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  #1  
Old 07-13-2021, 12:08 PM
KayaRV7A KayaRV7A is offline
 
Join Date: Mar 2020
Location: Colorado
Posts: 4
Default Tank Sealant debonding? Boost pump PSi increase?

Hello you guys, I have had my vans RV 7a for over a year,

Starting to pull some weird stuff out of the Drain sumps. Almost looks like sealant ?

Iíve also noticed my fuel psi now increases when I turn on my electric boost pump which never happened before. It sits at 22 to 24 psi with the engine running and jumps up to 29 to 30 psi with a boost pump on


Any ideas whatís happening??
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  #2  
Old 07-13-2021, 03:06 PM
KayS KayS is offline
 
Join Date: Jul 2009
Location: lake constance
Posts: 403
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I asked a similar question several weeks ago. The stuff at your picture looks black and somewhat large pieces. standard Van's tank sealant has a more grey colour. When your tanks are almost empty you should be able to see the tank sealant through the fuel cap holes. Does it have the same colour?

Btw... higher fuel pressure indication with boost pump running should be normal behaviour. Mine does the same. Why is that a concern for you?

Last edited by KayS : 07-13-2021 at 03:09 PM.
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  #3  
Old 07-13-2021, 08:18 PM
Freemasm Freemasm is online now
 
Join Date: Nov 2017
Location: Orlando
Posts: 481
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Post more info on your fuel system config/type and your chances of meaningful responses will increase a lot.

Let us know.
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  #4  
Old 07-14-2021, 05:31 AM
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DanH DanH is offline
 
Join Date: Oct 2005
Location: 08A
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Quote:
Originally Posted by KayaRV7A View Post
Starting to pull some weird stuff out of the Drain sumps. Almost looks like sealant ?
Pour your samples through a coffee filter until you have collected a few dry bits. Even old sealant should be obviously elastomeric when placed on a hard surface and poked/cut with a small knife. Rust, dirt, etc, should be crunchy, for lack of a better word. Now rub a sample between your fingertips. What do you see?

Quote:
Iíve also noticed my fuel psi now increases when I turn on my electric boost pump which never happened before. It sits at 22 to 24 psi with the engine running and jumps up to 29 to 30 psi with a boost pump on
Many installations exhibit that behavior, but the fact that yours changed behavior is worth noting. You didn't mention the brand of boost pump, so we can't know what sort of pressure relief valve it might have. That said, it's conceivable that the pressure relief is partially blocked or sticking.

I assume you did not build the airplane. Given the reported fuel pressure, you have a fuel injection system. Filtration prior to the fuel injection servo will vary with FI brand. You need to find the primary filter and open it for inspection. If the trash is entering the fuel system from the tanks, you should find some there. Report back.
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  #5  
Old 07-14-2021, 10:42 AM
abwaldal@gmail.com abwaldal@gmail.com is offline
 
Join Date: Jan 2017
Location: Battle Ground WA
Posts: 299
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When a tank is empty find somebody with a Vividia 350 borescope and have a look around your tanks.
Real interesting if you find some area that is flaking away. Some people have used multiple batches of Proseal when building their tanks instead of making up a big batch for the whole tank. And got a bad batch.
Seen it before. The ugly truth may rear it's head.
Hope not for your case. Crud in the fuel isn't good ever.
Art
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  #6  
Old 07-15-2021, 10:54 AM
TS Flightlines TS Flightlines is offline
 
Join Date: Apr 2010
Location: Ridgeland, SC
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Robert, you didnt say whether you have rubber flop tubes or even rubber hose in the tanks for something else. I assume not, so this debris is probably stuff coming from the fuel. IF you DID have a flop tube you would see it in the filters, and not in the drains. Unless of course, it was an unprotected rubber hose and the additives in the fuel were deteriorating the outer cover.

More info needed.

Tom
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