8 cylinder front engine iconic vehicle
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By checkmate1996
#72411
So at 429$ for a new one of these fuel dampers, I wanted to personally see what all the hub bub was about so I decided to cut it open. This donor was leaking fuel through the vacuum line causing a hard warm start condition generally taking two times to start the car the. It would be a rough idle for a moment or two until pressure built back up.

That being said, I didn’t see a smoking gun with the diaphragm but clearly fuel was leaking around it someway.
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By Sazerac
#73261
Checkmate, very interesting picture.

When you were having that warm start trouble, did you smell any gas as well?
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By checkmate1996
#73268
No in the car. But I did start to note the problem became progressively worse. The front damper is the first spot to look and sure enough when I pulled off the vacuum line fuel droplets came right out. Put a new one on and all good.
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By worf
#73274
A vacuum hand pump is your friend when you think you've got bad dampers or regulator if they don't just drip fuel out the vac lines.

Note also, that the rubber elbows and the other N-way connectors do not like being soaked with gasoline. So, if you find a bad regulator or damper, you should spring for a new set of all that rubber. And vac lines too.
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By Sazerac
#81770
Checkmate, so, I respectfully wonder, if we could not retitle this thread to something like the "Fuel Damper Discussion Thread?" The basis of the internals is such a great start!

I was having a warm start problem that also turned into a cold start problem and found a leaking fuel damper. After starting my car shortly, turning it off and disconnecting the vacuum line, I observed constant drops about 8 seconds apart for many minutes at the rear damper.

The interesting thing was that although I tested the dampers and regulator with a vacuum gauge pulling about 7.5" - 10" of mercury and they tested good, the rear damper was leaking anyway. Maybe I just didn't pull enough vacuum??

This is an interesting failure mode, because I would have thought that the vacuum test would have caught a bad damper.
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By checkmate1996
#81972
I've also run across issues where the hand vacuum pump didn't detect a leak. I don't know how scientific this method is but after removing from the car, I have shot some wd40 in the damper or fuel regulator and then hooked up an air compressor air nozzle to it at 40 psi. If I see any fluid spit out of the vacuum line then it's shot...YMMV!
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By Sazerac
#82521
As we speak I going through a fuel damper replacement. What I am wondering is how these thing really fail...

I like GB's view on certain of the key suspension bits, you need to replace them to get optimal performance. I also like Stan's view on the brake master cylinders: they are consumables after 20 years. The harmonic balancers also go with age, and the torque tube dampers have a finite lifetime.

The point is that any component with a rubber part is going to need replacement sooner than later in our aging fleet of 928s. Maybe I will try to cut the damper I just uninstalled up to see how it failed.
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By Sazerac
#83049
Further to my thread above, there is irrefutable evidence that ethanol destroys parts of our fuel system like the intake pump's hose that can get ingested in the main pump when it splits open.

Does anybody here think that ethanol can play a role in the failure of fuel dampers? Of course, like I said above, it's a part whose performance/reliability is determined by a natural, degrading substance, so it will fail sometime. But, is ethanol fuel something that accelerates this?

I ask this because it seems like my European friends with 928s have less problems with fuel lines and dampers aging and failing than we do here in the States!

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