Heinz found the reference, key 16 in my book. Funny thing when I filled up
with gas yesterday for the first time, I got a leak somewhere under the
driver side bogey wheels. Was in a hurry so did not ascertain exactly where
it came from but do not think it is the separator. Probably a bad vent line.
You are right the separator is part of the emission control circuit and
limits the input to the charcoal cannister to vapors only. I have not
removed mine yet but would not believe that you should be able to hear the
ball rattle, at least very loudly since it has to be quite light. The
separator consists of a very light plastic or metal ball inside a tube with
a seal at the top. As gas enters the tube it floats the ball higher in the
tube until it reaches the seal and than stops the gas from going any
further. The Gas vapors do not make it seal since the ball could not
displace enough gas vapor to float to the seal. Vapors pass to the
cannister where they are burned by the carburetor when the engine is
started. You should be able to check the separator on the vehicle by
connecting a 2-3 foot rubber or plastic tube into the input side (upper
connector)and hold it higher than the separator. Pour some water into it
and see if water runs out the bottom connector (towards the charcoal
cannister). If it does either the seal is bad or the ball in waterlogged and
to heavy to float, in which case it needs to be replaced.
I do not show any replacement for it. Something to check on though. I would
put a plug on the lower separator connector for now.
>Oops and apologies if this got sent before accidentally
>
>The Part# is 7028035, pg 12-2, key 16.
>
>
>
>>Heinz I don't have the coach here at the house so can't look at it to see
>>what you mean. do you have a GMC part # or better yet an illustrated parts
>>breakdown page and key number for it???
>>
>>
>>>Thanks Thomas.
>>>That'll help to replace the cannister, but it's the valve in the left rear
>>>wheel well that's the leaking culprit. Any ideas on that one?
>>>
>>>My coach is a '76 Transmode.
>>>
>>>Heinz
>>>
>>>-----Original Message-----
>>>From: Thomas G. Warner
>>>To: gmcmotorhome
>>>Date: Thursday, April 23, 1998 8:39 PM
>>>Subject: Re: GMC: Fuel/Vapor seperator valve question.
>>>
>>>
>>>>Heinz you did not say what year you have but if your coach was built
>PRIOR
>>>>to 1978, than the following information should be correct:
>>>>
>>>>Cannister, vapor GMC part # 7028131 (page 12-3 of parts book) coverts
>to:
>>>>
>>>>AC A-478-C
>>>>ATLAS ECF-1
>>>>FRAM CA-357
>>>>HASTINGS VF-1
>>>>MOTORCRAFT FA-300
>>>>PUROLATOR AF-15-M
>>>>SHELL SAB-4
>>>>TEXACO TEC-703
>>>>WIX 42998
>>>>
>>>>Hope this helps you.
>>>>
>>>>
>>>>>After getting fuel spilled a few times at the Charcoal Cannister I
>>>>>disconnected it and made a big loop in the fuel vent line side up high.
>At
>>>>>least now when some fuel spits out during fuel-up I notice it right away
>>>>>instead of only after a big lake appears under the cannister.
>>>>>
>>>>>It was to be a temporary measure, but it's been that way 2+ years or so.
>>>>>Since I'm still in fixit mode I thought I'd try to replace it and get it
>>>>>back to specs. Have not been able to find the plastic valve. Mine still
>>>>>rattles, i.e. the ball is not stuck. Short of physically disecting the
>>>valve
>>>>>it seems replace is the only option.
>>>>>
>>>>>Is there an alternative valve that could be used? Is the gizzmo and the
>>>>>associated cannister necessary? I assume it's to battle polution,
>but....
>>>>>
>>>>>TIA - Heinz
>>>>>'76 Transmode
>>>>>
>>>>>
>>>>>
>>>>>
>>>
>>>
>>>
>
>
>
