Foretravel Owners' Forum For owners and Fans of Foretravel Motorcoaches September 11, 2025 ...

I regularly bring the idle up to 1000 RPM as soon as the oil pressure is acceptable.

This issue has occurred only on the three occasions I cited, and those were all under cold/very cold conditions. No problems at any other time, and even on those three occasions the engine started normally and then died after 2-3 minutes at high idle, and then after it finally restarted it ran perfectly--both at high idle and then on the highway. Something unique is happening only under these quite cold conditions and then it happens only once.

I will change the fuel filters and carefully examine the system once Spring arrives, but until then it would be very interesting to find out if anyone else has experienced this unique, temporary fuel-starvation phenomenon.

My first thought was that the thickened fuel from the lower temps was showing fuel line leaks?

You could/should look for air leaks, but if it ran well and started well in a warmer environment, I'd be looking at a fuel problem.  Did you take on fuel during the trip?  Maybe you got some contaminated fuel.  Warm it up good with heaters and try it again.  If it acts the same, I'd sample the fuel tank.  Have a great day  ----  Fritz

Clogged fuel filters will usually rear their ugly head at higher power settings like going up hills or on ramps. A partially clogged filter will lose some of the algae/dirt/etc to the bottom while stopped and generally won't affect starting or idling.

Heading up a steep incline before shutting down with a partial fuel load can also introduce air into the system. If you park after such a climb, it's best to run the engine at a fast idle for a minute or two. Example would be a driveway or road with a pretty good angle and or slant to it just before you park and shut down.

I have a different thought on why it happens only in cold weather: differences in thermal expansion between different materials in the fuel system.  Specifically threaded joints and O-ring joints.  Example:  a brass male fitting threaded into a steel female fitting.  Brass will shrink about 1.5 times as much as the steel.  Normally the preload (or tightness) is enough to handle it, but if the connection is marginal it can show up only in cold weather.  Similar thing can happen with O-rings:  marginal at room temperature cold mean a small leak at cold temperatures.  I know my air brake system looses air about 3x faster in cold weather.

I would consider this a warning that it might get worse and start occurring in warm temperatures or after long periods (weeks) of being parked.  I think the advice is the same:  check all the fuel line connections, O-rings on filters and fittings.  You might just find the culprit when it turns easier than you expect it to.

Do you still have the original electric fuel priming system?  My understanding (from a buddy with a '95 U320) is they are full of O-rings, seals and potential leaks areas as they age.  Cummins advised him to get ride of the system which he did. 

I am just throwing this out there as a suggestion but what about a weak lift pump? Could it have problems pulling thicker more dense fuel?

......................what about a weak lift pump? Could it have problems pulling thicker more dense fuel?....................

MAZ,
I don't know the precise reason, but that was my exact issue with our '98 8.3 mechanical, at one point. In cold weather, in the fall, engine starting became slower and engine stumbled a bit on start, took a few seconds to run smoothly. Before the second Fall season turned to cold weather, I rounded up fittings and installed a lift pump output pressure indicator. Sure enough, pressure low. Dissassembled and used a Cummins Lift Pump rebuild kit.  The lift pumps themselves and the seals are severely attacked by today's fuels.  The design and the material compositions are constantly tweaked by Cummins to improve longevity.

Our Foretravel is now back in comfortable heated storage, but (once in preparation for our Christmas trip south and twice after returning home) we had interesting starting issues. (There were no issues when starting in warmer weather.) Everything ran perfectly on the trip (~2000 miles).

Once (temperature in mid 30s; no engine pre-heating), once in the mid teens (limited engine pre-heating) and once in the mid-teens (3+ hours Aqua-Hot engine pre-heating) the engine would fire normally, run for 2-3 minutes and then die. It would re-crank properly but wouldn't fire for several minutes and then would re-start and run well. No codes appear to have been thrown.

Any ideas on the root cause and what could-be done to correct the issues? (Yes--I already know we should "winterize" the coach by moving to a warmer climate. Seriously considering that when the opportunity presents itself!)

I don't disagree that you should have vented fill caps, at least our '98 and '02 both had vented caps. 
But you should never experience a vacuum on your fuel tank as there is a fitting on the fuel tank top suface connected to a length of fuel hose that runs down to a point near the front bottom surface of the fuel tank, usually held in place by a grommetted clip near the hose's termination.  All FT's should have either that vent hose or a"caved in" fuel tank.  Vacuum is not forgiving. 😬
Neal

David,

Have you replaced all the fuel hoses in your coach.  You don't mention them and your coach is certainly in the suspect model years.  My fuel lines caused engine dying after starting, but at warmer temps.  Did you try priming after each of your episodes?

Metal contracts when cold.  Sure doesn't hurt to retighten clamps and filters.  In a perfect world, diesel engines would run on air, but all I have worked on like a clean "un-aireated" supply of diesel.