fuel accumulator problem?

[don gilbert]

i'm losing "at rest pressure" and have a fuel pump check valve on order, but while reading a cis help book, i read that the bottom hose coming off the accumulator (my 82 has 3 hoses, two at the top and on at the bottom, the bottom one going back into the return line) is a "safety measure" the book didnt elbaborate any more on it. i unscrewed the bottom hose and fuel started pouring out of it. is this normal, is this where i'm losinf pressure?

[equality72521]

Not normal. If fuel is coming out the bottom of the accumulator then the diaphragm is bad.

[don gilbert]

I was afraid of that. new one is 250.00 should i waste time putting a used one on it, what is the shelf life of one?

[equality72521]

If a used one is cheap enough for you to take the risk...

I'm not sure if there is a certain age where most begin to die but I would suspect from reading all the posts here on Pelican saying the same thing that once the part is 20+ years old is has pretty much jumped the shark. It sucks shelling out $250 for something nobody will ever see and gives no increase in performance but sometimes ya gotta do what ya gotta do.

[boyt911sc]

Originally Posted by equality72521

Not normal. If fuel is coming out the bottom of the accumulator then the diaphragm is bad.

Not exactly all the time. The bottom line of the FA has fuel in it as part of the fuel return line system for CIS. The fuel dripping from this hose could be either fuel being returned to the tank or from FA. Plug this line and pressurize the delivery fuel line to determine the condition of the diaphram. If the FA diaphram is defective or damaged, fuel will be leaking out when the delivery line is pressurized. A pressure test will tell you if FA is leaking or not.

Tony

[equality72521]

Thanks for the better explanation. Either way he's losing pressure so it's either the check valve or the FA. Certainly replace the check valve first. But he said fuel "poured" out of the bottom. If I was a betting man I'd say the FA is bad.

[don gilbert]

good idea tony, going out to the garage rite now

[don gilbert]

pluged line, looks like about 65-70 lb of presurized fuel comming out the bottome of the accumulator, you think it might be bad?

[equality72521]

Tony may disagree but I'd say "FAIL".

[SCWDP911]

That sux Don. I am not that familiar with the FA design, but is there no way to disassemble and replace the diaphragm only? We have to do this sometimes with various plant instrumentation. Shouldn't be a big deal with exception of how they designed it. Any way to get in there? Is the diaphragm part of the pressure setpoint, or is it coming solely from a spring? Just wondering out loud, in case I need to do this sometime down the road. Will have to look at mine more closely tomorrow...'

[Kroggers]

I can not find it now, but I did read a thread on here recently regarding removing the FA from the system. Is this an option, or will it just create to many problems?

[equality72521]

Originally Posted by Kroggers

I can not find it now, but I did read a thread on here recently regarding removing the FA from the system. Is this an option, or will it just create to many problems?

Unless you create a new way to keep fuel pressure up after engine shut down you will lose pressure the fuel will vapor lock from the engine heat causing very hard hot starts. Once the engine cools and the fuel condenses back to a liquid the problem goes away.

[equality72521]

Maybe some kind of check valve???

[don gilbert]

just ordered a new one.

[boyt911sc]

Originally Posted by don gilbert

pluged line, looks like about 65-70 lb of presurized fuel comming out the bottome of the accumulator, you think it might be bad?

Don,

You just performed basic a FA test. The diaphram is NO GOOD and you need a replacement FA. This is one reason why residual pressure was not holding up. Used fuel accumulators are not that expensive. Rebuilding and replacing a ruptured FA diaphram may sound simple but it's NOT, unless you could re-seal it properly to withstand 60-70 psi of highly combustible liquid. This is not like rebuilding a WUR or AAR, an accidental leak from a rebuilt FA could cause fire damage on your precious car. I don't say it is not doable, but at this point of time I suggest to stay SAFE. Let the other people make the experiments on their cars first and wait for the results (????). Just my two-cents.

PM me and I'll lend one of my spares to you. Good luck.

Tony

[don gilbert]

thanks tony, i just orderd a new one from our host

[88911coupe]

Not to hijack this thread but is there any recommended way to store a fuel pressure accumulator or regulator while a car is being worked on? Mine are both sitting on a shelf for a rebuild and it just occured to me maybe they should be stored in fuel or something like Marvel Mystery oil...would it hurt to pour something like MMO into them?
Thanks,

[Moke81]

What happens when the FA is bad? will it not start?, hard starting? does not run well?

[don gilbert]

moke from what i've discovered, the FA keep a certain amount of pressure on the system when you shut engine off. around 15-20 lb. it has a rubber diaphram in it that goes bad and let your "at rest pressure", or residual pressure as some books call it bleed down which in turn let the system vapor lock. very hard to start a hot engine when it goes bad