Kim72

Re: efi fuel pumps, I know that in-tank ones are the preferred way to go but I would like to hear the pros/cons on in-line, outside the tank, returnless ones. Been looking at the MSD Atomic pulse width modulated (PWM) pump as an example. Any comments to share? Good or bad.

ajrothm

I use the Holley Dominator billet electric pump. Its inline, very quiet, never vapor locks on long drives. They do require a regulator and a return line though. There are several different models/sizes, depending on how much fuel you need. I have about 1500 miles on it and its been a good pump so far.

I think its best to run a return line on the high pressure style fuel pumps, it will certainly help prevent vapor lock.

mrvette

As per pix below I have an earlier DPFI setup on my car, and it uses the speed density computer, and so needs the L98 type FP regulator, set near 40 lbs.....there is a return line which is the 5/16 OD line per stock back to top of the tank on pass. side.....

I mounted the pump on the rear frame rail with a rubber wrapping and a hose clamp.....the suck end pulls through a filter from the stock pickup......the pressure side goes to the stock 3/8 dia. fuel line going forward, and it is bent upward near 5/7 cylinders, and of course high pressure FI hose used throughout......

the pump I use is by AIRTEX E 8228.......

txfatboy1

I have used the FORD truck frame mounted pump with very good success. It is designed to run outside the tank. They were used on late 80's to 90's full size trucks and were mounted on the inside of the frame rail under the driver seat area. All I have done is mount it near the tank , preferably below the tank. I also install the Ford inline inertia switch on ANY add-on electric fuel pump. It kills power to the pump if the vehicle is hit hard. Cheap insurance to prevent a fuel pump from continuing to run after an accident.

68sixspeed

On my ls7 68 camaro I started out with an external walbro 255, functionally fine until it got below 1/2 a tank of fuel then it would suck air in 2nd gear on hard acceleration. You could drive normal to almost an empty tank but could out accelerate it below 1/2 tank. Went to an in tank with corner pickups and no issues.

doorgunner

Same here....
mine lasted 20 years on my Ford truck...so I bought a replacement to use on the Vette with an adjustable fuel pressure regulator set at 6 psi and return line mounted at my Holley carb.. The pump & regulator totaled $100 with a lifetime warranty on the External pump/easy to replace if need-be. I also mounted it with rubber bushings a couple inches lower than the tank to prevent "starvation and over-heating".. I also have a separate relay to supply 12v to the pump

derekderek

but isn't a 45 lb pump putting an awful lot of fuel down the return line regulated down to 6 psi? and pressurizing the 50 year old fuel lines to 45 psi unnecessarily?