I've got an 03 3/4T 5.9 cummins. Last week it failed to start after running 1 hour prior with no problems. I changed the fuel filter and got it started. It ran great for three days but I went out to start it Saturday.........same thing, wont start. I pulled the fuel filter again and the canister is full of fuel. I've sprayed WD-40 in the breather tube but still won't start. Any suggestions?

 

I would start first by confirming that the LP is operating normally. Drain fuel canister and have someone turn key on and see just how much fuel the LP is moving. If the rail pressure sensor has failed it will cause a no start condition as well. Have you checked for codes? Any mods such as programmer or box? Fill out your sig so we can better help and diagnose your problem.

 

yeah look at the lift pump put a gauge on it

 

my vote is the lift pump too. need codes.

 

I would also like to add that the newer formulated WD-40 is non flammable.

 

Okay...... Mod are a HyperTech Power Programmer, K&N Filter. After running the Batteries down on Saturday from trying to get it started, I put it on the charger all night, Sunday, woke up to 8" of freakin snow, (March in Texas.....it ain't supposed to snow), and same thing....wouldn't start. I pulled the fuel filter and the canister was full of fuel. Monday morning, I was unloading my tools out, to have it toed to the shop. Got everything unloaded and tried again to start. It fired up after about 20 seconds of turn over. I hesitantly ran it all day Monday, starting and stopping as usual. It ran fine, no loss of power, NORMAL. Yesterday morning, I started it but it took a little longer than usual, but went to different jobs, started and stopped, if fired up every time. There's a retired Cummins mechanic down the road and I called him. He came over yesterday afternoon, we broke the seal on 4 or 5 injectors had turned the motor over. It had good fuel volume spraying out. There are no codes according to the odometer, (turning the key off and on three times) it reads "done". The truck has 184k miles on it. I'm still hesitant to drive it to far from home. Do yall think the lift pump would cause this problem, intermittent pumping like it was?

 

Might not be pump could be injector solenoid going bad.

 

Have you connected the Hypertech programmer and checked for DTC codes yet?
Sounds like the others are on the right track here but DTC codes may help as well.

GW