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Engine Idle and Power Problem


sachimore

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Need some advice guys. Have a 2002 Silverbird with 65K on it, well maintained and has never had "any issue" of any kind. Garaged and loved for 20 years. 

 

Recently noticed that at idle it is no longer the smooth no move tach needle at 1,100 RPM. It bumps. Every few seconds it’s like one of the combustion cycles is a little stronger than the others and the needle can bump up a couple of hundred RPM and immediately drop. Then hit again and again. You can feel the bump in the seat.

Few days ago I started to get a low RPM type burble when pulling away from a stop sign. A miss kinda. By 1,600 or 1,700 RPM smooth. The next day worse, the burble turned to a low RPM power loss as it leaned to actually cutting out. Smooth out moved to around 2,000. Next day worse in all directions but now I have an occasional feint back fire while the RPMs rise. But after 2,400 smooth as silk.

Whatever it is it is happening fast. I’m a decent mechanic but not electrical which this feels like.

Any ideas appreciated as I have no idea. Or at least where to start.

 

Thanks

 

Sach

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2 hours ago, blackhawkxx said:

Have you checked the spark plugs to see if one looks different from the others and their condition in general?

 

Adding to this, and agreeing, but also what's the other maintenance like?  Air filter?

 

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Often overlooked are vacuum lines. Those little things attached to throttle bodies and fuel pressure regulator. If even one of them is cracked it is gonna effect fuel pressure.

XX has a reference FPR. Referenced to vacuum in intake tracks. 

 

The easiest way to do it is to replace them all at once or it will take forever to figure out what line goes where etc.

 

Get foot or two of appropriate I.D. from Auto Zone, razor blade, and replace them piece by piece. 

Edited by tomek
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Plugs and filter all new 5K ago.

Rebuilt the entire bike 3 years ago except for the engine and trans. Did not see any need to touch them.

Some great thoughts here and will follow up.

 

Thanks guys

 

Sach

scoot.jpg

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First thing I'd check is the FPR (fuel pressure regulator).  I think you can get to the vacuum hose without disassembling stuff, but it's been a long time.  Pull the hose off and if there's gas in it it's done.  If there's no gas turn the key on to pressurize, if still no gas then it's probably fine.  My second thought is the test connector corrosion issue.

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1 hour ago, sachimore said:

Can somebody tell me where the fuel pressure sensor is

There isn't one.  The fuel pressure regulator is at the right side of the fuel rail.

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