Engine/Transmission (1998.5 - 2002) Starting problems-fuel leak

[Mpoland]

Need help to identify a hard starting problem. I believe that the injector pump keeps on loosing "prime". It acts like it does after changing the fuel filter. Cranks for a few times and then catches and starts rough before it smooths out. Noticed a small spray of fuel coming from the "return to tank" line, just passed the banjo fitting. (Have a new line on order. )



What I don't understand is first, why is this line under pressure. And second, after putting on a new "check valve", (the line that leaks, connects to a "check valve" at the bottom of the injector pump and runs to a 'T' at the rear of the block) I thought this would prevent the pump from loosing it's prime. That didn't work. I am still loosing prime on the injector pump.



Logically, I have a hard time understanding how counld a return line cause the injector pump to loose it's prime, especally when a check valve is in front of it.



Has anyone else had this problem?

 

[illflem]

The return is speced for 10 psi max, I guess this means that some pressure is allowable, probably caused by line restriction.

If you have more than 10 psi I would suspect a kinked line.



Check valves don't usually seal 100% unless there is a little bit of pressure, like the engine running.



When fuel leaks from your line it has be replaced by something, namely air. This is a slow process, that's why most fuel leaks only cause starting problems after the rig has been parked for a considerable length of time.

Since air seeks the highest point it ends up in the pump or injection lines. Air in the injection lines and pump compresses never allowing enough pressure to build to pop the injector open hence hard starting. This air compression in the lines is also the reason that it's often necessary to loosen the lines to bleed a system that's got a good dose of air in it.