|
When air is in the lines, the spray pattern is disrupted. In my case, I have a rebuilt head (new valve guides, seals, rebuilt injectors) and the bottom end is in good shape. When purged of air, the engine runs like a new one. Slowly, over a period of about 3 or 4 days it would begin to show the signs of air creeping back into the fuel system (nailing, rough starts) but when it runs well, it really runs well, smooth smokeless starts - no nailing whatsoever under any circumstance. That was the real clincher evidence that the problem was air. Even when the car was nailing, I could drive it real hard - 75 or 80 mph on the freeway for a couple of hours always purged it enough to run smooth for a while.
During the head refurbishment, the IP pump sat for about 3 months with the injector lines off. The PO burned B99 for a year, and I used B99 for about 4 months after first acquiring the car. All the fuel lines were 5/16" Gates and were swollen and distorted when I replaced them. The IP poly-connectors to the fuel filter housing had become brittle, but did not seem to be leaking - I replaced them anyway. The IP has no outward sign of fuel leaks. Somehow air was getting in. Many times I pondered the possibility that air was getting by the delivery valve o-rings when the car was off. Possibly negative siphon pressure was slowly pulling air into the pump. However, if that were the case, then the air would be purged after running for a bit. I would be very receptive to any input on this theory.
Air infiltration is a peculiar beast. A ghost with no direct trace to its whereabouts. Whatever I did, the engine is better now - for how long will be the question where all of my (and other's) theories will be tested.
|