Start up delay?

[RSchwarzli]

Hey guys, when cold starting the 90 (outside temp does not seem to matter) the truck seems to crank, catch, sputter and cough for a split second and then run smooth. Almost sounds like it runs for a fraction of a second, but then needs a little more cranking before it fully can run.



The truck developed this a few months ago but has not shown any issues. It almost seems (if it was a gas motor) that a spark plug is not firing in one cylindar. Does this make any sence? Any thoughts?



Thanks!



Robert

 

[Greenleaf]

Perhaps you are on the verge of a fuel line sucking air. It will likely become worse.



Look for a damp spot on the fuel hose or use a vac gauge. You could aslo test the lift pump supply psi. Change your filter, ect.



GL

 

[RSchwarzli]

Now that you mention it, I never did put that togeather. I have seen a small fuel leak under the truck after long periods of parking. You think that would be it?



Mechanically, what is causing this? Air in the fuel line??



Thanks!



Robert

 

[JLEONARD]

Yes air in the fuel line.

 

[Greenleaf]

The leak will not always show up as an external leak. we are VERY luck when it does so. Makes things easy!



A leak at the injection pump or generally anywhere after the lift pump will drain out and show up easily due to the pressure in said hose or line. If it leaks pretty good, the pump will starve for fuel and she will not start unless you crank a while or actuate the lift pump.



A leak in the suction side is a pain as mentioned above.

 

[JLEONARD]

You could put a couple psi air pressure in the tank via the fill tube ... that has made leaks show up for me on the suction side.

 

[RSchwarzli]

Thanks guys! I found one leak so far by the visual meathod. I will see what else I can find!



Thanks again!



Robert