| fuel pump discharge [message #280852] |
Sat, 27 June 2015 13:48  |
budworks521
Messages: 137
Registered: October 2013
Location: Grand Rapids MI 1974 Pain...
Karma: 4
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Gentlemen, just s few questions about the amount of fuel that should emit from the pump. I had the fuel line off the carb and tried running the engine with what was in the float bowl. I have a squirt stop squirt action on the fuel pump. Not a steady stream of fuel. Which is more desirable? I pulled the fuel filter off as well and replaced with a new one. Same syptoms. Runs and vac ok for some time and then shuts down. Both mufflers replaced. New module. thanks for any ideas.
1974 Painted Desert
455 upper half rebuild
constant project inexperienced mechanic
Grand Rapids Mi
Always trying to learn
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| Re: fuel pump discharge [message #280853 is a reply to message #280852] |
Sat, 27 June 2015 14:39  |
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wally
Messages: 643
Registered: August 2004
Location: Omaha Nebraska
Karma: 5
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budworks521 wrote on Sat, 27 June 2015 13:48Gentlemen, just s few questions about the amount of fuel that should emit from the pump. I had the fuel line off the carb and tried running the engine with what was in the float bowl. I have a squirt stop squirt action on the fuel pump. Not a steady stream of fuel. Which is more desirable? I pulled the fuel filter off as well and replaced with a new one. Same syptoms. Runs and vac ok for some time and then shuts down. Both mufflers replaced. New module. thanks for any ideas.
squirt stop squirt action on the fuel pump is normal with the engine mounted pump. If you have a pressure gage it should output 5 1/2-6 1/2 psi. I couldn't find a volume spec in the X7525 manual but a 1972 Cadillac manual reads 28cc minimum volume per pump stroke. I would imagine the GMC is pretty close to that.
HTH
Wally Anderson
Omaha NE
75 Glenbrook
[Updated on: Sat, 27 June 2015 14:55] Report message to a moderator |
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| Re: fuel pump discharge [message #280858 is a reply to message #280852] |
Sat, 27 June 2015 15:38 |
budworks521
Messages: 137
Registered: October 2013
Location: Grand Rapids MI 1974 Pain...
Karma: 4
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Senior Member |
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I can add a tad of gas once it starts to stall and it wants to continue to run. I firmly believe the ignition is ok. I am close to empty on my tanks but that has effected the running of the engine before...
1974 Painted Desert
455 upper half rebuild
constant project inexperienced mechanic
Grand Rapids Mi
Always trying to learn
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| Re: fuel pump discharge [message #280873 is a reply to message #280852] |
Sat, 27 June 2015 19:24 |
Chris Tyler
Messages: 458
Registered: September 2013
Location: Odessa FL
Karma: 7
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Pulsing is normal. How much will it put out in 15 seconds of idling?
Need to check pressure, as free flow is irrelevant if it cannot overcome a restriction
I use this inline to check FP:http://www.amazon.com/gp/product/B000BPZ4SW?psc=1&redirect=true&ref_=oh_aui_search_detailpage
On the pump squirt: remember that the accel pump will still squirt a couple times with an empty bowl
76 Glenbrook
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| Re: fuel pump discharge [message #280902 is a reply to message #280852] |
Sun, 28 June 2015 10:34 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Your gauges may be off calibration and tanks are too empty. Add at least 10 gal and try again. Should be fairly stout solid stream on pump stroke between pauses.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: fuel pump discharge [message #281045 is a reply to message #280852] |
Mon, 29 June 2015 23:18 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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budworks521 wrote on Sat, 27 June 2015 12:48Gentlemen, just s few questions about the amount of fuel that should emit from the pump. I had the fuel line off the carb and tried running the engine with what was in the float bowl. I have a squirt stop squirt action on the fuel pump. Not a steady stream of fuel. Which is more desirable? I pulled the fuel filter off as well and replaced with a new one. Same syptoms. Runs and vac ok for some time and then shuts down. Both mufflers replaced. New module. thanks for any ideas.
Sometimes the tank selector valve will fail in the open position to both tanks. If one is low, you will start to suck air.
Bob de Kruyff
78 Eleganza
Chandler, AZ
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| Re: fuel pump discharge [message #281049 is a reply to message #280852] |
Tue, 30 June 2015 06:01 |
budworks521
Messages: 137
Registered: October 2013
Location: Grand Rapids MI 1974 Pain...
Karma: 4
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Senior Member |
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I ended up pulling the fuel line off the carb and tested the delivery of fuel and it was pretty good streams of fuel. I replaced the fuel filter as well and saw that the vinyl bushing was doubled up and seated near the back of the carb. The manual show the bushing before the filter. Though it slides through the filter so must seat behind the fuel filter. I will try adding 10 gallons of gas. My switch for tank selection does work and you can see the gauge moving from one mark to the other as use change the tank selection. I was wondering if perhaps my idle compensator valve could be bad or choke could be the concern. As I stated the carb seems like it starts starving for fuel upon stalling and if I squirt a bit of gas into the carb it automatically wants to stay running again. Also, on a cold start the next day the float bowl is empty of gas and BUT if you try pumping the gas after it stalls the ports push gas but that could be gas located in the pump area and not the float bowl. Amazing carb .... thanks for the input
1974 Painted Desert
455 upper half rebuild
constant project inexperienced mechanic
Grand Rapids Mi
Always trying to learn
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| Re: [GMCnet] fuel pump discharge [message #281078 is a reply to message #281049] |
Tue, 30 June 2015 12:17 |
powerjon
Messages: 2446
Registered: January 2004
Karma: 5
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Also remember that the carb filter can be installed backwards and will cause similar symptoms. We were traveling with 3 other coaches going to AZ several years age. Stopped in Carlsbad NM for a few day to explore the area. One of our group change his fuel filter the next night and didn’t tell anybody. Going north to Artesia his coach would for 10 to 12 miles and then run out of gas. Seeing he had just changed the filter he thought the pump was bad and we change out his spare pump. Ran for a little bit and then died again. We sat and brainstormed what had change the last few days and he said that he had changed out the carb fuel filter. First question was is it in correctly? Took it out and turned it around and ran well with issues. Sometimes it can be the simplest things that can drive you nuts. I know that you have had a lot of suggestion, but if you have been changing the filter and still having the same issues you probably installing it the way you just took it out and and it is installed wrong. Spring and flat metal end goes towards the carb and the end with the hope goes towards the fuel inlet. The gasket the should be about half way down the inside of the filter housing on the carb.
Go to MM X7525A, Sec 6M, P2, Fig. 2 & Sec 6M, P18, Fig. 22
http://www.gmcmhphotos.com/photos/general-pictures/p58268-q-jet-fuel-filter.html
It is so easy to put that sucker in backwards if you’re not sure and guess. On the inlet end you have the rubber gasket and when you look inside the filter has a check valve that prevents back flow.
http://www.gmcmhphotos.com/photos/general-pictures/p58270-img-07751.html
http://www.gmcmhphotos.com/photos/general-pictures/p58271-img-07761.html
http://www.gmcmhphotos.com/photos/general-pictures/p58269-fuel-system-q-jet.html
J.R. Wright
GMC Great Laker MHC
Newsletter Editor/Publisher
GMC Eastern States
GMCMHI
78 GMC Buskirk 30’ Stretch
75 GMC Avion (Under Reconstruction)
Michigan
> On Jun 30, 2015, at 7:01 AM, Lawrence Harrison wrote:
>
> I ended up pulling the fuel line off the carb and tested the delivery of fuel and it was pretty good streams of fuel. I replaced the fuel filter as
> Well and saw that the vinyl bushing was doubled up and seated near the back of the carb. The manual show the bushing before the filter. Though it
> slides through the filter so must seat behind the fuel filter. I will try adding 10 gallons of gas. My switch for tank selection does work and you can
> see the gauge moving from one mark to the other as use change the tank selection. I was wondering if perhaps my idle compensator valve could be bad or
> choke could be the concern. As I stated the carb seems like it starts starving for fuel upon stalling and if I squirt a bit of gas into the carb it
> automatically wants to stay running again. Also, on a cold start the next day the float bowl is empty of gas and BUT if you try pumping the gas after
> it stalls the ports push gas but that could be gas located in the pump area and not the float bowl. Amazing carb .... thanks for the input
> --
> 1974 Painted Desert
> 455 upper half rebuild
> constant project inexperienced mechanic
> Grand Rapids Mi
> Always trying to learn
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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J.R. Wright
GMC GreatLaker
GMC Eastern States
GMCMI
78 30' Buskirk Stretch
75 Avion Under Reconstruction
Michigan
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