89 Navistar 7.3 idi----Learner Question

[snicklas]

Fellas, I picked this up reading through this thread and it's causing confusion a bit.

This is an

International S1600 Medium Duty Truck, a former U-Haul 26' truck, it's not an F-Series or E-Series based "little U-Haul"

There are some slight differences, but this truck has 1 tank, no FSV to have issues. The IP has a lower governed speed, and I remember when OldBull had a few Glow Plug Harnesses there was an extra wire in the harness specifically for the IH Truck..

He is working on on of these:

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Just wanted to make sure that everyone is on the same page.....

 

[Thewespaul]

Yes, the arm shuts fuel flow with the metering valve linkage, you can see the linkage the arm act on in the screenshot I posted. All db2s will have the two solenoids under the cover, one for the fss and one for the advance. The cover will only go in two ways, wide open throttle and the correct position. You want to have the arm behind the linkage where it rises up, if there’s something wrong with the pump and it won’t start with it in either position.

 

[hrsitton]

@Thewespaul

Checking if I'm understanding correctly: With the power off the FSS, the arm holds the inlet valve closed. With the power on, the inlet valve is allowed to open with the force of 4PSI from the lift pump?

What should happen if the lift pump in activated with the top cover off the IP?

@snicklas.

Yep, same truck. Box is 26'. Bumper to bumper is about 32'.

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[Thewespaul]

The fss closes the metering valve not allowing any fuel to the plungers, the lift pump will still supply fuel to the transfer pump in the injection pump cone, just no fuel will get to the plungers. You can run the engine with the top cover off, fuel that would normally be going out the return will just spill over the edges of the pump. You will have to manually operate the linkage to the metering valve to shut the engine off, and the idle will be a bit higher than normal but it would eliminate the fss from the issue. If the engine won’t start with the top cover off you’re likely looking at getting some work done on that pump.

 

[franklin2]

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Years ago that used to be me favorite truck to move in. Way before I knew what a idi was, all I knew was I could pack it very carefully from top to bottom, and get my whole house on it. It did not seem to care, it moved right along with no complaints. I never moved more than 60 miles back then, and also remembered always having to hold the diesel nozzle up out of the tank to top the tank off before turning it back in, it never used hardly any fuel.

 

[hrsitton]

@franklin2

Mine has windows on both sides and in front of the overhang. Access door and windows on the side. Inside 4" insulated ceiling, walls, and floor. 230 gallons fresh water, 80 grey, 50 black. Cook stove and oven, sink, shower and toilet, hot cold water, 3 different heaters. 7.5' feet in back was reserved for dirt bikes but has now become a tack room. And of course it got a paint job.

I've had two dirt bikes in it with an F150 2wd loaded with an atv towed behind in all states between and including Wyoming and Arizona. Put it all together myself. But now it's not running. But thanks to Wes Paul and his Band of Renown, it will soon....or later.

Started raining again so I'm inside for a bit. Dreading to try starting it without the cover because if it doesn't, that won't be good news, except I'll at least know.

Edit: I mis-spoke in another post. The GVWR is only 18k not 40.

 

[hrsitton]

The fss closes the metering valve not allowing any fuel to the plungers

This is puzzling me bigtime.

Is it possible to open the metering valve by hand with the cover off? I've tried to get something to move either forward or backward where the FSS arm sits and all feels rigid.

Is the metering valve held in place when closed by a fairly strong spring?

 

[Thewespaul]

This is what the fss acts on, it should move freely back and forth, as well as when the throttle is actuated.

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[hrsitton]

@Thewespaul

I'm wondering if the metering valve is stuck. The seat the FSS arm sits in is in a different location on mine than on yours. Mine is much farther towards the back.

I haven't figured out how to upload pics here since Google stopped showing them as a JPG but this link should take you to a side by side comparison.

https://photos.google.com/album/AF1QipNg1TdlszFAVJLDwv8_SbtJyh4fqO9HBxIOMG-0


Edit: Now that I'm looking at them there are other differences as well. It was getting late and the light was bad. Try to get some better pictures tomorrow.

Edit #2: I see the flat on the throttle shaft is in a different position. Maybe that it. But I still couldn't find anything to push either way.

 

[Thewespaul]

That’s because you have a 92 and below pump and you don’t have the torque screw adjustment. You should still be able to move the linkage pretty freely, if it’s a contamination issue then it might bind a little, but if it’s refusing to budge something has failed inside the pump.

 

[hrsitton]

Well, I've got to go to town tomorrow so I'll pick up a can of Seafoam to fill it with just to see.

When the throttle is rotated, a shaft was going in and out. But I guess that's not the metering valve.

I'll try some more tomorrow but the only way I could get anything in there to move back or forth either way was to rotate the throttle shaft.

 

[Thewespaul]

Circled in blue is the minimax rod, it is controlled by the throttle and moves back and forth in the case, it operates on the metering valve linkage to control fueling and should move the metering valve with the top cover off.

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It’s really starting to sound like something came loose inside the pump.

 

[hrsitton]

Tomorrow when there's good light I'll take a video with the throttle being actuated. That'll be later in the afternoon.

I'll hang on hope until tomorrow but if the IP is gone, the IP is gone.

If it is, I'm still thinking that the loss of power to the FSS could have resulted in catastrophic IP wear with no diesel entering the pump. Even I know those close fitting parts need a lot of lubrication going through them constantly.

 

[hrsitton]

Woke up with this thought. (4am)

The FSS is very strong in contraction when current is applied. When the current is cut off, the FSS plunger extends by a very weak spring. The spring is almost nothing.

So what happens when the current is applied? The fuel is opened to the IP via a very strong force applied by the FSS.

That suggests to me that the FSS is really a fuel turn on solenoid with the shut down being done by a spring when the FSS is relaxed when current is cut off.

I don't see how it could work any other way.

 

[hrsitton]

Found this:

Quote, "When the ignition is off, the solenoid is no longer energized and the return spring pulls the shut-off rack to the “OFF” position, which through the governor linkage rotates the metering valve to cut off fuel. End Quote

http://www.motormayhem.net/2009/10/11/stanadyne-db2-fuel-injection-pump/

So if the return spring is what actually shuts the fuel supply down, how could the engine run with the FSS and cover removed, since it appears the FSS is actually a FuelTurnOnSolenoid?