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people have been telling me that i have to pull off the intake manifold to change the fuel pressure regulator but from what i can see it gos right on top of the tbi it is a 4.3 vortec and the engine code is a z not a w hope u can help me out

Dustin, You are correct. The

Submitted by drivability on Sat, 09/10/2011 - 00:07.

Dustin,

You are correct. The Z engine is TBI.

Here is a link to the TBI breakdown on a 1994 (for instance):

http://www.autozone.com/autozone/repairinfo/repairguide/repairGuideContent.jsp?pageId=0996b43f80cb0b21

Hope this helps.

I will say that I'm curious why you want to replace it.

What kind of problem are you having? We might be able to save you time and money.

Post back with any info or questions. We'll be glad to help.

every now and again it seems

Submitted by dustin riggs on Sat, 09/10/2011 - 00:10.

every now and again it seems to backfire i guess you could say like a carbrater would do u dont hear it u just feel it like the engine has lost power for a split second and when its doing this and im at a stop and go to take off it will hesitate and its even worse when you really push it up hills like its bogging and it is gutless really when it does it its got 200 000 km on it and everyone keeps saying thats probably what it is

don't guess and throw parts

Submitted by jerryh20 on Mon, 09/12/2011 - 03:22.

don't guess and throw parts at it. check timing and fuel pressure. when was last tune-up?

Dustin, The problem you are

Submitted by Big Block 409 on Mon, 09/12/2011 - 04:50.

Dustin,

The problem you are describing is typical to a 90’s TBI 4.3 vortec like yours. Here’s what you gotta do. First of all it’s not a timing problem so and don’t mess with the distributor. The PCM determines and adjusts the timing as necessary. You gotta drive with a fuel pressure gauge attached to the engine. At normal operating temperature and at an idle the fuel pressure must be 9-13 psi. The same goes for when your driving with the gauge attached. Drive at different speeds and engine loads. If the fuel pressure is not between 9-13 psi then replace the fuel injectors and fuel pressure regulator. These are all one assembly inside the TBI. If the fuel psi is within specs, then you got one or more vacuum leaks.

well there is no vacume leaks

Submitted by dustin riggs on Mon, 09/12/2011 - 23:13.

well there is no vacume leaks actually when i pull the pcv valve out and put my finger there it is really strong but i also did a vacume test and all was good and the fuel pressure never droped below ten and was as high as 12 to 13 so i think im gonna try the pressure regulater first and see what that does

Dustin, Could very well be

Submitted by Big Block 409 on Tue, 09/13/2011 - 03:21.

Dustin,

Could very well be the regulator, but don't go throwin parts at the problem till you get it fixed. You're just gonna end up wastin time and money.

Clean the MAF sensor.
Clean the EGR valve and related passageways.
Thoroughly clean out throttle body.
How are the plugs and ignition cables?
Have they been replaced recently?
Are they A/C Delco?

On any GM vehicle you gotta use A/C Delco tune-up and ignition parts. If you don't the vehicle won't run right. Champion is crap so away from them. To clean the MAF use the product in the first link below. To clean the EGR and EGR passageways and the throttle body use the second link. Also do a scan for error codes and post any codes that are set.

http://www.amazon.com/CRC-05110-Mass-Sensor-Cleaner/dp/B000J19XSA

http://www.verylube.com/_new/product.php?lang=eng&n=106

everything u said to do ive

Submitted by dustin riggs on Tue, 09/13/2011 - 15:44.

everything u said to do ive done 3 months ago and i did use ac delco parts cause there cheaper then other ive allready cleaned everything and my truck doesnt have a maf sensor in it i did replace the regulater yesterday and it seems alot better but the problems so speratic that ill have to wait to see if it happens again ill double check the egr vaslve though i havent done that in a while

Hello Dustin, I just thought

Submitted by Helene Car Lady on Tue, 09/13/2011 - 16:27.

Hello Dustin,

I just thought it was necessary to tell you that (due to the original "OE" design defect) it's necessary to replace the fuel injectors as well. The fuel injectors and fuel pressure regulator are treated as one unit on your particular vehicle with your particular engine size. It's not recommended that you replace the regulator without replacing the fuel injectors as well, or visa versa for that matter. Please don't yell at me. I'm only the skilled master mechanic messenger here, who is delivering a message to you as to how it must be. If after replacing both (the injectors and regulator) your issue continues, the first thing you must do is answer the questions that continue to go unanswered. After doing that,(if the issue continues) you need to evaluate the primary and secondary ignition systems as a fault possibility and post the results.

Thank You
Helene

Dustin, You mentioned that

Submitted by drivability on Wed, 09/14/2011 - 07:38.

Dustin,

You mentioned that your problem was sporadic. Did your truck act up when you had the fuel pressure gauge hooked up?

no it did not act up but it

Submitted by dustin riggs on Wed, 09/14/2011 - 11:22.

no it did not act up but it did do it again on my way to school last night so i hooked it up to check the firing line and number 1 was about 35% weaker then the rest so when i pulled the plug out to swap with another to see if it was the problem it was badly corroded do to really bad gas the teacher said so ill be putting in a new set of plugs today. and again thanks for all your guys help i appreciate it

Hello Dustin, In an earlier

Submitted by Helene Car Lady on Wed, 09/14/2011 - 17:00.

Hello Dustin,

In an earlier posting you stated that the plugs (among other items) were replaced just three months ago. Are you now saying that in just three months time the plugs are corroded and fouled again? If that's the case then describe the fouling and post the results of a wet and dry compression test. BTW what's the mileage on your vortec? FYI a high amount of mileage warrants a compression and a cylinder leak down test to confirm engine integrity.

Thank You
Helene