hi there everyone i have a few questions
own a 24v cummins 98 qaud cab, with auto, its my daily driver , now im only getting 15mpg driveing steddy, this is not good, it does have a shift kit installed and that is my next question lately its been acting up it doesnt want to change from 2nd to 3rd this happens only now and then but seems to be increasing the tranny oil looks really clean i dont pull any trailers are carry anything super heavy , is this a bad sign , so back to my first question what can i do to get better mpg, i was tol up grade the intake filtter , and get a chip but there is so many , and do they truely work if so which brand , i am thinking maybe a 12v with 5speed could be the way to go , thanks for any help

 

Right now, many of us are getting about 2-4 mpg less in winter due to the winter blend of fuel. I currently get about 20-22mpg right now, but I have another fuel to burn. With your trans acting up, you might want to have the filter changed at the next service. This may help with the trans shifting. You may also want to look into a valve body for the trans to help, also.

Is your torque convertor locking up in the higher gears?

Do you have any aftermarket gauges on your truck?
What is your fuel pressure to your injection pump? Low fuel pressure here affects mpg up to 3 mpg.
Upgrades do help improve mpg also. Adding a intake system, bigger exhaust will help also.

When was the last time that you changed your fuel filter?

These will give you a start.

Others will chime in.

 

thanks for your reply , its actually a 99 ram not that much diffrent , its fitted with the 3 inch system , so whats the best size , i dont have any gauges yet but will fit them ,trans and fuel pressure , and what sort of intake system, isthere away to tell if its got stock injectors, thanks for any feed back,

 

since its not a 98 you hav a 24v, id be checking your fuel filter, and psi to the injection pump...

 

sorry to butt in but how do u check the psi to the injection pump? my mpg varies from 16-18 mpg

 

You need to buy a fuel psi gauge and install it, before the injection pump the min psi u want to see is like 5psi(and thats min) should be around 14psi if im correct... But im not so sure that would cause bad mpg's. Im thinking its ur tranny making the engine work harder... Have u checked for codes?

 

There is a schreader valve on the side of the VP-44, this is where you check the fuel pressure from the lift pump.



You will also need a tester like this, this one is from Harbor Freight and costs about $25.


The minimum pressure should be 10psi. The reason for worse fuel mileage is that the VP is having to work at getting fuel and not just supplying the engine. The VP has a pop off valve that opens at 14 psi that returns fuel to the tank, for lubricating and cooling the injector pump.