Carl - I tore my YF apart yesterday to replace pump diaphragm. It exhibited symptoms of a faulty diaphragm, but nothing I was able to visually SEE during inspection. When you speak of pin holes, are you able to see them?
I replaced it anyway, and I can’t seem to replicate the flooded hot start condition it had developed. I guess it must have helped.
Truck still isn’t performing quite up to its usual standards. I did check dwell (was good at 28-29) ran out of daylight before I could do any more diagnoses. It runs like it needs more timing. Maybe the dizzy slipped somehow. I’d find that weird but possible, I suppose.
If you stretch the rubber diaphragm, the pin hole may show itself.
