Hi
I have an evo 4 with around 500hp that runs great on idle and low rpms. But as soon as i get on throttle and the boost comes on(3500-4000rpm), it starts to fuel cut. I have cleaned the fuel filter and the fuel pressure is around 4 bar at idle. My guess is that the fuel pressure drops as soon as i hit boost but i don’t know why. Could it be the fuel pump? Or do you have any other ideas?

 

is your fuel system upgraded?

 

Hej på dig,

Is the vacuum/pressure hose connected to the fuel pressure regulator?

 

Is there a possibility that you may be confusing fuel cut with spark blowout? Pretty common on these cars if you have a weak ignition system and a large spark plug gap.

 

I have already checked the sparkplug gap, which is good. The fuel pumps are upgraded and both work. And the vacuum hose is connected to the fuel pressure regulator. I’m thinking that it might be a clogged fuel filter, and the fuel lines are not really connected like they should so i will check that.

 

Did you get an upgraded fuel siphon or drill out the stock one? If its not then fuel pressure will be high as **** in the tank and over run the regulator and injectors in boost. Also if you have a walbro 450 make sure its the high pressure 274 model, the 267 model bypasses at like 80psi.

 

That's not how that works.

 

Tell me more about how I fixed the issue on my own car......

The in tank pressure was too high causing the injectors to fire incorrectly, causing regulator pressure to be 70-80 psi at idle, and causing the in tank pump to bypass when in boost. All because the stock siphon diameter, on the stock hanger was too small to flow the amount of fuel the pump was trying to supply.