| Gas clog - selector switch or? [message #264892] |
Mon, 27 October 2014 08:47  |
kwharland
Messages: 246
Registered: November 2005
Location: Central Florida
Karma: 0
|
Senior Member |
|
|
Now that I've sorted out most of my carb and ignition problems, I've put 20 gallons of fresh gas in the tank but I'm not pulling any to the carb. Fuel pump is new as is in-carb filter. Fuel pump has suction and pressure as confirmed with gauges.
So my question is now, do the tank pickups have filter socks that may be clogged with the fine particles of rust that clogged the in-carb filter? Or can a selector switch block fuel flow? I'm hoping it's the latter for obvious reasons.
1978 Eleganza II
|
|
|
|
|
|
|
|
|
|
| Re: [GMCnet] Gas clog - selector switch or? [message #264901 is a reply to message #264900] |
Mon, 27 October 2014 10:16  |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
|
Senior Member |
|
|
Ken, I would recommend one of our vendors, like Jim K, as first choice. If
you have a well stocked local independent auto parts outlet that carries
the Standard parts line, they should have a replacement available as well.
I will look in my shop and see if I have an old one in the box to verify
parts number. Presently still in the house in my sweats, finishing up my
morning coffee and shaking out the cobwebs. Just returned from a GMC
Cascaders rally yesterday. We had a Roaring 20's Murder mystery evening on
saturday, complete with clothing and role playing, booze etc. Some of us
got more into the role playing than others did, but we all had a blast.
Some tech stuff, and lots of food & etc.
Jim Hupy
Salem, OR
78 GMC Royale 403
On Mon, Oct 27, 2014 at 8:08 AM, gene Fisher wrote:
> By pass the selector sw with a short price ofpipe for a test. Run on top
> of tanks
>
> Erf
>
> On Monday, October 27, 2014, Ken Harland wrote:
>
>> Thanks Jim, on my way to the shop to pull this one out. Any
>> recommendations on replacements?
>> --
>> 1978 Eleganza II
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>>
>
>
> --
> Gene Fisher -- 74-23,77PB/ore/ca
> “Give a man a fish; you have fed him for today --- give him a URL and
> -------
> http://gmcmotorhome.info/
> Alternator Protection Cable
> http://gmcmotorhome.info/APC.html
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
|
|
|
|
| Re: [GMCnet] Gas clog - selector switch or? [message #264902 is a reply to message #264892] |
Mon, 27 October 2014 10:14 |
powerjon
Messages: 2446
Registered: January 2004
Karma: 5
|
Senior Member |
|
|
Ken,
The answer to last questions is yes!
The socks on the fuel sender can plug up and cause issues. You can use air to blow the socks and remove most of the stuff that might be on the sock. Back where your selector valve is located at remove each of the lines that are connected to the valve from the fuel tanks, be sure to make each line as you can put them on backwards and the valve doesn’t care. You may need to plug each line to prevent spillage. Before you go to the next step, REMOVE THE GAS CAP! Fuel tanks do not like any pressure over 1/2 to 3/4 PSIG. You can cause your tanks to expand in ways you do not want! Just this small pressure will cause the tanks to expand noticeably. WITH THE GAS CAP NOW OFF, you can now use your air hose to apply line air pressure (60 to 80 PSIG) to attempt to clear the socks and not cause any issue with the tanks. When blowing each sock have someone listen at the gas filler tube up front for gurgling sound, do the procedure several times. Once you have done each tank to your satisfaction remove the inlet hose to the selector valve and blow air thru the selector valve and be sure to use the dash switch to see if the valve will allow air to pass in both positions. The last step is to blow air thru the fuel line from front to back to the selector valve, use low pressure here as you can see and hear if you are get air thru each side. Leave the hose off the selector valve and blow air from the hose at the fuel pump to the back and see if it is clear. TREAT GASOLINE WITH RESPECT and try and collect fuel in the lines as you blow the main fuel line, wipe up any spills and be sure no open flames and that your frig is off. If there are any cracks or spots that allow air to enter the fuel system before the pump you can suck all you want but no fuel will come to the pump. You test the line by pulling a vacuum on the fuel line to the front to when the hose connects to the selector valve. When was the last time the fuel tanks lines had been replaced? If they are of unknown age then they could also be in need of replacement too and you might hear air leakage from the top of the tanks when blowing the socks. JMHO on how I would do it. One other thought is 20 gallons of fuel will be in both tanks and you don’t know how much went into each tank. I might have gone to the Aux tank which is the front in the fuel system and almost none in the back which is the main tank. If the selector valve is not working then you have no fuel.
http://www.gmcmhphotos.com/photos/data/6466/GMCfueltanks.jpg
JR Wright
78 Buskirk Stretch
75 Avion
Michigan
> On Oct 27, 2014, at 9:47 AM, Ken Harland wrote:
>
> Now that I've sorted out most of my carb and ignition problems, I've put 20 gallons of fresh gas in the tank but I'm not pulling any to the carb.
> Fuel pump is new as is in-carb filter. Fuel pump has suction and pressure as confirmed with gauges.
>
> So my question is now, do the tank pickups have filter socks that may be clogged with the fine particles of rust that clogged the in-carb filter? Or
> can a selector switch block fuel flow? I'm hoping it's the latter for obvious reasons.
> --
> 1978 Eleganza II
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
J.R. Wright
GMC GreatLaker
GMC Eastern States
GMCMI
78 30' Buskirk Stretch
75 Avion Under Reconstruction
Michigan
|
|
|
|
|
|
| Re: [GMCnet] Gas clog - selector switch or? [message #265005 is a reply to message #264912] |
Tue, 28 October 2014 13:40 |
 |
Broham
Messages: 204
Registered: March 2013
Location: Detroit, Michigan
Karma: 0
|
Senior Member |
|
|
After running out of gas when I know i had 10+ gal in the aux tank, I took off my selector valve and found it had two positions, main tank and both tanks. So when the main was empty and I switched to the aux, it was open to both tanks and drew in air from the empty tank.
Ordered a new one from Jim K yesterday. Was told only difference was it has 5/16" not 3/8" ports. I'm assuming that 1/16" over the the 3" of travel through the valve would make a difference in a 20' gas line.
Todd P
Todd
Owner of a 1976 Eleganza II 26’
other toys:
93 Vette
84 Goldwing
and gone but not forgotten
72 CB750 Chopper
96 Caprice Classic
34 Ford roadster
94 Fleetwood
|
|
|
|
GMCforum
Search
Help
Register
Login
Home
