on the street or track?

without a hobbs switch and constantly running them.

good or bad?

suggestions?

 

Usually your return line is smaller than your feed so you will have fuel that is trying to make it back to the tank and can't because at idle you will have lots of fuel going back unlike when you are WOT. Plus in doing so you will be heating up your fuel which is not a good thing.

Its best to turn them on with a hobbs switch or get them to turn on at a certain boost level thru the PCM or boost controller.

 

How is it done through the pcm?

 

There is a trigger that can be set up in the PCM to trigger anything like nitrous or a meth kit. You can use it to trigger a fuel pump at a certain point. Geoff@EPS told it to me years ago.

 

i wired both of my 450's to be on all the time.

 

see some people say Yes to being on at all times with 0 issues. Others say No

which is it?

 

i dont see it heating the fuel up any more than a big external pump will. im not worried about it. personal preference imo.

 

Do tell more please

 

So no issues with over fueling at idle?

 

If you have a large enough return line it will be ok. I have my second pump set up to come on with a hobbs switch. I chose to do it that way only because it's unnecessary to run both pumps at the same time... The "heating the fuel" thing is probably minor, but it is less wear on that second pump, and quite frankly it's not all that much more complicated to wire a separate pump on a switch.

https://ls1tech.com/forums/fueling-i...g-install.html Post 9 has a diagram.

 

IMO there is no need to have both pumps on at idle. It will be circulating, and heating far more fuel than you need at idle. If you have the option to have the 2nd pump come on at boost why not do it?

I use the holley 1800 pump 2nd half is trigger by pcm at above 3psi & above 60% tps

 

I run both my walbro 340s all the time. Wired them together. Use a hot wire kit that has its own relay and hooks to back of the alternator.

 

i run my 2 044s on all the time. it dose heat the fuel up some but id rather have hot fuel then be on a hobbs switch that could fail when i need the other pump on and cost me a motor

 

I do know a real hobbs switch will damn near never fail

 

I run 2 255 walbros on all the time. I have my 3rd one hooked up to a Hobbs switch.
-6 return. No problems here.

 

its more wear and tear turning pumps on and off.....
you can also have fuel surge issues when you turn on and off a pump


I run both on all the time...
Holley 12-1800 dual fuel pump
-10 feed
-8 return

no problems


fuel really doesnt get heated up from pumps being on all the time..
it gets more heated up from being in lines in a hot engine bay and touching fuel rails that get hot because they are made of metal...


I put a charger on my battery, turned the fuel pumps on, and just ran them for about 20 minutes with a thermometer in the 20 Gallon fuel cell..tank was approximately 2/3 full
saw a 2* rise in fuel temps....

 

How is it more wear and tear when most of the time if you are street driving only one pump will be on? Mightymouse and many others have 2 and 3 pump setups with hobbs switches or setup thru the pcm to turn on at certain levels and they have had no issues.

Surge? Really that is what pressure regulators are for. GM used to put pulsators inline in the fuel system in the tank to control the surge because the factory regulator couldn't control the pulsing surge. Later on they disappeared because they figured out that with a higher pressure and a better regulator design they weren't needed. So, if the OEM's figured that out years ago, don't you think the aftermarket had that already covered?

True you are correct in that just the pump being on doesn't heat fuel but being near fuel rails that are heated in the engine bay is how they get heated.

Think of this though: Lets take your example, 20 gallons of fuel has 3 pumps in it. If one pump is on and the car is driving down the road the return fuel is somewhat heated in the engine bay and is returned to the tank where there is roughly 19 gallons left that is still cool. So that little bit of return fuel gets to cool back off. Now lets turn on all 3 pumps and now you have roughly triple the fuel going up front getting heated and sent back to the tank while you are still street driving. So now, we know we don't build our car for fuel economy, what happens when that 20 gallon fuel cell drops to 10 gallons? You lose that extra fuel to drop the temp of the return gas a couple of degrees. So heating the fuel is starting to happen unnecessarily. IMO I'm not running a pump if I don't need to.

 

twin walbro's here running all the time, no issues.

 

I run two 340s all the time in my S10.

 

No issues running dual 255s all the time in my setup