tuske427

iTrader: (1)

I still owe you guys a part #, my apologies for sleeping at the keyboard.

i'll look it tomorrow morning when I'm home. (I made myself a note and a reminder on my cell so I won't forget)

For today- here's a pic.

StevenK

Wow, that looks just like a stock one.

But if it flows both ways I'll definitely go pick one up if I can confirm the problem.

tuske427

iTrader: (1)

yes, it is a stock GM one. has a gm part#, etc...

it was reccomended with the electric fuel pump kit I bought. It's designed to vent both ways.

tuske427

iTrader: (1)

GM Part # 10033125 (pressure/ vacuum relief valve)

StevenK

Sweet, I'll go pick one up and see how it works.

Little update, over the weekend I pulled the hose off the EVAP hard line under the hood and capped the throttle body. The car still surges at startup, the fuel pump is still noisy (mostly at idle), but when I pull the fuel cap there is no more excessive pressure.

I'll go pick up that 2 way relief and give it a try, and hook my evap line back up. I'm beginning to think there might be something wrong with my fuel pump :-(

Dave88z

I looked at the pic of that valve and it looks the same as the factory piece. Before you go and buy it, look under the drivers side rear of your car. It should be there in the area around the fuel filter. My 88 IROC had one (or maybe it just looked similar) yours may also have one.

StevenK

10033125 is the stock thirdgen relief valve, just got off the phone with my local chevy parts guy

nathan44

Ls1 swap to 85 Trans am, i had a problem wit an inline holley blue pump when i was runnin' a carb'd 355. That is definitely gonna save me some time and headache caused i tossed the stock one. is it a piece i can get from auto zone or o'reillys?

StevenK

Ummm, the part he just gave me is the stock part, it will not vent two ways.

Havnt had a chance to do anything else on the car, I think I'm gonna call walbro and see what they have to say about this noise...

StevenK

Ok, so I can't figure this out....

I have a 2000 motor, an Aeromotive FPR set to 57 PSI, a Walbro 255 pump, a stock thirdgen tank. I have the incomming fuel line coming to the FPR, then from the bottom of the FPR to the return line, then I have the third line coming off the frame to the little plastic (im assuming) EVAP controller that sits on the intake, then going into the Throttle body.

What am I missing?

I just found a 2000 tank, with fuel pump for 75 bucks, should I swap mine out? What does the 4th gen tank have that I don't that keeps the fuel pump from getting all pissy and loud?

Dave88z

Try a search on walbro pumps. I thought it remembered others having problems with noisey walbro pumps.

StevenK

Well I went ahead and picked up a 2000 tank with stock pump and all the other crap on it (coal can I guess).

There are some wires on the parts attached to the tank, I assume I need to find the wires coming out of the ECM and extend them all the way to the back of the car?

Anyone done the wiring on the 4th gen tank?

Again, thanks for all your help guys.

ghettocruiser

iTrader: (17)

Did you get the body side wiring as well? If not, and you can still get it, I suggest that you do. It makes things easier.

But as for wiring, I have a thread somewhere... let me find it..

https://ls1tech.com/forums/conversions-swaps/559672-couple-wiring-questions-evap-fuel-tank-check-my-work.html

I never got any feedback..but I hooked things up like I have written and it worked. I had a donor car to work off of, so I just kept track of what wire went where.

Hopefully that helps ya out. Are you retaining the EVAP function? Or deleting it.

Justin

StevenK

Sadly the donor car is long gone, and I don't have the body wiring harness. I don't know if I am doing to delete the EVAP, why would I do that? The only reason I got this tank is because it has the coal can on it, and I figured that would help with my pressure problem. But if I don't hook up the EVAP, will it be ok?

ghettocruiser

iTrader: (17)

Steve,
Im not 100% sure how the EVAP works. However, I have it hooked up on my car, except I dont have to the fuel level wire hooked to the PCM. Didnt think I need it. But I throw codes for the EVAP system, so I dont think its working. In fact, when I pulled my EVAP solenoid and lines to relocate it all, I didnt even smell fuel in the lines. I thought i would be able to smell something... And I dont have weird pressure in my tank that I know of.

Point is, if you have the EVAP and all on the tank, and tahts what you got the tank for, go ahead and hook it up. Its certainly not going to hurt anything. You dont need the body side harness, it just makes the install cleaner and neater. Im sure you still have all your wiring diagrams and what not...so just make sure you hook it all up and you'll be good. I think there are a couple grounds that need to be hooked up, switched ign. to the pink wire, the one grey is fuel pump power, the purple is your gas gauge sender and needs to go to the gauge AND to the PCM for the evap to work correctly. Then there are two white? wires...I think those go to the white and blue plugs of the LS1 harness. If you need some more help let me know and Ill find my notes at home and help ya out.

Justin