can it be made to work?


reason i ask:
im going to multiport. but i want minimal downtime.... so if i can put a TPI pump in one weekend, and run it that way for acouple weeks, then put the TBI pump in, id like to do that.

what if i put a couple resistors inline with the pump so it turns slower?

 

I don't like your resistor idea- but I would think it would work fine if you had an AFPR and FP guage.

 

gauge wouldnt be a prob.. a $12 carb FP gauge would work.


but i dont have a AFPR and i dont really intend to buy one (or mod the stock one)

why would that make a diff anyway? shouldnt the FPR try to adjust it to the same pressure as always?

 

I don't see why it wouldn't work, I've looked at these fuel pumps before to possibly put to use in my car:

http://www.racetronix.com/product/RX..._Pump_Kit.html

 

You will be fine MrDude. The TPI and TBI pumps are dimensionally the same and it will bolt right in. It will not hurt a thing and your fuel pressure regulator will keep the right amount of pressure entering into the injector pod. Don't even try to use line resistors or anything. All of the fuel that is not used will just go back to your tank via the return line. Many TBI guys who have pump failures step up to the walbro 255 unit. It is tons more power full then a stock TPI pump and can support a multi port set-up up to 600 some hp at a constant 50+psi.

 

i just dont want the worse case option... you know, where the car is running massively rich from higher fuel pressue because the return line is too small or somthing.

 

Nope you will be fine. My good buddy has a walbro 255 in his car that is capable of supporting over 600hp at extreem PSI's. His car runs just fine because the regulator keeps it right around 15 or so PSI where he needs it. Don't sweat. Every TBI guy has one when their stocker goes out. The stock pumps can't support anything.

 

learn something new every day

 

Like they are saying, the FPR will do it to it, and since the pump is the same anyway, you don't need to change it. The FPR is on the manifold, you don't need to change the pump. It is a very large pain in the neck to do anyway. I have an LT1 in mine, which was TBI, and I have never had a problem. Good Luck.

 

I am planning on doing a swap to tpi on my 92 LO3 so this makes things easier for me. this way I can have my shop change my pump to a high performance tpi unit, and I can do the swap to on the engine side. I don't have the equipment to drop the rear and all that is required to change the pump. plus I will admit that I don't like the idea of crawling under a car on jack stands!!

 

I just re read some of this thread and now I am confused a bit. will the stock fuel pressure regulator be able to keep it around 15 psi, there was some talk of an adjustable regulator before. I really don't want to buy one just to be able to drive the car from the shop to my house. if it just runs a little rich I don't care because I only have to drive 12 miles from the shop to my drive way to swap the injection system.

 

The stock regulator will be fine. The adjustable one is for tuning and is not necessary with an aftermarket pump. It will still maintian the proper pressure no matter what pump you have.

 

So to clarify...A TBI equiped car can use an aftermarket TPI, or Walbro 255 fuel pump with no problems. The return line will return extra fuel to the tank, and the Fuel Pressure Regulator will maintian 15psi fuel pressure despite the higher pressure that the Aftermarket fuel pump will send.

Am I correct to assume that this is true, and that the stock fuel pressure regulator can do this?

 

No.

RBob.

 

Why no?

 

Yes you are correct. Lots of guys run these pumps in their TBI cars.

 

Thats great. Seeing as I run 15psi, and wouldn't mind trying 16 or a bit more I need one. Ive been searching for one but didnt know what was available to my car.

I have made my FPR adjustable, and have a fuel pressure gauge so i wanted room to tune it instead of being limited to just the 15psi that the stock unit puts out.

That Walsbro pump looks perfect

 

Please see Low C1500's response in this thread:

https://www.thirdgen.org/techbb2/sho...Walbro+AND+255

He is not the only one to discover the same problem.

RBob.

 

When my stocker was dying it'd put out 14 psi at idle with my afpr open as much as possible, then dive to 12.5 psi at wot. The 255 sits at 15 psi constantly. I didnt have the problem he described.

edit: thats with the high volume pump, also.

 

It will probably work ok. The only problem that you might run into is that, like said above, the regulator will build up a head of pressure due to the fact that it has a small orifice and it chokes when it has to handle alot of flow and a HP pump will flow more at lower pressures. dont put any resisters in line with it or anything like that. The pump draws alot of current and even large resisters will get real hot and possibly fry.

 

There is 2 pumps listed on the racetronix website. I am assuming the 255 unit you guys are talking about is the more expensive one, $169.99 (GSS340M), am I correct? Next question is since some of you are saying it provides too much fuel pressure, then could you go with the lesser expensive one, $159.99 (GSS307M), I am assuming that this one provides less fuel pressure? Correct me if I am wrong please. Is the lesser priced one the 190 unit I have heard would be better for TBI cause it's less pressure? Just trying to clear things up a bit. I am new to this fuel pump and pressure stuff. Thanks guys.

 

theres 2 things here... pressure and volume.


pressure is how hard the pump is pushing on the fuel.

volume is how much fuel is being moved.



your fuel pressure regulator keeps the pressure steady by holding the return line part way shut... and it opens and closes the return line restriction to keep the pressure constant.

the problem is, if the restriction(FPR) is all the way open, and the line is too small for the larger volume of fuel to return, the pressure goes up...

my main worry was that the regulator was just too small to regulate a walbro 255 pump.


as long as the exccess fuel can return to the tank, you can run any gph pump you want.

the question becomes, is the return big enough...... after talking to some people, i think the 255 is pushing it close, however, im also going to be using the 255 all the way when i go under boost later on, so i think im going to take the chance of running a lil rich at idle..

if you're staying TBI, id probly go with the 190 to keep it safe.

 

Thanks. Ya I am going to stick with CFI for now. I plan to switch to a single TBI in the future (soon I hope). I want to use the Holley 670 cfm unit. I have to drop my tank soon cause the filler neck is causing me all sorts of problems, seems like it was put in wrong and maybe it's the wrong one for my car. So in preparation for the Holley unit and since I have to drop the tank anyway I want to upgrade the fuel pump. I will stick with the 190 unit to be safe for sure. Thanks again.

 

Im running Multi Port Injection fuel pump, which seems to be working fine...... knock on wood. :hail: