4.3L W code fuel pressure regulator

bodean · 10-12-2007, 06:25 PM

We are having hard starting and rough idling problem. I am told that this is likely a pressure regulator problem. Where exactly is the fuel pressure regulator on a '93 4.3L W code engine. I was told by one source that it is part of the CFMI unit and has to be replaced as one unit at a cost of $500. Is it under the plenum and part of the CFMI unit, or a separate part? According to Auto Zone, this is a separate item at a cost of $42. What say you?

Stan

Hayden · 10-13-2007, 08:35 PM

It is under the plenum. As for the cost I dont know. Shouldn't be to much. I took my 93 S10 blazer with the 4.3 in to the shop and they said the same thing. $350 later it ran the same as it did when I brought it in. Took it to a better shop and they actually got dirty and found the real problem which was the fuel pump.

NCroadracer · 10-14-2007, 09:24 AM

The regulator is about $60 and you'll need an upper plenum seal kit also (another $65-$75), it's located in the injector spider body underneath the upper plenum.

To verify if your regulator is likely the cause of the problem, get a fuel pressure gage and hook it up. Key the ignition up without starting the vehicle.... watch the gage as you do this, it should ramp up to roughly 60psi then drop to about 55psi...and hold there pretty good (maybe losing a few pounds over the course of a few minutes) if it continues to drop steadily the regulator is leaking internally into your plenum and could very well be the cause.

Good luck and let us know how you make out.

bodean · 10-14-2007, 10:00 AM

We had already performed the pressure drop test and is why we suspected the regulator as the culprit. The pressure would jump immediately to spec., but would quickly fall off 20# or more in less than a minute.

The upper plenum gasket was only $9.98 at Auto Zone and in stock so we decided to go ahead and pull the upper plenum. Auto Zone also had a schematic of the plenum and the regulator so that we could tell what it looked like. The lower plenum had puddles of gas in it, so we replaced the regulator. Truck is starting fine now and runs considerably smoother. It no longer stalls when cold either. Thanks for all your help on this.

Stan

NCroadracer · 10-14-2007, 10:09 AM

Glad to hear you got the seal kit at a "Realistic" price... GM prices are a bit steep on this stuff. I only hope you didn't get the regulator there too... if so, you may wanna reserve another set of each for the near future...lol

10-12-2007, 06:25 PM	#1
bodean Full Member Join Date: Sep 2006 Location: N. Alabama Posts: 45	4.3L W code fuel pressure regulator We are having hard starting and rough idling problem. I am told that this is likely a pressure regulator problem. Where exactly is the fuel pressure regulator on a '93 4.3L W code engine. I was told by one source that it is part of the CFMI unit and has to be replaced as one unit at a cost of $500. Is it under the plenum and part of the CFMI unit, or a separate part? According to Auto Zone, this is a separate item at a cost of $42. What say you? Stan __________________ "Over the hill now.......and picking up speed."

10-13-2007, 08:35 PM	#2
Hayden Senior Member Join Date: May 2006 Location: Bay City,Michigan Posts: 382	It is under the plenum. As for the cost I dont know. Shouldn't be to much. I took my 93 S10 blazer with the 4.3 in to the shop and they said the same thing. $350 later it ran the same as it did when I brought it in. Took it to a better shop and they actually got dirty and found the real problem which was the fuel pump. __________________ There Is No Replacement For Displacement

10-14-2007, 10:00 AM	#4
bodean Full Member Join Date: Sep 2006 Location: N. Alabama Posts: 45	We had already performed the pressure drop test and is why we suspected the regulator as the culprit. The pressure would jump immediately to spec., but would quickly fall off 20# or more in less than a minute. The upper plenum gasket was only $9.98 at Auto Zone and in stock so we decided to go ahead and pull the upper plenum. Auto Zone also had a schematic of the plenum and the regulator so that we could tell what it looked like. The lower plenum had puddles of gas in it, so we replaced the regulator. Truck is starting fine now and runs considerably smoother. It no longer stalls when cold either. Thanks for all your help on this. Stan __________________ "Over the hill now.......and picking up speed."

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10-14-2007, 09:24 AM	#3
NCroadracer Senior Member Join Date: Apr 2007 Posts: 295	The regulator is about $60 and you'll need an upper plenum seal kit also (another $65-$75), it's located in the injector spider body underneath the upper plenum. To verify if your regulator is likely the cause of the problem, get a fuel pressure gage and hook it up. Key the ignition up without starting the vehicle.... watch the gage as you do this, it should ramp up to roughly 60psi then drop to about 55psi...and hold there pretty good (maybe losing a few pounds over the course of a few minutes) if it continues to drop steadily the regulator is leaking internally into your plenum and could very well be the cause. Good luck and let us know how you make out.

10-14-2007, 10:09 AM	#5
NCroadracer Senior Member Join Date: Apr 2007 Posts: 295	Glad to hear you got the seal kit at a "Realistic" price... GM prices are a bit steep on this stuff. I only hope you didn't get the regulator there too... if so, you may wanna reserve another set of each for the near future...lol