Hey guys!

I have recently bought a 1995 blazer with the 4,3 vortec CPI engine.
And believe it or not,, I have run into some problems with the beloved fuel system.

Now I have finally got it running, with a new AC DELCO EP381 fuel pump. But i am a little concerned that the fuel pressure is is going to destroy something,, because the pressure gauge shows almost 100 psi when the motor is running.

I see that the "problem" probably lays in the fuel pressure regulator. something that's a little odd, because the regulator to is new (Dorman 55162 Fuel Pressure Regulator bought at Mach 5 Auto on ebay)
And if its not produced with a malfunction, I believe that it should maintain a fuel pressure around 60 psi.

The thing i am wondering here, is if anyone knows if running the engine on so high fuel pressure can lead to more problems, or if its fine..?
The car start's up very easy and runs good, so if there is no reason for not driving with this pressure, I'm not going to take apart the intake plenum a 3th time just to get it right =)

Here is some footage that a took while testing the pressure after installing the new pump.

Thanks fore any reply. =)

 

Have you verified that the gauge is reading correctly by testing pressure on another vehicle, just to make sure that you aren't going on a wild goose chase because of a possibly faulty gauge?

If the reading is correct, it looks like the FPR is just deadheading the pump, not opening up and regulating pressure.

 

The regulator is not working properly. Either it is connected incorrectly or is just flat defective. Or I guess the fuel pressure gauge could be defective.

With key on and engine off, fuel pressure should be just above 60 and should stay above 50 for several minutes.

 

Okay,
no i haven't tested the gauge on anything else. so i will do that.

But is it even possible to connect the FPR in a way that it will not work?
If it's not leaking external or internal, and I have pressure that stays in the system,, Is it then even possible that i have managed to do something wrong when i assembling it ??


Thanks fore your replays =)

I will report back later with new discoveries.

 

There really isn't any way to install the FPR incorrectly where it wouldn't also leak. In this case, if the pressure gauge shows normal pressures on another vehicle, the FPR is likely just stuck shut, not opening at all.

 

Provided the gauge is accurate, the problem is either a bad regulator, or there's a restriction in the fuel return line. Check the return line from the manifold back to the tank. Make sure the return line and vapor line are connected correctly to the fuel pump module, (not transposed). If you had the pump out, the return line may have gotten pinched when reinstalling the tank. Another way to check is disconnect the return line at the nut kit, (rear of intake manifold). Stick a piece of hose on the fitting at the manifold and direct it to a suitable container, (gas can etc), then activate the pump by turning the ignition to the run position, don't start the engine. The pump will run for ~2 seconds and shut off, check pressure while the pump is running. Pressure should be 55psi to 61psi. If pressure is above that, bad regulator. If pressure is normal, the return line is restricted. Be aware that when the regulator is exposed to ~75psi or more, the diaphragm will be damaged and could rupture. Best to replace it, (after you find and fix the problem).

 

Kind of funny that gage with the bleed valve open should read near zero and its half way up. Think your gage is F ed.


Is that the same gage you used to determine the original problem or is it new?


Everything Swartlkk and Cpt. is true, lanny also for that matter. If you don't have another car to check the gage on plumb it to a tire it will be a little off do to air compression vs non compressible liquid. Close enough to see if the thing is way off.


Take the plenum off and give the reg a couple of small sharp rap's with a hammer for crap sake do it to the gage also.


Sorry it's a bit back wood's but we both have 95's and hammers work really good on them, at least from my experience.

 

It turned out to be the FPR that not was opening at all..
I tried the hammer on it gently, and some other things, but it refused to open..

So i put in the old one again..

Soo that was a lot of unnecessary work,,

I have once again learned that buying the cheapest alternative is not always the way to go =)

I do not recommend buying FPR of this brand ( Dorman 55162 Fuel Pressure Regulator )

 

Interesting, I need to get a replacement FPR soon, and I was going to get that exact Doorman one you listed, its the one that came with the torque tool correct? What brand you looking to get now?

 

I ran across bad regulators a few months ago, I had to replace my fuel pump so I figured regulator and filter would be good idea as well, except I purchased 2 faulty regs. In a row. And whoever thought it would be a good idea to locate the reg. In the plenum should be made to repeat the process of removing and installing for rest of their days, it's not hard, just stupid. As long as you get the o-rings and little spacer " if necessary, mine eliminated that by casting on new one" on correct and clip snapped in right it really can't be improperly installed. Again just a longer , and dumber process for such a simple thing.