DT466 no power

[LSchulz]

So, I've been on the road for just under 3 weeks with the bus in my signature, and we've covered about 4300 miles so far with no issues until the other morning. So, here's the list of things that have happened:



Coming into Dallas after driving overnight from New Orleans the bus started losing power on both diesel and veg. It also started idling lower, to the point where it would stall at a stoplight unless I used the hand throttle to kick the idle up. I have new filters on both the diesel and veg systems (along with vacuum gauges), so that's not an issue. Fuel pressure is ok, around 30 psi. I can't get more than about 12 lbs of boost out of it.



On flat ground, it can get up to it's normal cruising speed of about 62 mph, but it has no power pulling hills. Accelerating, it's fine until it hits third gear and about 2000 rpm, and then it hits a complete dead spot.



Last night coming into Houston, the shutdown solenoid let go, so I zip tied it up get to the dealer to get a new one. During the day today, it was starting hard - cranking for a few seconds, then winding way up before coming back to idle. Then this evening after parking it to let it cool before I changed the shutdown solenoid, it wouldn't start at all. I put the new solenoid in and it still wouldn't start. After playing with the throttle link and shutdown link for a minute, it fired instantly and ran fine. I shut it down to tighten things, and then it wouldn't start again until I cracked an injector line, at which point it fired instantly.



My guess is I'm getting air in there someplace, but I don't know where. The diaphragm that controls the amount of fuel delivered based on turbo boost? Like I said before, it runs fine, no smoke, it is just completely gutless all of a sudden.



Ideas?

 

[AndrewGray]

Check your fittings at the fuel tank. Make sure something hasnt hit them and cracked them or put a hole in the line. The fuel lines will run up along the frame on the left side to the pump. Make sure they havnt rubbed thru somewhere there. Check your fuel filters to make sure they are tight. Also when you change your fuel fiter, if they are the spin on type, make sure the old o-ring came off with the filter . If it didnt then you have the old one still on there and when you put the new one on , it isnt sealing . We run numerous farm trucks with the DT466. Very good engines. We have not had any real problems with them. The trucks get abused badly, silage and feed trucks, and are run with the foot pedal to the floor all day long!! If you have the DT466E , then the early models have electrical ghosts that were hard to find. I hope that is not the case. Seems to me you have air problem. Also check your fuel cap on your tank. They need to vent. If it doesnt let air in to the tank then eventually your pump wont draw fuel out because of the vacuum. We have had that happen. Try driving it with the fuel tank cap loose. I changed all ours from electric shut off to manual too. The silage trucks get so dirty and beat that I have had the shut off solenoind mess up and actually come on partially and restrict fuel flow. Just some ideas to look at . I doubt it is your injection pump. I have never replace an injection pump on the DT466, either the rotary or the inline. Very strong pumps. Believe me, if the pumps are weak pumps on these engines, the hired men here will find it!! Good luck and safe trip.

 

[AndrewGray]

Another thought here. You possibly could have gotten something in the tank that is being sucked over the fuel draw. We have had that happen too. It draws from the bottom of the tank or on the bottom of the side of the tank. Could be getting over it and pluggin it.

 

[LSchulz]

It's a mechanical engine, so no electrical demons to worry about (except the shutdown solenoid relay).

Filters are new (and have vacuum gauges) and everything's tight, and both tanks are breathing fine. Like I mentioned above, it doesn't have power on diesel or veg (there are two independent fuel systems, so it's pretty unlikely that I'm getting the same problem on both sides).

I think it's a problem with that diaphragm. Power comes and goes, mainly when I can run at high rpms to build boost. As soon as the engine slows down and I lose boost, then I think a leak in that diaphragm causes it to defuel even more. It did okay in Texas today where it's flat, but we're running into Colorado tomorrow, so that should be interesting.

 

[MMeier]

Lucas, check the line between the diaphragm and whereever it hooks up to, maybe its cracked somehow. But even so, it should still allow it to start. Where you guys stopping at in Vegas in 2 weeks?

 

[Greenleaf]

I have had the boost signal line break and/or wear through and the (school bus) driver didn't know it. I don't know how important that the AFC senses boost but on the Bosch P-Pumps here at the school (DT466/Cummins B engines) it dosn't seem to have any effect

 

[LSchulz]

I'm going to check that diaphragm, and the boost signal line looks fine, but I'm not sure that's what it is anymore. I just drove it from Austin to Colorado Springs, and it had okay power. It seemed to come and go, almost like a filter, but a much slower cycle. It can't accelerate at all, but once I get it up to speed, it will hold 60 pretty well, except for every once and a while when it struggles to do 35.

I stopped at International today, and they suggested changing the fuel filters again, even though I have very few miles on these ones. It's worth a try. Right now at idle, I get about 24 psi at the IP inlet, but they said it should be in the 30-35 psi range.

The other interesting thing is starting. If the engine is cold, it will fire right up. If it has been sitting a few hours, then it acts like it's out of fuel, and I have to crack an injector, then it fires right up. If it's hot (like when it stalled in traffic today) then I have to crack all six injector lines to get it to fire. Not sure what's going on there, but that's how it's been working. I'm going to pick up a can of either for the next time it stalls to see if that will get it going.

The dealer said the fuel pressure I have is a little low, especially for warm starts. So I guess I'll change both filters (diesel has only a couple hundred miles on it, and the veg has a vacuum gauge) and see what that does.

 

[MMeier]

Definitely sounds like it is losing prime/ sucking air somewhere. Get the crew under that thing and check it out!

 

[TFucili]

Long shot, but I had a 6. 9 that kept losing prime. Finally found a return line that had gotten porous. It didn't leak a solitary drop of fuel, but when the truck sat it would get airbound. Remember, though, that the 6. 9 had the fuel filter mouted up high and that's where the line was. Don't know if this applies to your DT, but thought I'd mention it.

 

[LSchulz]

It isn't really losing its prime. I have good fuel pressure at the IP inlet, and the longer it sits the better it starts. If I shut if off and try to restart right away, it's almost impossible. We're driving to Denver this morning, and then we have a couple days there so hopefully the shop there can take a look at it.

 

[Greenleaf]

WOW. Please let us know so's we can all learn a little something. I couldn't tell you where to begin.



I had a bad P-Pump once on a Cummins B. Turned out to be a sticky plunger. Not stuck. Just sticky. Was the worse when engine was at operating temps. Worked great when cool.



I hope that is NOT your case... ... ... ... ..... :{

 

[steved]

It might not be losing prime, but that still doesn't mean it wouldn't get air into the line... needing to bleed the injectors says air in the fuel to me... you may not be getting enough to cause a starvation or cavitation issue.



When I read your first symptoms, I was going to suggest looking at the throttle linkage... our's had a bad habit of loosening up and not allowing a true WOT...



steved

 

[CNeubauer]

What injector pump does it have? We've currently got five of the IH 400 series engines on our farm and have had four more in the past 10 years and when they get hard to start when warm with the rotary pumps it's usually a sign that the head in the pump is getting worn. In a tractor application that 12# of boost would also be really low, the one DT-466 we had in a tractor would run about 18# with the stock TO4 turbo.

 

[LSchulz]

I was only bleeding the injectors to make sure I was getting fuel out all six, and I was, and even with someone else cranking as I closed them up, it won't fire. A tiny shot of ether, and it's up and running.

The throttle linkage already fell apart, so I've taken care of that potential problem.

This engine has the P-pump. It was rebuild last spring, but when you look at what we're running through it, wide open throttle, all day long, it wouldn't surprise me if it needs some attention again.

As I mentioned before, it now takes ether to fire it up, but then it runs fine, although it is definitely getting weaker. With the throttle at the normal idle position, it shuts down, and I have to keep the engine speed around 1100 otherwise it stalls when I drop it in gear. Going out on the road is downright terrifying. It doesn't accelerate or pull hills at all. Boost can maybe hit 9 psi after a good downhill where I can really wind it up, but climbing I can only deliver enough fuel to hit about 4 psi.

It's going to visit the International shop here in Denver tomorrow.

 

[AndrewGray]

Let us know what they are thinking or found out. I have run into about all that has been mentioned here but doesnt seem to be the answer to your problem. Very frustrating I know and that is probably an understatement!!.

 

[LSchulz]

Here's an update on what we've found. The shop took a look at things on Monday, and found a bad lift pump, and of course they didn't have one in stock, so we had to wait for one to get shipped in from Las Vegas. They put that in this morning, but it still couldn't build enough pressure to pop the injectors without ether. They started to pull injection pump this afternoon, so we'll see what they find in there.

 

[tgordon]

And you were just close by there and could have gotten it yourself. It sounds to me like you are not getting fuel pressure. I would guess what you are seeing is a combination of problems, from running the veggie oil and the new ULSD. So far this year we have sent 2 injection pumps in to be rebuilt for customers and booth use road diesel, my gut feeling is after they start running that crap in the off-road fuel we will be swamped with injection pump failures.



Troy

 

[MMeier]

So, what finally happened with the bus?

 

[EKlem]

I know that they ended up getting a new injection pump and that solved the problem. They have put on a lot of miles since the problem was dealt with. I don't know exactly where they are right now but should be real close to returning to NH. I will tell him to jump in here with more details.

 

[LSchulz]

Yep, Klem's got it. We had a brand new injection pump put in while we were in Denver (too long for a rebuild), and it's been running strong since then. The pump was weak to begin with, and I think it was a combination of many miles, an International mechanic trying to bleed the system the wrong way, and a bad batch of oil (had a chemical degreaser in it we later found) that finished it off. We've been on the road 75 days now, and just ticked over 13,000 miles since we left, with about 7,000 on the new pump. Now we're having trouble starting on diesel - the lift pump is getting air locked somehow, but we're done in two days, so I'll deal with it then.