Where is the fuel pressure regulator on a 99' 4.3?

[Snake Eater]

I'm trying to find it, and also is it adjustable?

Thanks in advance,
Ron

[rat]

The fuel presure regulator is on the back of the spider injector block. It isn't adjustable that i know of. Most people just get an extra adjustable one and put it in the return fuel line.

[s10rz350]

it is adjustable if you break the little pin off the torx screw but...
1) dont drop it into the manifold.
2) you have to take the manifold cover off to get to it.
3) You shouldnt need to adjust it for any reason at aqll. If its not right you should replace it.

How much fuel pressure are you seeing when you turn on the key but dont start the engine?

[Crew Cab Sonoma]

Quote: Originally Posted by s10rz350

it is adjustable if you break the little pin off the torx screw but...

if you are refering to the pin in the center of the screw, most parts stores sell the hollow ended Torx socket sets for these.
not expensive. i bought a set.

[nystateofmind27]

Sorry to get a little off topic but, what kind of modifications do you guys think would be needed to install an external fuel in the place of the internal one? How hard can it be...

[Crew Cab Sonoma]

Quote: Originally Posted by nystateofmind27

Sorry to get a little off topic but, what kind of modifications do you guys think would be needed to install an external fuel in the place of the internal one? How hard can it be...

you would need to bypass, or disable the original regulator, and cut the return line somewhere to install a vac. modulated bypassing type reg. and tap into a manifold vac. source.

[s10rz350]

Quote: Originally Posted by Crew Cab Sonoma

if you are refering to the pin in the center of the screw, most parts stores sell the hollow ended Torx socket sets for these.
not expensive. i bought a set.

cool. I dont have a set but I never tried to adjust it. Only replaced it. I remember someone on the forum mentioning they broke it off. Looking at the the old one of mine I think that would be hard to do. Anythings possible.

[nystateofmind27]

Why would i need vacuum modulated bypass regulators and all this complicated stuff?

My goal is to use a walbro external 255 pump (electric) and take out the internal one. Any ideas?

[Crew Cab Sonoma]

Quote: Originally Posted by nystateofmind27

Why would i need vacuum modulated bypass regulators and all this complicated stuff?

My goal is to use a walbro external 255 pump (electric) and take out the internal one. Any ideas?

because the original regulator is that type. and its not complicated... you will need a bypassing reg. on about every oem FI system with a return line. thats just how the system works. continuous flow. the primary advantage of this is prevntion/removal of percolated or boiling fuel in the lines and rails, thus avoiding vapor lock, or bogging from excees vapor in the lines.

most port type FI engines use vacuum modulated fuel pressure. at idle, light loads, and deceleration, manifold vac is high, and fuel pres. is reduced. under WOT, or heavy engine loads, or engine not running, manifold vac is low, or non existent, and fuel pres. is increased. this helps to broaden the injector`s operating range.

the factory ECM/PCM programming is tailored around modulated fuel pressure..
any reg. you use should also have this feature in order to match the original regulator`s performance, and keep fuel curves within the expected norms for the computer.

most (but not all) aftermarket bypassing regulators have the vac modulation feature.

an inline pump is fine, as long as you keep it mounted below, and behind the fuel tank, in order to to ensure easy self priming.

[Ed W]

Quote: Originally Posted by nystateofmind27

Why would i need vacuum modulated bypass regulators and all this complicated stuff?

My goal is to use a walbro external 255 pump (electric) and take out the internal one. Any ideas?

I have been using the Walbro, with the stock pressure regulator and have had no problems.
The S-10 in question has stock internals, a chip flash, JBA headers, cold air induction and power pullies (they are a JOKE).

[nystateofmind27]

Quote: Originally Posted by Ed W

I have been using the Walbro, with the stock pressure regulator and have had no problems.
The S-10 in question has stock internals, a chip flash, JBA headers, cold air induction and power pullies (they are a JOKE).

Are u using an internal or external walbro? Maybe you can give me some more details on what was involved in putting it in. My AOL/AIM name is nystateofmind27 or PM me. Thanks.

[Ed W]

I am using a in tank Walbro 255lph, that is a very easy replacement for the stock GM pump - and cheaper too!

[nystateofmind27]

What other parts did u need besides the pump itself?

[Snake Eater]

Nothing is broke or needs replacing. I'm just going to up the FP by 5PSI so i can try for 7PSI with less duty cycle on the injectors.

[nystateofmind27]

Snake, why dont you install a vacuum referenced FMU which will put some back pressure on the return line? Thats what some charger and the mach turbo kits use.

[Snake Eater]

I could try that. Any links to where i can find one? If there not to much i may get one. Otherwise i will just up the line pressure 5#.

[nystateofmind27]

http://cgi.ebay.com/ebaymotors/ws/eB...spagename=WDVW

Cartech and machturbo sell the ones that are fully adjustable. Vortech sells one that has some internal disc system which sets a fixed ratio of boost to fuel pressure.

[Snake Eater]

Damn, i wish i would have seen that yesterday. I would have bought it then. I just bought the 1.25" spacers to bring the rear wheels out. Maybe next week.