Blk91Firebird

I apologize in advance for the confusing jumble of words you are about to read.

I converted my 89 daily driver firebird from tbi to Carb many years ago then busted my mildly built 350 with an eldelbrock 600 I had modified for dual feed (cant exactly remember why [#4]) So I threw in a complete 305 with a non cc quadrajet. Ran fine and smooth besides a little bog at WOT. Then had to move 17 hrs away for work and the car stayed and sat. I finally moved back and put another mildly built 350 in the car with a performer RPM intake and the old refreshed Edelbrock carb. it runs great as long as I run it hard. If I drive easy for a while then try to run it hard It runs good up until 4000ish rpms then starts starving for fuel losing all power, if you keep the throttle wide open it will pick back up for a moment then begin starving again this process will repeat itself 3-4 times then run great with no sign of starvation through all the rest of the gears I dont recall having this problem with the quadrajet 305, I may have had a vapor lock issue with the old 350 but Im not certain if that was this car or another one I worked on

Now for the things I didnt mention above
1. I'm using the tbi in tank pump with a holley non return style regulator

2. I'm only using one of the feed lines on the Carb (the original passenger side port) the other is blocked off

3. The car has an unpredictable Idle speed I will set it for 1200ish rpms (the lowest I can get it to idle) then drive it easy and all of a sudden the car is idling closer to 1600-1800 rpms. Run it hard for a lil while and its back to my preset 1200ish rpms

4. I believe I may have added the other fuel port to give my fuel line a straight shot from the drivers side fender to the carb instead of wrapping around the intake and getting hot

Now What do you think my problem is? Besides forgetting almost everything I knew about cars? and sorry for the messy over complicated post, ask and I will try to clarify

Thanks

-=Z28=-

iTrader: (3)

float levels off maybe? Not sure about edelbrok carbs. I have found tons of really in depth videos on you-tube about everything about every carb. maybe check it out. Good luck man. sorry I wasnt much help.

-Dan

MSgt Luttrell

Years ago I had a q jet carb that would not flow enough fuel to get down the quarter mile with out falling on it's nose just as you are describing. I tried everything to no avail and finally switched to a Holley 750, it flowed enough fuel to get me all the way down the quarter mile at full throttle.

Blk91Firebird

Thanks both of you I started thinking on my issue a lil more and started thinking maybe my fuel in the bowl is getting hot and boiling off when I open the throttle up? But after I typed it out it doesn't make much sense lol either way I rerouted my fuel line to my added drivers side inlet then ran another line from the passenger side port to my return line. On the return line side I installed a 2nd fuel pressure regulator set to a lower pressure to hopefully keep plenty of fuel in the Carb. My thought process was that this would keep fresh cool fuel circulating through my Carb. I didn't have the chance to test it out besides checking for leaks. Even if this doesn't fix my current problem it seemed like a neat idea. Does anyone see any problem with this or anything I didn't cover?

Blk91Firebird

tested out my a fore mentioned recirculating fuel setup and it seemed to do great on one aspect I no longer have the fuel starvation when I try and go from cruising to WOT but I'm still having trouble getting my idle to remain constant. I still need to do some slight regulator tuning, but I think one of my pressure gauges died on me so until I get another one I'm gonna have trouble getting it all set right. Im going to have to take some pictures soon, normally my ideas are shot down and my theories shot full of holes by now.

five7kid

iTrader: (14)

While it probably isn't related to your running issues, this is eventually going to cause you problems. The in-tank electric pumps require a constant flow of fuel through them to keep them cool. When you dead-head them with a non-return regulator, they will not have sufficient fuel flow to keep them cool, and they burn out.

You would be wise to change the regulator before your fuel pump dies.

Blk91Firebird

That was what I was thinking, which is why I used both my fuel inlets and regulated the pressure coming in and the pressure going out. I feel like I'm not describing this clearly, If I can find where my wife put the camera I will take some pictures and post them then I would love some feedback. Thanks

Blk91Firebird

Here is what I have set up
In the upper right is my regulator with my incoming fuel going through another filter a pressure gauge then into the drivers side of the carb. Then from the passenger side of the carb is another fuel line going down to the bottom right of the picture to my 2nd regulator which then goes into the return line back into to fuel tank.


Do you see any issues with this setup?


Oh and is my cam and intake what is keeping me from idling below 1200 rpms? The bottom of its listed operating range is 2000 rpms on the cam and 1500 on the intake

five7kid

iTrader: (14)

Not sure I'm properly understanding your setup, but I think it won't be sending anything down the return. The regulator operates off of outlet pressure, closing down the inlet when outlet pressure rises to the set point.

Blk91Firebird

I know I am getting fuel flowing through the return line to the tank for sure, You can hear it at the tank with the car off and the pump on. Also if I kink the line between the carb and 2nd regulator there is a large increase in pressure (11 psi) according to my gauge thats located between the first regulator and the carb. As soon as I release the kink the pressure drops back to 5.5 ish, that would indicate that the fuel is going somewhere correct?

I have the 2nd regulator set to about 4 psi so it shouldn't be able to reach that on the outlet and cut off fuel flow in an open line to the tank should it?

Blk91Firebird

I do feel like my regulator should have prevented that 11 psi spike in the first place now that I think about it

Blk91Firebird

After driving it for a few days I have only encountered one problem.
After being parked overnight on a hill with the front end of the car higher than the back my accelerator pump wasnt getting any fuel to it made it very hard to get the car started.
Otherwise everything has been going good still cant get the car to idle where I want it to tho
gonna recheck for vacuum leaks and do some other carb trouble shooting maybe distributor troubleshooting might even set the car on fire and walk away

Blk91Firebird

I'm idling at 900 rpms now. I retightened the intake and carb and did some more carb tuning. I backed my idle mixture screws out 3 full turns each does that seem like too much?

Like I said before I forgot alot of what I did know, but I thought I used to have it set closer to 1 3/4 of a turn out each