Re: Electric fuel pump push fuel through a mechanical pump
[Re: RUNCHARGER]
#1769579
03/03/15 02:49 AM
03/03/15 02:49 AM
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Joined: Jan 2003
Posts: 1,979 s. e. pa.
calrobb2000
top fuel
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top fuel
Joined: Jan 2003
Posts: 1,979
s. e. pa.
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hi yes a elect pump wll push fuel through a mech pump . i have had mine that way for years . drain holley change jets hit switch ad refill carb before starting engine . 1 problem in hot weather mech pump will sometimes not pull enough fuel through elec pump for climing steep grades or w o t operation in which case i flip the on switch and prob solved .
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Re: Electric fuel pump push fuel through a mechanical pump
[Re: RapidRobert]
#1769581
03/03/15 02:56 AM
03/03/15 02:56 AM
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Joined: Jul 2006
Posts: 4,319 Puyallup, WA
StealthWedge67
master
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master
Joined: Jul 2006
Posts: 4,319
Puyallup, WA
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Something is wrong if you're having to prime the carb everytime you start your car. The carb should have gas in the fuel bowl without needing the pump to fill it each time. I can let my car sit for a month or more, and it fires right up with no choke, my setup is just a Carter street pump feeding a Holley double pumper. The question you should be asking is why is my carburetor empty and where is the fuel thats supposed to be in it going?
My 2-cents says you've got other problems. I wouldn't be suprised if you're dealing with a flooding issue, not lack of fuel (??).
LemonWedge - Street heavy / Strip ready - 11.07 @ 120
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Re: Electric fuel pump push fuel through a mechanical pump
[Re: RUNCHARGER]
#1769585
03/03/15 12:32 PM
03/03/15 12:32 PM
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Joined: Jan 2003
Posts: 11,892 Benton, IL.
DaveRS23
Special needs idiot
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Special needs idiot
Joined: Jan 2003
Posts: 11,892
Benton, IL.
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It will work fine but you do not have to run parallel lines. I have a Holley electric back by the tank and it pushes through the mechanical just fine. I have both a manual switch under the dash for priming and the like and a micro switch that is actuated by the secondaries on the carb. That way, I don't have to listen to the electric pump all the time, but have the flow when I need it. This system has fed the Dominator on the street and track for years now.
Master, again and still
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Re: Electric fuel pump push fuel through a mechanical pump
[Re: gdonovan]
#1769587
03/03/15 02:07 PM
03/03/15 02:07 PM
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Joined: Jan 2011
Posts: 4,785 Utah and Alaska
astjp2
master
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master
Joined: Jan 2011
Posts: 4,785
Utah and Alaska
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I looked at doing this and using a 5 second relay: ignition on, 5 seconds of priming, pump off, start engine, ignition off, ignition on, 5 seconds of priming, pump off, start engine...but the relays are 40 dollars each. Tim
1941 Taylorcraft 1968 Charger 1994 Wrangler 1998 Wrangler 2008 Kia Rio 2017 Jetta
I didn't do 4 years and 9 months of Graduate School to be called Mister!
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Re: Electric fuel pump push fuel through a mechanical pump
[Re: Challenger 1]
#1769590
03/03/15 09:32 PM
03/03/15 09:32 PM
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Joined: Aug 2006
Posts: 84 PA
Jack Zupan
member
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member
Joined: Aug 2006
Posts: 84
PA
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Quote:
I have found using a stock enclosed air filter housing has slowed the evaporation of the fuel in my carb verses a open air, air filter.
What does this mean? Open vs. closed?
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Re: Electric fuel pump push fuel through a mechanical pump
[Re: Jack Zupan]
#1769591
03/03/15 09:51 PM
03/03/15 09:51 PM
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Joined: Feb 2015
Posts: 30 Norcal
Wildjones
member
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member
Joined: Feb 2015
Posts: 30
Norcal
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Quote:
Quote:
I have found using a stock enclosed air filter housing has slowed the evaporation of the fuel in my carb verses a open air, air filter.
What does this mean? Open vs. closed?
I'm thinking he is referring to a snorkel type air filter as being "closed" and a K&N style as being "open".
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Re: Electric fuel pump push fuel through a mechanical pump
[Re: RUNCHARGER]
#1769598
03/04/15 06:50 AM
03/04/15 06:50 AM
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Joined: Jan 2005
Posts: 3,699 Newport, Mi
Evil Spirit
master
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master
Joined: Jan 2005
Posts: 3,699
Newport, Mi
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If the engine just will not start unless the bowls are hand primed, that's one thing - I would certainly fix that issue. But I never understand why people want a stone cold engine that has sat even overnight to start instantly in the first couple rotations. Pretty good chance that all the oil has drained back into the pan, possibly draining the oil passages and the oil filter. There is also the possibility of lifters bleeding down. If they have sat overnight, I rarely attempt to fire any performance engine until I've cranked it and seen oil pressure. IMO an engine that needs to crank 10 seconds or so on that first startup after sitting any length of time is actually doing itself a favor and priming the oil system before it starts, and eliminating any possible dry startup damage. Many hydraulic cammed engines will sound totally different on startup if you "pre-lube" them first, since it gives the lifters on open lobes that have bled down a little a chance to pump up fully and "tighten" the valve train up. Just a little food for thought about starting that engine that has sat for a while - do you REALLY want it to start first roll?
Free advice and worth every penny... Factory trained Slinky rewinder.........
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Re: Electric fuel pump push fuel through a mechanical pump
[Re: RUNCHARGER]
#1769603
03/04/15 10:24 PM
03/04/15 10:24 PM
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Joined: Jan 2007
Posts: 7,664 IN
ahy
master
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master
Joined: Jan 2007
Posts: 7,664
IN
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Quote:
My plan is to loop off at the sending unit, build a bracket that bolts to the tie down attachments (E body) that mounts a 110 GPH electric pump and use the stock 3/8 fuel line up to the HP mechanical pump. All the repro stainless steel fuel lines will be uncut and if I have to run the electric pump all the time that's what I'll do but it sounds like I'll be able to just use it for a cold start and maybe when using WOT in 3rd and 4th. I'll let everyone know after I test it. I'll tie strap a fuel pressure gauge to the cowl when I first install the extra pump.
Sheldon
In general the electric pump will not flow fuel when turned off. The mechanical pump will not be able to "suck" through it. An electric pump bypass line with check valve is needed to allow the engine to operate with electric pump off. I used a brass check valve from the hardware store on my truck... more compact automotive type valves are available from Summit and others.
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Re: Electric fuel pump push fuel through a mechanical pump
[Re: Dr Dave]
#1769606
03/04/15 11:36 PM
03/04/15 11:36 PM
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Joined: Mar 2008
Posts: 1,913 central P.A.
HEMIDOG 70
top fuel
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top fuel
Joined: Mar 2008
Posts: 1,913
central P.A.
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Quote:
Please let me know what you come up with. I have a similar setup, 528", dual quads, shaker, not easy to prime the carbs and want to do something with an electric pump.
X2 no shaker here but I too would like to add a electric pump to prime for starts due to evaporation. I'm running a 528 hemi with dual quads and solid lift cam. I have extended crank times after the car has sat for longer periods.
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Re: Electric fuel pump push fuel through a mechanical pump
[Re: gdonovan]
#1769616
03/06/15 07:19 PM
03/06/15 07:19 PM
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Joined: Jan 2003
Posts: 25,618 Rio Linda, CA
John_Kunkel
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 25,618
Rio Linda, CA
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Quote:
Quote:
Quote:
Sorry to disagree, but the mech pump WILL pull through an elec pump. I have a Holley pump mounted by the tank that only runs when switched on.
As I stated earlier, not true on some pumps...Carters in particular.
I have a Carter pump, no problem.
You must have a vane-type pump, Carter gear rotor pumps are different:
"IMPORTANT NOTE: When using a gear rotor type pump.... These pumps cannot be used as a secondary unit ie, on a dash switch. They MUST be wired to run continuously from the IGN circuit as your PRIMARY and ONLY PUMP.
This pump type uses a DRIVEN gear and a RING gear to create a positive displacement and force fuel through to the carb. The gearing is similar to your oil pump. They do NOT have any check valves like a mechanical fuel pump, thus if they aren't running, you cannot DRAW fuel through them via a mechanical pump, etc ( at least, enough to have the engine remain running)."
The INTERNET, the MISinformation superhighway
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Re: Electric fuel pump push fuel through a mechanical pump
[Re: StealthWedge67]
#2697082
09/13/19 06:22 AM
09/13/19 06:22 AM
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Joined: Jan 2003
Posts: 9,963 Frostbitefalls MN (Rocky&Bullw...
gregsdart
master
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master
Joined: Jan 2003
Posts: 9,963
Frostbitefalls MN (Rocky&Bullw...
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I saw this old post and thought of a couple of improvements that could be added.Jegs sells a 5psi pressure activated switch you can use to either open or close a circuit' . it could be plumbed into the fuel line by the carb and used to run a relay that shuts the electric pump down at 5 psi fuel pressure and above. Also to make the line from tank to mechanical pump less restrictive, I would try putting a T fitting before the electric and have the electric pump on another line with a one way check valve in front of it, then join the two going to the carb. A bit of extra complication, but if results are worth it to you,,,,,,,,,
8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
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