6.2 erratic throttle

[Big E]

I have an '84 Suburban 6.2L W/Banks turbo. It has had an erratic throttle for some time, it started out just surging and slowing at freeway speeds, and now it randomly falls on it's face like it ran out of fuel or dies completely.

The vehicle has been in the family for a while an was treated to a new crate engine, trans, injector pump, and Gear Vendors unit before it was given to us. It has many small problems, loose ends, etc. I have performed the following items.

Replace fuel filter & water separator element
Installed 1/O battery cables, Huge difference
Replaced trans cooler & lines
Treated fuel system with Anti-bac
Changed all fluids and filters

Any ideas on my fuel/throttle problem?

[83Blzr62]

I had something similar happen to me. My car would randomly slow or die. It ended up being the supply line for the fuel pump had a small rip in it. Sometimes the rip would open and it would pull air and other times fuel would flow with just a little leaking out.

It might be an air leak in something.

[DmaxMaverick]

If you don't find any leaks, sounds like a lift pump dying. It would help if you had a fuel pressure gage handy, even if temporary.

[Big E]

Thanks for the input, it looks like fuel has been intermittently leaking on the front diff; I'll change all the soft lines, considering I just lost a heater hose on the last test drive, and go from there.

[DmaxMaverick]

If you have a small leak between the lift pump and IP, and are losing power, your lift pump isn't putting out. The IP will will draw fuel even if the LP isn't working, and run until power demand overcomes the pump's ability to supply fuel or air has a way to get into it. If you have a leak after the lift pump, it'd have to be pretty bad to stop the engine. You would have puddles and a huge decrease in mileage. If it leaks while driving at highway speeds, it would also cover the entire underside of the truck.