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Rattlinbone · Joined: 21 Jun 2009 Posts: 265 Location: Seattle, WA

Can anybody identify what these two things are? They are located in front of the gas tank, just above the right rear axle:

When I have the engine going for just a little bit, they drip gas, so I think they're part of the fuel system. I'm guessing that when I get the fuel pump going, the pressure is pushing the fuel through a hole or a bad seal or something.

Any ideas?[/img]
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Fred- 1979 924

Rich H · Posted: Sat Oct 30, 2010 3:59 am Post subject:

They are knackered!!

Fuel accumulators and my crystal ball says you have a hot start problem...
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1994 Lotus Esprit S4 - Work in progress...
1980 Porsche 924 S2 DITC Turbo - Original spec
1978 Homo-Sapiens - Tired spec
1953 Landrover S1 - Pensioner Spec

Rattlinbone · Joined: 21 Jun 2009 Posts: 265 Location: Seattle, WA

Is this it?
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Fred- 1979 924

Rattlinbone · Joined: 21 Jun 2009 Posts: 265 Location: Seattle, WA

By the way, I don't know the full extent of the gremlins there are still to sort out in the fuel system. I just had the engine rebuilt, and the gas tank was cleaned and relined and I have a new fuel pump and fuel filter, but I don't think I had these replaced. I will do so right away, of course. And I'll probably replace the lines and connections here as well.

The other major fuel problem I'm having is that I am not getting any fuel level reading on my dash fuel gauge. Any thoughts on how to track down that problem?
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Fred- 1979 924

Brockoli · Posted: Sat Oct 30, 2010 5:38 am Post subject:

Thats what my accumulators looked like before I replaced mine. Fixed my hot start problem too. Pretty easy fix.

Take your fuel sending unit out And clean it up. Pull up your carpet in the trunk and you will see it. Be careful not to break the wires the float rides up and down on
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'80 924 M471,Wideband O2, Full coilover susp,23/19 sways,Bilstiens,KLA Strut Brace,Roll Bar,Test Pipe,BBS RS, Willwood BBK

25% of a '87 944 Chumpcar http://straightpipe.ca/forums/showthread.php?t=2454

'79 924 Sebring Edition(Sitting)

Rattlinbone · Joined: 21 Jun 2009 Posts: 265 Location: Seattle, WA

Thanks for the advice. Say, when cleaning that fuel sending unit, what sort of cleaner should I use? Solvent or maybe just some soapy water?

Man, those accumulators are spendy units! On Pelican they're listed as '73 911 parts! Is there an aftermarket equivalent? Something I could find on a VW or an Audi or something?
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Fred- 1979 924

Brockoli · Posted: Sat Oct 30, 2010 6:32 am Post subject:

Ya not cheap but nothing really is with our FI.

Having the car start everytime even when hot is worth it in my opinion. I can remember having hot start problems and at the time I would be willing to spend more than a fuel acc to fix it
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'80 924 M471,Wideband O2, Full coilover susp,23/19 sways,Bilstiens,KLA Strut Brace,Roll Bar,Test Pipe,BBS RS, Willwood BBK

25% of a '87 944 Chumpcar http://straightpipe.ca/forums/showthread.php?t=2454

'79 924 Sebring Edition(Sitting)

!tom · Posted: Sat Oct 30, 2010 10:18 am Post subject:

Has anyone ever tried to make their own accumulator?

All you really need is a chamber that has entrapped air, like an anti-hammer device in plumbing.
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78 924 NA
5-lug

Paul · Posted: Sat Oct 30, 2010 10:23 am Post subject:

Air and fuel mix pretty well that's why the stock part has a rubber diaphragm and a spring to keep them separated.
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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.

Rattlinbone · Joined: 21 Jun 2009 Posts: 265 Location: Seattle, WA

Makes me wonder if it's not the accumulators that are bad, but the hoses, lines, joints or seals that lead into and out of it. I mean, those accumulators look like they are pretty simple units, how likely are they to fail? Wouldn't it be more likely that the fuel lines are bad?
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Fred- 1979 924

Paul · Posted: Mon Nov 01, 2010 1:15 am Post subject:

Are you asking why 30 year old rubber diaphragms might leak?
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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.

Rattlinbone · Joined: 21 Jun 2009 Posts: 265 Location: Seattle, WA

Not anymore. I did what this dummy should have done first, I read a book. There is a diagram of what is inside the accumulator cans in the Haynes manual. There's a spring and a diaphragm and some rubber bits and stuff. So, yeah, I can see how these would wear out.

I went down to a pick-n-pull salvage yard and yanked a couple accumulators off some 78 924s, and from the outside they look okay. I thought I might give them a cleaning before I try putting them on. Do you suppose it would be alright to run a little carb cleaner through them, just to get out any gunky varnished gas residue that mught have built up inside? Or would that screw up the rubber bits?

Yeah, I know it's better to get new ones, but new these items cost over $100 per, so I figured it wouldn't hurt to give these used ones a try before I go for broke.
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Fred- 1979 924

D Hook · Joined: 02 Nov 2002 Posts: 3158 Location: Omaha, NE

Might want to check but I thought the double smaller accumulators were superceded by the single large accumulator.

Check ebay also but be sure you know what you're looking for since there are several.
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'80 924 n/a SOLD

Slam · Posted: Tue Nov 02, 2010 3:50 am Post subject:

^ Yup - you can just get one good bigger one and dump the small pair.
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'88 944 Auto - may or may not resurrect

Rattlinbone · Joined: 21 Jun 2009 Posts: 265 Location: Seattle, WA

They don't have to be Porsche OEM parts, do they? Are there compatible units from other manufacturers?
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Fred- 1979 924