I took out my fuel tank to replace the fuel pump today (need higher volume for swap) and was shocked that it was working at all. there was so much junk stuck in the screen and the tank was full of trash. Cleaned it all up and got to thinking about what a P.I.A. it would be to have to do this with the engine in. That got me to thinking about an external pump.

If you have installed one tell me about the install. What kind, mounting location, wiring, where did you tap into the fuel line and are you happy with it?

TIA

I have not done one myself, However I have heard that you shouldn't bother with a DIS engine. It apparently needs a higher flow rate than an external can offer. If anyone else finds my statement incorrect, please enlighten us!

bump

I have installed external pumps in non-fiero cars. The only real issue is having the pump lower than the tank, so the fuel can gravity feed to the pump. Hard to do on a fiero.

-Dave

BTW: DIS has nothing to do with it. External pumps can run any engine. It is a matter of sizing the fuel flow and PSI for the type of fuel delivery system you are using. (injectors or carburetor)

[This message has been edited by IFLYR22 (edited 02-06-2010).]

I've done it on other cars going from FI to N/A motors. Just replace the pump with a like length of fuel rated rubber tube and install the pump on the frame rail near the tank. Tap into a power source that comes on with the ignition and splice into the fuel supply line.

However, with this car I am going to keep the FI and am concerned that as tooky as they are about the fuel pump and the ECU/relay, will installing an external pump be a smart thing to do.

Who knows ! Maybe it's time to blaze the trail !!!!

It's amazing how the in tank pumps will pump just about anything that makes it through the pre-screen.
I understand the need for an external pump when the tank is not a stock component of the car, or using an external pump in a car where the car originally was a mechanical pump... but why would you want to if the tank and sending unit are originally designed for it to be in the tank?
Most cars with in tank fuel pumps have had the tank sitting lower than the engine (allows better placement of the weight etc.), where as the mechanical fuel pump cars usually had the gas tank sitting higher so the gas can gravity feed to the pump. External fuel pump cars had the pump right next to the tank and at the lowest point possible near the tank.
You can get in-tank pumps to match the volume/flow rate and PSI you might want.

Another option might be to put a smaller separate tank higher on the frame that is fed by the in tank pump, and then use your external after that tank. I have not done the way you describe (with the rubber hose replacing the pump). The external pump has another relay that is powered exactly the same way the internal pump is. This necessitates two relays, but allows full power to both pumps and ensures the pumps turn off during a collision.

If the external pump is the only pump, just re-route the +12 V wire at the connector to the external pump, and add in your new ground wire. Leave the ground and the tank level sending unit wires alone. The relay system and oil pressure sending unit (backup power circuit) ensure that the pump turns off should the engine stop running for any reason (collision, etc.) I would want to leave that system intact.

just my thoughts.

-Dave

PS. My 3800 uses a Walbro 255 HP in tank. It's rated at 80 psi with 210 Liters (50 gallons) per hour. My pressure gauge consistently reads 48-51 PSI at idle.
Walbro makes the same pump in an external configuration as well.

[This message has been edited by IFLYR22 (edited 02-07-2010).]

Hey guys, good topic!
Dont want this to look like a hi-jack or anything, but sounds like we're going down the same road, might as well share some pointers rather then have two separate threads.

The timing is good for me, I just picked up one of these for my springtime project:


http://aeromotiveinc.com/pr...06-700-hp-fuel-pump/

It's a little overkill for what I currently require, but should prove to be adequate for future upgrades as well.
This unit is both frame mountable and submersible, which is why this thread is good for me because I have not decided where I am going to mount it.

Plan 1 - modify existing fuel tank sending unit to accept this pump
-pump will stay cooler submersed in fuel
-should be quieter?
-no worry about loosing prime or running dry
-PITA if it ever needs to come back out

Plan 2 - mount pump pump as low as possible on firewall
-pump will likely run hotter ( I have read alot of concerned customers reporting these things can get blazing hot)
-maybe noisier?
-possibility of loosing prime to pump, resulting in running dry until it sucks up fresh fuel again
-easily serviced
-will require modification/fabrication of existing sending unit to be turned into simple pickup/screen

or, Plan 3 - hybrid if you will
-mount pump as in Plan 2, however leave oe in tank pump in place, and have both connected together as was described previous..
My concern here is weather or not the two pumps will get along together ok? This aftermarket one moves alot higher volume than an oe one for sure... is it possible that it could actually suck harder than the oe one can blow? might I run into fuel starvation using this meathod?

I'll leave it at that for now and see what you guys think..

-Jay

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87 GT Stock 2.8L 5spd
86 GT Northstar 5spd

What will happen im curious on this fact as well? what will happen if u slapped a really high pressure fuel pump on the line will it try and over come the actual stock one or wat?

On my Series I 3800 swap years ago, I moved to an external pump as the factory one was very very low on pressure and at that time finding in-tank pumps was a nightmare. I used a Bosch 044, mounted on the left strut tower. In the tank, I simply replaced the pump with a length of bundy tubing of appropriate diameter and reinstalled the screen over the end of the tubing. Where the fuel line appeared in the engine bay, we cut it off near the firewall and fitted a brass fitting which acted as the joint between the steel line and a rubber fuel line leading to a fuel filter, then up to the Bosch, stock Bosch adjustable regulator and then over to the fuel rail.

The pump never had an issue, even in a lifting configuration. Just added to the obscene amount of noise in the engine bay

Given the proliferation of available high pressure in-tank units these days (both OEM and aftermarket), such a move isn't really a GREAT way of doing things... but it DOES work.

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I did on an 84 2.5L and had vaporlok issues all the time.

quote Originally posted by White Spyder: I've done it on other cars going from FI to N/A motors. ...

Ahhh - yeah - ah both the stock 2.5 and 2.8 are both fuel injected and normally aspirated.

[This message has been edited by phonedawgz (edited 06-25-2010).]

quote Originally posted by PR0X: What will happen im curious on this fact as well? what will happen if u slapped a really high pressure fuel pump on the line will it try and over come the actual stock one or wat?

The Volvo 240 uses a pre-pump in the tank that runs at about 5 psi and an external pump under the body that increases pressure to 50 or so psi needed for the fuel injection. You could do the same in the Fiero easy enough. You would need a real good reason to justify the work and expense. Unless you just like making easy things difficult.

Changing the fuel pump is no big deal. I can do it in less than an hour and that's without draining the tank. I wouldn't mess with an external pump. It's more trouble than it's worth.

Also I will get a hundred people on here to disagree with me (including the previous poster probably), but it is difficult for an external pump to go significantly higher than 14.7 psi without issues. It's gravity fed and you will cavitate the pump if you draw it out faster than atmospheric pressure can feed it.

As stated earlier you need the pump lower than the tank, which on a Fiero is nearly impossible. And you need a high flow inlet from the tank, so that you can keep the pump from cavitating. It's just not worth it to me.

[This message has been edited by jscott1 (edited 06-25-2010).]

Dennis

quote Originally posted by jscott1: Changing the fuel pump is no big deal. I can do it in less than an hour and that's without draining the tank. I wouldn't mess with an external pump. It's more trouble than it's worth. Also I will get a hundred people on here to disagree with me (including the previous poster probably), but it is difficult for an external pump to go significantly higher than 14.7 psi without issues. It's gravity fed and you will cavitate the pump if you draw it out faster than atmospheric pressure can feed it. As stated earlier you need the pump lower than the tank, which on a Fiero is nearly impossible. And you need a high flow inlet from the tank, so that you can keep the pump from cavitating. It's just not worth it to me.

I agree. With the in-pump fuel pump technology that we have today there is no need to use an external pump that it all probability will decrese performance. I am running the AC Delco EP376 Corvette fuel pump right now on my 3800SC swap and so far so good. The pump is still suspect as to its maximum HP capability so next season I'll probably try the AC Delco EP 381. That pump feeds 7.4L 454 cu in FI engines so it should have no problem keeping up with a boosted 3800SC and also run quiet. A Walbro will also give you high volume but they have a poor reputation and are noisy. Recently the Toyota Supra TT pump is finding popularity on boosted cars but it requres a different in tank holding bracket that will need to be fabricated to hold it in place. There are so many choices for in tank fuel pumps its foolish to not use them.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

You guys are looking at it all wrong, you can use external pumps on a fiero as a supplimental pump just fine, my 3800sc works great with the stock fiero intank feeding a walbro inline that i happen to have laying around from an old boost project, (it was free rather then buying an intank) Dont get my wrong and intank is easily the ideal way to go but an external pump used in conjunction with the stock intank is plenty, the intank stock pumps will flow enough volume without even trying thats volume NOT pressure.

My 3800 sc runs like this my old boosted ecotec ran like this and the 400 hp ecotec I built runs like this, cheap easy solution but had I had a free intank laying around I woulda gone that way. Up to 500 horsepower motors run like this Ive yet to see the inline suck more VOLUME then the stock intank can pump to it. Not saying it cant be done but Ive yet to see it happen on the power levels Ive done myself in fieros or various other vehicles.

May not be ideal but can work and does work.

I've also run a Bosch 044 inline pump. This thing outflows most in tank pumps and won't over heat the fuel like the aeromotive pumps do. There are other intank options that can outflow this but it is a very good pump to use as a supplement.

quote Originally posted by FieroFiend: You guys are looking at it all wrong, you can use external pumps on a fiero as a supplimental pump just fine, my 3800sc works great with the stock fiero intank feeding a walbro inline that i happen to have laying around from an old boost project, (it was free rather then buying an intank) Dont get my wrong and intank is easily the ideal way to go but an external pump used in conjunction with the stock intank is plenty, the intank stock pumps will flow enough volume without even trying thats volume NOT pressure. My 3800 sc runs like this my old boosted ecotec ran like this and the 400 hp ecotec I built runs like this, cheap easy solution but had I had a free intank laying around I woulda gone that way. Up to 500 horsepower motors run like this Ive yet to see the inline suck more VOLUME then the stock intank can pump to it. Not saying it cant be done but Ive yet to see it happen on the power levels Ive done myself in fieros or various other vehicles. May not be ideal but can work and does work.

Good point, the fuel pressure regulator determines the pump pressure, not the pump itself except where its capacity is exceeded, so as questioned above a higher pressure secondary pump is not going to push anymore pressure than the regulator demands, in addition to that, the secondary pump will bear the greater load being closest to the regulator so it will not be free flowing enough to out pump and pull a vacuum on the in tank pump which will be more of a booster, sort of like pushing on the back of a person that is pushing a load.

I have the internal and external Walbro pumps although the external hasn't been installed yet. The reason is that I intend to run higher than stock fuel pressures for better fuel atomization ~60 psi static plus what my boost signal adds to it, my injectors are rated as high as 87 psi, two pumps will help keep the pump heat down and service time up.