JCB 3CX Only runs below 3000 RPM

[more_coffee]

my 2017 JCB 3CX is testing my patience. I fixed a return line issue, then replaced the lift pump and all the filters, but now it's worse!
it won't start without a shot of quick starter fluid. and once running, it shuts off hard the instant I push it past 3000 RPM.

It feels like a massive air leak or fuel starvation, but I can't see anything leaking externally. Since replacing the lift pump and filters, what is the most likely spot for an air leak to get into the system that only shows up under high volume demand?

 

[Brickbreaker]

I'm no expert, but from my research, you should check the fuel tank pickup tube and its seal, as this is a common spot for leaks, especially when the demand is high. Don’t forget to take a look at the connections of the injector return line and the seals on the fuel rail. It’s crucial to bleed the system thoroughly from the tank to the injectors because any air trapped after replacing the filter or pump can lead to the exact issues you’re experiencing. Hopefully, members with hands-on experience can add more insight.

 

[golddigg3r]

Yep, @Brickbreaker is spot-on! Check your fuel pump and injectors for leaks or if they look worn. If you are really pushing the engine hard, these parts might fail, which could cause fuel starvation and your engine to stall.

 

[more_coffee]

done all of that, guys, but still it's not working like normal. I'll try to install clear fuel lines on the suction side of the system later, to inspect for air bubbles while the engine is running

 

[Alan]

That’s a smart move. The clear lines should help you catch any hidden air problems more easily. Keep us in the loop about what you discover, this one’s definitely a tough nut to crack.