Fuel pump questions

[Spartanzz]

So interesting question regarding fuel pumps....

So most of yall know I have my 87 GT project. For now, I'm completing the 3.4 I have for it to get it back on the road. But, i do have the longer term plan to swap in a 3.8 S/C. I'm curious if it would be safe/ok to order and install the "upgraded" fuel pump that i would need for the 3.8S/C now instead of buying one for the 3.4 setup and an upgraded one later?

Would i run into any issues running the upgraded pump with the 3.4?

[Fierofool]

Yes, you would have problems with the 3.4.  Higher pressure would increase the injector flow.  You would need to detune the fuel pressure regulator or install an adjustable regulator. 

AeroDon ran stock Fiero injectors for a while in his 3.4 before upgrading.  He put a coin in the regulator to increase the pressure sufficient to feed the 3.4.  He drilled a hole in the regulator cap and Dremeled a slot in the top of the regulator diaphragm screw so he could set the static pressure at 43.5 psi, then he reinstalled the upper intake.  I don't know that he ever installed an adjustable regulator. 

[Spartanzz]

Yes, you would have problems with the 3.4.  Higher pressure would increase the injector flow.  You would need to detune the fuel pressure regulator or install an adjustable regulator. 

AeroDon ran stock Fiero injectors for a while in his 3.4 before upgrading.  He put a coin in the regulator to increase the pressure sufficient to feed the 3.4.  He drilled a hole in the regulator cap and Dremeled a slot in the top of the regulator diaphragm screw so he could set the static pressure at 43.5 psi, then he reinstalled the upper intake.  I don't know that he ever installed an adjustable regulator.

So, if i understood correctly, if i went with one of the adjustable pressure regulators i should be fine to run the higher flow pump?

[Fierofool]

I think so.  While researching fuel injectors for my 3.4, I looked many charts that rated injector flow.  The flow increased with pressure.  You will probably be using a 3.5 bar MAP sensor with boost, and that will require higher pressure.  I believe the injectors you got from me were capable of flowing up to 22 psi with increased pressure.  When you're calculating, don't use more than 85% duty cycle.  80% if you can. 

Crank HP and number of injectors determine the required flow/hr.  A 4 cylinder engine producing 200 HP will require a larger injector than a V8 producing 200 HP. 

I think Injector Planet has a calculator

[Spartanzz]

I think so.  While researching fuel injectors for my 3.4, I looked many charts that rated injector flow.  The flow increased with pressure.  You will probably be using a 3.5 bar MAP sensor with boost, and that will require higher pressure.  I believe the injectors you got from me were capable of flowing up to 22 psi with increased pressure.  When you're calculating, don't use more than 85% duty cycle.  80% if you can. 

Crank HP and number of injectors determine the required flow/hr.  A 4 cylinder engine producing 200 HP will require a larger injector than a V8 producing 200 HP. 

I think Injector Planet has a calculator

So looked at prices on everything today....the adjustable FPR alone is more than an upgraded pump.....so guess ill just stick with a stock replacement for my 3.4 and just not be lazy and be prepared to drop the tank a second time...

Thanks for all the info though!

[Fierofool]

I talked with Garry Dammond last night.  He was the guy with the white GT with the SC.  He lost his fuel pump on the way back home, had to rent a 24 foot (that's all they had) UHaul box truck and Dolly to get home.  He had been running the original fuel pump all along, but now that he has to drop the tank he's going to upgrade.  He isn't running an adjustable regulator. 

I would spec a Grand Prix GTP fuel pump to see what it flows.  Then spec a Fiero pump to compare.  I think for the moment you're relegated to running the Fiero pump for the 3.4 to keep from overpressuring the injectors. 

[Raydar]

Pretty sure that my 3.4, even with all the stuff done to it, was running a stock pump.
I never changed it when I swapped the motor in, and when Ed had to do a warranty replacement due to a broken head bolt from the rebuilder, I'm quite sure he didn't either.  I never had any problem with it running out of fuel, even WOT, with 19# injectors.

[Spartanzz]

Pretty sure that my 3.4, even with all the stuff done to it, was running a stock pump.
I never changed it when I swapped the motor in, and when Ed had to do a warranty replacement due to a broken head bolt from the rebuilder, I'm quite sure he didn't either.  I never had any problem with it running out of fuel, even WOT, with 19# injectors.

Yeah i know im going to replace the pump while im trying to get this thing running....just cuz it has been sitting a good while. Was just trying to see if i should replace the pump with a stock replacment or upgraded one i will be using with the 3800S/C swap later on down the road.

With the cost of an adjustable fuel pressure regulator, it looks to make more sence (money wise) just to replace with a stock pump now, then drop the tank again when i get to the 3800S/C swap and put in an upgraded one.

[NoMad]

I was fortunate that mine had the adjustable FPR on it so I was able to upgrade without issue when I was trying to sort my dying issue. I am a ways from getting the fiero I to the shop but when I do, I don't believe the FPR crosses over to the new engine.