My 91 LS 400 has 150k miles on it - runs beautifully but has developed a starting quirk/issue???

Overnight, it went from a nice normal fairly quick crank/start to a long crank start.
After a day or two of this, I discovered that if I turn on the key for a quick (about 1 second) crank then off, then start it again, it cranks right up.
This is pretty much hot or cold...
Any ideas would be much appreciated.
As an aside, I have a 2001 Dodge Ram 1500 than developed the exact same symptoms, overnight.


/Don

 

The cure requires a correct diagnosis. The diagnosis would involve testing your fuel line pressure at shut-off against the required residual pressure. If you lose pressure quickly at shut-off, the fuel will vaporize in the lines during heat-soak. Then your morning start is trying to re-prime the fuel rail.
IF the above symptom was noted only when cold, I would question the cold start valve circuit. Otherwise, warm and cold:
a) leaky injector
b) leaky check valve at pump or regulator
Colin

 

Thank you. Colin - Hot/cold - makes not difference. One quick crank, then off, then next crank, it cranks right up.

I'm guessing the fuel pump check valve is part of the fuel pump itself?

Is there a check valve at the pressure regulator, or is that itself possibly the culprit?

Thanks so much for taking the time to respond.

I will check these out.

/Don