IS it possible for the IP to become Air locked

[crazpony]

When I drive my truck, long distances with a horse trailer loaded with horses it runs great. If I jump in the truck cold with no load, drive it a mile or 2 it stalls then become difficult to start, when I say difficult, I mean difficult. It will start, run for 15 to 20 seconds then stall. Today it told almost 3 hours before it ran steady again. On the final start today, after running for about 3 minutes after it finally stayed running, it kind-of burped, puffed a black smoke then ran great.

I noticed on short trips, if I start the truck, allow it to idle for 5 minutes, no problems.

New fuel filter, lift pump running fine, IP has 20,000 miles on it, new PMD on a remote mounted cooler. Why on long trip with a load all is good, going to grap a cup of coffee is a night mare?

[Robyn]

Try puting a clear plastic tube from the IP to the return line and watch whats happening.
If you are seeing bubbles coming out of the pump you are sucking air some place. Does this truck have a dual fuel tank setup??
If it does the fuel tank switch valve could be a place to start looking for air leaks.
The rest of the system from the electric pump on to the engine runs under pressure and would leak fuel at times if there were problems.
Check to see if you are getting air and then go from there.
Let us know

Robyn