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Home » Public Forums » GMCnet » [GMCnet] So what micron in line fuel filter would be needed for EFI. Since my carb filter got plugged after an in line filter?
[GMCnet] So what micron in line fuel filter would be needed for EFI. Since my carb filter got plugged after an in line filter? [message #322603] Thu, 24 August 2017 09:03 Go to next message
BobDunahugh is currently offline  BobDunahugh   United States
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Registered: October 2010
Location: Cedar Rapids, IA
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Since my carb filter got plugged with an in line filter before it. And now I'm going to EFI. So I will have in line filters to protect the vane fuel pumps again. As I'm not the brightest bulb on the tree over Throttle body EFI. Shouldn't I protect my TB like the carb filter protects the carb with a lower micron filter? So bottom line. Does a TB need more, or less filtration then a carb? Bob Dunahugh 78 Royale
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Re: [GMCnet] So what micron in line fuel filter would be needed for EFI. Since my carb filter got plugged after an in line filter? [message #322607 is a reply to message #322603] Thu, 24 August 2017 10:33 Go to previous messageGo to next message
Sandra Price is currently offline  Sandra Price   United States
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Bob, we use a metal Fram filter (don't know part #, 3/8" line), carry an
extra. No problems in the many thousands of miles we traveled in the GMC.
Had to change it twice. Not home to check part number for you.

Bob Price

On Aug 24, 2017 10:04 AM, "Bob Dunahugh" wrote:

> Since my carb filter got plugged with an in line filter before it. And now
> I'm going to EFI. So I will have in line filters to protect the vane fuel
> pumps again. As I'm not the brightest bulb on the tree over Throttle body
> EFI. Shouldn't I protect my TB like the carb filter protects the carb with
> a lower micron filter? So bottom line. Does a TB need more, or less
> filtration then a carb? Bob Dunahugh 78 Royale
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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Re: [GMCnet] So what micron in line fuel filter would be needed for EFI. Since my carb filter got plugged after an in line filter? [message #322610 is a reply to message #322607] Thu, 24 August 2017 11:49 Go to previous messageGo to next message
Justin Brady is currently offline  Justin Brady   United States
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Location: Bell Buckle, TN
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Bob,
This is the filter that Fitech includes with their kit. It is to be installed right before the throttle body (same as the carb filter)
It is 30 micron.

https://www.summitracing.com/parts/fif-80112?seid=srese1&cm_mmc=pla-google-_-shopping-_-srese1-_-fitech-fuel-injection&gclid=EAIaIQobChMIio2R1 Knw1QIVgoqzCh37ZgaBEAQYASABEgK1KPD_BwE


Justin Brady http://www.thegmcrv.com/ 1976 Palm Beach 455
Re: [GMCnet] So what micron in line fuel filter would be needed for EFI. Since my carb filter got plugged after an in line filter? [message #322622 is a reply to message #322603] Thu, 24 August 2017 23:13 Go to previous messageGo to next message
BobDunahugh is currently offline  BobDunahugh   United States
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Thanks Justin for that info.

Bob Dunahugh 78 Royale
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Re: [GMCnet] So what micron in line fuel filter would be needed for EFI. Since my carb filter got plugged after an in line filter? [message #322629 is a reply to message #322622] Fri, 25 August 2017 08:46 Go to previous messageGo to next message
jimk is currently offline  jimk   United States
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Location: Belmont, CA
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I tend to believe that all fuel filters are 30 Micron.
Particulates can clog an filter, but the slime will block the filter very
quickly without notice.
There are some really inexpensive filters out there. Stay away from them as
the MEDIA is not the same. Pay more and use major brand.

On Thu, Aug 24, 2017 at 9:13 PM, Bob Dunahugh wrote:

> Thanks Justin for that info.
>
> Bob Dunahugh 78 Royale
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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
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1-800-752-7502
Re: [GMCnet] So what micron in line fuel filter would be needed for EFI. Since my carb filter got plugged after an in line filter? [message #322644 is a reply to message #322629] Fri, 25 August 2017 16:42 Go to previous messageGo to next message
kstockwell is currently offline  kstockwell   United States
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Location: Putney VT
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Senior Member
I am looking to carry an extra fuel pump. I see the one suggested does not have a return line, and there's another that does.

In the parts lookup online (not right by any means) it says the one with the return line is right for my "Olds Toronado" engine. Of course I wouldn't buy that one because of the online thing; but it did make me look up what the heck the return line does, and from what I can tell its supposed to help minimize gas boiling away (vapor lock?). Is that an issue I hear people have with these engines? Can someone explain how the return line works, how it would minimize gas boiling, and then tell me why we get the pump without a return line?

I'm trying to learn/understand how stuff works; so pretend I know nothing and you're close Smile

thanks, i hope I'm not hijacking this thread.

kelly

PS i found 2 more carb filters in boxes from my PO, now I have 3 and 10 nylon washers. All set for awhile!


1978 Kingsley Putney VT
Re: [GMCnet] So what micron in line fuel filter would be needed for EFI. Since my carb filter got plugged after an in line filter? [message #322649 is a reply to message #322644] Fri, 25 August 2017 18:06 Go to previous messageGo to next message
Ken Henderson is currently offline  Ken Henderson   United States
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Registered: March 2004
Location: Americus, GA
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Senior Member
Kelly,

The mechanical fuel pump with the return line was original equipment on air
conditioned Toronados; it was never OEM on the motorhome. The return line
has a small orifice to allow a small amount of liquid or a large amount of
vapor to return to the fuel tank, through a dedicated return line (which
the GMC doesn't have as original equipment). That tends to alleviate mild
vapor lock by allowing the un-useable vapor to return to the tank.

IMHO, an electric pump (preferably two, one for each tank, replacing the
selector valve) back near the tanks, is a far better solution for vapor
lock as well as for redundancy and simplicity.

You DO NOT want that "feedback" pump unless you add the return line. Many
people have, for whatever reason, installed that pump without the return
line and then plugged the return fitting -- usually with a short piece of
hose, a 3/8" bolt and a couple of hose clamps -- An almost certain formula
for leakage, sooner or later.

NAPA's part number for the two pumps is only one digit apart -- I don't
remember either.

Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI & EBL,
Manny Brakes & 1-Ton, etc., etc., etc.
www.gmcwipersetc.com

On Fri, Aug 25, 2017 at 5:42 PM, kelly stockwell wrote:

> I am looking to carry an extra fuel pump. I see the one suggested does
> not have a return line, and there's another that does.
>
> In the parts lookup online (not right by any means) it says the one with
> the return line is right for my "Olds Toronado" engine. Of course I
> wouldn't
> buy that one because of the online thing; but it did make me look up what
> the heck the return line does, and from what I can tell its supposed to help
> minimize gas boiling away (vapor lock?). Is that an issue I hear people
> have with these engines? Can someone explain how the return line works, how
> it would minimize gas boiling, and then tell me why we get the pump
> without a return line?
>
> I'm trying to learn/understand how stuff works; so pretend I know nothing
> and you're close :)
>
> thanks, i hope I'm not hijacking this thread.
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
Re: [GMCnet] So what micron in line fuel filter would be needed for EFI. Since my carb filter got plugged after an in line filter? [message #322660 is a reply to message #322649] Fri, 25 August 2017 19:10 Go to previous message
kstockwell is currently offline  kstockwell   United States
Messages: 367
Registered: May 2016
Location: Putney VT
Karma: 4
Senior Member
Thanks Ken!
Completely makes sense. I don't want to run any fuel lines anywhere but I see why it would be good if you had those lines. The one I have doesn't have a return line, I was just curious about why the other would be "recommended".
I realize we're not all stock stuff.

The fuel pump was put in by the PO just before selling it to me. I'll be putting in the WIX fuel filter inline before it at some point.

-kelly

Ken Henderson wrote on Fri, 25 August 2017 19:06
Kelly,

The mechanical fuel pump with the return line was original equipment on air
conditioned Toronados; it was never OEM on the motorhome. The return line
has a small orifice to allow a small amount of liquid or a large amount of
vapor to return to the fuel tank, through a dedicated return line (which
the GMC doesn't have as original equipment). That tends to alleviate mild
vapor lock by allowing the un-useable vapor to return to the tank.

IMHO, an electric pump (preferably two, one for each tank, replacing the
selector valve) back near the tanks, is a far better solution for vapor
lock as well as for redundancy and simplicity.

You DO NOT want that "feedback" pump unless you add the return line. Many
people have, for whatever reason, installed that pump without the return
line and then plugged the return fitting -- usually with a short piece of
hose, a 3/8" bolt and a couple of hose clamps -- An almost certain formula
for leakage, sooner or later.

NAPA's part number for the two pumps is only one digit apart -- I don't
remember either.

Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI & EBL,
Manny Brakes & 1-Ton, etc., etc., etc.
www.gmcwipersetc.com

On Fri, Aug 25, 2017 at 5:42 PM, kelly stockwell wrote:

> I am looking to carry an extra fuel pump. I see the one suggested does
> not have a return line, and there's another that does.
>
> In the parts lookup online (not right by any means) it says the one with
> the return line is right for my "Olds Toronado" engine. Of course I
> wouldn't
> buy that one because of the online thing; but it did make me look up what
> the heck the return line does, and from what I can tell its supposed to help
> minimize gas boiling away (vapor lock?). Is that an issue I hear people
> have with these engines? Can someone explain how the return line works, how
> it would minimize gas boiling, and then tell me why we get the pump
> without a return line?
>
> I'm trying to learn/understand how stuff works; so pretend I know nothing
> and you're close Smile
>
> thanks, i hope I'm not hijacking this thread.
>
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1978 Kingsley Putney VT
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