Well I got my car running and out of the house.


I was staring to attempt some tuning in Megatune. I believe that the Old Emiss. / Vapor line is of an inadeaquate size for the return line so It was giving me all kinds of goofy (fluctuating) Fuel pressure readings. Adjusting the regulator seemed to have no affect on the fuel pressure either. I still got wild readings. I am going to fab up a return line in 3/8" that will dump back to the Fuel Filler neck in the back of the Car.

Greg

_________________
http://www.youtube.com/hyperpack

The original line in my car is 5/16" - thats more then enough for pressure and for return. The vent in the tank may be the restriction. Or if its a california car that vapor seperator would be.

Yes i am think ing that the vent in the tank is holding it back - also I believe it's too small - the Vent line on my car is only 1/4"

I got some 3/8" hard line at the store tonight and plan on fabbing that up tomorrow with a Return Feed into the Filler Neck.


Greg

_________________
http://www.youtube.com/hyperpack

A small section of my line was 1/4" and it was fine - it depends on your pump I suppose. I was using a walbro gsl392

I welded a bung into the sending unit for the return. If I had to do it again I'd do it to the filler tube. Maybe use one of these kits? Not sure if our filler tubes are 2" or not.

Pierre, That kit will pretty much accomplish what I am doing.

I was just gong to drill and weld a section of 3/8 to my filler tube.

Greg

_________________
http://www.youtube.com/hyperpack

I just looked at Summit's kit, and it looks like the deal, since it does not involve welding. Being afraid of blowing myself up, I used JB Weld and it worked fine. Most welders will not weld on a gas tank unless it has been filled with water. At least mine, who is a very experience auto welder would not. When I took my old tank out of the car, the JB Weld was still perfect. I JB Welded too nipples in the tank, one for the vapor cannister, and one for the return line. They gave zero problems that I was aware of. Again, that Summit kit looks like the thing. I wish I had known about it before, if for nothing other than the rubber coupling sections. APA sells it only in three foot lengths for $17/FOOT. That's right, I spend $54 dollars to get s small section of nitrile rubber.

What pressure are you trying to maintain? Is your in line pump below the tank?

BE sure to use genuine JB Weld. There is a cheap look alike from Loctite which is junk, junk, junk by comparison.

Sam

_________________

JB Weld - "better than baling wire." My favorite adhesive - awesome!

I have used on my return line fitting too.

1/4" should be big enough unless you have a huge pump, but 5/16" would be better.

Lou

_________________
Home of Slant6-powered fun machines since 1988

Lou, I have the same pump you do - but I think the real restriction is in the tank - Some of the f Body tanks have some sort of goofy check valve thing at the vapor line fitting inside the tank - I just dont really feel like pulling the tank to find out. so I have got myself another Filler neck and welded the return nipple to it. Working on it now.


Sam, I am trying to maintain ~43 Psi As that is what the injectors are rated at. The pump is in line with the tank - but not below it.

I would get everything from 20 to above 100 and the fuel pressure was just goofy.. making the car intuneable at this point without steady fuel pressure.


Greg

_________________
http://www.youtube.com/hyperpack

It would be an easy test - pull the return hose out of the vent, direct it into a large gas container, run the pump and see if the pressure is stable.

Problem Fixed. I put the Charcoal can back on and the vent line goes to it from the tank as set up from the factory.
The return line feed to the filler neck - and is pressure free - Fuel press. is stable.

Thanks, Greg

_________________
http://www.youtube.com/hyperpack

Good news! You can not get a stable tuning if the pressure varies by even a few pounds as the AF ratio varies when the pressure varies. Did you use metal or rubber return line?

Sam

_________________

I used both..

I bent up some 3/8 hard line and Connected it together with Hose.

Greg

_________________
http://www.youtube.com/hyperpack

That's good. YOu are working hard aren't you. That 3/8" line is not easy to bend. It takes a bit of Houdini to snake it through.

Sam

_________________

Great. Make sure you use real high pressure MPEFI hose.

Lou

_________________
Home of Slant6-powered fun machines since 1988

Lou I did for the Tank to pump and from pump to Fuel rail and from rail to regulator. I also used The Hi press. Hose from Reg to begin of return line.
The stuff I used was SAE 30R9

The larger section of my return line 3/8" is a bit less restrictive and I used the SAE 30R7 Stuff there. My return line is sort of like a backwards funnel. It goes from small to big.

5/16 to 3/8" where I added all the new line from under the Passenger door all the way back over the the filler neck on the Driver's side.

Oh and Sam I have a Small tubing bender from Home depot. That thing is great for jobs like this!

Greg

_________________
http://www.youtube.com/hyperpack