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Old 03-28-2019, 05:47 PM   #33
Delfin
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Join Date: Jan 2010
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Quote:
Originally Posted by Riverguy View Post
Thank you for confirming that Racor confirms that the vacuum gauge is useless when the engine is running under no load.


Still, Racor's dumb language adds to the confusion.


When I say "the vacuum gauge is useless when the engine is running under no load" and Racor says "...the operator must observe the needle while the engine is running at service speed", how are those different?


Here's how they are different.


For someone who normally runs at 1,800 rpm, they >>might<< think that running at 1,800rpm in neutral this is the same as "running at service speed". This is not true. When the engine is running at 1,800 rpm under no load, it is barely drawing more fuel than it would running at idle under no load.


This is a common misconception I have wittnessed dozens of times here on trawlerforum and pretty much everywhere else I go. Folks just can't seem to grasp the idea that engines draw fuel in proportion to the load presented -- not the rpm spinning. The load on a diesel engine determines how many GPH it is pulling, not the RPM!

Re: "You appear to be the only one who thinks the OP's reading of the vacuum gauge took place under no load."


All I had to do was look at his filter photos to know. That, and seeing dozens of people make the same mistake over the last 30 years or so (including me, once upon a time).
That's impressive. Although the OP never says he reads his gauge under no load (who does, anyway?), you can divine he is and when telepathy fails, you can also do so just by looking at a dirty filter. Wow.
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