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IO-470N Engine Stall (cont.)

IO-470-N

I am at a loss and this issue has basically had me grounded for 3 months now.

Here is a link to my previous post.
https://www.bonanza.org/community/member-forum/tech-tips/posts/aug-2023/io-470-n-engine-stalling/

Here is a video of it trying to die, and me saving with boost pump.
https://clipchamp.com/watch/mlCsHKIZPSG

Here are all the things that were checked/fixed.
* sniffle valve - no issues
* intake leaks - various minor ones fixed
* fuel system setup per 97-E3
* fuel flow divider p/n 631427A32 overhauled
* disassembled, cleaned, inspected, lubed, and reassembled bendix mag switch
* resealed both fittings on the fuel flow transducer
* engine driven fuel pump overhauled 3-4 years ago

The resealing of fittings on fuel flow transducer, I thought, fixed the problem as there was a leak and at rest would create a vacuum and pull in air. This would cause air to get into fuel line causing the problem. However, the plane sat for a couple weeks and when I returned to take her up the same issue, I've been having, came back. This time, way worse. Prior to the "fix" the plane work idle fine after it warmed up (maybe the air bubbles clearing out?). Now I can't keep it running without giving it a quick boost from fuel pump. While this issue was occurring I tried the following...

* would try to die between 700 rpm and 1500 rpm (didn't go higher)
* different mixture settings
* running on left mag (surefly)
* running on right mag
* the engine would die faster when cold and once warm there would be longer periods of time between it trying to shutdown.


There's no way I can fly this to a mechanic shop...no way. I can get an on field mechanic but I need to know what to try first. Anything I can investigate myself the better. That way I can say...replace x/y/z.

Model: Bonanza P35
Posted 11/22/2023 - 7 months ago
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Dave;

I just watched the vid (took several times to try and catch all parameters); my main takeaway was the FF dropped notably before the pressure dropped. Do you have a download of this (raw data or the excel spreadsheet from the JPI would be fine)? Looking at the markings on the pressure, it must be metered pressure, and that makes it more confusing as metered fuel pressure is nozzle pressure, so they should move in sync., if it is a fuel flow issue. Assuming it does this on either fuel tank selected?

You gave us calendar time in service on the engine fuel pump and flow divider, what about (hours & years) on the electric (boost) pump, fuel selector, metering unit, and SOH on engine?

If you have the download, please post here or email it directly to me at avstarshop@att.net (ABS office closed until Monday).

Mike
ABS Technical Advisor

Posted 11/22/2023 - 7 months ago
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IO-470N Engine Stall (cont.)