If I turn up the full power screw am I gonna wreck my fuel shuttoff solenoid? Just ordered a new one because mine gave up the ghost. Thanks.

 

with stock injectors, there is a good possibility. when you turn the fuel screw, you increase injection pressure. if the injectors are stock and have small orifices (which they do on i/c models), i believe the case pressure would increase in turn. with larger injectors, most shutdown solenoids have better chances of staying alive due to the injectors having larger orifices. that's the whole reason for the manual shutdown cable idea that someone came up with.

 

the way i see it is the amount of pressure and fuel being sprayed out at idle is the same no matter where the power screw is at. it is going to use only so much fuel to maintain the idle rpm. which is the only time the fuel needs to be shut off anyway. someone correct me if im wrong. lol its kind of late

 

well the power screw does increase your idle so it increases fuel.The shutoff solenoid failure is from the fuel flowing past the plunger.Fuel is always flowing past the plunger(not just at idle)and almost shaking it in its bore .this starts to shave metal off the sides(which sticks to the magnetic field)which jams the plunger

 

The 93 has a maxed fuel screw for about 1000 miles and its fine. I guess it takes more time than that. proabably 10 startup-shutoffs everyday.

 

I probably should keep my big mouth shut but. Mine has had the fuel screw 1/2 turn fron a runaway for about 30,000 miles and I have had no issues.

 

to all,

our "local diesel guru" (and he IS an expert, with over 4 decades of experience.) tells me that you can get away with turning up the screw without a "problem", essentially indefinitely, IF the screw is ONE FULL TURN from "runaway".
(when doing such a "turn up", Tom W____________ keeps a piece if 2x8 lumber handy to smother the engine. - he says that that is CRITICAL to doing the deed.)

yours, TN46

 

Its the backwash that kills the fuel shut off. Like wide open to nothing. With the fuel screw up and small injectors when you jump off the gas it causes a backwash and can tear the rubber tip.

 

If you recontour the tip of the plunger BEFORE it gets torn off, it will never get torn off.

 

Okay. I didn't know if I did the right thing or not by ordering a new one. Didn't want ANOTHER cable under my dash. Already got one for high idle. I might have to get that truck back on the dyno and start playing with it. Thanks Guys!

 

Mine finally gave up the fight last fall and my fuel screw is maxed out. I'm gonna replace it in the spring when I pull it out of storage and start daily driving it again.

For what its worth, my 93' has been sitting on a friend's farm since the fall and we've had -45*C temps, lots of snow and wind. It started up with no issue after sitting for 4 months in sub-zero temps.

 

I solved the problem by removing the rubber tip completely...
The plunger is large enough to cover the hole and no fuel pressure is going to tear up the metal tip.

 

They don't always shut off with bare metal.

 

The rubber tip on mine was perfect when I took it out. The coating must have worn off or something, because my truck wouldn't start. I didn't know if there's something I could with do the old one so i paid my $90 and ordered a new one. I have the recall injection pump installed too, so i don't know if it will make a difference or not. I will say that this plunger lasted 140,000 miles. My dad says that before that pump was installed, he was going through them like crazy.