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kartfreak · 08-20-2012, 02:07 PM

I've have a '90 Southwind P-30 454 TBI with about 58,000. First time out 7-8 years ago, we were on a very long (35 mi) grade on a very hot day, almost to top, something electric 'opened' and the engine quit. After about 30 minute 'rest', she fired up and havent had the problem since. Last week headed to Bonneville towing a heavy Jeep on a car hauler, we hit the Baker grade (18 mi) in 118 outside temp. Almost to top, had the same problem twice before reaching top of the hill. Gage was just about in the red, but not. (so hot, the propane valve had blown open and was venting) Got into Vegas OK that day. Next day was quite a bit cooler, and had no problems. Coming home Friday almost back to Vegas, it quit again.
Difference this time was we were coming down a long slow grade with no load on the engine, and temp at normal 1/2, just quit running. Of coarse, you loose the steering and brake assist when the engine stops turning, making for a high pucker factor, e ticket ride, with a lot of screaming and crying. Next day coming into Barstow and all the grades behind us, same thing happened, normal temp, long slow downhill. Always the same, 20-30 minute 'rest' and she fires up (i think barstow was more like45-60 minutes, it was about 108 outside) We towed the trailer home with the Jeep, and called the hook. Never got an idiot light, and it generates no codes. Where do I start looking?

trackman · 08-20-2012, 02:11 PM

Sounds like the rotor button under the distributer cap. Had that happen on a 94 Tiffin and that was the cause

Confusion · 08-23-2012, 03:45 PM

Engines need four things to run:
1. Air (the ability to take in and exhaust sufficient quantities)
2. Fuel (in the proper ratio)
3. Spark (at the proper time)
4. Compression

I would have to assume that the problem you are having is fuel or spark related since it's unlikely your compression or air intake are being affected.

Along with rotor button mentioned in the post above, I would suspect the ignition coil. I don't know if you have a distributor with the coil located in the cap or if the coil is separate but they can get flaky once they get hot. Assuming it has never had a good "tune up" I would replace the cap, rotor, coil, plugs, wires and pcv valve.

I would also suspect the fuel pump if electric. Fuel pumps typically rely on cool fuel to help cool the pump. In tank pumps have several gallons of cooler fuel sitting on top of them that helps keep their temps under control I have no idea if the pump on your motorhome is in the tank, on the frame rail or in the engine compartment but it could be an issue. If the pump is not in the tank I would also suspect vapor. An "easy" check for this would be to see if you're getting fuel pressure under the no-start condition but that's easier said than done on a class A.

angelman · 08-24-2012, 06:44 AM

I would start with cap, rotor and coil. Try to buy the higher quality parts from GM or NAPA. The cheap stuff just doesn't hold up. If that doesnt work tap into the pos+ on the distributor with a test light into the cabin area so you can see if the electric is failing under these conditions. If it is then I would trace back for the culprit. I had a faulty key switch on my 88 pace arrow that gave similar symptoms. Good luck.

speed racer · 08-24-2012, 07:05 AM

I would say yes to the above and add an ign module.

DonDee · 08-24-2012, 08:08 AM

All of the above..

tomwalt · 08-24-2012, 08:38 AM

Please let us know what it is/was - keep the parts you replace as spares.
As a thought, if yours is fuel injected, some of the earlier FI systems didn't have a good constant flow back to the fuel tank - so they basically just presurized the fuel line. Symptoms of this were that it wouldn't re-start when hot (like shuting down for lunch and it wouldn't re-start for 1/2 to 1 hour). This was vapor lock caused by the design. I saw this in the early 80's in single engine airplanes. Sometimes insulating or moving fuel lines away from hot components (exaust) would help. At 108 to 118 degrees, you are well within this ball park.
Check and make sure your radiator fan is running on high - that would contribute as well.

kartfreak · 08-28-2012, 02:17 PM

Thanks for the replys. After thinking about it, I ordered a coil, pickup coil, and ignition module, Delco parts from RockAuto, about 100 bucks. (all made in Mex and China btw) Im thinking I didnt get any codes because those parts aren't sensors, and dont send a signal back to the computer. (just a guess) I put a 5.0 in an old Ranchero about 20 years ago, and quickly went thru a couple Ign. modules. In the trucks, Ford put the module in a finned alum heat sink and mounted it on the fender panel. They are obviously heat sensitive, so thats my first guess. Problem is I wont know till Im out in the wild blue again, next trip is mid Nov. All the 'regular' tune up stuff was replaced about 1-1/2 years ago.
Im looking for a steal on a much newer rig. The 'old girl' is just getting too old, and I dont want to drop any real money in her anymore.
Thanks again for all your help.