no power on L8000

01-22-2006, 10:45 PM
I was wondering if anyone had a thought on my L8000. It's a 1987 L8000 with a cat motor. It operates fine at low speeds, however, tops out at 50 mph and will not pull hills empty. It shifts smoothly and the engine sounds great, 0 through 35 seem to have plenty of power then seems to struggle to reach 50. Almost as though it is bogging down but the rpms are not suffering and the engine doesn't seem to be choking. Any suggestions or thought would be great. Thanks, Nick

01-23-2006, 10:13 PM
Have someone follow you and make sure the exhaust is not blowing out visible exhaust smoke as you drive at higher speeds.

If there is no or very little smoke, try changing the air and fuel filters.

Also check the fuel pick-up tube in the tank. I have had jokers place an empty plastic shopping bag in the tank. This gets sucked up the pick up and cuts fuel flow and power.

If that does not help, check for a pinched fuel line, or a bad fuel pump.

If you have lots of smoke, look for a blown head gasket, failed injector pump, bad injector timing, leaking injectors, holed piston, or a blown/seized turbo

01-25-2006, 08:16 PM
Let me guess, a 1987 L8000 with a 3406 CAT diesel, correct?

With vehicles of this area, there are a few common causes for your concern:

1) Leaking "puff limiter", or "aneroid" as they are called. This sense "boost" from the turbo, as you add more boost, it allows the injection pump to add more fuel with it. When they fail, the engine runs well except it lacks power.

2) Restricted fuel lines. This happens quite alot, expecially on engines where the owners use fuel addatives. The inside diameter of the lines is reduced due to swelling of the hose. This restricts fuel flow, but is generally only noticeable near full RPM/power demands.

3) Degraded fuel lines allowing air into the fuel system.

4) Throttle does not make it into the "full fuel" poistion on the injection pump. This can be cured in many cases by adjusteing the throttle linkage.

5) Restricted fuel filters. This can happen from one tank of "bad fuel". It is fairly common, but the power loss is very sudden. Often accompanied with excessive white smoke.

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