| Inline Fuel Filters VS Factory Quadrajet Filter [message #345451] |
Wed, 17 July 2019 08:36  |
jtfred
Messages: 132
Registered: January 2015
Location: Grand Marais, MN
Karma: 0
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I've been thinking through the issues I had with a clogged filter on my most recent trip. 150 miles nursing the coach up the hills of the North Shore of Lake Superior gave me some time to think.
The PO of my coach did quite a few modifications when he had it. I am lucky that his workmanship was very good. One of the changes he made was to switch to electric fuel pumps. Each tank is rigged with its own fuel pump and an inline filter. The pumps are connected to run of the dash tank switch. When I was having my fuel supply issues last Thursday I reasoned that I could switch from the main tank to the auxiliary tank, thereby avoiding the inline filter on the main tank and continue on. That did not work. My problem wasn't resolved until I replaced the filter on the carb. Once that was replaced I was restored to full power. Over the weekend I also replaced the inline filters to be on the safe side and have a full set if filters in the spares kit in the coach.
So are my inline filters just acting as pre-filters? Should I run with just the inline filters and pull the carb filter? I'm okay with a "belt and suspenders" approach but am just wondering what others have done.
Thanks again!
John
1978 Eleganza
Grand Marais, MN
John Fredrikson
Grand Marais, MN
1978 Eleganza
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| Re: Inline Fuel Filters VS Factory Quadrajet Filter [message #345455 is a reply to message #345451] |
Wed, 17 July 2019 09:16  |
lqqkatjon
Messages: 2324
Registered: October 2010
Location: St. Cloud, MN
Karma: 5
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I know many take out the carb filter. But you just proved it is a good thing to have. I would not want that junk clogging up the carb itself.
it is important to know where your filters are, just in case. Some get a fuel supply issue and change the carb filter, and have no idea there is a filter somewhere under the frame of the coach.
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/
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| Re: Inline Fuel Filters VS Factory Quadrajet Filter [message #345470 is a reply to message #345451] |
Wed, 17 July 2019 12:32 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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The carb filter really IS your "last line of defense". If a little flake of rubber or some kind of sediment comes loose between your last in line filter and your carburetor, it will be caught by that filter. It is my understanding that the filter in the carb inlet is a finer filter than the available in line filters as well.
That said, if you have clean fuel tanks (you might) and can count on always getting clean fuel (you can't) it would be almost as good to just put an additional filter in the rubber line right before the fuel pump. It is also somewhat risky to change the carb filter too often because, if you're not really careful, you can strip the threads that the filter housing screws in to. Mine is still in there.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: Inline Fuel Filters VS Factory Quadrajet Filter [message #345479 is a reply to message #345451] |
Wed, 17 July 2019 14:49 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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If you loosen the carb mounting bolts, you can start the line into the filter space by hand to insure it isn't cross threaded. Run it all the way in by hand, snug it with two wrenches, then retighten the carb mount bolts.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: [GMCnet] Inline Fuel Filters VS Factory Quadrajet Filter [message #345483 is a reply to message #345482] |
Wed, 17 July 2019 16:05 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Never run with out the carb filter as that is the safty filter in case ant
particulets are generated after the pre filters.
What is plugging up your filters is not particulets, but gum. It will pass
through the filter.
We have few GM delivery trucks here and have removed the final filters at
times and regretted doing that.
People clean the bottom of the tanks, but not the top where the gum is
collected and the NEW Ethanal is washing them down.
On Wed, Jul 17, 2019 at 1:38 PM John Fredrikson via Gmclist <
gmclist@list.gmcnet.org> wrote:
> Johnny Bridges wrote on Wed, 17 July 2019 15:49
>> If you loosen the carb mounting bolts, you can start the line into the
> filter space by hand to insure it isn't cross threaded. Run it all the way
>> in by hand, snug it with two wrenches, then retighten the carb mount
> bolts.
>>
>> --johnny
>
> That is what I did when I replaced the filter on Thursday it just seems
> that every time I do anything with the lines up there I end up chasing a
> leak.
>
>
> Clearly the carb filter was catching more than the metal inline filters so
> they might not be the best. I am thinking about possibly swapping out the
> inline filters with something like this:
>
>
> https://www.amazon.com/Moeller-033320-10-Micron-Separating-Filter/dp/B07V3NPMBC/ref=pd_cp_263_1?pd_rd_w=y4i3r&pf_rd_p=ef4dc990-a9ca-4945-ae0b-f8d5 49198ed6&pf_rd_r=DVV2B4BEFX00HE0YMD95&pd_rd_r=f1449e80-a8af-11e9-b120-f170bfc69993&pd_rd_wg=GRc9O&pd_rd_i=B07V3NPMBC&psc=1&ref RID=DVV2B4BEFX00HE0YMD95
>
> And then pull the carb filter so I don't have to risk cross threading or
> leaking on top of the engine.
>
> John
> --
> John Fredrikson
> Fayetteville, GA
> 1978 Eleganza
>
> _______________________________________________
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--
Jim Kanomata
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: Inline Fuel Filters VS Factory Quadrajet Filter [message #345487 is a reply to message #345451] |
Wed, 17 July 2019 17:46 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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My daughter and I once moved a coach from California to Indiana. It had one of those big Wix filters in line and also one filter in the carb. The tanks had rust in them and everyday we had to change a filter when the engine quit. The filter we changed alternated daily between the big Wix one and the carb one. So the in carb one was catching stuff that the big Wix one missed. We carried two spare of each filter during the trip and bought a few more along the way. After doing it once, my daughter could change either filter in 5 minutes or so.
Keep the carb filter in place. If it is not catching stuff then you will never need to change it. If it is catching stuff then it is definitely needed.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: Inline Fuel Filters VS Factory Quadrajet Filter [message #345506 is a reply to message #345451] |
Thu, 18 July 2019 07:10 |
Chris Tyler
Messages: 458
Registered: September 2013
Location: Odessa FL
Karma: 7
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Senior Member |
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Racing or doing HP work with Q jets it is common pracice to remove the filters for better fuel flow. QJs are my favorite stret carb but one of their limitations is the single fuel inlet and needle/seat.
That said, I dont think the flow is going to be an issue in our application. An a 450-500 hp application, it might.
I do recomend a pre filter that will capure most of the contaminents and increase the life of the QJ filter- which can be tricky to replace. I boogered a couple when I was learning as a kid.
Personally, I run a glass "view all" filter at a low point down by the fuel pump. Double clamped with FI rated hose. Never had a leak, but if it does it goes to ground. I can tel at a glance if there is water in the fuel or a lot of particles, its reusable, and privides an easy way to drain the tanks via the carter electric pump.
76 Glenbrook
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