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Old 09-04-2005, 03:51 AM
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fuel regulator return line

i have a mallory 140 fuel pump that has to have a return line to the tank from the regulator.. where on the reg does it go and how big should the line be. with the pump deadheading against the reg the fuel pressure will drop from 8psi to 3psi at the end of the quarter. could it be that the pump just is not big enough. this is on a 550hp sbc, 850dp holley.. thanks for any assistance..

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Old 09-04-2005, 10:10 AM
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Who told you that 140 pump would power a 550 HP Motor?

Your out of fuel ....

Get a BG 280, BG 2 port and plumb it correctly:

http://www.4secondsflat.com/Barry_Gr...0Specials.html
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Old 09-04-2005, 11:02 AM
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i have been told that barry grant pumps are not very reliable and i do a lot of street mileage in my car. it was my local speed shop that told me that the mallory 140 would be suitable. a fella i know told me to call product engineering, but it is hard to find anybody over here [london, england] that has even heard of them. i have just looked at their site.. does any body here have first hand experience of their pumps etc.
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Old 09-15-2005, 02:29 PM
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Quote:
Originally Posted by zephyrc
i have been told that barry grant pumps are not very reliable and i do a lot of street mileage in my car. it was my local speed shop that told me that the mallory 140 would be suitable. a fella i know told me to call product engineering, but it is hard to find anybody over here [london, england] that has even heard of them. i have just looked at their site.. does any body here have first hand experience of their pumps etc.

It's a matter of getting a pump that is designed, and engineered to work within the parameters of what you are doing. If you use the wrong product for the application, or plumb it incorrectly you will have problems. How much street driving (time wise) are you doing? A BG280 would not be the proper choice for a street driven vehicle.
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Old 09-15-2005, 04:32 PM
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Or, lets make sure your current system is plumbed correctly so the current pump works as designed. That might make more sense since the current pump you have will flow 120 GPH at 6 PSI. That should feed a 550 HP motor unless you have some ungodly brake specific fuel consumption problem.

How big is the supply line from the tank to the pump and to the carb. Also is the pump height located below or at the bottom of the fuel tank? Is the pump by the tank? How do you pick up the fuel from the tank? It would make sense to have a 1/2 feed for this from the tank to at least the reg.

Later tonight I'll locate some links for plumbing options.
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Old 09-15-2005, 05:21 PM
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You need the matching fuel regulator

The pump's rate is good for alot of juice. It takes a 3/8" line coming and return, and 3/8's to the carb.

You need the bypass regulator with it. Pure and simple. This ensures you do not overpower your float bowl intake valve.

I have the GM 60 psi electric pump on mine, with the Mallory 4309 regulator. It nicely jacks my 60 psi pump down to a steady 6 psi. It doesn't creep and it works very well to allow the pump to work at full capacity without loading it up with pressure.

Stick with 3/8' and you will be ok. I have a buddy with a 550 hp engine with just the 5 psi pump and he gets lots of juice, so your pump will certainly keep up. Just use the 4309 with it.

Arn
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Old 09-15-2005, 08:59 PM
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http://www.centuryperformance.com/fuel.asp
This link should give you some guidance.
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Old 09-16-2005, 12:58 PM
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fuel regulator

my fuel system comprises ,,, fuel cell with -8 outlets,, 40 micron filter,, pump mallory 140,, -8 line to the regulator , mallory deadheading as supplied with the pump,,, -8 lines from reg to carb... the pump is 38 inches away from the cell under car.. i have just ordered a 150 micron filter to use in place of the 40 micron in case it is the filter that is the oroblem.. thanks for your suggestions.. zephyrc
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Old 09-16-2005, 01:08 PM
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38" away would seem extremely far. How high is the pump mounted in comparison to the outlets in your cell, and what size vent are you using?
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Old 09-16-2005, 02:12 PM
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Move the pump closer to the cell and put in a 3/8" return line, the plug to remove and and install the return line on is labelled on the casting. Look closely on the regulator casting you will see it.
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Old 09-16-2005, 02:37 PM
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You want to mount the 150 micron before the pump, just in case you were not sure. The 40 can then be mounted after the pump.
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Old 09-16-2005, 03:44 PM
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fuel pressure

the pump is approx 4-5 inches below the base of the fuel cell.. the cell is in the boot and the pump is below the boot floor.. the vent is just a peice of rubber tube about 5/16 of an inch.. the regulator supplied with the pump is a mallory unit .. it is a deadhead type ..not a bypassing type.... could the vent possible cause this sort of problem... zephyrc
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Old 09-16-2005, 03:56 PM
Technical Support Barry Grant
 
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Your vent may be a touch small for that pump, but the biggest thing is that it is not designed to draw or pull fuel. Mounting it closer to the outlet of the tank should help some. How do you have the pump wired?
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Old 09-16-2005, 04:11 PM
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fuel pressure

the pump is wired through a relay.. in order to mount it close to the cell, it would have to be in the boot. the last time i put my pump in the boot it failed within 3-4 hours running time,, i thought that it was to hot in the boot and mounted them under the car from then.. i will change the vent size tomorrow,, thanks for your suggestions.. zephyrc
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Old 09-16-2005, 04:56 PM
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Quote:
Originally Posted by zephyrc
the regulator supplied with the pump is a mallory unit .. it is a deadhead type ..not a bypassing type.... could the vent possible cause this sort of problem... zephyrc
So far as I have read, Mallory recommends a bypass unit with that pump.

That is likely a good chunk of your problem.

Good luck
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