Diesel pusher loosing speed up hill

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If it's steep and you still have it on cruise control it will keep trying to maintain the set speed.  Throttle back on the cruise control, say from 65 to 55, even more if it keeps "hunting" for gears.  If it hunts too much, take it off cruise control and throttle back more.  Yes, even DPs slow on steep inclines and/or at high altitude.

ArdraF
 
Rogmix said:
Diesel pusher cummins bogs down looses power going up a hill?
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Welcome to the forum. Not enough information to give a good answer. Is it loosing power or just slowing down on a hill? Do you have the cruse on? Do you have it in Econ mode? Have you tried to manually down shift?
Bill
 
The first thing to do is replace the diesel fuel filters, to rule that out. It only takes one bad load of diesel to plug them up. I always carry a spare.
 
if you have a air filter monitor check the red indicator on it that indicates blockage. On my sons Gulfstream DP, the air inlet on the side of the RV was too small and even with a new air filter, the inlet was restricting the air when the turbo tried to make boost. It was also low on power for this reason. We removed the tube to the air inlet grill on the rv side, the air was still filtered and it had more power.

another explanation in more depth,
My son owns a 93 DP Gulfstream and I found his problem with power was directly related to the air inlet on the side of the RV rear right that was under sized to allow full boost from the turbo. The tip-off was a red air filter minder indicating a clogged filter, the filter was new. Off the air filter canister the air inlet tube went to a inlet grill on the side of the RV, the opening where the 5" flex tube connects to the grill necks down and makes a turn. In that area there is a restriction that causes the filter to be in a vacuum when the turbo goes to boost. If the turbo inlet can't get full flow, it can't generate the designed boost. This appeared to be a factory installed grill on the side of the RV. Remove the top of air canister and see if it affects the power. The filter is still filtering the air but the inlet grill restriction is eliminated.
 
Sounds pretty normal to me. A big DP doesn't have the reserve horsepower of your car or SUV, so it slows down when the going gets tougher.

A typical car has less than 20 lbs of weight per horsepower, whereas a typical diesel pusher is about 100 lbs/hp. Big difference.

As the others have suggested, check/change your fuel and air filters to make sure you are getting your full rated horsepower.
 
First off, welcome to the forum.

Like others have already stated, we need more information.  Grades will knock the speed down on about any coach, not just diesels but is this something that suddenly came on compared to normal?  Are you driving it any differently than before, such as downshifting or not downshifting?  Any missing or stumbling, like it is starving for fuel?

Mike.
 
Is this a new problem.  Or is the loss of power a new problem.
Are.you towing more.weight then usial
Could b the transmission not down shifting to
 
After a hundred and fifty thousand miles of diesel RV driving I finally had fuel filters on my Cummins ISL plug up but when it happened the engine would cut out under a heavier load climbing grades, not just lose power.
 
I know this is an old post, but for those of us looking for information, I will add to it.

On the rolling hills of central Texas, my 37ft 1998 Newmar Motorhome with 5.9 diesel engine would drop 10 to 20 miles per hour. I was also having trouble getting to 65-70 MPH.

I replace the stock air filter with a performance air filter and got a slight boost. Now I can maintain 65-70 on simi-flat roads and I tend to lose less speed. Still seeing 5-15 MPH drop, so I am looking for more improvement!
 
Jeff said:
After a hundred and fifty thousand miles of diesel RV driving I finally had fuel filters on my Cummins ISL plug up but when it happened the engine would cut out under a heavier load climbing grades, not just lose power.
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I worked on tugs, when I were a younger lad, 99.99 % of the time when those twin V12 149 Detroits began losing power it was a fuel filter issue. We operated under a heavy load 24/7.
 
Do you have the cruse on? Do you have it in Econ mode? Have you tried to manually down shift?
I would go back to the stock air filter because none of the after market air filters meets the specks set forth by Cummins. You could dust your engine.
 
Clyde 'Buck' Grimes said:
I know this is an old post, but for those of us looking for information, I will add to it.

On the rolling hills of central Texas, my 37ft 1998 Newmar Motorhome with 5.9 diesel engine would drop 10 to 20 miles per hour. I was also having trouble getting to 65-70 MPH.

I replace the stock air filter with a performance air filter and got a slight boost. Now I can maintain 65-70 on simi-flat roads and I tend to lose less speed. Still seeing 5-15 MPH drop, so I am looking for more improvement!
Click to expand...
That is not a good idea; "performance air filters" pass more air through because they have less restriction. Less restriction means larger holes for air and dust to pass through.
You should find this ISO air filter testing informative: It's your money to spend on fuel or engine rebuilds, as you choose.
 
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