Hello everyone,
I have recently fitted a Suzuki DF50 (made in early 2000s I believe, the plaque is gone, unfortunately) (sold under Evinrude brand) to my boat and I'm having a few issues with the idle speed.
The engine starts fine and runs great under load but it idles at about 1100-1200rpm, which is a bit high for comfortable docking and driving around the harbour.
This is what I have tried so far:
I tried following the procedure from the manual by pinching the IAC hose and adjusting the idle air screw untill the engine spins at about 800-900rpm, however pinching the tube does not affect engine speed at all and the idle screw can be turned all the way in and rpm only drops by maybe 100. From my understanding of the engines air supply system, with both idle screw turned all the way in and IAC valve effectively blocked the engine should run very rough at idle or even stall.
During further investigation I found out that the IAC valve is burned out (reads open circuit on meter) and stuck closed, which is puzzling since the air screw should have an even more pronounced effect then, so I suspected a vacuum leak further down the line. To test for a leak I removed the IAC valve and plugged a smoke tester into the IAC hose leading to the port on the throttle body, however the only smoke I can spot flows back out of butterfly valve (plate looks closed and I dont see any stop adjustment screw or the like).
I have ordered a new IAC valve and will hopefully be getting that on monday but in the meantime I'm hoping that there might be someone here, who might have further ideas/insights...
I have recently fitted a Suzuki DF50 (made in early 2000s I believe, the plaque is gone, unfortunately) (sold under Evinrude brand) to my boat and I'm having a few issues with the idle speed.
The engine starts fine and runs great under load but it idles at about 1100-1200rpm, which is a bit high for comfortable docking and driving around the harbour.
This is what I have tried so far:
I tried following the procedure from the manual by pinching the IAC hose and adjusting the idle air screw untill the engine spins at about 800-900rpm, however pinching the tube does not affect engine speed at all and the idle screw can be turned all the way in and rpm only drops by maybe 100. From my understanding of the engines air supply system, with both idle screw turned all the way in and IAC valve effectively blocked the engine should run very rough at idle or even stall.
During further investigation I found out that the IAC valve is burned out (reads open circuit on meter) and stuck closed, which is puzzling since the air screw should have an even more pronounced effect then, so I suspected a vacuum leak further down the line. To test for a leak I removed the IAC valve and plugged a smoke tester into the IAC hose leading to the port on the throttle body, however the only smoke I can spot flows back out of butterfly valve (plate looks closed and I dont see any stop adjustment screw or the like).
I have ordered a new IAC valve and will hopefully be getting that on monday but in the meantime I'm hoping that there might be someone here, who might have further ideas/insights...