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Engine power loss

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M

moremonkey

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For the past several years I've had a recurring issue with my BN1 that only happens when running in third gear with RPM over 3,000. Because I generally don't find myself in that situation, I ignored the problem. But when the overdrive stopped working reliably last summer (just fixed), it became more of an issue.

Anyway, now that I am working my way through winter repairs, I thought I would see what the collective wisdom of the Forum has to say about this.

As I said, when the engine runs above 3,000 RPM for any sustained period, the engine will abruptly lose power and sound as if it fouled a plug. The car will struggle and fail to maintain its speed, even with WOT, make kind of a sick burrrrblllll from the tailpipe, and feel like it is running on less than all four cylinders. If I put the clutch pedal in and let the engine drop to idle speed for a few seconds and then blip the throttle, the problem cures itself and won't come back unless I take the RPM back up over 3,000 again under load.

Other than this specific situation, the car runs great.

Any ideas what's going on and how to fix it?
 
Check carburetor float condition and levels.

Check Fuel pump deliver rate

Check air filters for lack of flow.
 
Sounds like fuel starvation to me, which can be caused by a blockage, air getting into the fuel lines, floats as Keoke says, etc. In general, that is a situation where the engine is using up the fuel available to it faster that it is being replaced by the system. It is amazing how a fuel delivery problem can seem like a fouled plug.
 
Sounds to me like a an inline fuel filter may be the culprit. I have had two occasions over the years where I have had exactly the same symptoms you describe. In both cases it was an inline fuel filter that was limiting the amount of fuel at higher RPMs.
 
Yep, sounds like a fuel issue. Everything above mentioned and even possibly fuel tank, filters. Mine would just quit which turned out to be the fuel pump being clogged from a rusty fuel tank. Yours problem sounds different, though. Maybe running a constant fuel flow test by removing the line after your in line fuel line (if you have that set up) to see if a good, constant flow still occurs. Easy tasks first. That and then trying new filters, then check your floats. Wouldn't hurt to also clean up your electrical connections to your fuel pump.
 
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