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Sometimes sounds like it's spitting out a hairball

562 Views 8 Replies 4 Participants Last post by  GAmes
As with all the best problems this one is defying reproduction. Sometimes I will start my 97 Ram2500 truck it coughs and fusses and shuts down. I restart and give it a lot of throttle, acts like it's hacking out a hairball, and eventually it will start and blow out a large cloud of gray/black exhaust.

Then runs like there was never a problem until the next time.

Only things that seem to have any relation is sometimes parking on a slope, doesn't matter up or down. Sometimes having sat for awhile. More often when it's cold.

By the way, never happens in the presence of any of my mechanically gifted friends.
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Thanks. Any thoughts on where to start trying to track down the problem?


The supply side of things. Pressure test everything from the tank to the IP. A rag around a vacuum cleaner (hooked up to the exhaust side) inserted to the gas tank should be enough. Check for fuel leaks.


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Hook up the hose of a shop vac to the reverse side of the vacuum (exhaust). Place it in the gas tank and wrap a rag around it to seal it better. Turn it on. It鈥檚 basically forcing the fuel down the lines, so if there鈥檚 a leak, it鈥檒l present itself.

The supply side of the fuel system (tank to IP) will only present itself as an air leak when the truck is running. This is because the fuel is being pulled through those lines, not pushed, so any opening will allow air to be sucked through as well. So when the truck shuts off, air gets into the system. Typically, you can smell an air leak, but not see it.


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