Engine/Transmission (1994 - 1998) Bad Mileage

[randyco]

STILL BAD MILEAGE, AROUND 12-13 EMPTY, #10 PLATE , 5 SPD, 4. 10, 315 TIRES, 4" EXHAUST, TIMED AT 16, CLEANED PRE-FILTER, REPLACED FUEL FILTER, WHAT ELSE COULD IT BE ? NO LEAD FOOT HERE.

 

[DMC]

Take it for a 10 or 20 mile drive down the Interstate and check the miles traveled by the odometer verses the mile markers. I have 305/70/16 Wranglers and my odometer is actually off 10%. It records 10% less miles than it actually registers.



Your mileage doesn't sound that bad considering the size of the tires you have. another thing that can hurt your fuel mileage that is often overlooked is the proper venting of your fuel tank. Cold weather will really hurt your fuel mileage unless you are going on longer trips say at least thirty miles one way. I used to drive semi's over the road and the fuel mileage would go down about 20% during really cold temps say below 20*.



Good Luck



Don

 

[rnolen]

What do you mean by venting your tank? Is there some kind of valve I should be opening to let air out?

Thanks

Russ

 

[DMC]

There is a vent on top of your fuel tank. Can be seen by crawling under the truck and looking in between the straps that hold the tank up. Sometimes the vent will get clogged with mud or debris. If you hear a sucking sound when removing your fuel cap the tank is not venting properly. For some more points on this do a search for fuel tank vent.



Hope this helps



Don

 

[DMC]

Maybe this will help explain what I was talking about.



DodgeRam.org > Main > Diesel Index > 3rd Gen Maint > Low Power



Ram/ISB Low Power Solution

Excessive Vacuum may build in fuel tank which reduces engine power.





link---http://dodgeram.org/tech/dsl/ISB/low_power.htm



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Beginning in 1998 and continuing through 2001, there have been sporadic cases of low engine power caused by a plastic cap left on the fuel tank during assembly. This cap is on the tank vent port, and should have been removed when the tank is installed on the truck chassis. If the cap is not removed, vacuum will build in the fuel tank and engine power will drop because the fuel pump is unable to pull against the tank vacuum.



Most caps are red in color, but a few have been black. Simply pull the cap from the vent fitting circled in red on the drawing to the left. DO NOT remove the Auxiliary fitting cap. See photos below for other views.







Photo of vent cap location

Two More views of the vent (looking from the passenger side)



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Last Update July 3, 2001



Good Luck



Don

 

[rnolen]

Ok, Reading what you just posted it says is started in 1998. My truck is a 97. Is this for all 2nd generations or just 1998 thru 2001 like the link says?

Thanks again

Russ

 

[DMC]

All I know is that is where the vent should be. You may want to check this vent if you hear a sucking sound when you remove your gas cap.



Good Luck



Don

 

[rnolen]

I will take a look at it tonight and let you know.

Thanks

Russ

 

[randyco]

MY TRUCK IS A 1996 3500, POWER IS GOOD ,320 RWHP, THE ONLY PROBLEM I HAVE IS POOR MILEAGE. FUEL PRESSURE WITHIN SPECS. 181 DELIVERY VALVES, #10 CRANKED, 42 PSI BOOST, MILEAGE DROPS TO 10-11 TOWING, I GET AROUND 350- 400 MILES PER TANK. WHERE DO I GO FROM HERE? TRUCK HAS 73,000 MILES.

 

[LHartman]

That sounds about right Roc. I have 4:10's with an auto and I get about 13 -14 on average. When I'm on the freeway, I'll get 17 tops. Never been able to get it better than that.



Loren