Engine/Transmission (1998.5 - 2002) 4 mpg drop

[pangelechio]

Please excuse me if this was asked before but in my serch of old items I didn't find it. About 3 tanks ago my milage droped from 18. 5 to 14. 1, could this be completely due to winter fuel? My truck still runs the same, it just seems a little hungrier for fuel.



Oh yea, 24V 2000.

 

[JCyrbok]

Where are u from?? I get about 2-3 mpg less in the winter due to winter fuel and cold weather.



I think around here (S/E lower Mich) the stations switch to the "winter" fuel in October.



Just a though (If it applies)



J-

 

[pangelechio]

Where are u from?? I get about 2-3 mpg less in the winter due to winter fuel and cold weather.



I think around here (S/E lower Mich) the stations switch to the "winter" fuel in October.



Just a though (If it applies)



J-

I am in Oregon and I think they changed the fuel around the end of October. I have had people suggest issues like the lift pump getting weak but this is my first TD so I am at the mercy of everyone elses knowledge.

 

[drrhoades]

Have you changed your fuel filter? I get noticably less if mine is really dirty.

 

[ntillm01]

Two things right off the top of my head.

1) Winter diesel fuel, I don't know if it has less bang for the gallon, but it had additives for anti-gelling. I don't think that alone affects diesel fuel mileage. But I don't know the facts around this. With gasolene, absolutely, because 10% of that gallon isn't gas, it's another fuel (like MTBE).

2) In the cooler months (as in single-digits in SE Michigan lately!) I always get 2 MPG less than in the summer. Mostly it's because it is running below operating temperature for longer periods and needs more fuel when cold.



my 0. 02

 

[SRadke]

The winter blend they switch to here in the Willamette valley (if that's where you are) is hardly a winter blend. I've never seen a mileage diffrence from summer to winter. It just doesn't get that cold here... ... Heck, it frosted this morning for the third time this year I would suggest changing your fuel filter, but the last one I did required a new lift pump to get the truck going again.



-Scott

 

[pangelechio]

Thanks for all the good ideas. The guy I bought it from said it has been 10K or so since the fuel filter was changed. There was also a drain switch on the side of the housing he showed me and said he opened it after every time he filled up? Think I will go with the fuel filter. I am in PDX near Cummins NW so I guess I will pop by the and check it out.



Merry Christmas

 

[Supermod56]

Thanks for all the good ideas. The guy I bought it from said it has been 10K or so since the fuel filter was changed. There was also a drain switch on the side of the housing he showed me and said he opened it after every time he filled up? Think I will go with the fuel filter. I am in PDX near Cummins NW so I guess I will pop by the and check it out.



Merry Christmas

Yep, every time you fill up drain the water separator, if you forget once in awhile no biggie, haven't had any water in mine yet, knock on wood! And every 15000 change the filter, I do it every 10, they are cheap enough!



Tom

 

[KBalzuweit]

I see very little change in MPG between summer and winter. I have picked up a tank bad fuel and seen a BIG drop, then back up the next time. I try to buy my fuel at the bigger truck stops (Flying J), it seems with the fast turnover in fuel they have, there are less problems.

 

[claykelly]

Winter blend fuels do have a lower BTU rating in most cases, and you'll sometimes see a performance and/or MPG reduction because of that. It simply takes more fuel to do the same job.



Truck stop diesel can be tricky, there are many truck stops that only sell No. 2 as most over the road trucks have fuel heaters and can run straight no. 2 in all climates. The pumps are usually marked, sometimes not, just make sure you're getting a winter blended fuel !!

 

[barbwire]

What about the IAT sensor(dirty, or went south), or maybe the innercooler clamps (loose). Air filter?

 

[pangelechio]

What about the IAT sensor(dirty, or went south), or maybe the innercooler clamps (loose). Air filter?

Put a K&N in it, picked up 1. 5 MPG. Hoses and clamps in good shape and tight. Picked up a fuel filter from Cummins today and will put in this week. Last tank was back up to 15. 8 so its getting better but sure isn't the 18. 5 from 1st of November! Last tank from Flying J so we will see how it goes. They dropped the price down to 1. 85! Hope the quality didn't drop with it.

 

[cerberusiam]

Definitely check and clean the IAT sensor.



If your buying at Flying J I would highly suggest you find a different place to fuel. Between Pilot and Flying J its hard to tell which one has the worst auto diesel. My truck will loose 2 to 3 mpg and the 2000 PSD I occasionally drive will rattle like its has gas in it. I swear they cut the auto diesel with kerosene no matter the time of year. As far as I can tell the WY and ID stations have the same fuel so am guessing the OR stations are probably the same.



The best fuel I have found so far is the Big D or Shell stations. Their premium diesel seems to be the best for power and mileage around here. Chevron will work well also but it doesn't power as well.

 

[TSRAM]

Put a K&N in it, picked up 1. 5 MPG. Hoses and clamps in good shape and tight. Picked up a fuel filter from Cummins today and will put in this week. Last tank was back up to 15. 8 so its getting better but sure isn't the 18. 5 from 1st of November! Last tank from Flying J so we will see how it goes. They dropped the price down to 1. 85! Hope the quality didn't drop with it.

I would be taking the K&n out promptly if it was me. I have always used them on my gassers in the past myself, but quit in my CTD's after the build up of gunk on the turbo impeller became evident. I'm sure others will tell the same.

I believe Cummins holds as high regard for the K&N as they do Fram oil Filters.



How can all of you tell when they change to winter blend? I know I'm in the balmy south where it isn't as big a issue, but there have been a few nights of 20f. recently and have often wondered if they change here as well.

 

[GIT-R-DONE]

I also have seen a decrease in fuel mileage in the past 6 - 8 weeks here in PA. I went from 19-20 down to 15 - 16. I bet its in the fuel your buying.

 

[poor]

Where and what is the IAT sensor?

Definitely check and clean the IAT sensor.



If your buying at Flying J I would highly suggest you find a different place to fuel. Between Pilot and Flying J its hard to tell which one has the worst auto diesel. My truck will loose 2 to 3 mpg and the 2000 PSD I occasionally drive will rattle like its has gas in it. I swear they cut the auto diesel with kerosene no matter the time of year. As far as I can tell the WY and ID stations have the same fuel so am guessing the OR stations are probably the same.



The best fuel I have found so far is the Big D or Shell stations. Their premium diesel seems to be the best for power and mileage around here. Chevron will work well also but it doesn't power as well.

Thanks for any help in advance-as fairly new to these Cummins diesels!

 

[BV]

My 99 would lose 1-2mpg on winterized fuel and cooler temps. Standyne Performance formula would usually bring it back up.



If you need local help - Let me know - Marty

 

[terrywerm]

I'm in Minnesota, and the stations around here just started selling winter blend in the last couple of weeks after a cold snap. Personally, I stay away from the winter blend as long as the outdoor temperatures stay over -10* F but I do treat with Power Service during the months when the temperatures can go below freezing. This keeps the injectors cleaner, keeps the fuel from gelling, and helps to disperse any water that might be in the fuel. I also treat my fuel about once a month during the summer months, mostly to clean up the injectors.



The weekend before Christmas I had number 2 fuel (non-winterized) with Power Service added to it, and it was -8* on Sunday morning when I got back from Chicago with a load of liquid sugar (bigger Cummins). The CTD in the pickup started right up, was not plugged in, and had been sitting since Thursday. Oo. Ran like a top. Mileage had been right around 18. 5, but did dip a bit during the colder weather, down to about 17.



A couple of days later, I filled the tank with what was labeled as a 70/30 winter blend. Mileage dropped to 16. Now, several days later, with warmer weather, (in the 20's and 30's) the mileage has climbed back up to 17. Next fill will be straight #2 again, as long as the weather holds. When the forecasts start pointing at subzero cold again, I'll start putting in winterized fuel again.



Incidentally, we see a mileage drop in the over the road trucks during colder weather, too. Some of that drop is attributed to more idling time for cab heat, but the below zero temps bite into it even more. Everything turns harder in the colder weather, especially the tires, requiring more power, and more fuel.



Just my $. 02 worth. Hope you all have a great New Year!

 

[cerberusiam]

IAT is Intake Air Temp. It sense air temp for the ECM to decide on fuel injection amount. They have a habit of getting dirty and not sensing right so the ECM thinks it is cooler and jumps the fuel injection. Its located between the air horn and firewall on the side of the intake manifold.

 

[pangelechio]

Definitely check and clean the IAT sensor.



If your buying at Flying J I would highly suggest you find a different place to fuel. Between Pilot and Flying J its hard to tell which one has the worst auto diesel. My truck will loose 2 to 3 mpg and the 2000 PSD I occasionally drive will rattle like its has gas in it. I swear they cut the auto diesel with kerosene no matter the time of year. As far as I can tell the WY and ID stations have the same fuel so am guessing the OR stations are probably the same.



The best fuel I have found so far is the Big D or Shell stations. Their premium diesel seems to be the best for power and mileage around here. Chevron will work well also but it doesn't power as well.

It's a shame Shell is one of the better ones. It's . 50 a gallon more here!