Here is the what: 95 6.5TD suburban with 205000 miles on it requires 8-10 seconds cranking before start, Hot or cold. When it does lite, it putters to life, doesn't start with authority.
Observations:
Glow plug system working.
Cranking speed 150-200rpm.
I performed an injection line bleed on an injector thru the crank cycle and no fuel delivery was obsrved until the first initial sign of life.
My scanner gave me this data when a movie was recorded multiple times of the crank cycle.
At rest the desired fuel rate was 0 mm3, a normal condition.
When cranking speed was observed the desired fuel rate was 1.9-4.2 mm3 (1.9 being the lowest observed and 4.2 the highest in multiple attempts).
After start, engine rpm reaches desired idle rpm of 615, the fuel rate jumps to 12-15 mm3 and settles to10-12 mm3. at idle.
No other abnormal data parameters can be observed.
Other 6.5TD's that I have checked with my scanner in this fashion of varying years and applications show a cranking fuel rate of 10-19 mm3, what I would logically conclude to be a more reasonable start fuel rate. It takes more fuel to start a diesel than it does to idle it. The pitifly low start fuel rate observed on my scanner goes hand in hand with the mechanical observations listed above. I reasoned that the PROM contains the fuel rate map and could be a source of trouble, at $45 it seemed like a good place to start so I replaced it with no effect.
Anybody out there bump into a similar problem?