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Old 10-13-2021, 01:39 PM   #1
Mini-Skoolie
 
Join Date: May 2020
Location: Tannersville, NY
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Year: 2001
Chassis: International 3800
Engine: DT466e 7.6L
Question Air in fuel line - cracking injectors?

I’ve been reading through as many threads as I could find, but still can’t find any explanation of how to bleed air out of the fuel lines past the pump.

As a little background, I have a 2001 DT466e that I’ve been converting over the summer. I moved it occasionally during the conversion process, but since moving it to where I’m staying now (Central NY), it hasn’t moved in close to a month (oops!). To make matters even worse, I didn’t leave much diesel in the tank while it’s been sitting.

Finally realized I really needed to get the bus moving (and start doing it more routinely), and found for the first time that it wouldn’t fire up. Engine cranks, but never starts. I’m guessing this is a fuel issue since I typically need to be on the throttle to get it to start without dying right away. I haven’t changed the fuel filter since buying the bus back in April (planning on doing that now).

I checked the batteries and primed the fuel pump by the filter a lot. Never saw any clear signs of air in the system. Also checked the tank, and I don’t see any sign of buildup or water—although that’s just from pumping a bit out of the bottom. Now I’m wondering if their is air in the lines between the pump and injectors.

Can anyone give me any advice on how to check if this is the issue? And to “crack the injectors” (a phrase I’ve seen used a lot on this site), is this a reasonable job for someone who’s definitely not a mechanic? I do my own oil changes and other basic maintenance, but if I have to really start tearing down the engine I wonder if I should consider looking for help.

Any advice is appreciated!

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Old 10-13-2021, 01:59 PM   #2
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If you have a dt466e, it's a HEUI engine with unit injectors. Therefore you don't have a fuel injection pump, or fuel injection lines, so there isn't air in the lines, and there is no way for you to “crack the injectors” to bleed the air like one would on an older engine.

So forget about it.

When you said that you primed the fuel pump a lot, did you do this with the bleeder open? Did you replace the filter before or after you pumped? How many times did you crank and how long each time?

You need to open the bleeder and pump the plunger until you get a steady stream of fuel out the bleeder at each push. Then you tighten the bleeder and pump it more until fuel gets to the gear pump, at which point you're ready to try and start the bus.
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Old 10-13-2021, 04:52 PM   #3
Mini-Skoolie
 
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Thanks for the reply. It’s good to know I don’t have to worry about cracking the injectors. Slowly learning more about what I’m working with.

I only left the bleeder open for a pump or two at a time. It was sending too much diesel everywhere anytime I’d pump. But this was all before changing the filter.

I just picked up a new filter today, and will swap it out tomorrow. Then I’ll make sure to prime the fuel system the way you describe. I was letting the engine crank for 10-15 seconds at a time with a few minutes of rest in between, probably about 10 times total.

I’ll report back on whether I can get it to start tomorrow after changing the filter.
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Old 10-14-2021, 09:21 AM   #4
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Okay, pump it a bunch more after you close the bleeder and then try to start.

If it doesn't, the next step on a computerized engine is checking for trouble codes.
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Old 10-15-2021, 11:44 AM   #5
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Update: I changed the filter and tried pumping with the bleeder open. I may have gone a little too far. There was fuel coming out of the bleeder at first, but it stopped after I kept pumping. I’ve been pumping a LOT, and still no sign of diesel. I’ve been trying both with the bleeder valve open and closed with no success.

Any other ideas on how I can get fuel to the new filter? I don’t know where I’d be able to borrow a scanner to check for codes, so I’m really hoping I can get pressure in the line again.
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Old 10-15-2021, 12:36 PM   #6
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I've seen some use an air wand and shop rag through the filler neck. They pressurize the tank slightly which will force fuel up and through the bleeder screw.

I'd make sure you have plenty of fuel in the tank, since you said you ran it low, I assume you filled it up with a jug or two?

I've never had an issue getting one to bleed. With enough pumps you'll eventually get there.
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Old 10-15-2021, 02:22 PM   #7
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Last week on my 1999 DT466e I removed the bleeder/schrader/tire valve while priming vs trying to maintain the plunger inside the valve, open. Doing that, you know it is not closing inadvertantly.
I also had an inside dually tire valve extension in my junk drawer so added it so bleeder valve outlet is up.
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Old 10-16-2021, 10:19 AM   #8
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After a few hours of pumping, I managed to get fuel back up to the filter so it will come out of the valve. I tried starting the bus probably around 6 times or so after that—cranking for 10-20 seconds and letting it rest while I pumped some more. The voltage started to drop quite a bit (around 10.5V while cranking, 12 otherwise), so I’m trying to give it a chance to charge back up now.

While waiting, I decided to check error codes. I don’t have a scanner, but used the diagnostics button to get 111, 335, 236. Any guesses if it’s still an air in the fuel line issue, or if there’s something else I should consider?

I’m really hoping I can figure this out soon. I’m supposed to be on the road now, but am starting to wonder if I’ll need to call for help.
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Old 10-16-2021, 10:53 AM   #9
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https://hnctruckparts.com/service-in...ble-code-index

So right off the bat code 335 is very relevant to the engine not starting. According to the index it is "ICP unable to build pressure during cranking"

The 7.3 (T444E) and the DT466 (your profile says both for some reason) requires high pressure oil to fire the injectors. This code suggests either the sensor has failed and therefore can't see the engine has actually built up the required pressure (500 psi iirc) or some other part of the HEUI system has failed and it's not building the required pressure.

Try unplugging the ICP sensor and see if the engine starts then. Unplugging the sensor causes the ECM to default to an assumed value. Driving the vehicle like this is strongly not recommended, but it's a diagnostic test you can do.

On the 7.3 it is on the driver's side cylinder head near the front of the engine, but still in the valley.

On the DT466 it is underneath the valve cover on the high pressure oil rail towards the back of the engine. From my research, it appears there's a small pass through connector for just the ICP (look for 2 or 3 wires only) through the valve cover.
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Old 10-18-2021, 08:27 AM   #10
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Quote:
Originally Posted by Truthseeker4449 View Post
https://hnctruckparts.com/service-in...ble-code-index

So right off the bat code 335 is very relevant to the engine not starting. According to the index it is "ICP unable to build pressure during cranking"

The 7.3 (T444E) and the DT466 (your profile says both for some reason) requires high pressure oil to fire the injectors. This code suggests either the sensor has failed and therefore can't see the engine has actually built up the required pressure (500 psi iirc) or some other part of the HEUI system has failed and it's not building the required pressure.

Try unplugging the ICP sensor and see if the engine starts then. Unplugging the sensor causes the ECM to default to an assumed value. Driving the vehicle like this is strongly not recommended, but it's a diagnostic test you can do.

On the 7.3 it is on the driver's side cylinder head near the front of the engine, but still in the valley.

On the DT466 it is underneath the valve cover on the high pressure oil rail towards the back of the engine. From my research, it appears there's a small pass through connector for just the ICP (look for 2 or 3 wires only) through the valve cover.
This.

Also, unplug the sensor and look for oil. A lot of times if the sensor has failed, it will leak oil into the connector and then into the harness.
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Old 10-18-2021, 12:37 PM   #11
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Quote:
Originally Posted by Truthseeker4449 View Post
https://hnctruckparts.com/service-in...ble-code-index

On the DT466 it is underneath the valve cover on the high pressure oil rail towards the back of the engine. From my research, it appears there's a small pass through connector for just the ICP (look for 2 or 3 wires only) through the valve cover.
I'm trying to find the ICP sensor, but the only 3 wire connection I'm seeing is to the gray box on the driver's side of the engine that gets 120v DC power. Should there be a way to unplug the sensor without removing the valve cover? I'm not sure if I'd trust myself to safely remove and reattach the valve cover.

As a side note: I realized I left a chassis ground to the battery disconnected when I swapped the batteries. I reconnected it, but still no luck. Any chance this could have caused the error code and I just need to pull the batteries again so the ECM/ICP sensor can reset? I doubt it, but it sounds a lot easier than getting to this ICP sensor. I'd try it right now but it's been raining heavily the past few days. Definitely makes it a lot harder to troubleshoot...
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Old 10-18-2021, 12:55 PM   #12
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It's under the valve cover. So you'll have to remove the valve cover to see it. Being there is makes it hard to see if the sensor is wet, but if there's any oil on the plug at all, we typically change it.

Check for chafing on the wires too, they can rub on the oil rail and also on the valve cover harness too.
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Old 10-18-2021, 05:11 PM   #13
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Is your bus where someone can siphon fuel out of it? Since you left it low anyway any stealing of fuel will leave you in a bind. Sounds like it's out of fuel. EVERYONE should put a locking fuel cap on their bus immediately after purchase, you never know what can happen when you are away.
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Old 10-19-2021, 07:05 PM   #14
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Quote:
Originally Posted by Booyah45828 View Post
It's under the valve cover. So you'll have to remove the valve cover to see it. Being there is makes it hard to see if the sensor is wet, but if there's any oil on the plug at all, we typically change it.

Check for chafing on the wires too, they can rub on the oil rail and also on the valve cover harness too.
It is inside the valve cover?
What is the sensor next to the high pressure oil hose going into the hpo rail?
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Old 10-20-2021, 07:43 AM   #15
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You're right. Maxxforce dt has it on the rail under the cover. Old engines had the rail cast into the head and the sensor would screw into that rail.
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Old 10-20-2021, 08:33 AM   #16
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Quote:
Originally Posted by Booyah45828 View Post
You're right. Maxxforce dt has it on the rail under the cover. Old engines had the rail cast into the head and the sensor would screw into that rail.
My 1998 has a sensor in the removeable hpo and low pressure fuel rail, On the head below the valve cover about two inches closer to the firewall than the hpo line.

You can barely see it in the fuel filter picture I posted here in this thread earlier.

Online research appears to say the Maxforce line came out in 2007??

Do you suppose I have a newer replacement engine ???
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Old 10-20-2021, 04:23 PM   #17
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Quote:
Originally Posted by DoubleO7 View Post
My 1998 has a sensor in the removeable hpo and low pressure fuel rail, On the head below the valve cover about two inches closer to the firewall than the hpo line.

You can barely see it in the fuel filter picture I posted here in this thread earlier.

Online research appears to say the Maxforce line came out in 2007??

Do you suppose I have a newer replacement engine ???
I think it is highly unlikely an emissions complaint engine would've been retrofitted given the ease of rebuilding the DT466. The Maxxforce DT is for all intents and purposes a very different version of the DT466 that's a pile of garbage due to trying to meet the new emissions standards. The follow on Maxxforce 9 was even worse. If there's not a big DPF in the exhaust and your bus did not come from California, then no you don't have the newer engine.

Good to know the ICP is actually accessible on the older proper DT466. Shows what happens when you end up trying to Google truck information. Now if I could only convince my boss of this....
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Old 10-21-2021, 07:26 AM   #18
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Quote:
Originally Posted by DoubleO7 View Post
My 1998 has a sensor in the removeable hpo and low pressure fuel rail, On the head below the valve cover about two inches closer to the firewall than the hpo line.

You can barely see it in the fuel filter picture I posted here in this thread earlier.

Online research appears to say the Maxforce line came out in 2007??

Do you suppose I have a newer replacement engine ???
I was wrong again, thought the log was cast into the head, apparently it's bolted to it. Your picture shows the sensor at the top, behind the oil line.

It's been a long week, TGIF, oh wait....
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