See full version: Yamaha F4A Idle Adjust
By increasing the idle speed, it can be made to idle (very roughly) with the choke half way in, but seems to "choke itself" and die as soon as the revs are increased. And even with the highest idle setting it will not run at all with the choke fully in. [links]
Anyway, the problem I have is that the engine runs fine with the choke fully out - starts first pull, excellent telltail and seems to work pretty well under load. Perhaps slightly rough idling, but not terrible. However, as soon as the choke is pushed in even half way, it dies completely. This is the case even when it has been running for 20 minutes or so and is fully warmed up. [links]
My Yamaha F4A 4 stroke Outboard runs fine at speed but tends to idle a bit slow and can die at idle. Instead of just twiddling as I have (woth other engines) in the past, i thought I would download the service manual and adjust idle speed using the prescribed method.
Attached is the relevant section. It seems to have suffered from poor translation. Can anyone interpret please?
My problem now is that both motors idle at about 600 rpm's. According to my Yamaha owners manual, the low idle speed of these motors should be between 700 and 750 rpm. The problem I am having is that at 600 rpm's the port motor cuts off about 30 % of the time when switching between forward and reverse. Both motors seem to be starved for fuel at 600 rpm, but at 700 they run much smother. [links]
Can someone help me increase the idle setting of my twin yamaha 150's (4 strokes). I recently performed the 20 hr service for the motors (and thanks for all the comments on this site about crush washers,- comments were greatly appreciated - I recently installed a new crush washer). [links]
so , the question is, how hard is it to increase the idle speed of these motors? Is this something that I need to leave to the professionals, or is it something that an average joe with a screw driver can do?
at or near WOT MAP will be close to barometric pressure.
however VACUM will be close to 0"Hg.
gets confusing but I don't program ECU's. here
manifold absolute pressure is the INVERSE of intake manifold VACUM.
That would also explain the occasional stalling, likely has a vacuum leak causing incorrect fuel air mixtures.. [links]
Good luck and please post your findings.. here
Possible it may be a lean sneeze you are trying to explain? [links]
over the years and models I have seen it displayed in PSI,"Hg and "Hg pressure.
gets a bit confusing until you get used to what its trying to tell you.
Locate the idle stop screw, located halfway down the throttle lever, and loosen its lock nut. here
T25 Torx bit with a hole drilled in the center to receive the pin
Hold the throttle arm against the idle stop. Reposition the cam follower so that there is a gap of between 0.00 inch and 0.10 inch.between the roller and throttle cam. Hold the cam follower in this position and re-tighten the cam follower screw. [links]
Loosen the cam follower roller screw, allowing the follower to move without restriction. here
Rest the roller on the throttle cam and turn the idle stop screw until the curved front edge of the throttle cam aligns with the center of the roller. Re-tighten the idle stop screw lock nut. [links]
Has the IAC valve ever been cleaned?
Seems like mine needs it about once every season lately
Worth a try and it's free.
Let some carb cleaner soak into the area with the tabs and blow it dry.
Keep the cleaner away from the o-ring
The other conditions that I've read about that can cause gas in the oil is a motor that is "over-proped" and I believe that some of the 115hp motors have had the rings rotate and allow gas to get by them into the crankcase.
If you do a search for "making oil" you will find many discussions this subject.
There aren't any adjustments for you to make.
I believe that all the adjustments are made by the CPU and what the sensors are telling it.