Why doe my 1995 chevy blazer fuel pressure regulator keep going bad?

Asked by Sep 27, 2015 at 06:27 PM about the 1995 Chevrolet Blazer 4 Door 4WD

Question type: Maintenance & Repair

I have replaced the regulator 3 times and also the fuel lines inside the
manifold once. The pressure at the test port behind manifold is 50 lbs. The
pressure at the filter is 63 lbs. with fuel line disconnected and the meter
connected to a test pipe installed on the filter. I removed the air vane and it is
wet on the regulator side every time.

22 Answers

72,085

What motor is in there, your talking like it is a vortec motor with the fuel pressures of 63 lbs.

Yes 4.3l v6

72,085

Ok yes it is a vortec motor. Sounds like you have a spider array of fuel lines, injectors in each cylinder? since you have a test port up on the manifold to check fuel pressure? Never the less, at that port you need to be at a min. of 56 lbs. for the motor to run correctly. 55 to 50 lbs. and you have a hard starting condition. Say 52 and under it will not run. It also has to hold that pressure and not bleed off. Now, help me out here, what regulator, were is it located?

Inside plenum

72,085

Ok, let me look at some things,

72,085

Ok, #1 the regulator in these are notorious for leaking around the vacuum nipple. What you need to do is also look at everything else, to be sure. Disconnect power to the injectors, & remove the coil wire. Have the fuel line reconnected. Have someone cycle the ignition to build up pressure, and you look at the system for leaks, injectors, fuel lines, vacuum nipple at regulator. If the spider array and or an injector, you have to replace the hole thing (as it sounds like you did once) & or regulator again. I assume you have the plenum off, if not you can tell if there is a problem by doing a bleed down test by having your fuel pressure gage attached to the Schrader valve (text port) and have someone cycle the ignition so you can watch the gage, once it builds up to pressure, ignition off, watch the gage. It should not drop more than 5 lbs. and hold for 1 minute. Pressure goes down, problem under the plenum. I will be in and out today, but will check back....

I changed the pressure and return lines inside the plenum that come from the tank. I did not change the spider. I am changing the pump because when I bled the fuel pressure off there was air in the line. I will get back after I am done.

72,085

Ok , what pump? you said there was 63 lbs. after the fuel filter, which is perfect. Well I'll check back around 5:00 or 6:00 my time....doing some painting at some apartment.

Pump in the tank. The unregulated pressure should be higher. The pressure rating on the new pump is 80 - 90 lbs.

18,765

Dead pressure should be more than 63. And 50 at the manifold is low. I've been that route before, replacing the regulator by itself has a low success rate with me. I always ended up getting the Spider with it attached already. I hope it's just your pump.

1 of 1 people found this helpful.
72,085

Ok, that's good, as long as you got min. 56 lbs, 62 perfect up at the Schrader valve.

72,085

Andrew, the hole nine yards hey? He has gone through 3 regulators. That has to be a good $300.00 bills.

18,765

Ya, my own personal truck went through 2 regulators. One was defective and held pressure at 90psi, the second one wouldn't seat right. So I just bought the whole spider. Figured a truck from 94 with 240,000 miles it couldn't hurt

72,085

Hey man, thanks for the input on that spider assembly, jump in anytime.

72,085

Hey man, where you at with this?

I have a bad back so the pump replacement is taking a while, I am almost done. I will let you know if it works.

72,085

Once together, have fuel line hooked up at the plenum, pressurize and look for leaks before putting on the plenum back on...

Apologize for the misunderstanding but I never had the plenum off. I take the air vane off the top of the plenum and look for wet parts to see if it is leaking. I took the gas tank out and changed the pump. Pressure at test port is 59 lbs. and drops to 55 lbs. Runs better but still missing and backfiring. I had changed fuel regulator the first time and it leaked right away. Put in another and it lasted about 2 days before it started leaking. Also had no spark. Replaced ignition module. Still had misfiring and backfiring. Finally checked timing and reset it. Runs way better. The backfiring has stopped but still misfiring intermittently. I strongly believe I have a worn out timing chain. Thanks for all your help. Could a backfire in the intake cause the regulator to fail. Again thanks to all of you for the help.

72,085

Ok, last ideas here, you must have a lot of miles on her hey? check compression, plugs & wires. Your bleed down test is good, meaning no leaks, fuel pressure is good. Timing if off will make a back-firing condition. I don't think it affects the regulator but does burn up things under the plenum. Good luck and I am here.

Yes 193k. I have changed plugs, wires, cap, and rotor but did not help much. It runs better after moving the distributor but runs rough at steady speeds and will sometimes will die when first starting or when coming to a stop. Because of the mileage I still believe it is the timing chain. I will replace as soon as I can. Again thanks for your help.

72,085

I don't mind giving input. No doubt the chain & gears are worn, but before you put anymore money into it, check compression. It should be up around 150-160 lbs. you need a min. of 120 for a cylinder to fire. Another thing is the distributor, probably need to inspect it, take the shaft out, clean, and check for wear, slop, take the pickup coil off and make sure wires are good, clean up any rust.

I will do those things and post back what I find out. Thanks for your input.

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