89 Navistar 7.3 idi----Learner Question

[DrCharles]

I had a similar fuel pressure problem on an old BMW that drove me nuts. Finally I made the correct diagnosis - there was rust in the tank, and while the fuel injection circulated, it was sucking rust particles against the "sock" until it choked off the flow. I'd shut it off, and by the time I got through changing filters, pumps, pressure gauge locations, etc. the fine particles had settled back to the bottom of the tank. So it would work fine for a while... then plug up again


It gradually got worse until I had to shut off every 10 minutes for a few seconds. With a manual trans it was easy even at highway speeds The first rinse of the tank was the color of chocolate milk!

What confused me for so long is that the bottom of the tank (which could be seen through the pickup/gauge opening) was clean. The TOP of the inside was where all the rust was coming from. Work on cars/trucks long enough you'll see it all.

As Sherlock Holmes said, "How often have I said to you that when you have eliminated the impossible, whatever remains, however improbable, must be the truth?"

 

[Clb]

It could just be the e pump straining since it’s being deadheaded and fighting itself. Most e pumps have a internal bypass valve that really only works in a dead head scenario like this. When the pressure on the inlet side

edit of ip? End edit

becomes too great the valve will open and it will bleed fuel back to the inlet of the pump.

Edit back into ip?? End edit

That’s likely what’s going on when you see the pressure changing, it’s just the valve cycling on and off. Once the engine is running it shouldn’t be an issue.

These db2s have a babe style transfer pump in the cone of the pump, on a lot of ag applications where the tank is mounted above the engine there’s no lift pump because the gravity feed is sufficient to feed the transfer pump which bumps pressure up to 75-95 psi depending on advance settings

ok you guys tap the above quote to see my edits.
I'm not sure it really matters if I follow 100% but for the guys searching...

Op
Another tidbit
My sending unit quit reading allways on e....
After 5 tanks with black label chevron techron it cleaned off the coil windings and it now works

Got this trick here on obn

 

[hrsitton]

it was sucking rust particles against the "sock" until it choked off the flow

Yeah, but the idea somebody put plastic bags in my tank feeds my paranoid tendencies better.

But seriously, thanks. Did not think of that but that does fit.

When I bought the truck 10 years ago I installed brand new OEM seat covers and floor mat. As I recall, the floorboard had been cut open above the tank in the center where the pickup line goes in. I'll pull that tomorrow before dropping the tank. You may have saved me from dropping the tank.

Makes sense that the rust would migrate to the center of the tank.

I installed a spigot in the bottom center of the tank where the drain plug is for when I wanted some diesel for something. Just thought of that.

Ok. Got a plan.

Thanks @Clb. You should see the grunge under the bottom of the fuel cover after actually about 5 years with 10 gallons in a 50 gallon tank. Not hard to visualize what my sending unit may look like. Tank should be sealed to air but my cap didn't look like it.

I did dump a bunch of Seafoam in there when I parked it.

I'm totally blown away by the help I've been getting here.

 

[hrsitton]

Sand and gravel in the bottom of the saddle tank. Some as large as 1/4" across.

All the past pumps except the mechanical had filters. But just in case, I'll change the main filter again to be safe.

Tank coming off for a thorough cleaning.

It will be so great if that's the only problem and it starts right up after cleaning and new fuel.

Hey, I can hope.

 

[Thewespaul]

ok you guys tap the above quote to see my edits.
I'm not sure it really matters if I follow 100% but for the guys searching...

Op
Another tidbit
My sending unit quit reading allways on e....
After 5 tanks with black label chevron techron it cleaned off the coil windings and it now works

Got this trick here on obn

You must be registered for see images attach

Here’s a typical e pump with the lower case taken off. In red is the pressure relief valve, blue is the inlet and yellow is the outlet. When red is deadheaded (engine not spinning no path to return) the pressure will build until it overcomes a preset pressure rating on the pressure relief valve, this is to prevent overworking the pump. The pressure relief valves opens up a path back to the blue area which is the inlet of the pump, like I said all of this happens internally to the e pump, it’s effectively like putting a plug in the outlet and it would act the same way. This rapid opening and closing of the relief valve can make “needle dance” or rapid variance in pressure. In this case, it sounds like the op found his issue with the saddle tanks.

 

[Clb]

Thanx wes
That's how I thought the setup would work...
That's what I thought you meant,
For those doing do diligence this could be abig help.
So it looks like the trash in the tank aint helping....
o.p.....NNNNNNNEXT issue

 

[hrsitton]

40 days later......hope yall are still monitoring.

I was forced to suspend my efforts on the U-Haul/RV in order to build fences and set up other stuff on the ranch I'm relocating to. All is now done, except moving the RV.

Turned out there was a really weird pattern on the bottom of the saddle tank that looked like the trash it was not.

So anyhow, saddle tank was removed, all lines and pickup pipe including vent line were checked and clear. Pickup pipe has no filter. Just an open end pipe running to about 1/2 inch above the center bottom of the tank.

When it was clear the work would need to be suspended, the diesel from the IP was removed with a baster and filled with Seafoam. The feed pipe to the IP was loosened and removed at the filter. After draining it was also filled with Seafoam and re-tightened.

Ran a hot wire straight to the fuel shut off so it'd be open for certain.

I now do have a good 4.3 PSI reading at the top of the filter now. For 15 minutes or as long as I want. All air purged.

Tried 4-5 10 second tries. Nothing. No pooling in the clear IP return line. Loosened on injector feed about four turns. Couple more 10 second tries. Nothing. No fuel at the injector.

Not sure how much air was left in the IP when the cover was replaced and not sure how many 10 second tries it would take to purge whatever air was left.

In re-reading TheWesPaul's article I noted that it could take quite a while to purge the lines on an IP replacement.

Question: What is a good time to wait between the 10 second tries?

Also, there seems to be no rebuilt IP's for my truck so I'll need to send mine in for a rebuild. Any suggestions on some good reputable rebuildirs?

 

[snicklas]

When we were trying to get my sons 89 started the first time it took 4 or 5, 30 second cranking sessions to get it to start. Since we didn’t know if the IP or FSS worked, I did loosen the #2 injection line just to make sure there was actually fuel getting to injectors. I wasn’t trying to bleed the lines, I just wanted to see fuel dribble from the line. Also, at that time the glow plugs were not working, so ether was used as the starting aid.

So a procedure of what we did:

I was doing this with 2 people, so they made it a bit easier. I was under the hood, son was in the cab. Air Cleaner removed, batteries on a charge. (I had a set of jumper cables connected to a running vehicle due to location. If I would have been at home, my big charger would have been connected) I had everything I needed staged within reach so there weren’t any delays.

1. Set timer for 30 seconds (I know it sounds stupid, but trust me, it’s easier than replacing the starter, and 30 seconds can go by fast when doing something like this)

2. From under the hood, open throttle all the way, to WOT. I do this by reaching up with my left hand and pushing the throttle lever on the pump.

3. Have assistant engage starter, start 30 second timer.

4. Grab ether and give a quick spray while cranking. You may have to give more than one quick spray during the 30 second session. Not “hosing it down” just a quick shot, then wait, you can tell by the sound what’s happening. After a shot it may try and fire on a cylinder or three. When we were doing this, you could hear the starter try a speed up as the load on the starter lightens up when it’s trying to catch.

5. When the 30 second timer expires, disengage the starter, and stop everything. Time to “walk away” for a couple minutes.

6. Set the timer for 2 minutes. Yes, same reason as above. If the ambient temperature is high (like if you are trying this and it’s 90 out, maybe even set it longer) it was in the 30’s when we were doing this. This it the extremely important starter cool down period.

7. After the 2 minute cool down timer expires, return to step 1.

Once it catches, you may need to work the throttle to keep it running. That’s why I run it from under the hood, rather than have the assistant use the pedal. Normal reaction is to pull your foot off the pedal when it catches. I’ve had mine catch and die if you let it drop back to idle while trying to work the rest of the air out.

However, if you’re at 10+ of these sessions, then I’d say it’s not air. Either you’re not getting fuel to the IP, or the IP has some kind of issue.

I think @Macrobb posted a similar video trying to get one going sitting on the floor. His video is a good example of what I’m describing.

 

[BioFarmer93]

I'll probably catch hell from the other guys about this, but it works.. Disconnect the hot wire to your glow plug controller or however your set up is, just make sure they can't glow. With brake set, trans in neutral and key in run position, take off air cleaner cover and give a little spritz of ether to the intake, use screwdriver to actuate starter solenoid. Use tiny spritzes to keep her running until she starts running on her own. Don't forget to hook glow plug controller back up when finished.

(edit) Looks like sniklas and I were typing at the same time.. Great minds, and all that. !

 

[hrsitton]

What's the current wisdom about using WD-40 as a starting fluid?

 

[hrsitton]

Never mind.....seems the formula has changed and it no longer works.

Is there anything safer than ether, maybe about the same as WD-40 used to be?

 

[hrsitton]

What if a block heater was plugged in for a couple of hours and enough diesel was sprayed into the intake for it to run? That would be with leaving the glow plugs operating. Would it start and run?

 

[franklin2]

What if a block heater was plugged in for a couple of hours and enough diesel was sprayed into the intake for it to run? That would be with leaving the glow plugs operating. Would it start and run?

I would not use any sort of liquid into the intake of the engine. I would use the ether, short squirts won't hurt the engine if the glowplugs are disconnected/disabled.

Even when people use gasoline to help start a diesel engine, they do not pour gas down the engine, they soak a rag and hold it over the intake.

 

[hrsitton]

My concern is that ether is used as a starting aid and added to the diesel being injected. My IP is likely on the blink and will need to be sent for a rebuild/recondition. But first I'd like to be certain that it's not just a glued valve in the IP that an engine running, sort of, might shake loose.

So in my case, the engine would be running on straight ether with no diesel to dilute it. Just too worrisome for me not knowing first hand what a spritz or a small squirt is.

I've poured gasoline into the carburetor of many many gasoline engines to get them started so the thought came to me, "why not diesel?"

If a cylinder got too much it'd blow black, not enough it blow white, way to little it wouldn't fire at all.

So I'm curious what bad thing you think would happen with a small amount of diesel into the intake.

 

[DrCharles]

IDI's have a compression ratio of 21.5:1... there is a really really small compressed volume and piston to valve (and head) clearance. So it only takes a few cc's of fluid sucked into a cylinder to hydrolock it. Breaks rods, pistons or cylinder heads.

Gas engines by comparison have lots of room up there. Also the volatile fuel won't go off prematurely from the diesel compression heat (which is how it works, after all). I really wouldn't recommend you try it... people wiser than me have already recommended against it.