5 Ton Issue

[Floridianson]

No no intank pump and we need the PT spinning to creat rail pressure.

 

[tobyS]

No in tank fuel pump. It's suction.

As far as running with a bad pump...probably not...since the fuel is put into the cylinder on the compression stroke (pressure), not on the intake stroke (vacuum).

I keep my bet on a loose fitting or a small crack in the plastic line, probably very near a fitting. Only one of the lines are suction.

 

[paradeduty]

Easier to rule things out in my book. Good info for others to know that there is no pump in tank. Then my money is on pinhole in line somewhere. I still have a mystery air leak before the main fuel filter on one of my Detroits (M985) that has been a bugger to find. Replaced the fuel filter assembly (had a new spare) and the main pick up line to tank and checked the pick up tube in tank. Still a nuisance air leak. Be looking to see if the OP finds it and where.

 

[autoshopteacher]

My M817 became hard to start and had a very bad idle. It would surge and slow down; nearly died. I suspected that it was sucking air but there were no telltale wet spots on any of the fuel lines. I finally found several very small leaks by pressurizing the lines with air and the fuel would weep out. Leaks would not show under suction but showed up under pressure. I had new lines manufactured at the NAPA store and the problem is gone.

 

[tobyS]

Hey Autoshopteacher, I have one just like your photo (but no camo paint).

Yes, I thought about mentioning pressure and I agree with you. Of course having a bit of dish soap to see bubbles helps and any small holes in the tank would not be spotted unless you remove the pickup tube and block it (not hard at all).