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ManleyLawn
10-20-2003, 10:56 PM
i was wondering what could cause my fuel mileage to go down to almost 250 miles to a tank? i have a 96 dodge ram 3500 with the 12 valve cummins turbo deisel. it has 137,000 miles on it. i cleaned the air filter checked lines and hosesput additives in the fuel i just can't seem to figure it out. i haven't had a chance to take it anywhere because it is my main truck so any help or ideas would be appreciated. thanks

TLS
10-20-2003, 11:57 PM
Any large amout of smoke?

Any Diesel Smell?

Could have a leaky injector.?

Winter Fuel? (forgot to look where your from)

Is your parking brake on?

:eek:

The Lawn Boy Pro
10-21-2003, 12:04 AM
Originally posted by TLS
...Is your parking brake on?

:eek: Boy, that would be funny! Sure hope its not!!!!!

2 man crew
10-21-2003, 12:11 AM
Could be the transmission.:D

Lawncareguy
10-21-2003, 08:10 AM
Holy Cow! That is less than 7mpg! Do you have any excessive smoking? You could have an injector problem or fueling issue on the fueling ECM. I would take the truck to a Cummins truck dealer and have them plug it up and check the codes.

Too many variables to try and troubleshoot without knowing the codes.

ffemt1271
10-21-2003, 09:32 AM
1. change the fuel filter
2. get fuel pressure checked rule out lift pump problems)
4.check injectors
5.check all hoses and clamps on hoses connected from turdo to cooler and from cooler to engine.
6. has your fuel station changed to winter fuel blend(usually drops mileage a bit)

these are some things i thought of. most of them you can rule out your self.

ffemt1271
10-21-2003, 09:33 AM
1. change the fuel filter
2. get fuel pressure checked rule out lift pump problems)
4.check injectors
5.check all hoses and clamps on hoses connected from turdo to cooler and from cooler to engine.
6. has your fuel station changed to winter fuel blend(usually drops mileage a bit)

these are some things i thought of. most of them you can rule out your self.

blafleur
10-22-2003, 06:42 PM
Sounds like injectors or lift pump, or both. Very common in Cummins.

Randy J
10-22-2003, 09:53 PM
Actually on the 12 valve, injector or pump problems either one are pretty rare. As a matter of fact, I've never heard of a problem with either on that engine. Now the 24 valve is a different matter - many problems with the fuel pump on it. Didn't you have another thread on this? In that one, most people were saying check the valves - they need to be adjusted about every 30,000 to 50,000 miles on that engine if I remember correctly. The 12 valves were notorious for return fuel line problems, but that usually shows itself as a hard start cold problem. I'd be checking for a fuel leak somewhere though.
Randy

blafleur
10-22-2003, 11:30 PM
Again, I show my ignorance. This is a good question for dieseltruckresource.com, or turbodieselregister.com.

Bryan

ManleyLawn
10-22-2003, 11:40 PM
no leaks, i had it on the lift tonight and it was clean as a whistle. fuel filter, air filter and leaks..........all taken care of about 2 weeks ago or so........ i'm gonna stop by and talk to a diesel mechanic tomorrow morning hopefully he can hook it up to the scan tool for me. we'll see thanks for answering my posts

Tx Firefighter
10-23-2003, 10:34 AM
Sounds like your pump timing may have slipped.

24 Valve engines came out in mid 1998. Before then, it was 12 valvers.

12V Cummins are dead nuts reliable. Injectors and lift pumps do not fail on 12V engines. 24V engines average a lift pump about every 100k miles (about $170 cost).