What is the impulse limiter for?

[carboncow]

This is a little valve going into the upper manifold and the line runs to the top of the file reservoir under the high pressure pump.

#22 in the diagram.

Just trying to understand what systems can mess with low side pressure beyond pickup/tank check valve and low pressure pump. The former never found on my boat and the later not replaced...yet.

As seen: https://marinepartssource.com/impulse-limiter-volvo-penta-3860290

 

[AllDodge]

Its a one way valve which allows fumes to be pulled out of fuel pump housing, and stops any back fire going other way. If fuel pump tank gets full of fuel it will suck out the excess instead of letting it maybe leak out

 

[carboncow]

Do you ever see them fail in a way that can impact fuel pressures?

 

[AllDodge]

I don't, if they fail fuel starts get sucked in to the intake, but pressure at the rail would not be effected

 

[carboncow]

Thx. I figured a leak in some way would make the idle way worse too. Always something new to learn.