter and blew out gas lines. Has new water pump. It starts good and has no issues with half to full throttle until you are actually on the water in gear. It will run great for a 100 yards or so then with the throttle wide open the rpms will drop to about 2000 and will not go back up. It will run the rpms with the idle lever even though it won't with the gear shift throttle. I have checked the fuel pump and can see nothing wrong with the diaphram other than age. Any ideas?
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dt115, 87, running issues
First off, it is not good to race/ rev the motor in neutral with no load. It runs good for first 100 yds, then drops? Did you pump bulb to see if needed more fuel again?
When you inspected the pump did you see the small check valves? They are 2 small clear plastic discs below the diaphragms? Many times they break and fall apart, check those, they make the fuel pump work. And you can't buy them without buying the entire pump, so if they look good don't disturb them.
Have you tried pumping the bulb anytime while motor dies?
Do you have a repair manual for you motor?
your model has a throttle position sensor, a gear counting coil, pulse coils for each cylinder. We may need to test each of these by the manual.
Get back and let us know.Last edited by Solarman; 10-02-2014, 10:25 AM. -
Pumping the bulb had no effect on performance. The motor doesn't die it will just go to about 1/2 - 1/4 throttle. I only saw one disc in the pump. I will recheck ASAP. I also have a manual and will check the items you listed. Will let you know what I find. Thanks for the help.Comment
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dt115, 87, running issues
The 2 discs provide the positive & negative pressure needed to push the diaphragms in and out, causing the pump to work.
If it drops RPMs as you say, are there any codes popping up on the monitor gauge when this happens? I'm not sure if your monitor has a check engine light that may blink so many times to indicate a malfunction of sensor(s) , but the motor does have sensors and temp light on your oil monitor gauge, I believe. Can you tell what other features your monitor has? Should have ”temp” and ”oil”, then may have ”rev limit”, and possibly ”check engine” light? Without starting motor, can you turn key to on, to see if any lights that are on the monitor are flashing, if so, how many times? It should repeat 2 sets of flashes if it does this?
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