No fuel return??!
02-05-2010, 12:22 AM
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No fuel return??!
Hello everyone, I've got a little project right now its an '06 silverado, recently installed a vortech supercharger kit from an s10, with an inline zex 255 lb/hr booster pump, a 12:1 fmu, water/meth injection kit (haven't hooked it up yet). I'm running real lean between 14.5-15.1 (LC1 wideband).
I need to start tuning this thing, but can't cuz it's fucked!!!
There is no fuel returning to the tank on the return line, wtf????!
Here's the story - I drove it around for a few days, boosting here and there and checking/logging data with HP tuners to see where I was at. The fuel system isn't richening at ALL, and it should with the fmu. So I started eliminating variables, first was the aftermarket fuel pump which is installed correctly and checked out. The next was to get ohm readings for the new IAT sensor I installed and compare to the old ones, which ended up being the same (old IAT sensor is built into the MAF unit on the silverado).
So the next thing I checked was my fmu. I took it out and took it apart and curiously noticed it didn't smell like fuel (this thing should have been pumping fuel at all times when not in boost). It was broken (which now I understand was from it trying to work without fuel ) so I fixed it with some new gaskets/o-rings. As I was putting this thing back on tonight I decided to check the return line. So I start up the truck and slowly unhook the return line after the fpr and before the fmu and no fuel came out??? at all!? I hooked it back up and ran it for a few minutes, primed the system and then checked the return shrader valve. NO pressure! There's tons of pressure on the feed line with the engine off as I checked it and the shrader valve was pissing fuel out at me. I also noticed a very slow drip drip out one of my feed line compression fittings with the truck running.
My fuel pressure gauge is broken, autometer is going to send some new connectors next week so I can get an acurrate reading.
I think its the stock fuel pressure regulator, maybe when I took the intake manifold apart I didnt reinstall it properly??? Anyone ever heard of this happening?
It's pissing me off cuz I need that return fuel to start tuning, cuz thats how I'm going to lean it out with the fmu, and besides the obvious fact that I don't have fuel goin back to the tank
I need to start tuning this thing, but can't cuz it's fucked!!!
There is no fuel returning to the tank on the return line, wtf????!
Here's the story - I drove it around for a few days, boosting here and there and checking/logging data with HP tuners to see where I was at. The fuel system isn't richening at ALL, and it should with the fmu. So I started eliminating variables, first was the aftermarket fuel pump which is installed correctly and checked out. The next was to get ohm readings for the new IAT sensor I installed and compare to the old ones, which ended up being the same (old IAT sensor is built into the MAF unit on the silverado).
So the next thing I checked was my fmu. I took it out and took it apart and curiously noticed it didn't smell like fuel (this thing should have been pumping fuel at all times when not in boost). It was broken (which now I understand was from it trying to work without fuel ) so I fixed it with some new gaskets/o-rings. As I was putting this thing back on tonight I decided to check the return line. So I start up the truck and slowly unhook the return line after the fpr and before the fmu and no fuel came out??? at all!? I hooked it back up and ran it for a few minutes, primed the system and then checked the return shrader valve. NO pressure! There's tons of pressure on the feed line with the engine off as I checked it and the shrader valve was pissing fuel out at me. I also noticed a very slow drip drip out one of my feed line compression fittings with the truck running.
My fuel pressure gauge is broken, autometer is going to send some new connectors next week so I can get an acurrate reading.
I think its the stock fuel pressure regulator, maybe when I took the intake manifold apart I didnt reinstall it properly??? Anyone ever heard of this happening?
It's pissing me off cuz I need that return fuel to start tuning, cuz thats how I'm going to lean it out with the fmu, and besides the obvious fact that I don't have fuel goin back to the tank
02-05-2010, 05:25 AM
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Stop right there!!!!! You're running WAY TOO LEAN!!!!!!!!!!!!
On an 06, the regulator is inside the fuel bucket. You can't run an inline booster pump with the pressure being regulated inside the tank. You probably need to ditch all that FMU stuff, and the inline booster pump, pull the tank, and install the correct higher flow Walbro directly in the bucket. Then have a supercharged tune installed that supports earlier enrichment. Don't go any further till you get this straightened out!!!
On an 06, the regulator is inside the fuel bucket. You can't run an inline booster pump with the pressure being regulated inside the tank. You probably need to ditch all that FMU stuff, and the inline booster pump, pull the tank, and install the correct higher flow Walbro directly in the bucket. Then have a supercharged tune installed that supports earlier enrichment. Don't go any further till you get this straightened out!!!
02-05-2010, 08:21 AM
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wkdivr- I'm not running too lean to drive it or idle it when not in boost. Which is why this thing isn't going to see boost until I figure it out. And it's not going to be driven now without fuel in the return line.
What is giving me fits is why there isn't fuel in the return line??
Everything else aside, it doesn't matter where the fpr is I should still have fuel in the return especially at idle...
The booster pump is just that, it helps a the stock pump pull harder. The fmu isn't affecting the return line flow when not in boost. I mean the return line is completely dry right where it comes out of the manifold!! Somethings clogging or messing it up. I'm at my wits end and am about to pull this manifold apart to check out what could be wrong (its jst a real bitch to take apart the manifold on this truck, its the stupid GM poppet cpi...crap port injection more like it)
edit- just checked with GM performance, the regulator is part of the injector assembly....damn gotta start pulling stuff apart again
What is giving me fits is why there isn't fuel in the return line??
Everything else aside, it doesn't matter where the fpr is I should still have fuel in the return especially at idle...
The booster pump is just that, it helps a the stock pump pull harder. The fmu isn't affecting the return line flow when not in boost. I mean the return line is completely dry right where it comes out of the manifold!! Somethings clogging or messing it up. I'm at my wits end and am about to pull this manifold apart to check out what could be wrong (its jst a real bitch to take apart the manifold on this truck, its the stupid GM poppet cpi...crap port injection more like it)
edit- just checked with GM performance, the regulator is part of the injector assembly....damn gotta start pulling stuff apart again
Last edited by 383chevy; 02-05-2010 at 08:28 AM.
02-05-2010, 08:40 AM
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I'm confused as well.
How do you have GM poppet injectors on a Gen III truck? Do you mean its a '96? Not 06? We need a few more details on the setup so we can help you.
On an 06 truck, there is no return fuel line to the tank... Did you install one? The fuel pressure regulator is in the tank on the stock setup; the one line is pressurized coming from the regulator...
How do you have GM poppet injectors on a Gen III truck? Do you mean its a '96? Not 06? We need a few more details on the setup so we can help you.
On an 06 truck, there is no return fuel line to the tank... Did you install one? The fuel pressure regulator is in the tank on the stock setup; the one line is pressurized coming from the regulator...
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02-05-2010, 08:53 AM
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What exactly do you have? A GM Performance Parts engine in an 06 Silverado? The PCM's are completely different, and if you think you're going to pull more fuel thru the stock 06 fuel module in the tank with an inline booster......................................have at it!!!!
02-05-2010, 08:54 AM
#9
If your truck is a '96, disregard this... however, if your truck is really an '06 as your post mentions...
You do not have a return line. That's your evap line. Your fuel system is RETURNLESS. That means the FPR is in the tank, and no amount of inline pumps, boost-a-pump, or fuel management units are going to change your fuel pressure -- because they are all be canceled out by the FPR in the fuel bucket.
You do not have a return line. That's your evap line. Your fuel system is RETURNLESS. That means the FPR is in the tank, and no amount of inline pumps, boost-a-pump, or fuel management units are going to change your fuel pressure -- because they are all be canceled out by the FPR in the fuel bucket.
02-05-2010, 08:56 AM
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If your truck is a '96, disregard this... however, if your truck is really an '06 as your post mentions...
You do not have a return line. That's your evap line. Your fuel system is RETURNLESS. That means the FPR is in the tank, and no amount of inline pumps, boost-a-pump, or fuel management units are going to change your fuel pressure -- because they are all be canceled out by the FPR in the fuel bucket.
You do not have a return line. That's your evap line. Your fuel system is RETURNLESS. That means the FPR is in the tank, and no amount of inline pumps, boost-a-pump, or fuel management units are going to change your fuel pressure -- because they are all be canceled out by the FPR in the fuel bucket.
Thank You!!!!