Bus Breakdown 8v92

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On Saturday, we set out for a quick one-night camping trip. After arriving at a lovely Corps of Engineers’ Park on Lake Somerville, about 90 miles northwest of Houston, I stopped to register. When I got back in the bus, it would crank but wouldn’t start. It seemed like the engine wasn’t receiving any fuel, so I checked the fuel filter and confirmed it was getting fuel. I even tried to start the coach from the rear, but it still just cranked without firing.

This is a 1992 Angola Conversion equipped with an 8V92 engine and DDEC II, with 258,000 miles (about 50,000 since a full rebuild) and an HT 755 ATEC Allison transmission. As I continued troubleshooting, I noticed that when I turned the ignition key on, the Check Engine Light (CEL) and Stop Engine Light (SEL) didn’t illuminate as they normally would for a few seconds. However, the Check Transmission Light (CTL) did come on, which isn’t typical.

I attempted to check for codes on the ATEC and DDEC but had no luck—there were no flashing lights on the dashboard. I reached out to DFW Prevost for assistance, and they guided me through several troubleshooting steps over the next hour and a half, suspecting the issue was related to the DDEC or ATEC. We checked power to the breakers both front and rear, along with the relays, and everything appeared to be functioning normally. They consulted the wiring diagram and suggested that it was likely the ECM.

To make a long story short, I ended up calling Coach-Net for towing assistance since it was clear we wouldn’t be driving the bus anywhere. As always, Coach-Net was responsive, and a tow truck arrived within a couple of hours. By that time, it was dark, and the driver preferred not to tow the bus at night. He took my keys, and they towed the bus back to Houston on Sunday.

The bus is currently at Stewart and Stevenson, and they’ve started working on it. I’ll keep you updated on what they find. In the meantime, does anyone on the board have any thoughts or insights on this situation?

[MyPrevost]

Did you check the Allison transmission fuses located near the steering box in a nondescript 4×4 plastic box? I encountered a similar issue with our ’99 Marathon about a year ago. It took 12 hours to locate that box, even with help from Marathon, Allison, and Prevost!

Good luck with your troubleshooting!

[MyPrevost]

Yes if it is the same box. I spent some time finding the box and then walked through checking it with Prevost on the phone.

[MyPrevost]

I had a similar issue when trying to leave Kerrville last October after sitting for eight days, so I thought I’d mention it just in case. My coach wouldn’t start, and in that situation, both the check engine and stop engine lights were illuminated. It turned out I was low on coolant, which prevented the engine from starting. At the time, I didn’t have a jumper to check for error codes, nor did I have a Pro Driver to assist me.

Once I added coolant, the problem was resolved, and I was back on my way.

Best of luck with your situation!

[MyPrevost]

LOC,

Since we have the same vintage coach and engine, I would have been happy to lend you my DDEC code reader and come over to the lake to assist. I suspect there might be a sensor issue preventing the DDEC computer from signaling the injectors. Unless, of course, it was smoking when you tried to start it.

Also, not to criticize your process, but I’ve had several large vehicles fail to restart in similar situations, leaving me stranded on the road or in a tough spot. Because of that, I rarely shut off the engine when fueling, checking in at the RV park, or any other interim steps between leaving the hangar and parking for the night.

I’m interested to hear how your trip to Stewart & Stevenson goes. They mentioned they only have a few people left in the shop who are experienced with the 8V92, so I’d like to know how it turns out.

[MyPrevost]

Jerry,

I appreciate your advice about not shutting down until you reach your destination. I’ll do my best to keep that in mind.

Thanks,
Jim

[MyPrevost]

Jerry,

I think investing in a DDEC reader could be beneficial for my vintage coach. Where did you purchase yours, and what was the approximate cost, if you don’t mind sharing? Having one would allow me to diagnose issues more quickly—perhaps I could have identified that I needed a tow truck or even found and fixed the problem (though “fixed” might be optimistic). Would you be willing to offer some remedial classes on how to operate the DDEC reader? I assume it plugs into the port in the lower compartment below the driver’s seat and is relatively easy to use.

Regarding your other point, I agree. I usually keep it running while fueling or checking in, but for some reason, I decided to shut it down on Saturday. Thankfully, I was parked in a space and not blocking anything. If I had been in the way, that might have led to a divorce given how cheerful I was at the time!

I’ve had the bus at S&S in Houston at least ten times over the past five years for various repairs—injectors, a transmission sensor, several engine sensors, the oil pressure gauge in the engine compartment, and they’ve run the rack, among other things. S&S in Albuquerque handled my engine rebuild. Sometimes it takes a couple of days to get into the shop due to the availability of their 8V mechanics, but they’ve done a pretty good job so far. Do you have a reliable 8V mechanic you can recommend?

Loc

[MyPrevost]

Loc,

Are you coming to POG 3? JDUB checked out a bunch of Coaches at POG 2 with his reader.
Tom Chilcote
Trans-Specialists RV Batteries
tom@transpspecialists.net

[MyPrevost]

LOC,

I picked up my DDEC reader on eBay, where you can usually find a few for sale each month. They typically range from $500 to $700, depending on the included modules and whether it comes with a printer. You can also find the DDEC Troubleshooting manual on eBay fairly regularly.

Funny story: when we hooked up the reader to A$$Crak4U’s coach, it returned a code about a loose nut behind the wheel and something related to too much Viagra. What’s that all about?

As for 8V mechanics, the only one I have close at hand is my dad. He rebuilt and tuned 8V engines for 25 years but retired right around the time the DDEC systems became standard at Detroit Diesel. Oddly enough, he’s quite competent with CAT engines that have electronic controls. Go figure!

JDUB

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Tom,

I’m planning to attend, but I’m trying to reschedule a trip to Asia, and it’s not looking promising.

Jerry,

Since it seems I might not make it to POGIII, would it be possible for you to find a time that works for you to bring the bus up to Cypress? I’d love to get a close-up look at the DDEC reader in action, and I’m more than happy to offer something in return.

Loc

[MyPrevost]

Of course that assumes that the bus is actually fixed as indicated by S&S. I am concerned that I may have a similar issue as to what you diagnosed with Tom’s coach – they said something about a short between the seat and the steering wheel. I will post their diagnosis and repair after I pick the bus up later today.

[MyPrevost]

Hey Jerry, do you keep the Coach engine running when you go inside to pay for diesel? Is there no one inside the Coach during that time? Don’t gas stations typically require you to turn off your engine? – Gary

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LOC,

Just choose a weekend, and if I’m around, you can bring the coach to the airport, and we can connect it. I keep it at David Wayne Hooks, so it’s quite accessible, and I’m always up for a session with the coach.

Gary,

No, they don’t require me to turn off the engine, or at least I ignore any signs if there are. During the summer, the AC is running, so the engine stays at high idle, or honestly, it’s usually on high idle anytime I’m stopped for that long. Unless I’m adding oil or doing some maintenance around the engine, I typically don’t shut it down. I’m not concerned about someone jumping in and taking it when I’m the only one inside, as they usually don’t realize that there’s no one else in there. Plus, living in Texas, people generally assume everyone is armed, which effectively reduces the risk of car or bus theft.

That raises an interesting question: has anyone ever filled up their coach with a gun tucked in their pocket or waistband?

[MyPrevost]

You mean like the derringer in my pocket, the Glock 40 in front of the bus, or the 12-gauge in the rear? A long time ago, I had a driver who, while fueling in broad daylight, had a guy sneak up next to the truck, press a gun to his head, and take his wallet and watch—all while he was holding the fuel nozzle. Fortunately, the bad guy got away without anyone getting hurt, but the driver definitely needed to change his pants.

Rest areas are the worst; you always need to be aware of your surroundings.
Tom Chilcote
Trans-Specialists RV Batteries
tom@transpspecialists.net

[MyPrevost]

How about those fuel stops that have the sigh full service?

Is that a no no for a bus?

How does that work?

Or is that something else just for Truckers?

JIM

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