Another 454 Vortec Build Thread - Documenting, Q&A, Help

[Bachert24]

After thinking about this a minute, I don't think you had the lines pinched off totally.
If you had a pressure line pinched off, you would get 0 pressure reading. If you pinch the other off, you should get way more pressure.

Yeah that makes sense I’m going try again

 

[BeXtreme]

Yeah that makes sense I’m going try again

Also, the return line will be the one not running through the filter.

 

[Bachert24]

Also, the return line will be the one not running through the filter.

10-4 that helps a ton! I seen 2 soft lines going into hard lines that were stacked on top of each other and tried both, will look a little more closely this time around. I get very little time to mess with this during the week, and of course the person limiting my time is also the one saying "when will the truck be running?"

 

[Bachert24]

You will just end up chasing your tail and spend tons of money to potentially solve nothing like that. There have been lots of good advise on how to simply troubleshoot your problem and you seem to completely ignore it and instead laser focus on something that everyone is telling you IS NOT the problem.

There is no fuel pressure sensor on your truck. The Fuel TANK pressure sensor is only used for EVAP system testing when the truck is first turned on and is not used in your application... regardless of whether there is a sensor installed in your fuel sending unit. The fuel pump itself is the same for almost all GM trucks/SUV's from ~96-2003.

Put a fuel pressure sensor on the rail and then test the pressure(I know you already did this). Record the pressure key on/ engine off. Turn key off and record how fast the pressure drops(PSI/second). Then do what spareparts said and pinch off the return line. Record the key on/ engine off pressure. Turn key off and record how fast the pressure drops(PSI/second). If your pressure with the return line pinched off is over 60psi and it doesn't bleed off very fast after you pinch the return line closed, your entire problem is the FPR. Full stop.

Ok tested following alldatadiy guide. Pull pressure was only 4 psi low on the rail and also 4 psi low with return line pinched off. With that data alldata still says FPR so I’m doing that this weekend. In both instances pressure dropped about 1 psi every 5 seconds so injectors are not ruled out but I believe FPR is the culprit for the running conditions.

 

[Supercharged111]

Ok tested following alldatadiy guide. Pull pressure was only 4 psi low on the rail and also 4 psi low with return line pinched off. With that data alldata still says FPR so I’m doing that this weekend. In both instances pressure dropped about 1 psi every 5 seconds so injectors are not ruled out but I believe FPR is the culprit for the running conditions.

If that's your only observation, then it's equally likely that an injector or 8 are piddling into the intake manifold and dropping your pressure too. Or a check valve (if it exists) not checking. I'd do injectors and regulator together to rule them out, both are notorious for this.

 

[Spareparts]

What do you mean 4 psi low with return line punched off?
If the fuel pump return line is actually pinched off the pressure should jump to over 70PSI. Mine went up over 80 PSI with a new pump.
If you are 4 PSI low with the return line pinched off your fuel pump is shot or fuel filter is almost totally clogged.

 

[Bachert24]

What do you mean 4 psi low with return line punched off?
If the fuel pump return line is actually pinched off the pressure should jump to over 70PSI. Mine went up over 80 PSI with a new pump.
If you are 4 PSI low with the return line pinched off your fuel pump is shot or fuel filter is almost totally clogged.

It went up to 58 psi, test wanted to see 62 psi. Anything under 62 it directed me to FPR. Implication is FPR is working but not fully regulating. My guess is the injectors are actually the real issue causing leak down. My wife stated in the first test it jumped to 62 psi with key on then immediately dropped to 54 then started to drop 1 psi every 5 seconds. To me, that’s injectors. Fuel pump may also be weak.

 

[Carlaisle]

Spec is 56-62. 58 is perfectly acceptable. The fact that it immediately dropped to 54 is not. If it was my money and labor I would bet on the injectors. They're widely regarded as junk for good reason.

 

[BeXtreme]

Spec is 56-62. 58 is perfectly acceptable. The fact that it immediately dropped to 54 is not. If it was my money and labor I would bet on the injectors. They're widely regarded as junk for good reason.

That is not the spec with the return line blocked off.

It went up to 58 psi, test wanted to see 62 psi. Anything under 62 it directed me to FPR. Implication is FPR is working but not fully regulating. My guess is the injectors are actually the real issue causing leak down. My wife stated in the first test it jumped to 62 psi with key on then immediately dropped to 54 then started to drop 1 psi every 5 seconds. To me, that’s injectors. Fuel pump may also be weak.

As others have said... repeatedly. Those symptoms do not jive with a FPR. The second you blocked off the return line, you took it out of the equation. This is either a blocked fuel feed line(sock pickup in the tank or fuel filter that I recommended you change before running this test), a bad power/ground feed to the pump, or you have a bad pump. The bleed down could be from the pump or injectors, but once you blocked off the return line and the bleed down still existed, it can't be coming from the FPR unless it is leaking into the vacuum line going to the manifold(which would be obvious by just removing the vacuum line, which was one of the recommended test steps).

 

[Carlaisle]

I missed where he said the return was pinched off. In this situation, pressure would have to spike well above 62. If there is a manufacturer provided spec for this I am not aware of it.