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RobertN
Joined: 19 Apr 2015
Posts: 142
Location: Lisburn Co Antrim
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 Posted: Tue Nov 17, 2015 8:49 am Post subject: Fuel Accumulator test |
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Hi guys, can anyone advise on proper way to test my fuel accumulator, on or off car?
Loosing pressure when engine is left to sit after an hour, I'd turns and splutters a few times before starting. Once started you can switch off immediately and restart straight away!
Plenty of second hand accumulators from salvage yards, but would prefer to know if they actually work before buying. Also new is around £169.00!!!
Robert.
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Robert.
Porsche 924 N/A 1984.
Electrical Engineering Sales to Control panel builders. |
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Paul
Joined: 02 Nov 2002
Posts: 9491
Location: Southeast Wisconsin
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| Posted: Tue Nov 17, 2015 10:17 am Post subject: |
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Remove the slotted screw on the bottom, if fuel leaks out, its toast.
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White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
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Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy. |
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RobertN
Joined: 19 Apr 2015
Posts: 142
Location: Lisburn Co Antrim
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| Posted: Tue Nov 17, 2015 5:46 pm Post subject: |
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Cheers Paul. Screw is seized completely. Tried lots of wd40 with no luck. The unit looks like it came from the Titanic!,
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Robert.
Porsche 924 N/A 1984.
Electrical Engineering Sales to Control panel builders. |
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RobertN
Joined: 19 Apr 2015
Posts: 142
Location: Lisburn Co Antrim
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| Posted: Tue Nov 17, 2015 8:37 pm Post subject: |
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Paul,
Just wondering if I got one from a salvage yard would I be able to test it on the bench.?
Robert.
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Robert.
Porsche 924 N/A 1984.
Electrical Engineering Sales to Control panel builders. |
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Rasta Monsta
Joined: 12 Jul 2006
Posts: 11733
Location: PacNW
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| Posted: Tue Nov 17, 2015 11:53 pm Post subject: |
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That test would be done as follows:
Is the accumulator from the salvage yard?
If YES, then accumulator is bad.
In seriousness, bench test would require 100psi of fuel, although I guess a smoke test might reveal a leaking diaphragm.
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Toofah King Bad
- WeiBe (1987 924S 2.5t) - 931 S3
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RobertN
Joined: 19 Apr 2015
Posts: 142
Location: Lisburn Co Antrim
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| Posted: Wed Nov 18, 2015 12:32 am Post subject: |
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was thinking of testing via an air pressure guage and compressing air into the unit and looking for a drop in psi? Seen this just now online!!
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Robert.
Porsche 924 N/A 1984.
Electrical Engineering Sales to Control panel builders. |
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jason c
Joined: 13 Jan 2014
Posts: 1018
Location: Nwi
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| Posted: Wed Nov 18, 2015 12:45 am Post subject: |
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You don't new fuel or high pressure. High pressure is only needed to compress the spring, which never goes bad. You can test it with a leakdown type of test as you ask (if the bottom screw is removed).
You can also use a mityvac type vacuum/pressure tester. Plug one line & pressurize the other with the bottom screw removed. |
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Kenodog
Joined: 25 Jun 2003
Posts: 2669
Location: Vancouver,B.C.
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| Posted: Wed Nov 18, 2015 1:13 am Post subject: |
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Put a torch on the screw, a little heat will get it loose. 
Leigh
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RobertN
Joined: 19 Apr 2015
Posts: 142
Location: Lisburn Co Antrim
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| Posted: Wed Nov 18, 2015 1:21 am Post subject: |
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Hi Leigh.
Can you advise how to heat this while the unit is installed as I am nervous about applying a naked flame to the "fuel" accumulator??
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Robert.
Porsche 924 N/A 1984.
Electrical Engineering Sales to Control panel builders. |
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Rasta Monsta
Joined: 12 Jul 2006
Posts: 11733
Location: PacNW
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| Posted: Wed Nov 18, 2015 1:21 am Post subject: |
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If you choose not to test it with real world pressure (can't imagine why you would)_ I would sure recheck it following installation.
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Toofah King Bad
- WeiBe (1987 924S 2.5t) - 931 S3
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fiat22turbo
Joined: 18 Jan 2006
Posts: 4040
Location: Portland, OR
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| Posted: Wed Nov 18, 2015 1:30 am Post subject: |
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| RobertN wrote: | | Cheers Paul. Screw is seized completely. Tried lots of wd40 with no luck. The unit looks like it came from the Titanic!, |
WD-40 is only a Water Displacer, it doesn't do much to help break up rust. Get a real rust treatment solution like PB Blaster. Heat helps, but not a great idea with fuel system stuff  Percussion adjustments can help though!
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose) |
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jason c
Joined: 13 Jan 2014
Posts: 1018
Location: Nwi
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| Posted: Wed Nov 18, 2015 9:39 am Post subject: |
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| RobertN wrote: | Hi Leigh.
Can you advise how to heat this while the unit is installed as I am nervous about applying a naked flame to the "fuel" accumulator?? |
He is kidding, don't do that.
The diaphragm is rubber, it will leak at 1 psi if it is bad. A leak is a leak. Any leak is bad. Pressure is only needed to compress the spring, spring pressure is what compresses the fuel & thus maintains pressure while the system is idle. Since the spring doesn't go bad (the diaphragm is the only wearable part), high pressure isnt needed to test. The screw must be removed to test because the air leaking through the diaphragm will collect in the bottom portion, giving a false reading. |
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Paul
Joined: 02 Nov 2002
Posts: 9491
Location: Southeast Wisconsin
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| Posted: Wed Nov 18, 2015 12:31 pm Post subject: |
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remove screw
place in vise upside down
borrow your kids soap bubbles
apply over the hole the screw was in
block the outlet, your finger will do
apply about 10 psi of air to the inlet
if you see bubbles, toss it...
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy. |
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