POOR MILAGE?

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I HAVE A 1993 W-250 EXTENDED CAB 4x4. 5 SPEED MANUAL, 3. 54 AXEL RATIO(I THINK) 95000 MILES ON CLOCK. . REGULAR OIL/FILTER CHANGES. FUEL MILAGE IS DOWN TO 12 - 14 MPG. NORMAL DRIVING CITY/HIGHWAY. . LOTS OF BLACK SMOKE ON START UP. .
SUSPECT I NEED INJECTORS?? ANYONE HAVE ANY IDEAS ABOUT WHAT TO CHECK?? SOURCE FOR NEW OR REBUILT INJECTORS. .

 

[Archive]

When was the last time you replaced the fuel filter and the air filter. These, if dirty, can significantly reduce mileage and performance.

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92 Dodge LE, Cummins, reg cab,4X4,3:54 gears, Auto, Black/w Maroon Int.

 

[Archive]

Fuel and Air filter would be my first check.
Excessive fuel consumption, black smoke and low power have symtoms that are common to all three: Bad fuel, or injection pump timing, restricted or damaged injector nozzle, Air filter clogged, or air leak at the turbo boost tube to the manifold. Did this come on suddenly, or gradually?

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92cum'ns 5spd 4wd all possible mods. to void warranty.

 

[Archive]

The air and fuel filters are a good place to start. I also would look at having the e valves adjusted. I noticed a marked improvement in performance when all of the above was done.

 

[Archive]

You might look at your intercooler hose connections. If you have a leak in in the air induction system, you'll have a lot of black smoke on acceleration. Wouln't hurt to check the tightness of all the clamps either.
Bill

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97,3500,CC,4x2, Auto, 4. 10LSD, All Options incl Leather, PacBrake, 3 Pos Lockup Switch, PrimeLoc, Jardine 4" Cat-Back Exhaust, 45 Gal. RPM Aux Fuel Tank, Mag-Hytec Covers, Painless Wiring Kit, Reese 20K Hitch, 80% Towing 12,000+LB 5th Wheel, 2000-3500QC, HO Engine, 6 Speed, SLT+ on Order

 

[Archive]

Yep. as Ram and Bill have stated - turbo pressure path, thru the intercooler to the intake manifold needs to be leak free. And the valve setting needs to be on spec. A thought - is the intercooler leak free?

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92cum'ns 5spd 4wd all possible mods. to void warranty.

 

[Archive]

I have a 92 and had power loss and less then desired fuel mileage. I was doing some checking to trouble shoot the problem and decided to test my innercooler. I made the necessary things to pressurized the innercooler and found a pretty good leak. It was in the metal tube where it makes the 90 degree bend and attaches to the intake. I think it was a defect when it was built and it took a little while to go bad the rest of the way. I did the old JB Weld trick and retested, it solved the leak problem. Later on I had my injectors tested and three of them were not right, I had new tips put on all of them.

 

[R C Cola]

Amazing what that JB will do. Did an oil pan on a road grader 5 years ago, no leaks yet.