Hello all, here is my first post in your forum.
I have a 2000 Suzuki DF70 and have consistent hard starts when the engine is cold. I have gotten a service maunal and read a bit on the internet and may have the problem narrowed down. Tell me what you think.
Essentially the motor will require allot of turning over before it fires up, almost enough to run the battery out of juice. when it starts to fire, it starts off with a single pop, then gradually increases until it starts. Then the motor runs perfectly (as far as I can tell) for the rest of the day, including restarts even if it is off for an hour or so.
It appears as if I have good spark and fuel pressure in the delivery pipe. So here is a fairly concusive test - I pulled the boat out after setting a week, removed the IAC Valve to permit full airflow into the intake manifold and the motor started instantly.
This is what I know about the IAC Valve - when the motor is cold, the duty cycle for the selenoid is suposed to be 100%, then when the motor is warm, the duty cycle is reduced to 20%. At startup and Idle/trolling the throttle body is essently closed off, the airflow comes from the bypass and the IAC Valve. The bypass is regulated with a set-screw and should allow for about 600 rpm's without any air from the IAC valve, when you add the 20% airflow from the IAC after warmup you get about 700 rpm's, then the IAC increases and decreases to maintain that perfect 70 rpm's.
So it appears as if I am not getting enough air through the IAC valve at a cold start - but the question is:
how do I know if the problem is the IAC Valve, or the ECM, or bad wiring or connector, or a sensor like the MAP sensor. In fact, there are 4 sensors that provide info for the operation of the IAC Valve.
Again, does any one have an opinion on this condition, or have you seen this before?
Thanks so much, from a new forum member.
I have a 2000 Suzuki DF70 and have consistent hard starts when the engine is cold. I have gotten a service maunal and read a bit on the internet and may have the problem narrowed down. Tell me what you think.
Essentially the motor will require allot of turning over before it fires up, almost enough to run the battery out of juice. when it starts to fire, it starts off with a single pop, then gradually increases until it starts. Then the motor runs perfectly (as far as I can tell) for the rest of the day, including restarts even if it is off for an hour or so.
It appears as if I have good spark and fuel pressure in the delivery pipe. So here is a fairly concusive test - I pulled the boat out after setting a week, removed the IAC Valve to permit full airflow into the intake manifold and the motor started instantly.
This is what I know about the IAC Valve - when the motor is cold, the duty cycle for the selenoid is suposed to be 100%, then when the motor is warm, the duty cycle is reduced to 20%. At startup and Idle/trolling the throttle body is essently closed off, the airflow comes from the bypass and the IAC Valve. The bypass is regulated with a set-screw and should allow for about 600 rpm's without any air from the IAC valve, when you add the 20% airflow from the IAC after warmup you get about 700 rpm's, then the IAC increases and decreases to maintain that perfect 70 rpm's.
So it appears as if I am not getting enough air through the IAC valve at a cold start - but the question is:
how do I know if the problem is the IAC Valve, or the ECM, or bad wiring or connector, or a sensor like the MAP sensor. In fact, there are 4 sensors that provide info for the operation of the IAC Valve.
Again, does any one have an opinion on this condition, or have you seen this before?
Thanks so much, from a new forum member.
