Hole shot hesitation

[DeepCMark58A]

Have a 1990 115hp oil injected Mariner. Motor starts right up idles well never runs rough. The only issue when I hammer the throttle there is a 1-2 second bog before the rpms go up. This is after the motor is warmed up and happens every time. Carb adjustment. Think it is rich or lean?

 

[racerone]

This motor only runs on the top 2 cylinders at idle.----It takes exact set-up on linkages / accelerator pump to transition to 4 cylinders at around 1800 RPM

 

[airshot]

This motor only runs on the top 2 cylinders at idle.----It takes exact set-up on linkages / accelerator pump to transition to 4 cylinders at around 1800 RPM

Boy that sounds like trouble waiting to happen...was this system reliable????

 

[racerone]

They built it for many years.-----Very little fuel goes into the bottom 2 cylinders at idle.----Carburetors ( bottom 2 ) kick in again at around 1800 RPM.----Actually quite simple and reliable.

 

[DeepCMark58A]

Good info thank you it's normal. Makes sense now

 

[Dave1027]

The bottom two carbs don't have an idle circuit. Instead there is an accelerator pump connected directly to the bottom two cylinders that gets them going when throttling up.

You can do a basic test of the accelerator pump function while idling on muffs. Simply depress the accelerator plunger with a screwdriver. That should cause the bottom two cylinders to fire making the RPMs jump.

 

[DeepCMark58A]

There is no doubt the other cylinders are kicking in but there is a slight hesitation.

 

[Dave1027]

There is no doubt the other cylinders are kicking in but there is a slight hesitation.

Well, the bottoms would eventually kick in without the accelerator pump. The accelerator pump just makes them kick in sooner. That's why I brought it up.

 

[Faztbullet]

Make sure bottom injectors are clean...