WWWBoard New Message: Message 1661: No Power in Forward
WWWBoard: Message 1661
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Posted by Bill on 05/07/03 at 8:44 AM
Subject: No Power in Forward
Message Posted
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Here's an old posting from Don Moyer which may help:This condition is usually caused by something that was done incorrectly during the course of effecting repairs on the engine since the last time that it ran OK. As an example of the kinds of things we've discovered in this category: Five times during calendar year 1999, spark plug leads were installed in an improper sequence following a tune up! By the way, I believe it is cylinders 2 and 3 that can be reversed, and the engine will run fairly well in neutral, but will have practically no power in forward. According to one caller, his plug wires were reversed for an entire season before he found the cause of his power loss.Another recent maintenance "oops" involved a minor repair of the exhaust system which required that the manifold be removed. On reinstallation, the old gasket was improperly installed resulting in intake leaks and very poor power under load. Difficult though it may be to sort out each and every thing that could have been done wrong during recent maintenance work, this is the most fruitful place to start.Assuming that there was absolutely nothing done to the engine since it was last running OK, check the following areas for potential problems:1) Check for something hanging on to the prop.2) Check basic integrity of the engine by a quick compression check. For the purpose of diagnosing a major power loss, a simple check using your thumb over each spark plug hole is more than adequate. If your compression is sufficient so as to make it impossible for you to hold your thumb over each spark plug hole while cranking the engine with the starter, the cause of your power loss is not a major mechanical failure. If compression is weak in two adjacent cylinders, or water is observed in any of the combustion chambers, the head gasket has probably failed. If compression is "zero" in any of the cylinders, a valve has probably stuck open.3) Check for proper carburetor function. Normally, an Atomic 4 will accelerate almost "explosively" as you flick the throttle forward. If there is any hesitation or mild backfiring, a lean condition caused by dirt in the main jet is the most frequent cause. In most cases, a problem related to a fuel issue will manifest itself in neutral as well as in forward, but in mild cases, a lean condition might be missed in neutral, but will surely show up under load.4) Check for proper ignition. As in the case of subtle lean fuel mixtures, there are subtle ignition problems that can show up under load but not necessarily in neutral. In this category, plug condition is the best indicator. If one plug is noticeably blacker (or oilier) than the rest, look for the relatively few things that can affect only one plug, such as the plug itself, the plug lead or a cracked distributor cap. If all the plugs are badly fouled, check things that can affect all plugs, such as a loose condenser, badly worn points, shorting coil (or oil leaking from the coil), cracked distributor cap or a bad coil lead.
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