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Old 10-23-2010, 05:56 PM   #1
firefighter777's Avatar
Join Date: May 2010
Location: Saint Louis
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Tough Start and Engine Pulsing

So when I start my engine it'll take a few cranks to start but if I just turn it to on and let it sit for a a couple seconds it'll start right up. Would that be spark plugs needing a change?

Also, when the engine is running (more so for the first 10 minutes of it running) the engine "pulses". The rpms will go up and down in a 200rpm window. For example it'll go from 600 to 800 back to 600 and so on. I threw some fuel injector cleaner in but it did nothing.

Can anyone shed some light on this for me? My jeep has 46,000 miles btw.

Thanks All!

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Old 10-24-2010, 01:16 AM   #2
Join Date: Oct 2010
Location: Amarillo, TX
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I'm not the most mechanical guy, so other's I assume would have more valuable information. With that being said, have checked your battery and battery cables. Mine had just a little bit of corrosion that was causing it to start pretty rough. It would really idle rough after start up. I cleaned the connections and coated them with a little Vaseline and now she starts like a champ every time. Hope it helps.

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Old 10-24-2010, 01:37 AM   #3
Join Date: Oct 2010
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I'm a stupid teenager but I'll give it my best shot.

Now if you were to crank it over really fast from the off position, it takes awhile? But if you left it on the "on" position for 2 or 3 seconds, it starts easier? The only thing that comes to mind is that the fuel pump is building up pressure when you leave it on the "on" position for a few seconds.
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Old 10-24-2010, 10:45 AM   #4
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It's most likely the fuel pressure regulator bleeding off the fuel pressure after it sits for a bit rather than holding it like it's located on/near the fuel pump and to change it, you gotta drop the fuel tank. You may also have to buy it and the fuel pump as a complete assembly...not sure if you can buy it separately. Definitely NOT the spark plugs though.
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Old 10-24-2010, 10:47 PM   #5
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would replacing the fuel pump entirely fix this?
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