Too high fuel pressure

[KieranA]

Hi everyone,

I have a C117 CLA 220cdi and have been experiencing what seems like wayyy too high fuel pressure. I replaced the leak off pipes due to having a fuel leak from a seal, when I removed the leak off pipe fuel was pouring out for a good few minutes probably about a litre of fuel and i removed the fuel cap to try and relieve some pressure and fuel started coming out the fuel cap too. I let it run up for a bit and drove and checked it and found that cylinder 4 leak off pipe seal (closest to HP fuel pump) was bubbling. Anyone had anything similar to this? Possibly a LP or HP fuel pump? Thanks in advance

 

[Matej123]

Hi everyone,

I have a C117 CLA 220cdi and have been experiencing what seems like wayyy too high fuel pressure. I replaced the leak off pipes due to having a fuel leak from a seal, when I removed the leak off pipe fuel was pouring out for a good few minutes probably about a litre of fuel and i removed the fuel cap to try and relieve some pressure and fuel started coming out the fuel cap too. I let it run up for a bit and drove and checked it and found that cylinder 4 leak off pipe seal (closest to HP fuel pump) was bubbling. Anyone had anything similar to this? Possibly a LP or HP fuel pump? Thanks in advance

I have the same issue, i am suspecting a injector leaking compression and causing bubbling in fuel tank....I can hear a rumble in my fuel tank. Did you figure out what the issue was on yours?

 

[amgv12power]

Good shout

 

[mersum1es]

I remember reading two cases where injector nozzle has been worn heavily, and coming loose. Then exhaust pressure is getting a route to the fuel side and causing tank pressurized. I still can't figure out how exhaust gasses CAN go to LOW pressure fuel side, perhaps cut section pictures I have seen are more 'functional', not exact one... but like said, that has been confirmed. When you pull out injector, you can wiggle nozzle a bit, and holder hole is clearly worn bigger than original.

 

[Matej123]

I remember reading two cases where injector nozzle has been worn heavily, and coming loose. Then exhaust pressure is getting a route to the fuel side and causing tank pressurized. I still can't figure out how exhaust gasses CAN go to LOW pressure fuel side, perhaps cut section pictures I have seen are more 'functional', not exact one... but like said, that has been confirmed. When you pull out injector, you can wiggle nozzle a bit, and holder hole is clearly worn bigger than original.

The issue was that my 2 injectors are letting compression go thru the low pressure side. Cause the injectors were bad.

I replaced all 4 injectors.