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  #1  
Old 10-20-2003, 11:45 PM
ManleyLawn ManleyLawn is offline
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cummins fuel problem

i have a 96 dodge ram 3500 with th cummins 12 valve diesel. i have been getting very poor fuel mileage. it has 137,000 miles on it. it has progressivly gotten worse. ive tried additives and cleaning the air filter and checked fuel linesfor cracks etc. would you guys give me your thoughts and opinions on this. thanks
oh yeah it gets a bout 250 miles to a tank (29)gallons...
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Old 10-21-2003, 07:35 AM
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Grassmechanic Grassmechanic is offline
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Is it blowing black smoke? Did you have the valve lash adjusted every 48,000 mi? Is someone siphoning fuel from your tank? More info, please.
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Old 10-21-2003, 08:55 AM
sdwally sdwally is offline
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Valve train probably needs adjusting, especially if the injectors are unit injectors(no diesel injector pump with steel injector lines running to injectors on the exterior of the engine.) You may also have some injectors with bad spray patterns, ie. pull the injectors and have them rebuilt.
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Old 10-21-2003, 02:25 PM
ManleyLawn ManleyLawn is offline
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yes it is blowing black smoke and no no one is siphoning gas from my tank and i haven't put 48000 miles on the truck but i'm sure the valves could be adjusted is that something that i can do or should i take it to a diesel tech?
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Old 10-21-2003, 02:27 PM
ManleyLawn ManleyLawn is offline
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thanks for the info
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Old 10-21-2003, 08:22 PM
Randy J Randy J is offline
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i'm trying to remember, I think the valves need adjustment on the old 12 valves about every 30,000 miles. It's not hard to do, if you're at all mechanically inclined. If not, than any diesel shop should be able to do it.

Randy
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Old 10-21-2003, 09:21 PM
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Grassmechanic Grassmechanic is offline
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Initial valve adjustment is at 24,000, then every 48,000 afterwards. It sounds like injector pump may need adjusting.
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Old 10-26-2003, 01:47 AM
ManleyLawn ManleyLawn is offline
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ok i talked to 2 diesel mechanics and they both said that it sounds like the injetors may need cleaned or replaced. the one also said that they have had cummins motors come in with over 200,000 miles on them and never have the valves touched i dunno i think i will give this lucas additive a full tank and see if it helps clean the injectors. thanks for the input
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Old 11-05-2003, 01:09 PM
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floridalawncare floridalawncare is offline
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manley has the right idea. my uncle has one with over 500,000 and never a wrench on the engine. also be sure your air filter is in top notch shape. this is very important on any diesel. if these things don't work, your injection pump timing is adjustable. sometimes wear on your cam drive components can cause it to get a little out of time. it'll still run if it's not to far out, but not that good. i'd let a qualified tech perform this procedure.
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