2nd Gen Non-Engine/Transmission Too much power?

[MCarstens]

I have a '99 HD2500. It has more power than I need, but is only getting 12. 5 mpg (11. 5 mpg with a trailer). I do have a topper that sticks above the cab about 7 inches, but find it hard to believe that is the total problem.

I have taken it to the local cummins shop - "nothing I can do, you should take it to Dodge". I took it to Dodge "nothing that we can do to these things, they're all electronic you know".



Is there something that can be done? Can I buy under-sized injectors?

This morning I noticed the snow by the tailpipe was the color of raw diesel for about a 4 foot diameter circle - should I be concerned about this? It was about -5 F this morning.



Thanks,

Mike

 

[DKarvwnaris]

I have a '99 HD2500. It has more power than I need, but is only getting 12. 5 mpg (11. 5 mpg with a trailer). I do have a topper that sticks above the cab about 7 inches, but find it hard to believe that is the total problem.

I have taken it to the local cummins shop - "nothing I can do, you should take it to Dodge". I took it to Dodge "nothing that we can do to these things, they're all electronic you know".



Is there something that can be done? Can I buy under-sized injectors?

This morning I noticed the snow by the tailpipe was the color of raw diesel for about a 4 foot diameter circle - should I be concerned about this? It was about -5 F this morning.



Thanks,

Mike

If you have diesel dripping from the exhaust, you had best stop driving the truck before the turbo catches on fire, or the oil pan overflows with diesel and pushes all the motor oil out of it.

I highly doubt you have diesel draining out of the exhaust personally, most likely you are seeing a crack or hole in the fuel tank costing you gallons of fuel with each fillup. (I bet you have happened to see it next to the exhaust since the tank is on the street side and the exhaust is curb side which will naturally make the fuel leak drain to the curb by road slope).

Have it towed to a reputable Cummins dealer and authorized service center.

Taking the truck to a dodge dealer will do nothing for you but empty your wallet first, and second get your truck referred to the cummins shop in 90% of most engine repair issues.

Fill the truck up immediately before taking it in for service and have them look the tank over for leaks, including the filler neck. (if you're capable of getting under the truck and looking for leaks, you should be able to find the source, but I don't know your current weather outside, so this may not be a favorable task).

Only other thing I can readily think of is a leaking fuel line, possibly the return. If it was the supply, you may have trouble starting due to air in the system?...



If you bought the truck used, did the previous owner "bomb" the truck possibly? Did you have the shop check the injector timing before dismissing them from the repair? If you have a tractor pull equipped truck, you may just need to find someone with a need for black smoke power and swap their stock parts with you.

I have not seen many cummins truck get below 14 mpg, something is definitely a miss.

 

[bmoeller]

Sounds like you have a fuel leak, not related directly to engine operation. That will kill your mileage in a hurry. After that problem is solved, then I'd start looking into other things.



There are some sensors that can get dirty (and can be cleaned), and will have an effect on the mileage.

 

[Turbo Tim 1]

A faulty Intake air temperature sensor will cause poor mileage and a bad lift pump has been known to cause poor mileage. Do you know what your fuel pressure is?

 

[DKarvwnaris]

A faulty Intake air temperature sensor will cause poor mileage and a bad lift pump has been known to cause poor mileage. Do you know what your fuel pressure is?

I was under the understanding that if the lift pump is not providing enough pressure on the 24 valve engines, the injection pumps will attempt to compensate for the difference and fail shortly after?

 

[Turbo Tim 1]

Mine was basically dead when I bought the truck with 24,000 miles on it, I replaced it and now with 141,250 miles it's still on the original VP. I guy I know up in Maine bought a 2002 brand new, anyways he was having big issues with fuel mileage from the day he got it, he towed his camper to South Carolina and got 5 mpg where he use to get 10 with his gas job. In the end they found a bad/dead lift pump (truck had 8-10,000 miles on it at this point). The VP-44 doesn't always fail just because the lift pump is out, mine ran perfectly fine with zero psi and I have no idea how long it was dead, maybe since new I don't know, but I do know Mikes was dead for close to 10,000 miles and his VP is still going strong too.