Hey guys anyone have any ideas on a 12v with these symptoms.
When started cold and parked with the nose pointing upwards it will run for about 10 seconds then stall
When started cold on a level ground it will not stall
When started warm it will not stall
We put a gauge on it and when its started the fuel pressure will rise to about 10psi then drop to 0-4 (varies if in hill or not) so we looked at the OFV and it looks ok but we gave the spring a little stretch anyways. FP while at idle (after initial prime) is 25-27 and 32-35 at free load 2500rpm and it stays fine while driving.
It seems to be loosing prime sitting over night when parked in the driveway with the nose up but not so bad on level ground.
FP was a DC replacement approx 30k ago.
FF and preheater screen we just changed.
Anyone have a similar issue?

 

Got an air leak somewhere in the lines.

Get a rag and an air hose and put some pressure in the fuel tank - see if you can spot any leaks.

 

Yeah that what we have been thinking but there are no obvious signs of leakage.
I am trying to understand how parking on a hill can make any difference and the only thing I can think of is if the leak is in the return line or before the LP allowing fuel to drain back to the tank.
It would seem that from the LP to the FP it is staying charged since the engine flashes up and runs for 30-40 seconds before dying plus that section is pressurized enough that a leak should be visible....no?

 

i would start by dropping the tank. most of the trucks i have seen with similar symtons had problems with the pick up tubes in the tank

 

heres a link similar problem
https://www.dieseltruckresource.com/...d.php?t=200071

 

Did you check the fuel heater electrical connector to see is the pins are burned or wetness?

 

Ok thanks guy I will look closer at those. The pre-filter screen was pulled and cleaned but I dont know about the wiring for the heater.

 

As stated above, you probably have an air leak. The most common sources of the problem are the fuel lines, the fuel preheater, and the installation of the fuel filter. The fuel lines will dry rot over time and develop tiny air leaks that you cannot see but they are there. If your lines are original, they are due for replacement with some marine diesel grade line. The plug on the fuel heater tends to burn out and leak as well. Trying unplugging it and looking for any diesel residue. Also, if you have some really really thick grease, try packing the plug full of it and see whether it changes your symptoms. The reason that I mention the fuel filter is that sometimes people accidently double up on the center o-ring and it will not seal with two of them in there.

In selected cases, the problem is actually right at the tank. The metal elbows on the top of the tank do rust and will sometimes fail. This can be checked by pressurizing the tank as digital bullet suggested. If the actual pickup tube has failed, you will most likely see a correlation with the symptoms and the level of fuel in the tank.

Good luck.

 

Just wanted to update and thank all the people that responded.
Turns out it was the fuel heater where the wires go in were burnt and allowing the fuel to bleed back, a new heater and all is good again