Home » Public Forums » GMCnet » Fuel pump in but no pumpy
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| Re: Fuel pump in but no pumpy [message #362861 is a reply to message #362854] |
Tue, 16 March 2021 12:12   |
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The carb bowl? Or the pump itself? I was wondering if the lever was engaging the cam. I put it in at TDC and it bolted right up, but nothing comes out of the line... :-/
73 Canyon Lands, (a.k.a. The Yellow Submarine) West Los Angeles CA
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| Re: Fuel pump in but no pumpy [message #362862 is a reply to message #362854] |
Tue, 16 March 2021 12:46 |
lqqkatjon
Messages: 2324
Registered: October 2010
Location: St. Cloud, MN
Karma: 5
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Senior Member |
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getting fuel up to that point of the engine can be a task. especially if fuel lines are not perfect. you are trying to suck gas about 25', to a point that is probably 12-24" above the fuel level in the tanks with a pump that is borderline able to do that task.
I highly recommend an electrical pump back by the tanks at least for the aux side... simple, helps vapor lock when needed and priming of fuel system for cases like this. 10' or less of fuel line, and it should be quick to give a gravity feed of gas from some other gas source. get the engine started quick that way, then hook up the fuel line stock and it should start sucking. also making sure gas tanks are fuller helps. I know when I have drained out gas, it usually takes about 15 gallons in the tanks to get fuel flowing right at first.
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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| [GMCnet] Re: Fuel pump in but no pumpy [message #362863 is a reply to message #362861] |
Tue, 16 March 2021 12:58 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Shan,
A bit of unsolicited advice: Replace that mechanical pump with a block-off
plate and a bypass tube. Install 2 electric pumps (I like Carter 4070's),
powered through a SPDT relay controlled by the tank selector switch on the
dash. Eliminate the tank selector solenoid valve (which is almost certain
to give you trouble at some time, possibly leaving you beside the road) by
connecting one of those electric pumps to each of the tanks (use the
selector valve's wiring to control the relay). Tee the pumps' outputs
together into the OEM feed line.
With that setup, you'll have redundant pumps, eliminate the valve as a
failure point, and, if you mount the pumps near the tanks, you'll probably
never have a vapor lock problem; also, some add a prime button for
long-idle starts.
It's not a very expensive upgrade but a valuable one.
JMHO -- based on 20 years running that way.
Ken H.
On Tue, Mar 16, 2021 at 1:13 PM Shan Rose wrote:
> The carb bowl? Or the pump itself? I was wondering if the lever was
> engaging the cam. I put it in at TDC and it bolted right up, but nothing
> comes out
> of the line... :-/
> --
> 73 Canyon Lands, (a.k.a. The Yellow Submarine) West Los Angeles CA
> _______________________________________________
> GMCnet mailing list
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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: Fuel pump in but no pumpy [message #362865 is a reply to message #362862] |
Tue, 16 March 2021 13:47 |
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lqqkatjon wrote on Tue, 16 March 2021 10:46getting fuel up to that point of the engine can be a task. especially if fuel lines are not perfect. you are trying to suck gas about 25', to a point that is probably 12-24" above the fuel level in the tanks with a pump that is borderline able to do that task.
I highly recommend an electrical pump back by the tanks at least for the aux side... simple, helps vapor lock when needed and priming of fuel system for cases like this. 10' or less of fuel line, and it should be quick to give a gravity feed of gas from some other gas source. get the engine started quick that way, then hook up the fuel line stock and it should start sucking. also making sure gas tanks are fuller helps. I know when I have drained out gas, it usually takes about 15 gallons in the tanks to get fuel flowing right at first.
Got both tanks about 3/4 full. Thought of the booster pump set up, but the old mechanical one worked even with my Holley street avenger set up, which I'm installing a new 083670 aluminum job. More on that later but makes it run like a raped ape. But need gassy to goey...
73 Canyon Lands, (a.k.a. The Yellow Submarine) West Los Angeles CA
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| Re: Fuel pump in but no pumpy [message #362873 is a reply to message #362865] |
Tue, 16 March 2021 15:42 |
lqqkatjon
Messages: 2324
Registered: October 2010
Location: St. Cloud, MN
Karma: 5
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Senior Member |
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up until I installed the EFI a couple years ago, I installed a $50 cube pump on my coach back in 2010 when I first bought it. was a "jim bounds" install as that is where I seen it done. just plumbed into the aux feed before the selector valve and powered off the selector valve wire. Switch to Aux at dash just before starting coach and you could hear the pump. set the choke and the engine would fire on crank almost immediatly. Then switch back to "main" on dash and drive. few times on hot days when in traffic you could get the chug of vapor lock and a quick switch of the tank switch and boom- power and drive away.
I have been around coaches that sit, have no electric fuel pump, and crank till the battery cables melt, or battery dies and no start. Hook up an aux fuel source up and get the engine running. then switch back to the tanks, and it usually will run. last one just a year ago, the coach was parked nose up, and it would not suck any fuel. got the coach on level ground and hooked up an electric pump to the fuel tank hoses. quickly had fuel coming out of the tanks, hooked the fuel line back to the mechnical pump and that coach drove home.
that mechnical pump is just what it is. you have to get those hoses primed somehow. Electric pump is easiest.
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: Fuel pump in but no pumpy [message #362875 is a reply to message #362873] |
Tue, 16 March 2021 17:19 |
blur911
Messages: 166
Registered: December 2020
Location: Kingston, Ontario
Karma: 4
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Senior Member |
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lqqkatjon wrote on Tue, 16 March 2021 15:42up until I installed the EFI a couple years ago, I installed a $50 cube pump on my coach back in 2010 when I first bought it. was a "jim bounds" install as that is where I seen it done.
If I were to keep my eyes open for an electric fuel pump, what pressure range would I be looking for?
IIRC it should insert into 3/8" hose.
Burl Vibert
Kingston, Ontario
1976 GMC 26 foot, Sheridan reno, don't know original model but we call her Roxie
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| [GMCnet] Re: Fuel pump in but no pumpy [message #362877 is a reply to message #362875] |
Tue, 16 March 2021 18:25 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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This is a hard one to beat:
Amazon.com: Carter P4070 In-Line Electric Fuel Pump: Automotive
Ken H.
On Tue, Mar 16, 2021 at 6:19 PM Burl Vibert wrote:
> lqqkatjon wrote on Tue, 16 March 2021 15:42
>> up until I installed the EFI a couple years ago, I installed a $50 cube
> pump on my coach back in 2010 when I first bought it. was a "jim
>> bounds" install as that is where I seen it done.
>
> If I were to keep my eyes open for an electric fuel pump, what pressure
> range would I be looking for?
> IIRC it should insert into 3/8" hose.
> --
> Burl Vibert
> Kingston, Ontario
> 1976 GMC 26 foot, don't know the model
> _______________________________________________
> 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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| [GMCnet] Re: Fuel pump in but no pumpy [message #362878 is a reply to message #362877] |
Tue, 16 March 2021 20:18 |
Keith V
Messages: 2337
Registered: March 2008
Location: Mounds View,MN
Karma: 0
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Senior Member |
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be very careful of those cube pumps, some like the edlebrock ones do NOT lift fuel so I'd not use them for the Aux pump.
The facet pumps DO lift, so they work.
The carter is the best one
________________________________
From: Ken Henderson
Sent: Tuesday, March 16, 2021 6:25 PM
To: GMC Mail List
Subject: [GMCnet] Re: Fuel pump in but no pumpy
This is a hard one to beat:
Amazon.com: Carter P4070 In-Line Electric Fuel Pump: Automotive
Ken H.
On Tue, Mar 16, 2021 at 6:19 PM Burl Vibert wrote:
> lqqkatjon wrote on Tue, 16 March 2021 15:42
>> up until I installed the EFI a couple years ago, I installed a $50 cube
> pump on my coach back in 2010 when I first bought it. was a "jim
>> bounds" install as that is where I seen it done.
>
> If I were to keep my eyes open for an electric fuel pump, what pressure
> range would I be looking for?
> IIRC it should insert into 3/8" hose.
> --
> Burl Vibert
> Kingston, Ontario
> 1976 GMC 26 foot, don't know the model
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
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_______________________________________________
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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: Fuel pump in but no pumpy [message #362879 is a reply to message #362878] |
Tue, 16 March 2021 20:50 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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I use the 4070 Carter electric pump on my auxiliary fuel line. Wired to
come on when I switch tanks with the dash switch. METAL IN LINE fuel filter
ahead of the Carter pump. Has worked well there for several years. JWID.
Jim Hupy
Salem, Oregon
On Tue, Mar 16, 2021, 6:19 PM Keith V wrote:
> be very careful of those cube pumps, some like the edlebrock ones do NOT
> lift fuel so I'd not use them for the Aux pump.
> The facet pumps DO lift, so they work.
> The carter is the best one
> ________________________________
> From: Ken Henderson
> Sent: Tuesday, March 16, 2021 6:25 PM
> To: GMC Mail List
> Subject: [GMCnet] Re: Fuel pump in but no pumpy
>
> This is a hard one to beat:
> Amazon.com: Carter P4070 In-Line Electric Fuel Pump: Automotive
> https://www.amazon.com/Carter-P4070-Line-Electric-Fuel/dp/B000CIQ5DG/ref=asc_df_B000CIQ5DG/?tag=hyprod-20&linkCode=df0&hvadid=312442771380& ;hvpos=&hvnetw=g&hvrand=1418768408273136619&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1015250&am p;hvtargid=pla-569979893960&psc=1
>>
> Ken H.
>
>
> On Tue, Mar 16, 2021 at 6:19 PM Burl Vibert wrote:
>
>> lqqkatjon wrote on Tue, 16 March 2021 15:42
>>> up until I installed the EFI a couple years ago, I installed a $50
> cube
>> pump on my coach back in 2010 when I first bought it. was a "jim
>>> bounds" install as that is where I seen it done.
>>
>> If I were to keep my eyes open for an electric fuel pump, what pressure
>> range would I be looking for?
>> IIRC it should insert into 3/8" hose.
>> --
>> Burl Vibert
>> Kingston, Ontario
>> 1976 GMC 26 foot, don't know the model
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
_______________________________________________
GMCnet mailing list
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| Re: Fuel pump in but no pumpy [message #362880 is a reply to message #362854] |
Tue, 16 March 2021 22:18 |
Rick Staples
Messages: 126
Registered: May 2014
Location: Johnstown, Colorado, USA
Karma: -1
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Senior Member |
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Duce,
Since it worked before, and the only thing changed was the fuel pump, I'd start there. I'd disconnect the fuel line from the pump (suction side), attach a vacuum gauge, and crank the engine with the starter for ~30 seconds or so. The gauge should read at least 5 or 10 inches of vacuum, and should hold that reading for at least a minute or so. If it does not, I'd pull the pump off and recheck it.
Work the lever by hand and make sure it pulls vacuum. If it does not, you've got a defective pump. It happens!
If the pump works manually, look for scratches on the side of the lever. It is sometimes possible to install the pump a little cockeyed, so the lever essentially "misses" the cam in the engine, then no pump action. Reinstall carefully.
If the pump DOES pull vacuum when the engine cranks over, I would check carefully for any small leaks in the fuel lines from tanks(s) to pump. Any small leak in those lines will allow air to enter instead of fuel. (Been there, done that, although not on the GMC.) If you have access to a "Mity-Vac" or similar vacuum pump and reservoir, attach it to the fuel line and make sure you can draw fuel from the tank.
All the suggestions about electric pumps are generally good ones. I have a Carter 4070 pump in my auxiliary fuel feed, with a primer switch on the dash. It does help to overcome vapor lock on occasion. OTOH, the original mechanical pump is simple, safe, good enough for GM, and worked for 45 years. It should work now.
My 2¢, HTH
Rick Staples
Rick Staples, '75 Eleganza, Johnstown, CO
"Advice is a dangerous gift, even from the Wise to the Wise, and all paths may run ill." -Tolkien
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| [GMCnet] Re: Fuel pump in but no pumpy [message #362881 is a reply to message #362880] |
Tue, 16 March 2021 22:38 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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Keep in mind that a Vain driven pump need a filter to maintain long life,
Several of our customers have with out these pumps by not having a filter.
Go to our sight and see how we do it to avoid vapor loc by mounting them
outside the frame and close to the tanks.
On Tue, Mar 16, 2021 at 8:19 PM Richard H Staples
wrote:
> Duce,
> Since it worked before, and the only thing changed was the fuel pump, I'd
> start there. I'd disconnect the fuel line from the pump (suction side),
> attach a vacuum gauge, and crank the engine with the starter for ~30
> seconds or so. The gauge should read at least 5 or 10 inches of vacuum, and
> should hold that reading for at least a minute or so. If it does not, I'd
> pull the pump off and recheck it.
>
> Work the lever by hand and make sure it pulls vacuum. If it does not,
> you've got a defective pump. It happens!
>
> If the pump works manually, look for scratches on the side of the lever.
> It is sometimes possible to install the pump a little cockeyed, so the lever
> essentially "misses" the cam in the engine, then no pump action.
> Reinstall carefully.
>
> If the pump DOES pull vacuum when the engine cranks over, I would check
> carefully for any small leaks in the fuel lines from tanks(s) to pump. Any
> small leak in those lines will allow air to enter instead of fuel. (Been
> there, done that, although not on the GMC.) If you have access to a
> "Mity-Vac" or similar vacuum pump and reservoir, attach it to the fuel
> line and make sure you can draw fuel from the tank.
>
> All the suggestions about electric pumps are generally good ones. I have
> a Carter 4070 pump in my auxiliary fuel feed, with a primer switch on the
> dash. It does help to overcome vapor lock on occasion. OTOH, the
> original mechanical pump is simple, safe, good enough for GM, and worked
> for 45
> years. It should work now.
>
> My 2¢, HTH
> Rick Staples
>
> --
> Rick Staples, '75 Eleganza, Johnstown, CO
>
> "Advice is a dangerous gift, even from the Wise to the Wise, and all paths
> may run ill." -Tolkien
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
--
Jim Kanomata
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.gmcrvparts.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: Fuel pump in but no pumpy [message #362883 is a reply to message #362854] |
Wed, 17 March 2021 02:40 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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OK, Now that everybody has got you convinced that you need an additional pump, lets get this going with what you have installed. Remove the hose to the input side of the fuel pump. When you removed the hose on the input side while installing the replacement pump, air got in the line and the fuel drained backwards all the way down to the tank. That new pump does not like pumping the air out of that long line to get to the gas. It pumps gas well and air very poorly.
I use shop air and a rag. Remove the gas fill and insert the shop air and a rag. Apply air in 1 or 2 second bursts. When the gas starts flowing out of the removed line, have a second person install the line back on the pump and immediately stop the air.
Install the hose clamp and go start your engine. You might have to crank a bit to fill up the line past the pump and the carb bowl. I have done this many times. One time I used a portable air tank instead of shop air on a coach parked out in a field that had not run for many years.
Be careful with shop air. You only need enough to get fuel to flow out of the hose that you disconneted from the fuel pump. You definitely need two people. If one tries this the fuel will run back to the tank before you get up front to reconnect the hose. I have done this with a handheld vacuum pump but it takes a lot of hand pumping to get all of the air out of that very long line.
Once you get it running again you can decide if you want to do one of the suggested electric fuel additions for future use. I have a Carter P4070 on mine but rarely need it. Colonel Ken's suggestion of two P4070s is a good one too.
Good luck....Ken B.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: Fuel pump in but no pumpy [message #362888 is a reply to message #362883] |
Wed, 17 March 2021 08:28 |
lqqkatjon
Messages: 2324
Registered: October 2010
Location: St. Cloud, MN
Karma: 5
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Senior Member |
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Ken- always has words of wisdom. He stated it perfectly, the mechanical pump pumps gas well, air poorly. That describes the problem to a T.
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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