I have a 1992 blazer 4wd, with theCMFI system. I have a problem with it fouling plugs on only right side of the motor. I've replaced the fuel pump, cap rotor, wires, fuel filter twice, plugs & as soon as I lite it, it runs fine fer about a min. then strats to stumble, till I open it up. Then then back to idle, it acts like the fuel isn't returning back to the tank??? But I dont want to tear into the intake system unless I know what it is. If anyone can help, Thanks, Mike

 

Check other posts on this site about fuel pressure regulator leaking.

I have read that if it leaks then the pass side plugs foul out with excess fuel since the regulator leaks on that side of the intake.

To check you should be able to remove the throttle body and look down the pass side of the intake. If it is golden in color then you have fuel washing down the intake and getting into the cylinders from other than the fuel poppet valves.

There are lots of posts and pics on how to fix this.

There is also a Technical Service Bulletin at the dealer about replacing the current poppet valve/injector setup with a newer setup that came on the 2004 models. A true fuel injection spider with Multitech injectors...

It is less expensive if all you need to fix is the regulator and possible the fuel lines leading into the spider.

If you have to replace the spider then it gets into hundreds of dollars

 

Thanks, I'm on it right now! Oh, and your words are to the point, (which is bad ***, in my book). Thanks again ! ! ! Mr. Chevy

 

Ok, I got the plenteum tp off, there was gas on both sides(little puddles). It looks like the fuel came out of the little hole on the back of the fuel presure reg. So I got the new gasket and fuel presure reg. for a 2004 4.3 gasket same but the presure reg. is got a Looks like something you could putt a vacume hose on. Is it vac. or ? ? ? HELP !
Plus, the passenger side was really clean and the other side was black, (inside).

 

Sorry for the late response... Anyway, here's my 0.02

Why did you get a FPR for a 2004? They are completely different injection systems... It may work though... Don't know. If you can take it back and get the proper FPR, that would be best.

The FPR regardless of the system (CPI or SCFI) uses the vacuum reference of being inside the intake plenum to regulate the fuel pressure accordingly. The vacuum reference port that looks like it is supposed to have a vacuum hose on it is probably just a throw back from an application for the same FPR with it mounted outside the intake manifold where vacuum reference would have to be plumbed to the regulator through a vacuum hose.

Also, while you are in there, you may want to replace the o-rings in the CPI unit as well as the nut kit. The nut kit includes the fuel lines internal to the plenum. If you have fuel on both sides, then you have an additional leak besides the FPR.

Good luck!

When you get it back working properly, please let us know! Also, if you wouldn't mind, please tell us about your experience through the repair (ie. trouble spots, things to watch out for, etc). Thanks!