TBI to Carb Swap.. What Fuel Pressure Regulator is best? - Third Generation F-Body Message Boards

19camaroRS89 · 02-12-2010, 11:33 AM

I'm just getting ready to swap a carb 350 into my '86 TA, I want to run the electric fuel pump that is already in the tank. I'm wondering what the best fuel pressure regulator would be to run. I'll probably just be running a quadrajunk or an edelbrock 650 carb. If I remember right the stock fuel pump only pushes around 9-13 psi of fuel pressure?

Any details would be appreciated.

Apeiron · 02-12-2010, 11:47 AM

Mallory 4309 seems to be the popular choice.

1ADan · 02-12-2010, 01:51 PM

I was very satisfied with the Mallory part as well.

Primetime91 · 02-12-2010, 01:58 PM

It has to be a return-style regulator, so that really limits your choices. I love my mallory

There's another company that makes one too, Barry Grant I think?

I think the stock fuel pump puts out more pressure than that... even though it's only a TBI pump

92RS_Ttop · 02-12-2010, 02:52 PM

I've got the Mallory regulator as well. I'm still running the stock V6 pump which puts out something like 60-70 PSI, IIRC. No problems here, but I've only been running it for one summer so far. I'll be swapping out the pump for one from a TBI car soon though just to make things a little easier for the regulator.

And yes, the stock TBI pump is rated 9-13 PSI. Usually they run closer to 12PSI IIRC.

irocmackey · 02-12-2010, 04:00 PM

just did same thing. I used a aeromotive Part # 13301. Cost me 120 bucks. So far so good. Got it down to 6psi no problem.

19camaroRS89 · 02-12-2010, 09:44 PM

Thanks for the input guys, I'm going to order the Mallory regulator and see how that works out.

Any suggestions on fuel line routing and a good spot to mount the regulator?

one92rs · 02-12-2010, 09:57 PM

i got the one from barry grant since it had a gauge port on it.

Apeiron · 02-12-2010, 10:01 PM

You can put a gauge onto any outlet port on a multi-outlet regulator.

Primetime91 · 02-12-2010, 10:22 PM

You want to mount it close to the carburetor

92RS_Ttop · 02-13-2010, 07:11 AM

Quote:

Originally Posted by Apeiron

You can put a gauge onto any outlet port on a multi-outlet regulator.

I thought the gauge had to be mounted right at the carb's inlet to be accurate?

92z28camarokid · 02-13-2010, 07:46 AM

Well the really you just want it as close to the carb as u can, having it right on th carb inlet well idk how much more accurate you could get lol. As long as it's fairly close u won't Have any problms with accuracy

one92rs · 02-13-2010, 08:16 AM

Quote:

Originally Posted by Apeiron

You can put a gauge onto any outlet port on a multi-outlet regulator.

yes sir with the use of another fitting in the mix. ive always went by the less fittings the better.

92RS_Ttop · 02-13-2010, 08:57 AM

That's good to know. I think I'm going to move mine. I have it right on the carb's inlet but it interferes with the base of my air cleaner and you should see the cluster**** of fittings I had to cobble together to get everything to fit.

19camaroRS89 · 02-13-2010, 05:50 PM

one92rs, that's exactly what I had in mind for location..

I'm tearing the 305 tonight while it's nice out (15 degrees, damn MN), hopefully by next weekend I'll have it finished.

Any other suggestions with the whole swap are welcome. Thanks.

Primetime91 · 02-13-2010, 06:54 PM

Use something like this if you want to mount the regulator and gauge within a few inches of the carb and have it all fit under your air cleaner: http://www.summitracing.com/parts/SPE-29883/

(This part is for an Edelbrock BTW)

one92rs · 02-13-2010, 09:34 PM

http://www.thirdgen.org/techboard/ca...bi-update.html (carb install from tbi UPDATE !!!!!!!!!!!!!!!!)

89_ho_rs · 02-14-2010, 08:45 PM

Quote:

Originally Posted by one92rs

yes sir with the use of another fitting in the mix. ive always went by the less fittings the better.

i put mine in the very same spot. out of the way and easy to do. i also run the 4309 but i switched to the holley blue pump. love it. its louder than the stock pump but who cares.

19camaroRS89 · 02-15-2010, 09:11 AM

I decided instead of going through with swapping in the 350, to just throw my tbi edelbrock performer on the 305 already in it. I would assume that everything thats been discussed is still accurate, I dont know of any significant differences between the two blocks?

On a side note, I ran some numbers and found that my trans am was originally a 305 tpi car. Why the hell would anyone swap a tbi 305 in place of a 305 tpi?? Must have blown up the original haha.. Oh well.

I got the original (and very hacked up) wiring harness pulled out, next step is getting the manifold gasket, regulator, and then the wiring.

19camaroRS89 · 02-15-2010, 07:10 PM

I ended up buying a napa regulator for temporary, it is almost identical to the holley "volumax" P# 12-704 ( http://www.holley.com/12-704.asp ). Obviously there is one inlet and two outlets, I was wondering if it mattered which "outlet" goes to the carb and which one goes to the return line.

Quick update, got the new manifold installed as well as the carb and distributor. Might get to the wiring tonight, if not, tomorrow.

89_ho_rs · 02-15-2010, 08:09 PM

i know that you are supposed to use a return style or a bypass regulator but i had a buddy that used that one with his stock pump. either one will work. but you should put a return in.

89_ho_rs · 02-15-2010, 08:11 PM

hope all goes well best thing i did was swap out the tbi for the carb.

Apeiron · 02-15-2010, 09:04 PM

Quote:

Originally Posted by 19camaroRS89

Obviously there is one inlet and two outlets, I was wondering if it mattered which "outlet" goes to the carb and which one goes to the return line.

Neither is the return, that's a deadhead regulator. You'll kill the pump with it, or at best you'll flood the carb.

19camaroRS89 · 02-15-2010, 10:12 PM

Quote:

Originally Posted by Apeiron

Neither is the return, that's a deadhead regulator. You'll kill the pump with it, or at best you'll flood the carb.

Deadhead.. What would one of these be used for then?

That being said, I'll be returning that regulator tomorrow. I think I'll play it smart and order that Mallory 4309, seems like everyone's happy with those.

Thanks for the heads up, killing the fuel pump would not have made me happy.

Apeiron · 02-15-2010, 10:16 PM

A deadead regulator is used with a pump that has an internal bypass. When the regulator restricts pressure to the carb, the bypass in the pump opens and excess fuel just circulates within the pump, or through a return line from the pump back to the tank.

The stock pump doesn't have an internal bypass. All the fuel it pumps it tries to force through the line no matter what.

19camaroRS89 · 02-15-2010, 10:21 PM

Good to know. I just placed my order for the mallory regulator so hopefully everything else goes smooth.

19camaroRS89 · 02-28-2010, 07:45 PM

**UPDATE**

Alright so I got my Mallory 4309 in last week and hooked it up. I played with it for a little while and ran into what I thought was an issue.

Anytime I set the pressure past about 5 psi the fuel lines and gauge would start pulsing. The gauge would go between 5 psi and about 10psi when it was pulsing. I could also hear something from underneath the car every time the gauge pulsed.

Has anyone run into this problem?? I am running stock inlet and return lines still.

92RS_Ttop · 02-28-2010, 08:33 PM

It shouldn't be pulsing like that with stock lines. I used(and still have) the stock V6 pump, lines, and filter on mine.

Do you have any rubber in the lines under the car or are they all steel?

Is the noise under the car coming from the back where the tank is, or up front more?

How do you have the regulator hooked up? The return line goes in the bottom port and the feed line and line to the carb go into 2 of the 4 ports on the sides.

If its connected properly, try disconnecting the feed line from the regulator and running it into a bucket and turn the key on and see if you still get the pulsing. If you do, then its a pump issue. If not you may have a bad regulator.

19camaroRS89 · 03-05-2010, 09:08 AM

Quote:

Originally Posted by 92RS_Ttop

It shouldn't be pulsing like that with stock lines. I used(and still have) the stock V6 pump, lines, and filter on mine.

Do you have any rubber in the lines under the car or are they all steel?

Is the noise under the car coming from the back where the tank is, or up front more?

How do you have the regulator hooked up? The return line goes in the bottom port and the feed line and line to the carb go into 2 of the 4 ports on the sides.

If its connected properly, try disconnecting the feed line from the regulator and running it into a bucket and turn the key on and see if you still get the pulsing. If you do, then its a pump issue. If not you may have a bad regulator.

I disconnected the feed line, no pulsing.. I have the regulator hooked up properly. I actually got the motor running and found that it doesn't pulse while its running. However, if I rev it up a couple times the FP gauge does bounce around a little but eventually steadies out. Is it possible that my return line is too restrictive? I don't see why it would be but you never know I guess..

Again, I don't know if this is something I should even be concerned about but I wanted to make sure I was doing everything properly as this is the first time I've tried a setup like this.

On the bright side, the TA runs great!

92RS_Ttop · 03-05-2010, 11:39 AM

Sounds like your return line is too small or is partially/completely blocked. What size return line are you using?

My gauge does bounce a bit, but its minor movement. If yours is moving more than 1 psi back and forth, that may indicate a more serious problem, but fluctuations are normal.

What pressure do you have it set at?

Have you driven the car at all since you got it? Or was it not running?

19camaroRS89 · 03-06-2010, 08:31 PM

The car is running.. I have the regulator set around 5.5 to 6 psi and it's running great. I haven't driven it yet, I live in MN and refuse to let my 3rdgens touch salt. I believe the lines e 3/8 but not entirely sure.

I'm going to hook up a fuel pressure gauge right at the regulator on the by pass end and see if it is high.. I would imagine that the return line should have low fuel pressure? I'm not going to worry about the pulsing to much but I just wanted to make sure that it wasn't something important.

92RS_Ttop · 03-07-2010, 12:54 AM

Yeah, definitely keep them indoors in the winter if you can. The only good thing about winter is it gives me a great excuse to work on the car. I can tear it all apart and not worry about having it back together to go to work.

I have my pressure set around 6psi as well. If its running ok for you, I wouldn't mess with it anymore.

I'm honestly not sure what the return line would see pressure-wise, but I would imagine it would be the difference between what the pump puts out and what the carb is getting. But I could be completely wrong about that.

19camaroRS89 · 03-07-2010, 10:38 AM

Yeah that is the one of the nice parts of winter, more then enough time to work on them... on the flip side when it's -20 and your garage isn't heated, your garage time doesn't last too long.

Like you said I'll just leave it alone till it gets warmer out and I can drive it a little and see how it responds.

92RS_Ttop · 03-07-2010, 08:26 PM

Quote:

Originally Posted by 19camaroRS89

... on the flip side when it's -20 and your garage isn't heated, your garage time doesn't last too long...

I completely agree with that sentiment. Especially when you're laying on the cold concrete under the car with a garage door that leaks around the bottom.

19camaroRS89 · 03-08-2010, 11:28 AM

Quote:

Originally Posted by 92RS_Ttop

I completely agree with that sentiment. Especially when you're laying on the cold concrete under the car with a garage door that leaks around the bottom.

Yup and on top of that usually if you're lying on the floor you're lying in antifreeze, oil, T-fluid, or water.. I can't wait till spring. haha.

FormulaWolf · 03-11-2010, 11:12 AM

I love the Mallory reg that I got, hooked a gauge to it that is very handy. You know mine does the same ticking thing? I ran short of time before I could disconnect all the temp lines and connect a permanent solution. One thing I did notice is that if you squeeze the return line to narrow it, the tick goes away. If you let the pressure build up in the system after running for awhile, the tick goes away. My guess was that there was a bit of resistance in the return line which may cause the diaphragm in the unit to somewhat.. flap. What throws me off is when I squeeze the rubber line I have that connects the reg to the return line, the ticking goes away. Maybe that is just causing the pressure to transfer back to the main line and stress the pump. Anyway, I think your onto something with the return line being small or clogged. Hmm the tick seems quite common though.

Quote:

Originally Posted by 92RS_Ttop

Sounds like your return line is too small or is partially/completely blocked. What size return line are you using?

My gauge does bounce a bit, but its minor movement. If yours is moving more than 1 psi back and forth, that may indicate a more serious problem, but fluctuations are normal.

What pressure do you have it set at?

Have you driven the car at all since you got it? Or was it not running?

FormulaWolf · 03-11-2010, 11:15 AM

By the way.. note to all.. Be careful with those cheap regulators. They don't handle pressure well and rot out quickly. I've had one rot then start spraying fuel directly at my alternator. I will NEVER suggest one for any reason.

poboyracin · 03-11-2010, 12:21 PM

I used a Holley regulator and the GM return fitting that was designed for the ZZ3 Camaro swap kit. The regulator and the fitting was 55.00. http://www.s10v8.com/store/product_i...products_id/49

five7kid · 03-11-2010, 12:51 PM

Quote:

Originally Posted by poboyracin

I used a Holley regulator and the GM return fitting that was designed for the ZZ3 Camaro swap kit. The regulator and the fitting was 55.00. http://www.s10v8.com/store/product_i...products_id/49

If the photo is accurate, that's false advertising. That is not a return style regulator.

19camaroRS89 · 03-11-2010, 05:06 PM

Quote:

Originally Posted by FormulaWolf

I love the Mallory reg that I got, hooked a gauge to it that is very handy. You know mine does the same ticking thing? I ran short of time before I could disconnect all the temp lines and connect a permanent solution. One thing I did notice is that if you squeeze the return line to narrow it, the tick goes away. If you let the pressure build up in the system after running for awhile, the tick goes away. My guess was that there was a bit of resistance in the return line which may cause the diaphragm in the unit to somewhat.. flap. What throws me off is when I squeeze the rubber line I have that connects the reg to the return line, the ticking goes away. Maybe that is just causing the pressure to transfer back to the main line and stress the pump. Anyway, I think your onto something with the return line being small or clogged. Hmm the tick seems quite common though.

Glad to hear that I'm not the only one who has experienced this. I'm not gonna worry about it right now.

poboyracin · 03-12-2010, 06:51 PM

Quote:

Originally Posted by five7kid

If the photo is accurate, that's false advertising. That is not a return style regulator.

The ad is wrong. It's not a return regulator and it's not supposed to be.

When I did the ZZ3 swap kit many years ago in my '87 TBI 305 Camaro, the kit came with a dead head regulator and a restiction fitting. The restriction fitting goes on the other side of the regulator and is used for the return. It has a .042" hole in it that flows enough fuel to keep the pump cool. (GM PN 10185093) Why the engineers did it like that instead of using a return regulator, I don't know. But, it lasted 6yrs like that on the same pump so it does work well. Now that I'm doing another Camaro I looked for that fitting and found out it costs around 80.00 at jegs. A little web searching found that link above and it's a lot cheaper so I bought it. It's the same setup.

FormulaWolf · 05-31-2010, 07:42 AM

Quote:

Originally Posted by 19camaroRS89

Glad to hear that I'm not the only one who has experienced this. I'm not gonna worry about it right now.

I'd hate to raise an old thread but I wanted to say that I shortened the rubber return line that goes to my stock hardline and the ticking went away. Fuel pressure holds where it needs to be. With the tick the pressure would bounce from 5 to 8 psi on each tick.

HottestZ28 · 10-22-2010, 09:18 PM

I too had and still have this proble with the mallory 4309...and for those who think running a larger return... doesnt help I decided after being pissed off to drop the tank buy a holley blue pump and run 3/8 metal line from tank to regulator and back to the tank and use one of the larger vapor lines into the sender so there was no restriction going back. First startup same thing after I raise the pressure past 3 1/2 starts bouncing and gets more vilolent as you increase. Now if you think about, prove me wrong but if it doesnt bounce at 0 PSI that mean 100% of fuel is returning to the tank with no restriction why at 3 1/2 is there a problem. So I pulled the regulator apart and noticed the diaphram is very hard and not at all plyable. Now do I order a diaphram or get a better regulator like Aeromotive because the diaphram shouldn't have hardend that quick with pump gas