|
09-03-2017, 07:52 AM
|
#1
|
Senior Member
Join Date: Sep 2002
Location: seattle,wa USA
Posts: 1,025
|
Fuel mileage improvement
Since the ISB fuel pump was replaced a year ago, my fuel mileage has improved from 7.5 mpg to close to 10 mpg. This is based on 11,455 miles traveled on all kinds of road conditions in the lower 48 states.
Cummins diesel, ISB 24 valve with 66,xxx total miles and an Allison 6 speed transmission. Typically drive 62 - 66 mph on the interstate, which accounts for 90% of the miles. 28,000 pounds total weight, INCLUDING the 4,000 toad. Diesel gen set runs about 200 hours this past year, total hours close to 5,000.
I know, at times when fueling, there is foam or air which causes the pump to shut off before it's actually full, but over time, this should equal out.
Has anyone else experienced this same increase in mileage after replacing the fuel pump or does it have more to do with the diesel engine finely breaking in?
__________________
Gary, Maxwell and the Beanie Weenie.
2002 Newmar Kountry Star. Cummins ISB 24 valve
2017 Mazda Miata MX-5 toad on a double axle car hauling trailer
|
|
|
|
Join the #1 RV Forum Today - It's Totally Free!
iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!
You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!
|
09-03-2017, 08:43 AM
|
#2
|
Senior Member
Join Date: May 2005
Location: British Columbia
Posts: 3,838
|
Quote:
Originally Posted by tizzyfit
Since the ISB fuel pump was replaced a year ago, my fuel mileage has improved from 7.5 mpg to close to 10 mpg. This is based on 11,455 miles traveled on all kinds of road conditions in the lower 48 states.
Cummins diesel, ISB 24 valve with 66,xxx total miles and an Allison 6 speed transmission. Typically drive 62 - 66 mph on the interstate, which accounts for 90% of the miles. 28,000 pounds total weight, INCLUDING the 4,000 toad. Diesel gen set runs about 200 hours this past year, total hours close to 5,000.
I know, at times when fueling, there is foam or air which causes the pump to shut off before it's actually full, but over time, this should equal out.
Has anyone else experienced this same increase in mileage after replacing the fuel pump or does it have more to do with the diesel engine finely breaking in?
|
I can only think of two possible causes for such an event. The first being the break-in theory. However it seems a bit steep in such a short time frequency.
The second, and I have experienced this once, is a transmission program change. This would require that the service people, for some reason, disconnected the chassis batteries briefly. When this occurs, the transmission configuration remaps the operations of shift patterns and timing. Still, your change seems pretty drastic. Mine was a whopping 10% or so, no where near your numbers.
Anyway, that's all I can come up with.
Peter
__________________
Peter - Doctor of Mixology
KADB 2013
|
|
|
09-03-2017, 10:46 AM
|
#3
|
Senior Member
Join Date: Sep 2002
Location: seattle,wa USA
Posts: 1,025
|
Quote:
Originally Posted by Lug_Nut
I can only think of two possible causes for such an event. The first being the break-in theory. However it seems a bit steep in such a short time frequency.
The second, and I have experienced this once, is a transmission program change. This would require that the service people, for some reason, disconnected the chassis batteries briefly. When this occurs, the transmission configuration remaps the operations of shift patterns and timing. Still, your change seems pretty drastic. Mine was a whopping 10% or so, no where near your numbers.
Anyway, that's all I can come up with.
Peter
|
Hi Peter, Interesting comment about the Allison transmission. Rocky Mt Cummins in Billings, MT replaced the fuel pump. I was heading ESE to Rapid City, SD. The following morning, on the way to Sioux Falls, SD, the transmission WOULD NOT upshift, so my maximum speed was 45 mph on the interstate where the speed limit was 80 mph. Not fun listening to the emergency flashers blink/buzz constantly for 7 or 8 hours. I spoke with the Allison repair facility in Sioux Falls and they suggested I take it to Cummins next door and have them run the diagnostic, which they did and it showed NOTHING. The mechanic played with it for 7 hours and took a flyer on replacing a solenoid on the top of the transmission. He said, in 20 years, he'd seen a few fail and they didn't show up on the diagnostic. So, for a $75 part, it seemed like a good bet. Sure enough, that was the problem. Getting back to your comment, I'm not sure if they reprogrammed the Allison transmission or not, but it's something that could have happened and might account for the improved MPG. The only other thing I can think of, Rocky Mountain Cummins made the decision, WITHOUT asking me, to disconnect the Banks program from the engine. The only difference I noticed from that was neither the boost gage and the turbo temp gage moved off of zero from the moment I left Billings, MT.
__________________
Gary, Maxwell and the Beanie Weenie.
2002 Newmar Kountry Star. Cummins ISB 24 valve
2017 Mazda Miata MX-5 toad on a double axle car hauling trailer
|
|
|
09-03-2017, 05:02 PM
|
#4
|
Senior Member
Join Date: Oct 2016
Posts: 275
|
I can't help you with why your mileage suddenly changed. I can confirm though, that your 10 mpg is very consistent with what our ISB has given us in our 2013 Ventana LE 3434 since we got it, so I think you can count on it remaining at that level.
Years ago we had several 5.9 liter Cummins engines, and they were always very fuel efficient. Our last motorhome had a 9 liter CAT engine that averaged about 7.2 mpg, so I was thrilled to learn that our current motorhome with the ISB engine was back up in the area of 10 mpg.
Good luck with your motorhome, and I hope the fuel economy stays where it is!!!
Ed Headington
|
|
|
09-03-2017, 06:56 PM
|
#5
|
Senior Member
Spartan Chassis
Join Date: Aug 2015
Location: SW, MO
Posts: 162
|
When I replaced the factory fuel pump with an after market in our ISC I gained about 1.5 mpg.
Don
__________________
Happy Motoring
Don Susan
2000 Newmar DSDP 3894, Cummins 330, Spartan, MM,
2004 Pilot toad
|
|
|
|
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
|
|
Thread Tools |
Search this Thread |
|
|
Display Modes |
Linear Mode
|
Posting Rules
|
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts
HTML code is Off
|
|
|
|
» Recent Discussions |
|
|
|
|
|
|
|
|
|
|
|
|
|