Dillon93dillon

I have a 2000 5.3l installed into a 79 chevy 3/4 4x4..

the 2000 has a FPR built into the fuel rail, vacuum controlled.
Feeding the system is a walbro 255, with an-6 fuel line. and 3/8 hard line.

ive been having lots of issues with running way rich, thinking it was intake gaskets, MAF, IAC... etc

but today i got a chance to hook up a fuel pressure gauge, turned my key and the gauge spiked to 110 psi, slowly dropped to 30 psi and stopped. okay... then i started it, and it was running with fuel pressue at 110, (way rich and smoking)

and it blew of my fuel rail FPR again...

what else can i do to control this fuel issue? do i need another regulator or should the truck one be fine?

here is some live data i also have

any input or help would be great

Old Geezer

iTrader: (3)

Sounds like you have a return line issue....
How is the return plumbed back to the tank?

usmcz28

iTrader: (3)

There's a corvette style fuel filter with the return built into it. I dont recall the part number but if you search for it you can't miss it, IIRC it also helps regulate the fuel pressure.


Found the link to the regulator:

https://ls1tech.com/forums/conversio...8-34-ebay.html

pdsq98gt

So let me get this straight... You're using a return style fuel rail with a vacuum regulator AND a vette filter/regulator? Did you cap the return line on the fuel rail?

Dillon93dillon

No extra regulator, just the vacuum regulator, and original return setup, no vette filter.

i figured out my high pressue issue, was the sending unit into the tank would flow enough so it caused high pressue, but...

its still rich on bank 2..

garys 68

iTrader: (1)

Is it throwing a code?

LS1MCSS

iTrader: (18)

Let me guess, you had the return hooked to the 5/16 line coming off the sending unit? If so, that line has a restriction made into it at the top of the sending unit because it's only for a connection to a charcoal cannister.

Dillon93dillon

No codes. only for missfire

and yes, i did hook it up there, and exactly right i forgot about those charcoal canisters.... because they were removed very long time ago haha.

hopefully i can modify it somehow when i drop my tanks today.

what im wondering..., i have the dual tank setup, and that one return line. so does this only return to one tank? or will it split return to both?

im thinking it only goes to the passenger side, so if i run my drivers side it will suck it dry in ten min putting it all in the other tank.

garys 68

iTrader: (1)

A misfire will usually throw a code, ie bad injector, plug, wire. Try swapping the O2 sensors and see if the rich condition will go to the other bank.
Btw a dual tank setup is going to need a valve for tank selection and return. You might check OEM valves on dual tank new trucks.

Dillon93dillon

i took my tank out and fixed my return line issue, so now at idle, walbro 255 is running about 45 constant psi. ive seen 60 when it primes, but at idle and WOT its around 52-55.

yeah no check engine lights, i drove it after the fuel fix, it was still smoking, but it could have been because of the fuel saturated in there. not sure didnt drive long enough.

No smoking issues now, had to clean out the pipes.

all of the live data was looking good when i hooked up tech 2 today, 02 sensors were reading correctly everything.

the VSS tho was saying i was moving at 13mph standing still...
from what i remember about wiring is that these speed sensors send out a AC current, which being next to other wires the AC current would alter and change, (pick up other surrounding voltage) so when i moved this VSS wire away from the rest of the wires, it went to 0mph like it should.

not only did i fix that, but by the ecm thinking it was moving was causing my higher idle, when it went to 0mph it instantly went to 600 rpm and held steady.