Hi Guys-

First let me thank you all for the great information on this site!

My son just bought a 1985 F250 with a 1994 7.3 IDI. This truck has a lot of "custom" features that were installed to rig things to work that had failed without having to spend money.

We were told by the previous owner that he had installed an electric booster pump to help with cold starting. (Massive air intrusion!) This pump is wired to a cab switch which we were told to turn on before starting and then off once the motor is running.

I corrected a number of fuel leaks, and noticed that the mechanical lift pump is not hooked up.

Where this gets strange for me is that the truck seems to run fine without ANY operating lift pump. I drove it home on the highway like this.

With the electric pump switched off, there is no fuel pressure at the fuel filter's Shrader valve.

I can hear a slight difference in the sound of the engine with the electric pump turned off(it is quieter).

Can an IDI really run normally without a lift pump of any kind?

I am thinking that I should rewire the electric pump to run whenever the ignition key is in the "on" position.

Thanks!

Bob

 

They can, depends on the truck usually. Most times they will barely run, and this WILL destroy the injector pump, usually sooner rather than later.

 

Thanks.

I was afraid of that! Who knows how long it has been run with no lift pump!

I will be re-wiring it so the electric pump runs when the key is on and keeping my fingers crossed that the IP does not go belly up too soon.

Bob

 

The injection pump will pump fuel. It has an internal pump. Not that i would recommend to do it that way. If you starve the ip of fuel it will kill it. I know i did it already.

 

I ran my 6.9 a good 150 miles towing once without it, I couldn't figure out why I couldn't break 10 psi of boost, until I stopped and shut the truck off and didn't hear the pump when I turned the key back on. It never hurt anything, but it is definitely not a recommended procedure.

 

I would advise leaving the pump wired thru the switch. If you do that you will be able to turn the pump off in an emergency situation(accident, line breakage) when you don't want fuel being pumped all over the street or engine bay.

 

if the truck is wrecked bad enough that the engine shut off with the key on, having a fuel leak is the least of your worry's.

if you are worried about the pump running with the engine off and key on, wire it to the ignition switch and put an oil pressure switch in the line. this way the E-pump will only run if you have oil pressure.

 

What is the best e pump to use to replace the lift pump a part # would help a lot.

 

facet duralift #40285 is the one to get. 4-7 psi, 33 gph, and will dead lift 10 ft straight up.
by the time the glow plugs go out, the fuel bowl will be full and the pump shut off.

 

How does that let the pump run to prime the system before the engine started?

 

It doesn't

 

i was thinking the same thing.i would just install an inertia switch if i was worried of such things.likely could source one from a modern car at the salvage yard cheap and hook it in easy enough.they work well.very,very rarely do they trip when they are not supposed to.takes a pretty big bang when mounted properly.well of course they have to be reliable,otherwise you'd see soccer moms broken down all over the place.


one step further,get a good deal too;
https://www.ford-trucks.com/forums/1...l#post10774080