Fuel pressure regulator on Blazer 4.3L CPI W engine (incl'd EGR and IAC check/clean)

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Fuel pressure regulator on Blazer 4.3L CPI W engine (incl'd EGR and IAC check/clean)

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Blazer Forum >> Mechanical & Maintenance >> Do-It-Yourself >> Fuel pressure regulator on Blazer 4.3L CPI W engine (incl'd EGR and IAC check/clean)

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Fuel pressure regulator on Blazer 4.3L CPI W engine (in... - 2/20/2007 8:10:31 PM

kerander

Posts: 117
Joined: 1/14/2007
Status: offline

How to replace fuel pressure regulator on Blazer 4.3L "W" CPI engine

See bottom for notes on EGR & IAC valves, etc.

Symptoms of a failing FPR are problems with a steadily decreasing amount of power and fuel economy, very strong fuel/exhaust fumes, black soot on drivers side plugs, black soot coming out of exhaust system, failure of catalytic converter or muffler, rough idle, knocking. The truck might show the SES light with the computer throwing OBDII [Alpha] Code P0172 indicating a rich fuel mix on bank 1.

The fuel pressure regulator on this model fails often.

To check if your FPR is failing, (or the internal fuel lines or spider fuel distribution and injection unit):

Tools req'd: sockets - 8mm, T30 or T27, T20; possibly a flashlight and WD-40
The air plenum is the large somewhat shiny cast iron “cap” on the upper manifold with the black plastic VORTEC cover on it.

Remove the negative connector from the battery (8mm)

Relieve pressure from the fuel lines by locating the Schrader valve (like a car/bike valve) at about 2:00 behind the plenum. Remove the cap by twisting and press the plunger with a screwdriver while holding a shoprag over it to catch any fuel that may be released. Vehicles that are not running should not retain much fuel pressure (therefore releasing little, if any, fuel and pressure), but be on the safe side.

Remove the VORTEC cover on the top of the plenum using Torx (T30). Underneath is a round black plastic component sitting in the middle of the plenum. This is an air flow regulator.

Remove the electrical connector and two Torx screws (T20) from it. Gently twist it back and forth by hand while pulling up to remove it. A little WD-40 around the edges might be needed to help it out.

Peer through the open hole to see into both “banks” of the upper manifold.

The passenger side contains the FPR, which is clearly visible (round gold colored component). It and the entire passenger side compartment appear very clean here. This is a good indication that fuel has been coming out of the FPR into the space. The driver’s side has no such problem. Taking this into account and considering how often this part fails, it’s pretty reasonable to conclude at least the FPR is bad.

Although you may not see washing at this point, the FPR might still be failing. Washing would be defined as an indication of fluid leaking out of something and creating a clean (like bare metal, in the passenger's side pics from my engine) area that differs from the rest of the surroundings *note in the pic w/ plenum off the clean vs. darkened area on the passenger's side. You can quite literally see the sprayed area delineation. If yours is as bad as mine, and everything is very clean in/on one area, you can bet there's a leak. You might also smell strong gas or exhaust fumes if there's a problem (mine was VERY strong), and/or see pooling of gas. Normally the driver's side will be fairly carbon laden, while the passenger's side will be somewhat copper colored.

You could of course take the plenum off and have a close visual inspection of all parts to be sure. Any sign of washing would more than likely indicate failure of a part (e.g. clean area near fuel lines could indicate a leak in them). Many posters have said that the CPI fuel injection units do not fail very often and that being the case it would be a good candidate to be replaced with a used part if necessary as it is very expensive (~$300). However, the FPR (~$40) and fuel lines (~$90), and obviously the gasket if replaced, should

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< Message edited by kerander -- 5/9/2007 1:08:15 PM >

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95 Blazer T-10 4.3L CPI "W" 4x4 4D 120K LT