Air intrusion

[Coyote6985]

Hey anyone know why my clear air intrusion symptoms nearly go completely away when the weather is warm? when its cold it idles like hell but when the weather, not the engine is warm it runs well enough to only have a power surge at 2500 rpm. im kinda stumped at this point

 

[Austin86250]

yes I’ve had air intrusion do that before, but the surge at 2500 sounds more like a weak fuel pump

 

[Nero]

Could also be a leaking injector return cap. What have you tried fixing so far?

 

[Coyote6985]

i have bypassed the tank selector valve, done all the cap o rings, deleted my water separator for now, and replaced the rubber line on my mech lift pump

 

[Coyote6985]

i dont think a weak lift pump should cause a huge power boost. now the stuttering yeah

 

[franklin2]

i dont think a weak lift pump should cause a huge power boost. now the stuttering yeah

It can. The injection pump uses the incoming fuel pressure to adjust the timing inside the pump. When the incoming fuel pressure starts going up and down, it can cause the timing to go up and down which can cause the surging/power boost.

The most common problem I have seen that causes this is the sending unit where it comes out of the tank will get pinholes in it, causing it to suck a tiny bit of air.

 

[Coyote6985]

It can. The injection pump uses the incoming fuel pressure to adjust the timing inside the pump. When the incoming fuel pressure starts going up and down, it can cause the timing to go up and down which can cause the surging/power boost.

The most common problem I have seen that causes this is the sending unit where it comes out of the tank will get pinholes in it, causing it to suck a tiny bit of air.

oh okay thank you! that makes sense. ill check that out