Detroit 6v92 died

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Detroit 6v92 died

August 28, 2022, 06:56:27 pm

Driving down i30 east of Dallas engine died. Cranks just fine. Changed both fuel filters prime filled then pumped them. Still no fire. Waiting for tow now, what a bummer.

Re: Detroit 6v92 died

Reply #1 – August 28, 2022, 07:42:36 pm

Let the engine cool down a little and carefully check the antifreeze level in the radiator. There is a coolant level sensor that will shut the engine down if coolant is low. Add water if needed and try starting again. Also check overflow tank to make sure that has coolant at the recommended level.

Re: Detroit 6v92 died

Reply #2 – August 28, 2022, 08:01:14 pm

The DDEC will make sure you have not suffered anything serious. I would suspect a fuel contamination problem. When was the last time you fueled? Did it suddenly die or did you lose power for a few seconds? How was the engine temperature? How hot did it get? Low oil pressure or low coolant level will cut the engine power for 30 seconds and then shut down. Did you use the DDEC reset switch on the dash?

If it's not bad fuel or restriction, open the dash top and use the switch against the back wall. There are two switches, one marked transmission and one for the engine. With the key on, flip the engine switch and write down the code the little light bulb flashes. Do you have the maintenance book that tells what the codes indicates? If not, I can post it.

Because of where the steering wheel is, it's easy to miss the warning light for the DDEC. It caught me the day after we bought our U300.

Keep posting with a detailed description of what happened, engine temp, miles since fueling, etc, etc. etc.

Pierce

Re: Detroit 6v92 died

Reply #3 – August 28, 2022, 08:38:27 pm

I have been on the phone with Ken he does not have power at his data connector under dash and the check engine light will not flash. There are 2 fuses according to wiring diagram that power ecm does anyone know where they are located. Should come directly off of battery.

Re: Detroit 6v92 died

Reply #4 – August 28, 2022, 09:10:16 pm

First, do you have all the warning lights on when you turn on the ignition switch? The ignition solenoid may have failed or a wire has come loose. It's the big silver solenoid close to the steering column.

I have taken photos of the fuses and relays. The DDEC fuse is #10. If you look at the fuse block and go to the left end, go over one row and the 10 amp fuse is the closest one to the driver in the second row from the left. The diagram is on the flip up lid on the inside and can be seen when it's opened.

The DDEC relays are #4 and #6. Number 4 is the last one screwed on the wooden bulkhead wall with #5 below and the other #6 relay being the first one on the 4 relays on the wooden divider. A diagram for the relays is also on the flip up dash top. Use a flashlight or smart phone flashlight to read them.

Pierce

I'm about to have dinner but I will post the photos in an hour or so.

Re: Detroit 6v92 died

Reply #5 – August 28, 2022, 09:37:35 pm

Don't let the tow truck driver take the drive shaft off. Pull both axles.

Still have not heard if you used the DDEC rocker reset switch to the left of the steering wheel?

Check coolant level. If you have a leak, the engine will shut down.

Check engine oil level.

Do not reset the DDEC with the rocker switch unless you have checked levels and monitor the temp and oil pressure if it starts. If it starts and there is still a fault, it will shut down again after 30 seconds.

Here are the photos with arrows.

Pierce

Re: Detroit 6v92 died

Reply #6 – August 28, 2022, 09:52:30 pm

I have no power on plug under dash to read ecm with pro link. The ddec fuse is good and all fluids are ok.

Re: Detroit 6v92 died

Reply #7 – August 28, 2022, 10:00:36 pm

Does 6v92 have a fuel shutoff solenoid similar to my Cummins 8.3?

If affirmative, failure or malfunction of that solenoid will result in no start/no run.

Re: Detroit 6v92 died

Reply #8 – August 28, 2022, 10:22:26 pm

Mine has shut down on low coolant you can put a jumper wire across the low coolant switch on the back of the radiator and it will run if that's the problem.

Re: Detroit 6v92 died

Reply #9 – August 28, 2022, 11:09:15 pm

Quote from: Chuck & Jeannie – August 28, 2022, 10:00:36 pm

Does 6v92 have a fuel shutoff solenoid similar to my Cummins 8.3?
If affirmative, failure or malfunction of that solenoid will result in no start/no run.

No, it does not have a main injection pump like a Cummins but rather unit injectors for each cylinder. Some CATs also have unit injectors for each cylinder. No juice to the ECU, no diesel to the injectors. The two camshafts have an extra lobe for each cylinder so when the engine turns over, the pushrod creates pressure in the unit injector but with the DDEC ECU, the computer sends a signal to each injector for when to open and how much fuel is injected for the throttle opening. With the mechanical engines. a hollow rod or "rack" moves and controls the fuel. Hence the saying, "run the rack" for mechanical engines. All fuel for the injectors goes through internal passages in the cylinder heads so the engine looks clean on the outside as there are no injector lines or any kind of wiring even for the Jake brake the later U300s have. Even the liquid cooled aftercooler is hidden under the blower.

Mechanical versions of our engines don't need any electricity to run as there is no ECU. Some have air start or you can just bump start the coach.. But, to shut the engine down, there is a solenoid that pushing on the rack lever cutting off the fuel. It instantly returns to the run position so nothing is used to open the fuel. They also have an emergency lever that shuts off all the air to the engine in case of a turbo or blower seal failure.

Some Bosch P pumps have a fuel shut off solenoid like the 8.3 while others utilize a vacuum shutoff with no electricity needed to supply fuel.

Pierce

Re: Detroit 6v92 died

Reply #10 – August 29, 2022, 10:28:55 am

Using a test light or multimeter, check to make sure you have voltage at the DDEC fuse.

Here is the DDEC connection schematic from our forum: https://www.foreforums.com/index.php?media/item/3277/

U300 12V schematic also from our forum under media: https://www.foreforums.com/index.php?media/album/194

Have you done or had any work done on the coach lately?

Check this page for codes and go to the upper right hand corner and click on the pages in yellow to move to the next page or the page before: DIAGNOSTIC CODES l WHAT THEY MEAN

Any unusual events before the engine died? It turns over OK but just won't start? Have you changed fuel filters? What was the terrain like when it died? Flat, on grade, etc? Did you try the hand primer pump? Again, when was the last time you fueled? Check the see through plastic cap on the bottom of the primary filter for water or algae?

I've been on the forum since 2008 and can't remember a DDEC ECU failing. A possibility but unusual.

Did you try the bypass switch on the dash under the headlight switch?

Pierce

Re: Detroit 6v92 died

Reply #11 – August 29, 2022, 11:16:36 am

I-30 east of Dallas is a little hilly- no grades.

Re: Detroit 6v92 died

Reply #12 – August 29, 2022, 02:47:25 pm

Pierce,
No work done on coach. Changed both filters pre filled then pumped until fuel seeped out of loose upper filter. Was driving on level ground when it just turned off, no beeping or anything. Can not read codes cause ecu no power to ddec port. What switch under light switch?

Ken

Re: Detroit 6v92 died

Reply #13 – August 29, 2022, 04:31:59 pm

Are you in a secure location? Please advise as we have no idea if you are at a shop, campground, etc, etc.

Look at the switch just to the left of the parking air brake. It's marked "override" and will let the ECU operate at partial power for 30 seconds. The key has to be on for the override switch to work.

Do you get any white smoke out the tailpipe when cranking?

You need to check to see if the ECM fuse that I posted about has power to it with a test light to check it. A ground is close by or used the ignition solenoid's body as a ground. If the fuse has power, the little engine switch in the photo should cause the little bulb about 6 inches away to flash. The key has to be on.

I take it that the engine turns over normally but just won't start. Even if you fill the filters, the engine may need quite a few 15 or 20 second tries to get fuel to the injectors if you have run out of fuel. Wait at least a minute between cranking. After I fill the filters and tighten them, I use the hand pump until it gets hard to pump. I keep trying to pump for another minute to make sure. Our hand pump is on the frame rail on the right side but since you have a rear radiator, it may be somewhere else. Without pumping, the engine may not start.

Pierce

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Re: Detroit 6v92 died

Reply #14 – August 29, 2022, 04:54:24 pm

I was on frontage road half blocking one lane. I did not try override switch. The coach is at Stewart Stevenson now.
Did pump till got hard and still no go. Thanks for all the thoughts and help. Will let everyone know what was wrong

Ken

Re: Detroit 6v92 died

Reply #15 – August 29, 2022, 06:06:46 pm

S & S should fix you up. Glad you are not out in the sticks. Hoping for a cheap easy fix.

Pierce

Re: Detroit 6v92 died

Reply #16 – August 30, 2022, 10:26:07 pm

Subscribing.

Have same engine, I don't remember seeing any posts here about 6V92 engine die on the road.

Really curious what the issue is.

Re: Detroit 6v92 died

Reply #17 – August 31, 2022, 04:02:00 pm

Will update what was wrong once Stewart Stevensons gets done with it. I am hoping just a sensor or 1 of the 20 amps fuse. I could not find them in the dark so off to s&s.

Ken

Re: Detroit 6v92 died

Reply #18 – September 01, 2022, 03:41:17 pm

Just talked to Stewart Stevenson and a inline 5 amp fuse for ecm blower. Replaced and drove then fuse blew again, now they are thinking ecm problem. Going to put a another one in to test theory.

Ken

Re: Detroit 6v92 died

Reply #19 – September 01, 2022, 04:49:49 pm

Quote from: kpbowser – September 01, 2022, 03:41:17 pm

Just talked to Stewart Stevenson and a inline 5 amp fuse for ecm blower. Replaced and drove then fuse blew again, now they are thinking ecm problem. Going to put a another one in to test theory.

Ken

Maybe the ECM blower motor is drawing too much current? There's always the possibility of a worn spot in the wire's insulation.

Art

Re: Detroit 6v92 died

Reply #20 – September 01, 2022, 05:34:11 pm

ECM Blower? What is that? I've never heard of an ECM blower. All of our U300 6V-92TAs have a DDEC II (2) ECM. Our ECM are in one enclosure on top of the engine. It has a fuel line that runs through it to cool it.

DDEC I (1) did have two boxes, one on the engine and one in the cab. There may have been a fan for the one in the cab but it was my understanding that all Foretravel 6V-92TAs have DDEC II fitted.

Attached is the schematic for the DDEC II. As you can see, there is no ECM fan motor. All the connections are listed in the box in the top left corner of the schematic.

Am I missing something?

Pierce

Re: Detroit 6v92 died

Reply #21 – September 01, 2022, 06:54:32 pm

Need to check spelling meant ecm fuse blew.

Re: Detroit 6v92 died

Reply #22 – September 01, 2022, 07:15:47 pm

OK, thought they were selling you on the easy 8 cylinder modification.

The ECM fuse in the second row is supposed to be a 10 amp, not 5 amp. Thought you said it was OK in reply #6. I don't see a second fuse on the under dash fuse map.

Disregard my #4 and #6 relays as they are for the Allison computer.

Pierce

Re: Detroit 6v92 died

Reply #23 – September 01, 2022, 07:46:01 pm

I just checked Foretravel's B2035 Schematic and our 1993 U300 has different locations for the fuses than their schematic does. You might check the label on the flip up dash top to make sure yours are the same as ours. I don't see a DDEC fuse label on the B-2035 schematic. And ours only has one fuse for the ECM.

Pierce

Re: Detroit 6v92 died

Reply #24 – September 01, 2022, 08:31:37 pm

So what I am understanding is that the ECM fuse blew because it was undersized, it had a 5 amp fuse where it should have been a 10 amp fuse. You had my undivided attention when you posted it just died driving down the road. That crosses my mind a lot when you 7 or 8 hundred miles from home. Dennis

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