Has anyone connected a relay to the LP giving it constant 12 volts when the ecm is varying voltage? Basically wiring it to run at full blast like the fass does? Directly to the battery but controlled still by the ecm on\off. I still have poor pressure and just installed a new pump and filter. Thanks everyone

 

My holley blue is run off of 2 30 amp relays but is triggered by the stock lift pump wire. It gets a constant 12 volts.

 

And you see a steady 15 psi? Why two relays? you only need one.

 

If you are reading this, I got the FASS and see 17 psi all of the time. Awsome machine.

 

BigBlue,
Why do you run two 30 amp relays? The pump only pulls 4 amps.

I am having an issue with the ECU flickering voltage when it first kicks on. I used one of my heater grid relays (disconnected the heater grid) and thought I burned it up. I put a new one on the fender but have been having the same issue. When the ECU gives it 12 volts it is fine but it cycles three or four times before it does.

Randy

 

The LP is run at 50% duty cycle while cranking to avoid hard start conditions. You do not want to run it continuously while cranking. After the engine fires the ECM goes to 100% duty cycle for the LP. If you use the stock wire to the LP to switch a relays it will mimik the stock behaviour. (It will time a little differently due to the inertia of the relays though)
The flickering while cranking will wear down the relay pretty quick. You can either replace the relay with a solid state relay (basically 2 transistors) or make an "easy swap" relay. (Means having one in the glove box )

HTH

AlpineRAM

 

Might want to check the specs.....the Holley Blue pump will pull considerably more than 4 amps.

 

Holley Blue Electric Fuel PumpsFeed your need for fuel.

These Blue electric fuel pumps from Holley feature an improved design for street and strip applications, a new lower housing casting for enhanced fuel flow, and a tumble-polished billet look with the distinctive blue logo. These pumps have a 110 gph flow rate, draw only 3 amps, and have a maximum pressure of 14 psi with an externally accessible pressure relief valve. They weigh only 3 lbs., and include a mounting bracket.


This was taken from SUMMITs web site. I am running the BLack which pulls 4 amps. I too use A 30 amp relay because it is commonly availible. I was curious about using two.

I've considered putting a CAP and diode in the relay control to hold it on during the start cycle and just haven't got to it yet. I don't think 14 PSI - filter drop would be too much for starting. I don't like the pulse on an electric motor. It is not good for it and could be part of the reason for relibility issues.

Randy

 

Is the best way to controll your pump,I think. I have used this method for many years without any problems.

 

I have never in my life seen a relay wear out. As long as they are used between 5-18 volts and not over their operating parameters they will last as long as the truck. I have been in car audio and accesories for about 5 years now. I use countless relays on remote starts, neons, strobes, FUEL PUMPS, actuators and never had one fail. I have taken apart installs over 10 years old and the relays still work. Its my logic I guess. If there were ever a problem it would be the last place I would look.

 

Over all relays are reliable. Over current is most likly to kill them, but we do have a high number in our (my job) application that fail from power dropping off and on. We are are also dealing with 400HZ 115V. Most of our stuff is more finickey (sp).

My main worry is with the start/stop on the pump. Also the (relitivly) high current at (pump) start up. I would just prefer to not have it.

Randy

 

Interesting....I have messed around with a few Blue pumps on past projects and could fuse them at no less than 15 amps.....

 

When the ECM runs the the fuel pump it doesn't pulse it it, just lowers the voltage to the pump.

 

Put a meter on the LP leads. It is a pusle, not a lower constant V.

Randy

 

How come the the pump control wires don't pulse the relay ? I have solid battery voltage to the fuel pumps.My guess it never drops low enough to release the relay completely.