Bad IAC valve

[Wickedcummins]

I put new plug wires.. but the rotor and distributor cap have been the same for maybe 3 years.. same as the plugs I believe..

mallory is crap throw in garbage and install OEM

[Wickedcummins]

If you have a durty throttle body then yes a bad IAC will kill the engine. Clean the IAC and throttle body! Your boat dies at top speed?

So it runs fine as long as your not wot ? Or it dies when accel? Dies how? shuts off or starts missing or ? ??? More information of excatly what it does

[h2osk8er00]

When was the last time you put in plugs, wires, and distributor cap and rotor? I did that this year and it made a world of difference in perceived power and ease of starting and idle. Distributor cap was in really bad shape so bought a new Mallory cap and rotor.

I put new plug wires.. but the rotor and distributor cap have been the same for maybe 3 years.. same as the plugs I believe..

[laserfish]

When was the last time you put in plugs, wires, and distributor cap and rotor? I did that this year and it made a world of difference in perceived power and ease of starting and idle. Distributor cap was in really bad shape so bought a new Mallory cap and rotor.

[h2osk8er00]

Also my idle sound rough to me while in the water.. there seems to be a lot of vibrations and noises that shouldn't be there.. it doesn't really do it on dry land that I notice.. Thanks Guys!

[h2osk8er00]

or cause it to "hunt" for idle... but not stall at WOT/top speed


hence IDLE valve.... It is just a bypass for once the throttle is closed to still let air into the motor so it can keep running/idle

If you are at full throttle and slam it into neutral or let off the gas a lot and it stalls you probably have a stuck IAC. ( throttles closes but still needs a lot of air to keep the motor running so IAC opens all the way up if it is stuck lack of air will make it stall)

So I am thinking I must have this problem.. but what other issue would this cause? Could this be my mysterious acceleration problem at start? I'm going to clean my IAC and see what happens.. but I have those exact symptoms... When I bring the boat from a higher RPM back to the Idle position... the boat will stall.. Only if I do it very drastically though.. If i just slow down from a plane or something like that, it is fine.. Glad I found this post though.. May save me from having to bring the boat in to a rip off mechanic.. God Bless Tigeowners.com..

[lohe]

or cause it to "hunt" for idle... but not stall at WOT/top speed


hence IDLE valve.... It is just a bypass for once the throttle is closed to still let air into the motor so it can keep running/idle

If you are at full throttle and slam it into neutral or let off the gas a lot and it stalls you probably have a stuck IAC. ( throttles closes but still needs a lot of air to keep the motor running so IAC opens all the way up if it is stuck lack of air will make it stall)

[jsz]

do those valves go bad or can you clean them. And I thank you for your advice

You can clean them with throttle body cleaner. I've done it several times.

A bad IAC will cause the boat to run rough or stall at IDLE. When there is no throttle, the IAC opens to let enough air through so it won't stall. If it is dirty or clogged, the motor will choke out.

[chpthril]

do those valves go bad or can you clean them. And I thank you for your advice

In my experience (20 years repairing autos), 90% of the time, an IAC related symptom can be cured by cleaning the IAC and the throttle plates. The other 10% is either a bad IAC (usually the ones found on FORD products) or an ECM reflash or PROM change for the old-school ECM's.

[ereed969]

do those valves go bad or can you clean them. And I thank you for your advice

[ereed969]

I am getting so frustrated. I took it to a boat shop and at fisrt they told me it was the fuel pump, and maybe the fuel cooler, and that the IAC vavle was bad. Then they called back and said that they got the fuel pressure where it should be. So they told me that it was just the idle air control valve. But that made no since to me. I thought that was just for the idle. My wife and I are looking at a very glassy lake right in front of our house and can't do anything about it. Very frustrated.

[chpthril]

Nope. It's either a loss of fuel or ignition.

[ereed969]

Could a bad IAC valve cause the boat to die once it is at top speed.