If there are a number of them its more than likely the Fuel Injector O Rings.
There are 2 rings total per injector- 1 in the rail 1 in the intake.
These O Rings are about 1/2-3/8 in diameter and fairly thick- I would say .09" round or so.
And you went through a re-manufactured engine in the same way your original? Thats weird...
Whoever is doing your swaps is at least taking the time to change the fuel injector o rings at least.
__________________
-Ryan
|