Long time reader, First time posting!

[Bean104321]

Hey Skoolie nation! I’ve been wanting to join the club for years, and with my military separation coming up next month, now felt like the perfect time to start a new adventure for myself and family. Found a unique rig that pulled the trigger on, its a 2003 Thomas Saf-T Liner with 24v Cummins, and Allison 2000 trans with only 20k miles. Was purchased from 3rd party but originally came from govt auction with all fluids, refrigerant reclaimed, batteries removed and no knowledge pass down so definitely a gamble.
This past weekend I installed new batteries, filters and fresh fluids. She cranks and will start with some starting fluid but not getting power to lift pump. I'm worried possible bad ECU cause aware its a common issue.

Curious if anyone with a similar bus/ drivetrain combo might be willing to chat to help with some diagnosing or have a wiring schematic for that might be helpful. Attached are some photos, also wondering if anyone might know what this mystery switch under the dash to left of steering wheel might be?

 

[s2mikon]

Research the insurance real well. It is becoming a real problem.

 

[ewo1]

Found a unique rig that pulled the trigger on, its a 2003 Thomas Saf-T Liner with 24v Cummins, and Allison 2000 trans with only 20k miles. ............ She cranks and will start with some starting fluid but not getting power to lift pump. I'm worried possible bad ECU cause aware its a common issue.

Curious if anyone with a similar bus/ drivetrain combo might be willing to chat to help with some diagnosing or have a wiring schematic for that might be helpful.

Welcome to the Journey. I too was a long time lurker until I finally got my first bus...

If you have the VP44 pump on your motor, they have a well documented failure characteristic.

VP44 are known to have overheating issues that kills the pump controller.
the number 1 way they get overheated is by constantly running your fuel tank with less than 1/4 tank of fuel. It is fuel that keeps the pump cool. Constantly running under 1/4 tank deprives the fuel pump from "extra" fuel it needs to keep it cool. This is why many people will modify the fuel system with an extra lift pump so that the VP44 does not overheat.

I once had a BB TC2000 with a 24v, got rid of it fast!
The problem it had was a dead pedal. I rebuilt the pump, still had the dead pedal. that problem turned out to be a bad engine ECM.

I am not saying this is your problem but what I learned about that issue is that you REALLY need diagnostic software to look at the engine. You need to pull codes. Anything less and your just shotgun guessing and that will require deep pockets.

Here is the thread where I tried looking for help and info, I hope there is something there that gets you turned in the right direction.

2000 Bluebird tc 2000 code issues.

Hey, new member here. I am looking for any help i can get or maybe somebody who has fixed this same issue. I have a 2000 Bluebird tc2000 with the 5.9 cummins and Allison transmission. I have just replaced the VP44 injection pump with a used vp 44 injection pump. I know this isn't ideal but...

www.skoolie.net

Again, your really need diag. software and the ability to read DTC's.

 

[nikitis]

Buses do not like to sit. They are designed to run. If you only have a 20k mile bus, it means it sat for a very long time if it's a 2003. So what I would do in your situation is flush everything you can flush, fuel lines, radiator, oil pan. Possibly take out and clean injectors.

Once put back together she should be in great condition. And run the engine hard after doing the above to break in and burn up any corrosion that could of possible formed in the engine in the piston areas.

Then it's a matter of maintaining like anyone elses, and she should last a really long time.

That is if there isn't already some other underlying issue not mentioned.

 

[Bean104321]

Welcome to the Journey. I too was a long time lurker until I finally got my first bus...

If you have the VP44 pump on your motor, they have a well documented failure characteristic.

VP44 are known to have overheating issues that kills the pump controller.
the number 1 way they get overheated is by constantly running your fuel tank with less than 1/4 tank of fuel. It is fuel that keeps the pump cool. Constantly running under 1/4 tank deprives the fuel pump from "extra" fuel it needs to keep it cool. This is why many people will modify the fuel system with an extra lift pump so that the VP44 does not overheat.

I once had a BB TC2000 with a 24v, got rid of it fast!
The problem it had was a dead pedal. I rebuilt the pump, still had the dead pedal. that problem turned out to be a bad engine ECM.

I am not saying this is your problem but what I learned about that issue is that you REALLY need diagnostic software to look at the engine. You need to pull codes. Anything less and your just shotgun guessing and that will require deep pockets.

Here is the thread where I tried looking for help and info, I hope there is something there that gets you turned in the right direction.

2000 Bluebird tc 2000 code issues.

Hey, new member here. I am looking for any help i can get or maybe somebody who has fixed this same issue. I have a 2000 Bluebird tc2000 with the 5.9 cummins and Allison transmission. I have just replaced the VP44 injection pump with a used vp 44 injection pump. I know this isn't ideal but...

www.skoolie.net

Again, your really need diag. software and the ability to read DTC's.

Welcome to the Journey. I too was a long time lurker until I finally got my first bus...

If you have the VP44 pump on your motor, they have a well documented failure characteristic.

VP44 are known to have overheating issues that kills the pump controller.
the number 1 way they get overheated is by constantly running your fuel tank with less than 1/4 tank of fuel. It is fuel that keeps the pump cool. Constantly running under 1/4 tank deprives the fuel pump from "extra" fuel it needs to keep it cool. This is why many people will modify the fuel system with an extra lift pump so that the VP44 does not overheat.

I once had a BB TC2000 with a 24v, got rid of it fast!
The problem it had was a dead pedal. I rebuilt the pump, still had the dead pedal. that problem turned out to be a bad engine ECM.

I am not saying this is your problem but what I learned about that issue is that you REALLY need diagnostic software to look at the engine. You need to pull codes. Anything less and your just shotgun guessing and that will require deep pockets.

Here is the thread where I tried looking for help and info, I hope there is something there that gets you turned in the right direction.

2000 Bluebird tc 2000 code issues.

Hey, new member here. I am looking for any help i can get or maybe somebody who has fixed this same issue. I have a 2000 Bluebird tc2000 with the 5.9 cummins and Allison transmission. I have just replaced the VP44 injection pump with a used vp 44 injection pump. I know this isn't ideal but...

www.skoolie.net

Again, your really need diag. software and the ability to read DTC's.

Thank you I appreciate it, I didn't want to get to into the weeds with the original post but ya a bad ECM is kind of what I'm leaning towards. The VP44 is not the original one because has a "remanufactured" sticker right on top. The resettable 10a fuse for PUMP (assuming lift pump) was getting warm and tripping, unplugged the lift pump and fuse was fine. Figured shorted lift pump so replaced it with new one, now not getting power to lift pump but fuse not tripping.
Wiring schematic on the inside panel just highlights fuse and relay locations really. Contacted Thomas with the VIN to look up any wiring schematics and they had a hard time finding anything and the one schematic he emailed me is pretty much useless cause so blurry you cant even read the font. Figured Id have better luck here with people who have already gone down this road.

 

[Bean104321]

Buses do not like to sit. They are designed to run. If you only have a 20k mile bus, it means it sat for a very long time if it's a 2003. So what I would do in your situation is flush everything you can flush, fuel lines, radiator, oil pan. Possibly take out and clean injectors.

Once put back together she should be in great condition. And run the engine hard after doing the above to break in and burn up any corrosion that could of possible formed in the engine in the piston areas.

Then it's a matter of maintaining like anyone elses, and she should last a really long time.

That is if there isn't already some other underlying issue not mentioned.

Hey Nikitis, ya I agree nothing likes to sit for long periods of time and I definitely plan on driving the wheels off her once get her running again. The fluids were all drained except the fuel and gear oil. The bus is located in New Jersey and I'm 5 hours away in Virginia. The plan was to fill it with fresh fluids, get it running, and get it back to VA to do a more thorough cleaning, inspection, check for leaks and proper radiator flush. Making it mechanically sound is first and foremost before thinking of even gutting or starting and renovations.

 

[nikitis]

Yeah it may not need much, really depends on how long it sat and in what environment. The items I listed are for the more drastic approach. Something I would likely do. It's just a suggestion and may not need it.

 

[ewo1]

Thank you I appreciate it, I didn't want to get to into the weeds with the original post but ya a bad ECM is kind of what I'm leaning towards. The VP44 is not the original one because has a "remanufactured" sticker right on top. The resettable 10a fuse for PUMP (assuming lift pump) was getting warm and tripping, unplugged the lift pump and fuse was fine. Figured shorted lift pump so replaced it with new one, now not getting power to lift pump but fuse not tripping.
Wiring schematic on the inside panel just highlights fuse and relay locations really. Contacted Thomas with the VIN to look up any wiring schematics and they had a hard time finding anything and the one schematic he emailed me is pretty much useless cause so blurry you cant even read the font. Figured Id have better luck here with people who have already gone down this road.

Did you test the wire with a voltmeter? If the fuse was getting warm and tripping before, and not now, bad or loose ground maybe?

If your not getting power to the new lift pump, run a new temp wire, fused of course, to the pump and see if the pump now works...?

Here is a drawing for the VP44. I could not find one for a bus back when I went searching, could only find one for a Dodge ram pickup truck. In this drawing, it does reflect a VP44 relay in the wiring system. Maybe your bus follows this same type of wiring configuration???

 

[ewo1]

This is NOT my work product, I do not take any credit...

Found this info on the school bus fleet forum, thought it might help shed some light on your dilemma

SOURCE-> Cummins lift pump issues ?? - School Bus Fleet Magazine Forums

Here is the shortest version of my understanding of the VP44 5.9 Cummins , 24 valve engine.

The small lift pump is mounted on the left side, drivers side just behind on slightly below the fuel filter assembly. Have someone turn the ignition key to the on position. Place your hand upon the lift pump. Have them crank engine then immediately stop cranking with the key placed in run position. You should feel the lift pump vibrating strongly.

At this point you know the computer is calling for the electric lift pump. If you have a pressure gauge you need to place it between the fuel filter and the VP44 Injection pump. Now if your electric lift pump is not reading a minimum of 10 to 15 psi it is weak, or there's restriction at the fuel filter or fuel return line check valve may be open all the time. It is at the rear of the cylinder head in the fuel line junctions. You could also be loosing prime in fuel line between pump and fuel tank. Take the fuel cap of the tank, use a shop rag and an air blower and wrap rag around your air blower. Gently trigger your blower on and off for short periods of time while someone cranks the engine through a few cycles of cranking for 30 seconds then rest starter for 15 seconds and try it again. If it starts and runs you'll at least know your VP44 has not seized up yet. If it doesn't start after this, use a little ether in spurts, not constant. You do not need allot of ether. If it won't start now here is another thing to check. Loosen three fuel injector lines and have someone crank engine over several times. If you have fuel coming through one line the VP44 is stuck on that cylinder, if nothing is coming it's stuck between cylinders which can happen. If it's coming through all three lines remove air filter and see if it is stopped up or has been water logged and sucked into the engine.

Here is something I like to do to verify electrical at the lift pump. Use your volt meter and connect straight pin to the back side of the lift pump connector plug. Place pin out clips to the positive and negative points. Plug the connector back in. Place meter up by windshield where you can easily see it while trying to crank your engine.

You should be reading battery voltage. Anything less - you have a wiring issue with resistance or possible wire breaking in the harness frl. Computer to the lift pump. The computer grounds the circuit for the lift pump to run based upon seeing a signal from the crank sensor. If no power at all is coming from the computer - replace the crank sensor at the side of the block just below the lift pump area.

So you see there's several things to consider and I haven't covered them all.

It's rare to have a computer issue. The old lift pumps has deficiencies.

 

[Slapdash]

Welcome!

 

[Anax]

Welcome! I hope you get it figured out and it is not an arm and a leg. It sucks getting a bus and then shortly there after not run! I know from personal experience. I haven’t gotten past the new member thread lol.

 

[Bean104321]

Did you test the wire with a voltmeter? If the fuse was getting warm and tripping before, and not now, bad or loose ground maybe?

If your not getting power to the new lift pump, run a new temp wire, fused of course, to the pump and see if the pump now works...?

Here is a drawing for the VP44. I could not find one for a bus back when I went searching, could only find one for a Dodge ram pickup truck. In this drawing, it does reflect a VP44 relay in the wiring system. Maybe your bus follows this same type of wiring configuration???

I have saved and printed all your wiring schematics from previous posts and greatly appreciate it! I was thinking about running a jumper wire to the lift pump, but I also was not getting 12v to the VP44 pump on pin #7. It was getting late and I had to pack up all my tools to hit the road back to VA so had to throw in the towel for the trip. I have a mobile mechanic going to take a look tomorrow and will keep you guys posted. Im praying for a bad relay or fuse I missed, but have a gut feeling bad ECU.

 

[Bean104321]

Update: It did up being a bad ECU, plus a few other electrical issues from sitting for so long.

Just got back the other night from NJ with the bus. It still has a few quirks to work out haha, but it ran great, shifted smooth, brakes worked, no air leaks or issues, all the lights worked, couldn't be happier for its first 300 mile journey in who knows how many years.

Only road side stop to ziptie shut one of frontend doors due to bad latch. And no heat because I believe the heater core valves were closed, didn't even think about it when filling the coolant system. It was a colddddd 6hr road trip!

 

[Mr P]

The VP44 pump is cooled by the bypass fuel, thus supply volume must exceed demand. Weak lift pumps can't supply that extra fuel, and the injection pump overheats. It's not a fuel tank level issue. Monitor fuel supply pressure so it's always got a few PSI even at max power.

In my pickup truck repair experience, the ECU is rarely the problem. More likely to be wiring or sensor issues.