fuel pump only on when cranking

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Feb 10, 2010 | 01:41 AM
  #1  
i'm sure it seems like a weird question, but should the fuel pump turn on when you first turn the key to the ignition on position. it sounds like the pump at the engine is going,(or at least something is making noise up there) but the pump in back isn't turning on until i start cranking. i'm asking because i think its the pump that is why the car isn't starting but looking for ideas, just thought that was weird when i was testing thigns the other day. thanks for the info guys
also, if the pump ends up being fine, where is the relay so i can test that, the fuse is fine i already checked that
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Feb 10, 2010 | 02:14 AM
  #2  
well. you need three things for a 4 stroke to operate. fuel. spark. and air(compression)..
all techs know that you are supposed to verify mechanical operation is proper (check compression) but now-a-days with modern engines its usually the spark or fuel that is not there.. check for spark first (its the easiest) then fuel then compression..
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Feb 11, 2010 | 01:27 PM
  #3  
When turning the key to on the on position, the fuel pump is supposed to run for a few seconds to build pressure on the rail. Like Bigern said is usually fuel and/or spark that keep the engine from firing up. If you got spark then you'll need to check for fuel. If you know where the feed fuel line is, disconnect it (put a rag over the joint to keep from fuel spraying everywhere). Turn the key to the on position and see if fuel pours out. If no fuel is present or a very small amount comes out I'd check to see if the fuel filter is plugged. If fuel filter is ok then check the pump. I'd take a jumper lead and bypass the relay and connect the pump to a 12v source to see if it runs. If it runs then the relay is most likely the culprit. If pump does not run then pump= dead. See if this helps you out.
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