HPOP Reservoir Slow Leak Down

[JAP]

Truck has almost 300K miles. When I got it, the HPO reservior was empty. I filled it and the truck fired right up. Fired up 3 more times in the following week. Left it sitting for a month and went to fire it up today and the reservoir is empty again.

It doesn't seem to be external, so where should I start looking first?

 

[907DAVE]

Injector o-rings(upper), front pump seal(HPOP) and mounting gasket.

It could also be in the reservoir gasket, but not likely.

 

[JAP]

Thanks Dave. I'm pulling the injectors as soon as I get the truck back to my house, so I'll reseal the HPOP when I do that.