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| Issue with rough idle and stalling with electric fuel pump [message #364923] |
Wed, 23 June 2021 11:23  |
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Tom Lins
Messages: 372
Registered: February 2004
Location: St Augustine, FL
Karma: 1
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Senior Member |
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I have what to me is a strange issue that I don't understand.
I am hoping someone has run into this before or has some things I can check.
Just got the coach out of the storage area and brought it to the house for some cleaning in anticipation on takeing some short trips.
It had been sitting for 8 months or so with fuel stabilizer and an almost full tank.
It was running a little rough so I changed the plugs (NGK) and wires.
It ran noticeably better so I called it a day after doing some cleaning.
Next day I went out to drive it back to the storage yard and during warming it up it started to run very rough and stall.
Some background:
I replaced the failed isolater with a yandina combiner last week and during troubleshooting I got a 20v reading on the center post of the isolater.
I do not have a mechanical fuel pump only a Carter electric pump. That was done by one of the PO's
The carb is a rebuilt I got from JimK just before the Pandemic when I had 2 FITech EFI's go belly up in 2019.
So this carb has not been run more than 500 miles.
Right now when I start it and warm it up it runs rough like it is missing unless I turn off the the electric fuel pump (there is a switch on the dash)
When I turn off the electric pump after 5 to 7 seconds the idle smooths out at about 900 rpm.
When I turn on the fuel pump after 5 t0 10 seconds it starts running rough and will stall if I do not touch the gas pedal.
I have also noticed that when I turn on the pump the volt meter on the dash drops from about 14 to about 13.
Tom Lins
St Augustine, FL
77 GM Rear Twin, Dry Bath, 455, Aluminum Radiator Quad-Bag Suspension Solar Panel
Manuals on DVD
YOUTUBE Channel: GMC Dealer Training Tapes
http://www.bdub.net/tomlins/
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| [GMCnet] Re: Issue with rough idle and stalling with electric fuel pump [message #364926 is a reply to message #364923] |
Wed, 23 June 2021 11:50  |
Keith V
Messages: 2337
Registered: March 2008
Location: Mounds View,MN
Karma: 0
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Senior Member |
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What is your fuel pressure with the pump on?
________________________________
From: Tom Lins
Sent: Wednesday, June 23, 2021 11:23 AM
To: gmclist@list.gmcnet.org
Subject: [GMCnet] Issue with rough idle and stalling with electric fuel pump
I have what to me is a strange issue that I don't understand.
I am hoping someone has run into this before or has some things I can check.
Just got the coach out of the storage area and brought it to the house for some cleaning in anticipation on takeing some short trips.
It had been sitting for 8 months or so with fuel stabilizer and an almost full tank.
It was running a little rough so I changed the plugs (NGK) and wires.
It ran noticeably better so I called it a day after doing some cleaning.
Next day I went out to drive it back to the storage yard and during warming it up it started to run very rough and stall.
Some background:
I replaced the failed isolater with a yandina combiner last week and during troubleshooting I got a 20v reading on the center post of the isolater.
I do not have a mechanical fuel pump only a Carter electric pump. That was done by one of the PO's
The carb is a rebuilt I got from JimK just before the Pandemic when I had 2 FITech EFI's go belly up in 2019.
So this carb has not been run more than 500 miles.
Right now when I start it and warm it up it runs rough like it is missing unless I turn off the the electric fuel pump (there is a switch on the
dash)
When I turn off the electric pump after 5 to 7 seconds the idle smooths out at about 900 rpm.
When I turn on the fuel pump after 5 t0 10 seconds it starts running rough and will stall if I do not touch the gas pedal.
I have also noticed that when I turn on the pump the volt meter on the dash drops from about 14 to about 13.
--
Tom Lins
St Augustine, FL
77 GM Rear Twin, Dry Bath, 455, Aluminum Radiator Quad-Bag Suspension Solar Panel
Manuals on DVD
YOUTUBE Channel: GMC Dealer Training Tapes
http://www.bdub.net/tomlins/
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Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com
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| [GMCnet] Re: Issue with rough idle and stalling with electric fuel pump [message #364931 is a reply to message #364923] |
Wed, 23 June 2021 11:59 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Tom,
If possible, you need to put a fuel pressure gauge at the inlet to the card
to check the output pressure of the electric pump, 'cause it sure sounds
like the carb's float is being "sunk" (overpowered) by that pressure,
causing you to have an over-rich idle mixture.
JMHO,
Ken H.
On Wed, Jun 23, 2021 at 12:24 PM Tom Lins wrote:
> I have what to me is a strange issue that I don't understand.
> I am hoping someone has run into this before or has some things I can
> check.
>
> Just got the coach out of the storage area and brought it to the house for
> some cleaning in anticipation on takeing some short trips.
> It had been sitting for 8 months or so with fuel stabilizer and an almost
> full tank.
> It was running a little rough so I changed the plugs (NGK) and wires.
> It ran noticeably better so I called it a day after doing some cleaning.
> Next day I went out to drive it back to the storage yard and during
> warming it up it started to run very rough and stall.
>
> Some background:
> I replaced the failed isolater with a yandina combiner last week and
> during troubleshooting I got a 20v reading on the center post of the
> isolater.
> I do not have a mechanical fuel pump only a Carter electric pump. That was
> done by one of the PO's
> The carb is a rebuilt I got from JimK just before the Pandemic when I had
> 2 FITech EFI's go belly up in 2019.
> So this carb has not been run more than 500 miles.
>
> Right now when I start it and warm it up it runs rough like it is missing
> unless I turn off the the electric fuel pump (there is a switch on the
> dash)
> When I turn off the electric pump after 5 to 7 seconds the idle smooths
> out at about 900 rpm.
> When I turn on the fuel pump after 5 t0 10 seconds it starts running rough
> and will stall if I do not touch the gas pedal.
> I have also noticed that when I turn on the pump the volt meter on the
> dash drops from about 14 to about 13.
>
>
> --
> Tom Lins
> St Augustine, FL
> 77 GM Rear Twin, Dry Bath, 455, Aluminum Radiator Quad-Bag Suspension
> Solar Panel
> Manuals on DVD
> YOUTUBE Channel: GMC Dealer Training Tapes
> http://www.bdub.net/tomlins/
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] Re: Issue with rough idle and stalling with electric fuel pump [message #364933 is a reply to message #364931] |
Wed, 23 June 2021 13:26 |
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Tom Lins
Messages: 372
Registered: February 2004
Location: St Augustine, FL
Karma: 1
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Senior Member |
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Ken Henderson wrote on Wed, 23 June 2021 12:59Tom,
If possible, you need to put a fuel pressure gauge at the inlet to the card
to check the output pressure of the electric pump, 'cause it sure sounds
like the carb's float is being "sunk" (overpowered) by that pressure,
causing you to have an over-rich idle mixture.
JMHO,
Ken H.
On Wed, Jun 23, 2021 at 12:24 PM Tom Lins wrote:
Well Ken your HO turned out correct as usual.
put my FI pressure meter on the fuel line and measured 25 lbs of pressure.
I am leaving the meter connected so I can measure the pressure once the new P4070 is installed.
Thank you all.
I will report back after the new pump is in
Tom Lins
St Augustine, FL
77 GM Rear Twin, Dry Bath, 455, Aluminum Radiator Quad-Bag Suspension Solar Panel
Manuals on DVD
YOUTUBE Channel: GMC Dealer Training Tapes
http://www.bdub.net/tomlins/
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| Re: Issue with rough idle and stalling with electric fuel pump [message #364943 is a reply to message #364923] |
Wed, 23 June 2021 21:41 |
kingd
Messages: 592
Registered: June 2004
Karma: 2
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Senior Member |
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Sounds like the pressure relief valve in the pump is stuck. This could happen while sitting over the winter. I don't have my /Carter pump handy but I think there is an external screw with a spring under it and the relief shuttle. See if you can find it and if the shuttle is stuck.
DAVE KING
lurker, wannabe
Toronto, Ontario, Canada
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| [GMCnet] Re: Issue with rough idle and stalling with electric fuel pump [message #364948 is a reply to message #364943] |
Thu, 24 June 2021 10:12 |
Keith V
Messages: 2337
Registered: March 2008
Location: Mounds View,MN
Karma: 0
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Senior Member |
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He has a pump that was for Fuel injection. It's a high(er) pressure pump.
It needs a pressure regulator or a lower pressure pump
Keith Vasilakes
Mounds View MN
76 exRoyale
MicroLevel
________________________________
From: Dave King
Sent: Wednesday, June 23, 2021 9:41 PM
To: gmclist@list.gmcnet.org
Subject: [GMCnet] Re: Issue with rough idle and stalling with electric fuel pump
Sounds like the pressure relief valve in the pump is stuck. This could happen while sitting over the winter. I don't have my /Carter pump handy but I
think there is an external screw with a spring under it and the relief shuttle. See if you can find it and if the shuttle is stuck.
--
DAVE KING
lurker, wannabe
Toronto, Ontario, Canada
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Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com
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| Re: Issue with rough idle and stalling with electric fuel pump [message #364957 is a reply to message #364923] |
Thu, 24 June 2021 15:55 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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What is your system voltage? I didn’t see a good resolution to that mentioned 20V issue. Pump output is pretty tied to voltage and tracks pretty close. I prefer a good 120A isolator, then add the combiner to that using the binding posts on the isolator as a convenient junction block.
John Lebetski
Woodstock, IL
77 Eleganza II
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| [GMCnet] Re: Issue with rough idle and stalling with electric fuel pump [message #364958 is a reply to message #364955] |
Thu, 24 June 2021 15:53 |
Keith V
Messages: 2337
Registered: March 2008
Location: Mounds View,MN
Karma: 0
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Senior Member |
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Ah the pump change wasn't clear in the OP.
Glad you got it fixed, I wonder what caused the pressure increase, debris in the relief valve?
________________________________
From: Tom Lins
Sent: Thursday, June 24, 2021 3:48 PM
To: gmclist@list.gmcnet.org
Subject: [GMCnet] Re: Issue with rough idle and stalling with electric fuel pump
kingd wrote on Wed, 23 June 2021 22:41
> Sounds like the pressure relief valve in the pump is stuck. This could happen while sitting over the winter. I don't have my /Carter pump handy
> but I think there is an external screw with a spring under it and the relief shuttle. See if you can find it and if the shuttle is stuck.
This Carter P4070 is a sealed unit.
--
Tom Lins
St Augustine, FL
77 GM Rear Twin, Dry Bath, 455, Aluminum Radiator Quad-Bag Suspension Solar Panel
Manuals on DVD
YOUTUBE Channel: GMC Dealer Training Tapes
http://www.bdub.net/tomlins/
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com
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| [GMCnet] Re: Issue with rough idle and stalling with electric fuel pump [message #364959 is a reply to message #364958] |
Thu, 24 June 2021 15:55 |
sgltrac
Messages: 2797
Registered: April 2011
Karma: 1
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Senior Member |
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Frog strangler??
Sully
Bellevue wa
On Thu, Jun 24, 2021 at 1:53 PM Keith V wrote:
> Ah the pump change wasn't clear in the OP.
> Glad you got it fixed, I wonder what caused the pressure increase, debris
> in the relief valve?
> ________________________________
> From: Tom Lins
> Sent: Thursday, June 24, 2021 3:48 PM
> To: gmclist@list.gmcnet.org
> Subject: [GMCnet] Re: Issue with rough idle and stalling with electric
> fuel pump
>
> kingd wrote on Wed, 23 June 2021 22:41
>> Sounds like the pressure relief valve in the pump is stuck. This could
> happen while sitting over the winter. I don't have my /Carter pump handy
>> but I think there is an external screw with a spring under it and the
> relief shuttle. See if you can find it and if the shuttle is stuck.
>
>
> This Carter P4070 is a sealed unit.
> --
> Tom Lins
> St Augustine, FL
> 77 GM Rear Twin, Dry Bath, 455, Aluminum Radiator Quad-Bag Suspension
> Solar Panel
> Manuals on DVD
> YOUTUBE Channel: GMC Dealer Training Tapes
> http://www.bdub.net/tomlins/
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
_______________________________________________
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Sully
77 Royale basket case.
Future motorhome land speed record holder(bucket list)
Seattle, Wa.
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| [GMCnet] Re: Issue with rough idle and stalling with electric fuel pump [message #364963 is a reply to message #364962] |
Thu, 24 June 2021 16:20 |
sgltrac
Messages: 2797
Registered: April 2011
Karma: 1
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Senior Member |
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Aha
Sully
On Thu, Jun 24, 2021 at 2:15 PM Tom Lins wrote:
> sgltrac wrote on Thu, 24 June 2021 16:55
>> Frog strangler??
>>
>> Sully
>> Bellevue wa
>
> We get thunder storms that at times seem like they could strangle a frog.
> Most afternoons this time of year.
> --
> Tom Lins
> St Augustine, FL
> 77 GM Rear Twin, Dry Bath, 455, Aluminum Radiator Quad-Bag Suspension
> Solar Panel
> Manuals on DVD
> YOUTUBE Channel: GMC Dealer Training Tapes
> http://www.bdub.net/tomlins/
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
Sully
77 Royale basket case.
Future motorhome land speed record holder(bucket list)
Seattle, Wa.
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