hi I've got an 87 Turbo II with 550 primaries, and 720 secondaries. I just got my walbro 255, and am planning on rewiring the fuel pump with a relay and a 10 gauge wire directly from the battery. my question is will the stock fpr be able to handle the higher volume of the walbro, or will I be running rich??
I plan on boosting between stock and 18psi. I've heard about rising rate fuel pressure regulators, would one of these fit my application???

 

You will run slightly richer with the Walbro due to it's higher output pressure.

Don't use a RRFPR, get the correct size injectors for your application instead.

I hope that's not the stock turbo and intercooler you're planning to run at 18psi. That would be plain silly...

 

agreed! I am pushing for 14-15 on an upgraded turbo however I didn't run that high without getting front mount. Also the stock turbo is only good for maybe 12 psi. If you keep your ride at 11 to maybe 12psi you can use the stock ic.

 

so I dont need to upgrade my FPR? It's a front mount with a T04. the 550 primaries and 720 secondaries are just temporary till I can get a stand alone, then I'll be running 1800 secondaries and 720 primaries.

 

anybody??

 

Will the stock regulator be OK?? and how much boost can the stock FPR handel.

 

The stock FPR will be fine. Remember the FPR works like a wastegate. When it gets to be too small, fuel pressure goes up, not down. Boost has little to do with it. When the pump is too big, then you need to replace the FPR. Plenty of people run Walbros with the stock one. It's not ideal, but it's not a problem.

 

alright thanks alot

 

I just upgraded to a walbro (purchased from tweak) and i noticed that when i dropped it in it feels like it is running extremely lean. the throttle response is more than admirable in neutral. but, as soon as it is in gear, it bucks like crazy. Also, when i am cruising around 2k rpms or so, it gets the most bucking. after about 2.5-3k rpm, it is driveable, but still feels EXTREMELY underpowered and also will not go above 3.5k rpms. did i get a low pressure walbro and need an aftermarket fpr?? whats the dilly yo? also, the old fuel pump worked fine.

Thanks for the help,
Ry.

 

Install a fuel pressure gauge and see what the pressure in the rail is. That's the only way you'll EVER know. Anything else is just guessing. I'm not talking a permanent gauge on the dash, just a mechanical gauge connected to the fuel inlet hose.

 

Yep you will run slightly rich. Now if you remove the FPRR (fuel pump relay resistor) setup and go straight in with full voltage all the time, you will definitely be running rich.

Especially idle and low load, you engine won't be consuming much fuel and the FPR won't be able to divert enough fuel to maintain the right fuel pressure.

The ECU determines when to run the pump at the higher voltage, usually under a descent load and good fuel consumption. If you're going stand alone you may want to consider an aftermarket FPR. Then you can remove the FPRR system with no worries.

Oh and don't get a RRFPR, you need just a standard 1:1 FPR--especially if you are going standand alone. The RRFPR is just a crude way of adding fuel at higher boost--your standalone can do the same thing much more accurately.

HTH,

Scott

 

It's not the Walbro causing the problem.
Wait, let me restate that...it's not an overly rich problem caused by the Walbro upgrade fuel pump causing your problem.

When running rich, it just causes the engine to bog.
If you're getting "bucking", it's a lean condition or something else.


-Ted