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Fuel delivery problem with Video [message #277920]

Sat, 16 May 2015 15:20

Tony Cook

Messages: 121
Registered: August 2014
Location: Torrance CA

Karma: 0

Senior Member

In line filter before Mech.fuel pump video shows why i am leaning out driven around the block a few times and temp here in LA 70 deg so dont think its Vapor locking cause its hot out haha any thoughts. . "Fuel drop '77 GMC MOTORHOME" on YouTube
https://youtu.be/hV9qbRD7E-I

Tony Cook 77' Kingsley ' SuperSession 77 ' Torrance Beach,CA

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Re: Fuel delivery problem with Video [message #277922 is a reply to message #277920]

Sat, 16 May 2015 15:41

wally

Messages: 643
Registered: August 2004
Location: Omaha Nebraska

Karma: 5

Senior Member

Tony Cook wrote on Sat, 16 May 2015 15:20

In line filter before Mech.fuel pump video shows why i am leaning out driven around the block a few times and temp here in LA 70 deg so dont think its Vapor locking cause its hot out haha any thoughts. . "Fuel drop '77 GMC MOTORHOME" on YouTube
https://youtu.be/hV9qbRD7E-I

Man, it looks like sucking air in somewhere. Does it do the same on the other tank?

Wally Anderson
Omaha NE
75 Glenbrook

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Re: Fuel delivery problem with Video [message #277923 is a reply to message #277920]

Sat, 16 May 2015 16:04

Tony Cook

Messages: 121
Registered: August 2014
Location: Torrance CA

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Senior Member

Yes it does do it on both tanks only saving grace is i have added a pusher pump on the Aux tank to hit if VL but kinda sux that i would have to run on Aux tank the whole time to keep line preasurized

Tony Cook 77' Kingsley ' SuperSession 77 ' Torrance Beach,CA

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Re: Fuel delivery problem with Video [message #277924 is a reply to message #277923]

Sat, 16 May 2015 16:16

wally

Messages: 643
Registered: August 2004
Location: Omaha Nebraska

Karma: 5

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Tony Cook wrote on Sat, 16 May 2015 16:04

Yes it does do it on both tanks only saving grace is i have added a pusher pump on the Aux tank to hit if VL but kinda sux that i would have to run on Aux tank the whole time to keep line preasurized

You might try running it on another tank just to see. Some have used a boat tank to get a crippled coach moved. Bypasses the original fuel system. Odd you you redid fuel lines and it still happens. I wonder if the selector valve is OK.

Wally Anderson
Omaha NE
75 Glenbrook

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Re: Fuel delivery problem with Video [message #277925 is a reply to message #277924]

Sat, 16 May 2015 16:46

jhb1

Messages: 303
Registered: February 2004

Karma: 0

Senior Member

I had a similar problem and have fuel injection so 40 psi after the external electric pump. Turned out to be a small crack in the selector valve and it was sucking air found this after dropping the tanks and changing all the fuel lines and still had the problem. I pressurized just the lines and soaped the selector valve to find a hairline crack in the outlet connection of the selector valve after changing the valve all the problems disappeared.

John H. Bell
77 Royale; QuadBag,Manny OneTon,Honda EV4010, FITech
Montreal Qc.

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Re: [GMCnet] Fuel delivery problem with Video [message #277933 is a reply to message #277920]

Sat, 16 May 2015 20:20

USAussie

Messages: 15912
Registered: July 2007
Location: Sydney, Australia

Karma: 6

Senior Member

Tony,

I can't determine the flow path of the gas through that filter, who makes that filter and what it the part number?

For the hell of it go to a parts store and get a solid metal can one that has 3/8" inlet and outlet lines, install it and see if the
problem continues.

I have not kept up with this thread and if you've already answered these questions please forgive me for re asking them:

1) have you dropped and cleaned the tanks?
2) have the strainers in the tanks been replaced?
3) have you replaced the fuel lines with ethanol compatible lines?

Regards,
Rob M.
The Pedantic Mechanic

-----Original Message-----
From: Tony Cook

In line filter before Mech.fuel pump video shows why i am leaning out driven around the block a few times and temp here in LA 70 deg
so dont think its Vapor locking cause its hot out haha any thoughts. . "Fuel drop '77 GMC MOTORHOME" on YouTube
https://youtu.be/hV9qbRD7E-I
--
Tony

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Regards, Rob M. (USAussie) The Pedantic Mechanic Sydney, Australia '75 Avion - AUS - The Blue Streak TZE365V100428 '75 Avion - USA - Double Trouble TZE365V100426

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Re: [GMCnet] Fuel delivery problem with Video [message #277937 is a reply to message #277933]

Sat, 16 May 2015 21:45

Tony Cook

Messages: 121
Registered: August 2014
Location: Torrance CA

Karma: 0

Senior Member

Filter is a 3/8 Mr.Gasket clearview filter .I put this in to see what my fuel looked like prior to having tanks redone . All hoses replaced and shop said they replaced tank socks and senders were good . Wasn't really confident in there work from the get go but was told that every thing was changed. I have put on a pusher pump off the Aux line for Vapor Lock down the road . So that does help but dont want to have to run on Aux tank the whole time

Tony Cook 77' Kingsley ' SuperSession 77 ' Torrance Beach,CA

[Updated on: Sat, 16 May 2015 21:49]

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Re: Fuel delivery problem with Video [message #277940 is a reply to message #277920]

Sat, 16 May 2015 22:53

Bob de Kruyff

Messages: 4260
Registered: January 2004
Location: Chandler, AZ

Karma: 1

Senior Member

Tony Cook wrote on Sat, 16 May 2015 14:20

In line filter before Mech.fuel pump video shows why i am leaning out driven around the block a few times and temp here in LA 70 deg so dont think its Vapor locking cause its hot out haha any thoughts. . "Fuel drop '77 GMC MOTORHOME" on YouTube
https://youtu.be/hV9qbRD7E-I

Looks totally normal to me--what do you expect it to look like?

Bob de Kruyff
78 Eleganza
Chandler, AZ

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Re: Fuel delivery problem with Video [message #277946 is a reply to message #277940]

Sat, 16 May 2015 23:12

Bullitthead

Messages: 1411
Registered: November 2013

Karma: 5

Senior Member

The pump is sucking and pumping air...find the leak like John described.

Terry Kelpien ASE Master Technician 73 Glacier 260 Smithfield, Va.

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Re: Fuel delivery problem with Video [message #277947 is a reply to message #277946]

Sat, 16 May 2015 23:21

Bob de Kruyff

Messages: 4260
Registered: January 2004
Location: Chandler, AZ

Karma: 1

Senior Member

Bullitthead wrote on Sat, 16 May 2015 22:12

The pump is sucking and pumping air...find the leak like John described.

I think on the suction side this is normal

Bob de Kruyff
78 Eleganza
Chandler, AZ

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Re: [GMCnet] Fuel delivery problem with Video [message #277948 is a reply to message #277933]

Sat, 16 May 2015 23:21

Bullitthead

Messages: 1411
Registered: November 2013

Karma: 5

Senior Member

Rob,
The fuel enters the filter through those small holes you can see on the right hand side in the video. Then it passes through the filter screen (which can be cleaned) to a tube inside the filter that is the output. These filters work better when they are mounted vertically, as they will purge air that way and also allow debris to fall off the filter element when the flow stops.

Terry Kelpien ASE Master Technician 73 Glacier 260 Smithfield, Va.

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Re: Fuel delivery problem with Video [message #277949 is a reply to message #277947]

Sat, 16 May 2015 23:39

Bullitthead

Messages: 1411
Registered: November 2013

Karma: 5

Senior Member

I must have tipping my glass when reading...he's got that filter on the suction side? That is not a good filter for suction, but it will work if it is plumbed correctly and the glass canister is good and tight. I have it AFTER the pump on the Bronco and do not have any problems.
If the fuel is draining back after shut down then the fuel pump check valve is not sealing. Could just be some debris in that valve, but getting it out of there might be difficult or impossible. Malfunctioning check valve will also stop the pump from pumping. Easy fix is replace the pump, but I would still check the supply line for a leak.

Terry Kelpien ASE Master Technician 73 Glacier 260 Smithfield, Va.

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Re: Fuel delivery problem with Video [message #277950 is a reply to message #277920]

Sun, 17 May 2015 00:23

Tony Cook

Messages: 121
Registered: August 2014
Location: Torrance CA

Karma: 0

Senior Member

Well this sounds promising. Yes it is before fuel pump didn't know this wasn't a good place for this type of filter. Just wanted to see what my fuel was doing since having a lean issue. I will be removing for sure

Tony Cook 77' Kingsley ' SuperSession 77 ' Torrance Beach,CA

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Re: Fuel delivery problem with Video [message #277952 is a reply to message #277950]

Sun, 17 May 2015 00:52

Bullitthead

Messages: 1411
Registered: November 2013

Karma: 5

Senior Member

I would do like Rob said and get one of the steel can filters in the line before the pump and use the glass one after, mounted in a place where I could see and service it easily. Disconnect the input line to the pump and put a hand vacuum pump on it, drawing FROM the pump, and see if you can develop any vacuum. That should let you know if the check valve in the pump is working.

Terry Kelpien ASE Master Technician 73 Glacier 260 Smithfield, Va.

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Re: [GMCnet] Fuel delivery problem with Video [message #277954 is a reply to message #277948]

Sun, 17 May 2015 02:28

USAussie

Messages: 15912
Registered: July 2007
Location: Sydney, Australia

Karma: 6

Senior Member

Terry,

That's what I thought. The operative words in your note below are "small holes." It's a total GUESS but they appear to be about 1/8"
diameter and another GUESS that there are two of them. If I'm GUESSING correctly the fuel is traveling down 3/8" ID rubber lines
from the tank and then into the 3/8" OD steel line welded to the top of the front crossmember into another rubber hose and then out
two 1/8" holes into to filter.

That reduction will cause the flow to be reduced significantly which is why I suggested that Tony get a metal housing filter with
3/8" OD inlet and outlet tubes.

Regards,
Rob

-----Original Message-----
From: Terry

Rob,
The fuel enters the filter through those small holes you can see on the right hand side in the video. Then it passes through the
filter screen (which can be cleaned) to a tube inside the filter that is the output. These filters work better when they are mounted
vertically, as they will purge air that way and also allow debris to fall off the filter element when the flow stops.
--
Terry

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Regards, Rob M. (USAussie) The Pedantic Mechanic Sydney, Australia '75 Avion - AUS - The Blue Streak TZE365V100428 '75 Avion - USA - Double Trouble TZE365V100426

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Re: [GMCnet] Fuel delivery problem with Video [message #277955 is a reply to message #277952]

Sun, 17 May 2015 02:59

USAussie

Messages: 15912
Registered: July 2007
Location: Sydney, Australia

Karma: 6

Senior Member

Terry,

Thanks for the vote of confidence; however, I am going to disagree with you regarding moving the glass filter to the outlet of the
pump.

On numerous occasions we have reached a consensus that locating a glass or plastic fuel filters in the engine or Onan compartment is
not the best idea.

Same goes for rubber fuel lines from the Olds fuel pump to the carb.

Here's Double Trouble's fuel delivery system story:

1) Tanks dropped and cleaned in 2008 by Ken Frey when I bought Double Trouble
2) Metal can fuel filter installed between line welded to cross member and inlet of mechanical fuel pump by Ken Frey
2) Tanks dropped in 2009 by me because I was curious to see what they looked like internally along with the level sensors.
3) All fuel lines replaced with Ethanol compatible line in 2009.
4) Facet 1.5 to 4.0 psi fuel pump installed between Aux tank and selector valve; it comes on when AUX is selected.
5) New steel fuel filter installed between solid fuel line welded to front crossmember.
6) Metal can fuel filter removed, blown through, and re-installed in 2009, 2010, 2011, 2012, and 2013. In 2014 I replaced it despite
the fact it was still easy to blow through.

To date I have never had any problems with fuel delivery.

Regards,
Rob M.
The Pedantic Mechanic

-----Original Message-----
From: Terry

I would do like Rob said and get one of the steel can filters in the line before the pump and use the glass one after, mounted in a
place where I could see and service it easily. Disconnect the input line to the pump and put a hand vacuum pump on it, drawing FROM
the pump, and see if you can develop any vacuum. That should let you know if the check valve in the pump is working.
--
Terry

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Regards, Rob M. (USAussie) The Pedantic Mechanic Sydney, Australia '75 Avion - AUS - The Blue Streak TZE365V100428 '75 Avion - USA - Double Trouble TZE365V100426

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Re: Fuel delivery problem with Video [message #277960 is a reply to message #277920]

Sun, 17 May 2015 09:05

Tony Cook

Messages: 121
Registered: August 2014
Location: Torrance CA

Karma: 0

Senior Member

Rob my fuel system is almost a carbon copy of yours on what i have done cept i have a Carter on Aux line and now will be removing Mr. ASSket filter as this could be why the fuel starving issue.....I hope. Do you or most still run with the Qjet filter ? Thanks everyone always a big help Tony

Tony Cook 77' Kingsley ' SuperSession 77 ' Torrance Beach,CA

[Updated on: Sun, 17 May 2015 09:15]

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Re: [GMCnet] Fuel delivery problem with Video [message #277964 is a reply to message #277955]

Sun, 17 May 2015 10:50

James Hupy

Messages: 6806
Registered: May 2010

Karma: -62

Senior Member

My personal opinion based upon seeing 4 fuel line related fires in GMC
motor homes is this: NO RUBBER HOSES FROM THE MECHANICAL FUEL PUMP TO CARB,
AND NO IN LINE FILTERS OF ANY KIND IN THAT SAID LINE EITHER. NO PLASTIC in
line filters anywhere in the fuel system. Metal throw away types as well as
spin on cannister type water separating are ok, if they do not restrict
flow or drop fuel pressure. Use ONLY Barrier type alcohol resistant rubber
hoses, and check them frequently. Finally, if you smell gasoline after
refueling, find the cause sooner than later.
Jim Hupy
Salem, Or
78 GMC ROYALE 403
On May 17, 2015 12:59 AM, "Robert Mueller" wrote:

> Terry,
>
> Thanks for the vote of confidence; however, I am going to disagree with
> you regarding moving the glass filter to the outlet of the
> pump.
>
> On numerous occasions we have reached a consensus that locating a glass or
> plastic fuel filters in the engine or Onan compartment is
> not the best idea.
>
> Same goes for rubber fuel lines from the Olds fuel pump to the carb.
>
> Here's Double Trouble's fuel delivery system story:
>
> 1) Tanks dropped and cleaned in 2008 by Ken Frey when I bought Double
> Trouble
> 2) Metal can fuel filter installed between line welded to cross member and
> inlet of mechanical fuel pump by Ken Frey
> 2) Tanks dropped in 2009 by me because I was curious to see what they
> looked like internally along with the level sensors.
> 3) All fuel lines replaced with Ethanol compatible line in 2009.
> 4) Facet 1.5 to 4.0 psi fuel pump installed between Aux tank and selector
> valve; it comes on when AUX is selected.
> 5) New steel fuel filter installed between solid fuel line welded to front
> crossmember.
> 6) Metal can fuel filter removed, blown through, and re-installed in 2009,
> 2010, 2011, 2012, and 2013. In 2014 I replaced it despite
> the fact it was still easy to blow through.
>
> To date I have never had any problems with fuel delivery.
>
> Regards,
> Rob M.
> The Pedantic Mechanic
>
> -----Original Message-----
> From: Terry
>
> I would do like Rob said and get one of the steel can filters in the line
> before the pump and use the glass one after, mounted in a
> place where I could see and service it easily. Disconnect the input line
> to the pump and put a hand vacuum pump on it, drawing FROM
> the pump, and see if you can develop any vacuum. That should let you know
> if the check valve in the pump is working.
> --
> Terry
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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Re: [GMCnet] Fuel delivery problem with Video [message #277968 is a reply to message #277960]

Sun, 17 May 2015 16:15

USAussie

Messages: 15912
Registered: July 2007
Location: Sydney, Australia

Karma: 6

Senior Member

Tony,

What is the PSI output of the Carter on the Aux line? This fix for vapor lock was installed by JimB, he uses the lowest output Facet
pump available (1 - 4 psi).

One must keep in mind that if the diaphragm in the mechanical fuel pump fails an electric "boost" pump upstream will pump fuel into
the crankcase and that damage the engine pretty quickly!

Here's a link to a mechanical fuel pump cross section drawing,

http://www.enginebasics.com/Engine%20Basics%20Root%20Folder/Images/Fuel%20Pump%20Mechanical%201.gif

I reckon if the diaphragm developed a small hole or tear it would pump fuel into the crankcase as well so worrying about the
electric boost pump doing so might just be a moot point.

I got to thinking about this and that GeneF mentioned he was aware of a mechanical fuel pump that got transferred from a failed
engine to a second engine and it too failed. I'd guess that the engine failure was caused by the mechanical fuel pump diaphragm.
Anyone else ever hear of this?

Regards,
Rob M.
The Pedantic Mechanic

-----Original Message-----
From: Tony Cook

Rob my fuel system is almost a carbon copy of yours cept i have a Carter on Aux line and now will be removing Mr. ASSKet filter as
this could be why the fuel starving issue.....I hope. Thanks everyone always a big help Tony
--
Tony

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Regards, Rob M. (USAussie) The Pedantic Mechanic Sydney, Australia '75 Avion - AUS - The Blue Streak TZE365V100428 '75 Avion - USA - Double Trouble TZE365V100426

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Re: Fuel delivery problem with Video [message #277973 is a reply to message #277960]

Mon, 18 May 2015 00:20

roy1

Messages: 2126
Registered: July 2004
Location: Minden nevada

Karma: 6

Senior Member

Tony Cook wrote on Sun, 17 May 2015 07:05

Rob my fuel system is almost a carbon copy of yours on what i have done cept i have a Carter on Aux line and now will be removing Mr. ASSket filter as this could be why the fuel starving issue.....I hope. Do you or most still run with the Qjet filter ? Thanks everyone always a big help Tony

I use a carter p70 for each tank with a spin on filter for each. No mechanical pump or selector valve also leave the quadrojet filter in place it won't hurt anything and is good insurance for the needle valve keeping debree out of the carb.

Roy Keen Minden,NV 76 X Glenbrook

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