6.0 Falls Dead, Cranks Up?????????

[JJAB]

Here is something i just thought about. I am running a Sorenson fuel pressure regulator, autozone part #800-329. In the part description it says it is for a returnless fuel set up and it is supposed to regulate pressure to 50psi. But it says the regulator is ajustable. How is it adjusted.

Ok, I have the truck intake on this 6.0, what fuel pressure regulator do I need to get that will install in the truck intake but regulate the pressure at 58to 60.

[JJAB]

Also, just a thought. You know how the 80's trucks come with the vacuum restrictor in line on the vacuum hose from the booster to the carburetor. Well I have a factory 2002 truck vacuum hose, straight hose no restrictor, going from the booster to the back of the intake. Could this "open" hose be choking the motor down during braking or sudden decceleration?

[Clyde65]

Do you have a return or return less fuel rail? 50psi isn't enough.
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[JJAB]

It is the return style fuel system. The truck has the "truck intake" with the feed line and the return line.

[BR3W CITY]

Dude you are confusing the effing heck out of me.

I don't think a vacuum resistor has anything to do with anything on these motors, as I sure as heck don't have one.

You have a fuel pump that don't know the output of....the 80-90psi pump will be regulated back properly, I would be concerned that a 65psi (peak) pump might run the risk of being insufficient under certain load conditions.

That FPR listed doesn't fit LS series truck according to the "make it fit" listing on the autozone website....how did you end up with this one? Did the original one fail, or are you for some reason (please tell me no), running 2 fpr's?

[JJAB]

My apologies. No I am not running two regulators. When I told you the two different psi of the pump, I was reading online about the airtex fuel pump and it stated that with the same part#, EP3270, some of the pumps are 65psi and some are 80-90psi. Also, the sorenson 800-329 regulator sold at autozone is the replacement regulator for an 2002 Chevy 2500. No jerry-rigging, it fit right in place on the fuel rail of the intake. The reason for purchasing the regulator was just instinctive amongst buying other new parts when doing the swap.

As far as the vacuum resistor, I was just throwing something out there as a possibility.

[BR3W CITY]

Aight, thats just me being frustrated that I can't help you fix it so far

Ok, so even if its a new regulator, we've thrown out all the easy stuff, time to start looking at the less-likely problems. I'd see if you can trade the reg in as defective, just to try a new one to look for improvement.

Might be worth it to doublechekc the fuel pump wiring and make sure it didn't ground out or come loose or something like that....my brain hurts on this damn thread...I need your truck running.

[JJAB]

BR3W CITY, man i appreciate your dedication to this thread!!! I will be trading the regulator out tomorrow. I will definately get back to you ASAP. Thanks again to all.

[ls1nova71]

This is the kind of thread nightmares are made of! But first off, I wouldn't put much faith in that Autozone website. It also says the regulator bolts on! Anyway, have you checked to see what the pressure is with the engine running with the vacuum line to the regulator unhooked? Also, is this a DBC set up? I've seen IACs not be able to open fast enough when you let off the throttle and cause stalling issues. Also not having a VSS will cause quick stop stalling since the PCM doesn't know you're stooping it doesn't adjust the IAC.
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[JJAB]

Awesome information!!! I have not checked for fuel pressure with the vacuum line off the regulator, but I will do this today before installing the new regulator. Yes, this is a drive by cable setup.If it turns out to be the IAC not opening fast enough, what is the fix? Thanks!!!!

[BR3W CITY]

Good thoughts Ls1Nova!


I'm also wondering if its possible that a problem with the MAF could be involved? I mentioned it earlier but it didn't seem like the prime suspect. Usually it would throw a low-input voltage code, but MAF failures can cause stumbling and stalling, weird engine response etc. If the MAF isn't placed within a reasonable (but not too close) distance from the TB, and on the correct portion of the intake, it can be problematic. What are you running for an intake elbow or CAI or?

[Clyde65]

I have a question, if your running the truck intake and the return style fuel rail, why a regulator? the fuel rail has its own regulator. I would personally change to a Walbro 255 pump or a Pierburg pump, or at least one that puts out about 100psi, let the regulator do its job.

[JJAB]

Clyde, first thanks for the question to aid me in fixing the problem. The regulator that i am referring to is the regulator on fuel rail. That is the regulator that i was referring to that i replaced or bought new while doing the engine swap. Lastly, will either of the two pumps you just mention fit in factory EFI sending unit from a 1990's model suburban gas tank/sending unit?

BR3W and LS1 Nova, truth is the MAF is placed not more than 4 to 5 inches from the throttle body, directly in front of it. My friend, whom I did the swap for, hasn't bit the bullet to buy a kit with proper elbow, etc.. to properly located the MAF. So, from your comment, I see this could be a real big problem.

Thanks!!!!!!!!

[BR3W CITY]

GM recommends 6-12", and on the upper 1/3 of the pipe, between 12 and 3 usually...and the issue with having a super short intake or putting the MAF right in front, is that supposedly the air turbulence is too great that close to the TB, and the subtle changes in TB position cause erratic changes in air flow across the MAF and can trigger running and fueling issues. IIRC, MAF failure can cause the pcm to use a different or adjusted table (don't quote me on that part, but i swear I've discussed it with someone here before)

fwiw, this is the intake setup I'm using. The MAF is about 11-12" inches away (max that my harness reached), and clocked to about 2 oclock.

[JJAB]

I got you. I cant ask for a much better visual pic than that. As always, the knowledge gained here is plentiful. Thanks!!

[Clyde65]

JJAb, I honestly do not know if they will fit what your using, however I do now they will go on the frame rail as an external. I have the Pierburg and it is from a Mercedes ( I think). I bought my stuff for the CAI from these folks and made my own

http://intakehoses.com

[4x4toy]

The MAF, double check and see if it is installed correctly, air flow direction.

[JJAB]

Guys, I finally got a chance to attempt to change out the fuel pressure regulator. Now, I am really wondering what regulator you guys are running. When I checked the fuel pressure regulator a few days back, the truck intake fuel rail pressure was reading 50psi. That regulator was part number #800-329(psi rated at 50psi). After speaking to BR3W City, LS1 NOVA & Clyde 65 they advised me that rail pressure need to be ay least 58-60psi. So, I thought that a simple regulator change to part#800-471( psi reated at 62psi) would solve my problem, but the part of the regulator that actually sticks into the fuel rail is too large in diameter. For those of you running the truck intake, what regulator are you using?

[Clyde65]

I am just running the stock 4.8l fuel rail with return. I know my pump puts out around 100psi, the motor needs 58-60 at the rail.
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[JJAB]

So clyde, you are running the stock fuel pressure regulator?

[Clyde65]

Yes sir!
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[JJAB]

Guys, I am at a loss. I replaced the new regulator with a stock regulator. Rail pressure is correct and the truck is still acting up. After checking rail pressure today, i shut the truck off, I tried to crank the truck up again it just didn't want to start. Almost like it wasn't getting fuel, them finally after continuously turning it over, it crunk up. After a very short test drive, the truck did the same thing, anytime I am not on the accelerator the truck just dies. I checked the MAF, and it is turned the correct way.Before you ask, it has a brand new battery and the alternator is new, so its getting a full 12 volts. I m just frustrated because on the tune(driving), the damn truck ran like a scalded dog. A day after the tune, the truck started acting up. The only thing I did after the tune was back all the rocker arm bolts out, appplied locktite and retourqued back to 22 ft. lbs. Im at a point to where I want to reach out to clyde65 or clinebarger to put your eyes on it to try and figure this out. You both are in Texas within 100 miles of me. Thanks in advance.

[BR3W CITY]

I've got nothing but time...you kick for gas and give me a place to stay and I'll just come down and look at the dang thing.
Sure its like 23 hours...no biggie.

[clinebarger]

Originally Posted by JJAB

I want to reach out to clyde65 or clinebarger to put your eyes on it to try and figure this out. You both are in Texas within 100 miles of me. Thanks in advance.

It will have to be a weekend, Snowed under at work, Got scanners & all that at the house.

[BR3W CITY]

Damn, thats a first DFW gets snow before Milwaukee.