67 Firebird Fuel system Upgrade
 

My Firebird has never run at the power level I expected. I have not driven it much over the recent years as I have / added other toys taking the limited fun time.
After the engine refresh roller cam swap last year, spending more time on it now. Searching this forum for trouble shooting tips, I finally nailed it to the fuel delivery system. I have a pressure drop when accelerating and a flow test yield low volume. I took the wide band from my 2004 GTO, and definitely running lean. Carb is Qjet 800 cfm done by Cliff years ago. Engine is 455, ported 6X, roller cam similar to a high lift 041. Street car for cruising and fun. Currently have a Carter mechanical pump, and stock 3/8” lines.

I am thinking of two options to address this.
1. Robbmc 550 fuel pump, his ½”fuel tank sender unit, Inline Tube can custom make a ½” line and also supply a ¼” return line. This will be around $700 for the parts
2. Tank Inc electric fuel tank / pump kit. About $950
I believe the Tank Inc route may be better. My concern is routing the two -6AN push lock fuel hoses (feed /return lines) and where to put the regulator.
Any install advice ?

Your pump itself is likely fine for your level of HP, it’s the small stock fuel lines with all of its tight bends and no bottom feed from the tank, the pump has to suck instead of being pressure fed by the weight of the fuel in the tank.

If you want to do it right once with room for growth go with the Tanks system. 8an feed and return.

I've said this many times. I typically just do a tanks inc setup with -8 feed and return on anything that's approaching 500hp or more. That way I'm done with the fuel system for good and it'll support anything you want to throw at it. It's a reliable and quiet setup as well.

As far as install I usually follow original fuel lines with the -8 lines unless I see a better route. It's installation specific per car.

As far as Pontiacs go I always mount the regulator where the original fuel pump was. Make a bracket and mount it there, then I bend a steel line from there to the carb much like a factory setup.

If your not up for all that you could attempt to save some money by just installing a Robbmc pump and run it that way first to see if it's ok. It may or may not work well enough but it's only $200 to try that first.

Agreed with OCM and Formula that the way to do this right and once is to go with the Tanks Inc setup.

The first gen F-body tank is a nice piece that looks factory. Don't skim on the fuel sending unit though, spend the little extra for the floatless sender, or for even more accuracy, get one of the fancy LiDar senders. -8 feed and return as stated.

I run my -8 lines along the passenger side of the car, in the same location as the original fuel line/s. You can either do as Formula mentions if you want to try and retain a more stock look, or you can also run the lines up the firewall to the regulator. Yet another option is to run the regulator near the tank and run a single line forward. Lots of options and none of them are predominantly right or wrong.

This isn't the cheapest way to do it, but if you go with something like a Walbro 255, you'll support over 600 hp, won't run the bowls dry at WOT and should you ever decide to move to EFI of some kind, all you need to do is change the spring in the regulator.

Regarding the regulator near the tank, is that a good idea? Always read the regulator should be as close to the carb as possible for best results..not sure why but seems to be what most people say/do.

A friend that owns a body body shop and does high dollar builds & LS swaps in classic cars likes to use the factory corvette type regulator that mounts back by the tank, very clean install and only 1 line for feed to the EFI/carb.

I am considering going tanks inc to replace my robbmc set up that works great overall but has some random cut out issues on low 11sec runs with a Q-jet, I have a nice robbmc regulator that can work for efi or carb, just not sure of best place to mount it. I like FJs idea of mounting by the stock fuel pump but wont that contribute to heat soak more than being up closer to the carb?

X2 always read the regulator should be close to the carb as possible

Don’t forget wiring the tank pump. I love the in tank setup but for just a cruiser I would think about the mechanical pump. We have done both, both work but one is much simpler to install and maintain if the pump does fail. Again it’s all about what you’re doing with it. Good luck either way.

I did the tanks Inc thing after fighting mine forever.

I now have a Terminator X system but I ran the in tank unit with a carb for like a year and it was great.

I also have my regulator near the tank and a short return line which operates fine.

To be fair when I had the carb I had the regulator in the engine bay and a full return line, but now that I know the remote regulator works fine I wouldn’t run all the extra line again.

Rocktimus- Which pump did you use with the carb? Im sure the regulator by the tank works fine, GM did that on 4th gen firebirds & vettes, but is it ideal or could it be better by the carb/FI? What type of line did you use for feed/return? And where did you run them?

Anyone able to confirm or comment on the reason most say to have the regulator near the carb for best results? Maybe related to having the most consistent or accurate pressure? Might only be for carbs and FI doesnt matter as much? If the reg by the tank works ok for a carb, that saves extra work running a long return line.

I dont remember the exact model because I didnt buy it, this was a lucky local find. Guy had a turbo LS 68 Camaro that he was parting out. So the pump is way overkill for me. It was made to support like 700 boosted HP, which means its good for like 900 NA.

Im using the fixed Holley regulator and filter in one setup. Its not adjustable, it sets you at ~60 psi and thats what you get. I have a 1/2 stainless line that runs most of the length of the car. -8 AN line in the engine bay and making up the short return system from the filter/regulator. A couple of very short pieces of injection pressure-rated rubber as jumpers here and there.


On the "why is this better" part of it. It might technically be "better" to have the regulator closer to the carb, but considering so may of the OEMs do it the other way I gotta think better is a relative term. One that can be over-ruled by the convenience of not putting all the extra fuel line in.

Theoretically, having the regulator near the tank vs the carb should not matter. Fluid pressure in a line increases simultaneously across the entire length of the line or tube. I will say having the regulator up on the firewall, near the carb does make access to it much easier. It's more serviceable that way.

Thanks for the replies. Just curious why some or most Ive read say that the reg should be as near to the carb as possible... maybe thats only for carbs & FI is different?

For an adjustable reg, it would obviously be easier to access in the engine bay area as opposed to crawling under the car if needed. But for FI it doesnt need adjusted.

On my robbmc 1100 pump, it can be dialed down to ~7psi and not need a regulator for my 1978 Q-jet but that limits the flow a lot, so for track use I use a regulator and can turn up the psi to about 8.5 on the reg without overpowering the needle/seat and turn the pump up for more flow. That might be beneficial on a electric pump too, street use adjust to 5-7psi for most q-jets & other carbs, but for track use you can turn up the psi a bit if that improves fuel supply. Just speculating and probably needs tested to see if that would help.

If the reg can be back by the tank for a carb that would make for a much simpler return set up.

That may be due to different type of regulators being used. If you're regulating something without a return line, you're dialing down fuel delivery to the carburetor. With a return system common with an electric fuel pump, you need a bypass regulator. That works by sending the amount of volume necessary to create a given pressure while returning any remaining fuel back to it's source.

OEM's haven't had regulators in the engine bay for quite a while. With modern PWM pumps, most are deadhead systems that sent fuel volume based on input to a fuel rail pressure sensor. Those OEMs that do still use return style systems often have the regulator near the tank. I would say it doesn't matter as a result. If you feel more confident with it closer to your carb, run it in that configuration.

Makes sense. Might be that a deadhead regulator is whats supposed to be best near the carb, my current set up is deadhead so I have it as close to the carb as possible.

The robbmc regulator like many others can be either type by changing the spring & using different outlets. I like the idea of being by the tank for easier return line routing, I have 1/2" & -8 for feed from tank to pump & pump to carb, running a short return from regulator to tank sounds like the best option. Will do some more research & ask tanks inc & robbmc what they suggest for regulator location when the time comes.

Sorry for the hijack but hopefully this info can help the OP or others considering in tank pumps.

Na, been doing it for many years that way, doesn't matter how hot it gets here, 105-110-115+ degrees outside and it never causes an issue with heat soak or vapor lock, even with the junk 91 pump gas we have.

Edit:
I should add that now of course I say this and it's probably critical to point out that as I mentioned in the post below I run a full length return line from that regulator, so that regulator always has constant fuel flow through it no matter what the engine is doing. If it's idling it's moving more fuel back to the tank so there is no stagnent fuel just sitting in that regulator getting hot.

Now if you try dead heading a system like this with the regulator mounted off the fuel pump boss on the engine, there are no guarantees that you won't run into some hot fuel issues, because well.....it's dead headed and when the car is idling that fuel just isn't going anywhere.

As far as where to put the regulator, there are many thoughts on that.

Me personally, I prefer a return line the full length of the car, which means my return style regulators are always mounted somewhere near the carb or EFI unit. Whether it's on the engine at the stock fuel pump location, the frame, or up on the intake, doesn't really matter to me, just depends on what the purpose is of that particular car, whether I'm hiding things or not.

The biggest idea of a full length return is to keep that fuel circulating. Anything along the entire run of the car that has the possibility of heating up the fuel before it gets to the engine, whether it be anything near the exhaust, even if it's the radiant heat off the blacktop, has a handful of not so great affects. Worse case being vapor lock or hot start issues. The cooler the fuel the better off you are in many ways. You can think of it this way, the closer the return style regulator is mounted to the carb, then the shorter the feed line has to be that has the stagnant fuel in it, and the longer stagnant fuel sits in the line the more heat it picks up, the shorter the line the less chance of that.
By stagnant I mean fuel that doesn't move much at all when at idle and slow moving situations when the engine isn't demanding much fuel flow. Now the fuel has a chance to pick up heat. No matter what you do, you're going to have a feed line that has stagnant fuel, obviously more so if you dead head a system or run a regulator way back at the tank. It's better to make that line as short as possible from the return regulator to avoid or at least reduce the chance of hot fuel situations.

That's basically the thinking behind that deal.

Now there are other arguments that can be made about pressures and how accurate they are based on where the regulator is mounted. That's a bit of a different discussion.

Good points. For many earlier year cars the feed line is on the passenger side & runs next to the headers along the frame as well as crosses over at the front of the oil pan literally clamped to the pan/timing cover bolts, so if heat is a concern that location could be an issue. I do use heat wrap on the lines in those areas just to be safe.

Road heat isnt really a concern in midwestern or northern states, Iowa gets some very hot/humid days in the mid to upper 90's, even hits 100-103 some years, but I dont usually drive when its that hot with no A/C and when I do Ive never had a vapor lock issue with a deadhead mech pump... electric pump has much higher psi thats supposed to eliminate or reduce vapor lock.

I guess it comes down to where you want to mount the regulator or investing in a full return set up, sounds like it can work both ways with a full or short return line.

Yes you are right, electric pumps are better with vapor lock because they are very good at pushing fuel, even at 6 psi they are better at fighting vapor lock than a mechanical and of course as psi goes up things get better too. Mechanical pumps typically aren't very good at pulling fuel so they are more sensitive to those problems.

Thanks for all of the feedback. I noticed Tanks Inc "kit" includes -6AN, and there is no mention of -8AN on their site. Not sure if that is an issue fitting the bigger line with their pump and regulator.