We have checked the fuel lines, the fuel filter, the return lines, got to the lift pump and found moderate fuel on the outside of it, all other leads exhausted but this...we ordered a lift pump today..... any leads or pointers!!!! The motor will run approx an hour then will accelerate up several times and then quits...
Air in the fuel system indicates a leak on the primary/suction side of the fuel system. A fuel leak is always going to be on the secondary/pressure side of the fuel system.
Symptoms of air in the system would be, hard starting, surge at idle or rough idle, engine misses under load, low power.
Symptoms of a leak would be, hard starting, engine misses under load, low power, excessive fuel consumption and of course fuel all over the place.