Firebird Nation banner
1 - 20 of 23 Posts

·
Registered
Joined
·
15 Posts
Discussion Starter · #1 ·
So I built a 468 and put it in my 79, and while I am working out the details on drivetrain upgrades (another topic for another thread) so I don't tear too much up, I have been driving it to work and having a blast.

I don't currently have a thermostat installed, and the weather here has been pretty mild. Car hasn't been running over 180 degrees. Yesterday, it was in the mid 80's and when I went to lunch, I ended up getting in some stop and go traffic. the motor got up to just over 200 degrees, which didn't really bother me, but then the car shut off. I was able to start it, and it would run for a minute or two, and then shut right off again.

Happened about 7 times...

No real warning, no funny noises, just all of a sudden, off she goes.

I finally decided to park it at a local business and hitch a ride back to work. Before I left though, I was looking at my fuel filter - I have one that sits in line just before the split that goes to each carb bowl. It's glass, and i could see what looked like a little bit of bubbling in there. I have rubber fuel line going up from the fuel pump to the carb right at the front of the block and i am wondering/guessing if I could be boiling the fuel and causing the problem I had yesterday.

Anyone have any thoughts on that? If that's what the problem is, any suggestions on how to either reroute or fix?
 

·
BillyMagg
Joined
·
306 Posts
So I built a 468 and put it in my 79, and while I am working out the details on drivetrain upgrades (another topic for another thread) so I don't tear too much up, I have been driving it to work and having a blast.

I don't currently have a thermostat installed, and the weather here has been pretty mild. Car hasn't been running over 180 degrees. Yesterday, it was in the mid 80's and when I went to lunch, I ended up getting in some stop and go traffic. the motor got up to just over 200 degrees, which didn't really bother me, but then the car shut off. I was able to start it, and it would run for a minute or two, and then shut right off again.

Happened about 7 times...

No real warning, no funny noises, just all of a sudden, off she goes.

I finally decided to park it at a local business and hitch a ride back to work. Before I left though, I was looking at my fuel filter - I have one that sits in line just before the split that goes to each carb bowl. It's glass, and i could see what looked like a little bit of bubbling in there. I have rubber fuel line going up from the fuel pump to the carb right at the front of the block and i am wondering/guessing if I could be boiling the fuel and causing the problem I had yesterday.

Anyone have any thoughts on that? If that's what the problem is, any suggestions on how to either reroute or fix?
Well you are concerned about heat, so first I would install a thermostat? its possible that you are getting some kind of a vapor lock??? but my first thought is possibly some kind of accelerator pump leaking or whatever and interrupting your fuel flow?? bubbles could be coming from air entering your fuel system.

with the engine kold, pull your fuel line and your coil wire, place the end of the fuel line in a container and crank it until you observe the fuel coming out of the line, it should be the fuel diameter of the fuel line in a very steady stream, if not you may a leak or blockage in the fuel line or a bad fuel pump.

I have heard fuel boil in the bowls with a severe over-heat condition?? so if all the other tests come up fine, warm the engine up to operating temp. Shut it off and listen to see if you hear the boiling hissing???

above all have a suitable fire extinguisher handy, more importantly make sure the fuel has no source of spark or ignition??
 

·
Registered
'70 Esprit TA clone Pontiac 400
Joined
·
1,039 Posts
The quick check for overheating fuel lines is to wrap them in aluminum foil anywhere they are near a heat source like headers/exhaust or engine block.

That said, you didn't mention if the fuel tank was new/clean? New sock on pick up? Tank properly vented? Lines replaced? New fuel pump? Mechanical or electric pump? Pressure regulator? Rubber sections between tank and carb all new and rated for fuel? Possibility of your rubber hose kinking when it gets hot? Return line from pump or regulator? Charcoal canister functional?

Were you able to drive it home once it was cooled down?

Sounds like you were filling up the carb cranking it over to get it restarted but you weren't getting enough volume to keep the carb filled once it was running. So it would run till the flow couldn't keep up with demand.

It's common practice to use a gutted thermostat or a reducer if you don't want a thermostat. Might consider it.
 

·
Registered
Joined
·
576 Posts
Do you have a return line from your fuel pump back to the tank? These new ethanol fuels have a much lower boiling point. A return line helps keep the fuel cool by keeping it moving.
 

·
Registered
Joined
·
15 Posts
Discussion Starter · #6 ·
Thanks for all the responses - I got called out of town for work, so it delayed my responses back.

About two hours after I parked it at a local business, I went back and it completely cool. Started it up and drove it home with no problem.

Never got over 180 degrees.

The gas tank and sock filter are completely clean. All new rubber hoses rated for fuel. Hard lines are original. Brand new Edelbrock mechanical fuel pump delivering around 6 PSI fuel pressure. I don't have a fuel pressure regulator. the tank is vented, but i have no return line back from the fuel pump. The Edelbrock didn't have provision for that like the original pump did. I also have no charcoal canister line either.

Later, I started it up and drove it around to get it up to temp - 180 degrees, then let it idle in the driveway until it finally got up to just over 200 degrees. It started intermittently doing the "bubbling" in the glass fuel filter again, but never stalled out. Hit the throttle a few times, but it stayed lit.

I thought about wrapping the fuel line in header wrap, but that stuff is too high dollar for the little bit i would need.
 

·
Registered
Joined
·
1,013 Posts
You said you saw bubbles in the fuel filter, you might want to check for a leaky line between the tank and the pump. You may be sucking air in somewhere, even if it doesn't appear to be leaking fuel.
+1

This is what I thought of right off the bat...Good luck man.
 

·
Premium Member
Joined
·
5,002 Posts
My 470 could never run a Mech fuel pump. It always got vapor lock in the line when the weather got warm. Put a Holey Blue elec pump in and never a issue again
 

·
Registered
Joined
·
1,013 Posts
Zippy,

Is that a Fuel Tank Electric Fuel Pump or one in the engine compartment (Pull/Pusher) type?

The reason I ask is the guy put a Holley 110 psi fuel pump on the gas tank of the white TA I own, and I was not going to use it, I prefer to keep it sucking towards the engine compartment, with my past and fires...lol

I did not think having 110 psi gasoline pissing all over if the line blew a leak...

Last thing.

500 horse engine 400 built to 455

850 Holley

what type of fuel pumps can and will work. to supply under demand?

Thanks, and great seeing ya again
 

·
Premium Member
Joined
·
5,002 Posts
Zippy,

Is that a Fuel Tank Electric Fuel Pump or one in the engine compartment (Pull/Pusher) type?

The reason I ask is the guy put a Holley 110 psi fuel pump on the gas tank of the white TA I own, and I was not going to use it, I prefer to keep it sucking towards the engine compartment, with my past and fires...lol

I did not think having 110 psi gasoline pissing all over if the line blew a leak...

Last thing.

500 horse engine 400 built to 455

850 Holley

what type of fuel pumps can and will work. to supply under demand?

Thanks, and great seeing ya again
110PSI? No I think you mean 110 GPH. Carbs only need 4-5 PSI. The Holley Blue is 110GPH and 14PSI max. Mine is at the tank. They don't like to suck long distances. There better at the tank. They actually need to be installed below the fuel line for priming. No worries of fuel leaks under pressure if you use good lines and fittings. I ditched the stock metal line for a Hydraulic hose with AN fittings on the ends. Hose runs from pump at tank to just under the pedals where they come through the firewall. There I swapped to Stainless Braided. Don't need the looks under my car and Hyd line is way cheaper than stainless. Yet it is still metal braided, Rated for many times the pressure, and is approved at the race track. Under the hood, the stainless line runs to a Pressure regulator. There it drops to 4PSI for my Q-Jet. Never had a delivery issue with my 500+ HP. But when I had a manual pump, it couldnt keep up to the aceleration forces.

Only thing I will change on this rebuild is the addition of a return style regulator. I had a Dead Head type before. And where it makes no real difference to the pump, (the pump has a internal bypass at 14psi) It makes the pump quieter. With the metal line it was real loud, the Hyd makes better, but a return style will make it even quieter. And help keep pump cooler.

My pump lasted 5-6 years before the brushes went.
 

·
Registered
Joined
·
4,254 Posts
"...what type of fuel pumps can and will work. to supply under demand?..."

RobbMc. They offer a 550hp version, and an adjustable 1100hp version. I've got one of these, along with 1/2" alum line, on my 455 bracket car. A friend ran one on a 4.5" stroker(755hp) dirt track engine(elec pumps not allowed). It had a 1050 Dominator carb on E-85--no fuel supply issues.

The RobbMc is available with a return line.

http://www.robbmcperformance.com/products/pontiac550.html

http://www.robbmcperformance.com/products/pontiac1100.html
 

·
Registered
Joined
·
4,254 Posts
My 470 could never run a Mech fuel pump. It always got vapor lock in the line when the weather got warm. Put a Holey Blue elec pump in and never a issue again
Back in the old days I kept a stock pump on my 455 bracket cars, just for putting around in the pits and back down the return road. I had an electric, with a built-in regulator(Carter or Holley), back at the tank, as a pusher pump. Turned it on just before staging, then off, just passed the finish line. Still used 3/8 line, and inline NAPA 3033 filters. Never had a supply problem, to the Q-jets. But then we only ran down into the low 12's and high 11's--about 400hp/500ft lbs, maybe ?

Back when I first started racing, with my '69 GTO Stocker, we were not allowed to run elec pumps. To cool the fuel in the pump-to-carb line, we kept lots of clothes pins in ice/water, then clamped all of 'em we could, on the metal line, then changed 'em out after a run, and again right before the next run. I saw this suggested in a Hot Rod mag. It worked. And I've got pictures to prove it. :yes

Later, I mounted a "cool can", which contained a coil of fuel line, which ran thru the ice filled can. The elec pump & cool can combo cured all our hot fuel issues, at the track. Of course, this would not be feasible for a street car.
 

·
Registered
Joined
·
1,013 Posts
Here is my question.

I would prefer not to have to modify anything back at the tank.

I really dont think I want to switch the Holey Fuel system over to my blue bird.

I also am not a big fan of mechanical actuated pumps, (factory)

Is there an Electric Fuel pump that can be in the engine compartment that can meet the demand?

I see You put up some mechanical ones rated at 550 AND 1100 hp. I guess I could run one of those in worst case...

I also guess Ill look up the Holley stuff maybe its not an act of congress to install...I have regulator and all require parts...

But I will show you why I dont want one pressured to 110...

I will be cleaning this up next time I work on TAs, since Ill b e pulling the engines and swapping plus adding the Tremic 5 speed...

Here is the pic, as you can see the red stuff....all over the engine and intake. That was a blown fuel line coming off a Holley Fuel pump mounted at the tank...
 

·
Registered
Joined
·
4,254 Posts
"...But I will show you why I dont want one pressured to 110..."

Those electric pumps don't make 110lbs of PRESSURE. :no

Some of those which are intended to use a regulator make about 14lbs of pressure--NOT 110lbs. :no

So, unless your regulator is set too high, or fails, 14 psi should not cause any problems. You can use either metal line, fuel injection hose, or high dollar braided fuel line, to insure that your line will have no problem handling the 14 psi. You definitely don't want a fuel leak, with the fuel at 14 psi. :no

The Holley "black pump" mentioned, is said to be "Preset to approx. 14 psi".

http://www.jegs.com/i/Holley/510/12-815-1/10002/-1?CAWELAID=1710692240&CAGPSPN=pla&gclid=Cj0KEQjwoYi4BRDF_PHHu6rI7NMBEiQAKZ-JuPOGjquBPlXrftb6wQ3uq5UyYbNmPcnEYKicBz_FOxMaAsCK8P8HAQ

Max pressure for the red Holley pump is 7 psi. Many don't use a regulator with this pump.

http://www.summitracing.com/parts/hly-12-801-1/overview/

There's also a blue Holley pump.

http://www.summitracing.com/parts/hly-12-802-1/overview/

The Holley pumps can be rebuilt.

http://www.summitracing.com/search/brand/holley/part-type/fuel-pump-rebuild-kits

For street use, I've read that some guys plumb in 2 electric pumps, in case one fails. Also, if you don't use a mechanical pump, you can run all the fuel line to the passenger side of the car. :yes
 

·
Registered
Joined
·
1,013 Posts
Yep thats what was done...

Ooops...

The fuel lines were run up under passenger side of vehicle...Looks like I will have to just bite the bullet...

Crawl under the car and remove the Holley stuff get all new higher pressure rated lines, and re build the system.

I already have the 08 AN connectors I believe I will have to see if they are 06 or 08 I think 08 right at Half inch...

I will see if I can go Holley Pump, shoot may as well save the equipment and set it up right...

If I run into major issues I will switch to the mech for 1100 horse engine that one for 275...

Thanks guys.

Cannon13

Did you ever get your solved ?
 

·
Administrator
1994 Firebird Formula 381ci LT1 / TH400+GV O/D
Joined
·
14,425 Posts
If you are looking at that kind of HP, you want a -10AN feed line in the suction from the tank to the pump. You do not want any sharp 90's in the route. If you have to use a 90 at the tank outlet, make it a long radius elbow if possible. You want the inlet to the pump to be as low as possible, in no case above the minimum level in the tank. You do not want to loop the suction line up over the axle, and locate the pump in front of the axle, at least not without a check valve.

You do not want any appreciable pressure drop or heat transfer into in the suction line. You do not want head loss because the pump is above the fuel level. Due to the high vapor pressure of gasoline, any appreciable pressure loss can cause the fuel to flash to vapor. The whole thing is defined by a calculation called net positive suction head (NPSH). Once you get to the pressure side, you should be able to use a -6AN line. I run 800 HP off a -6AN line, but that is a high pressure (58psi) fuel injection setup. The problem with making the line too large is that while it will reduce pressure loss on the pressure side of the pump, the larger mass of fuel can cause a sudden loss of pressure on a hard launch (1+ G), when the mass of the fuel pushes backwards on the pump discharge. That's just the time when you don't want the fuel pressure to suddenly drop.

Note that NHRA rules prohibit the use of rubber fuel lines (non-OEM), except for a short length (12-inches max, total) at the engine compartment to absorb engine flex. Except for braided S/S lines, when run next to the flywheel/bellhousing area, the fuel lines must be enclosed in a 16-inch length of steel tubing, 1/8-inch minimum wall thickness. Fuel lines cannot be run in the driveshaft tunnel.

Make sure to run the lines clear of the exhaust system, and use a quality insulating material if you are close to anything hot. The DEI Heat Sheaths are pretty good, with both a thin aluminized layer to reflect the heat, and a thin internal fiberglass insulating layer.
 

·
']['exXxas']['itan
Joined
·
759 Posts
Fred. Im not sure of the NHRA or IHRA requirements for the fuel system but Im going to run -10 braided from tank sump to 20micron filter screwed into the pump. Will have the regulator connected directly to the pump output with the bypass hose -8 going back to the other baffled bung in my sump. -8 braided from regulator to .500" aluminum tubing, insulated clamped to body/subframe connectors all the way to the firewall, then -8 to fine filter, and of course -8 split to 2ea -6 flex to the carb bowls. Will this meet NHRA requirements? Should support up to 600hp easy? All fittings will be the smooth radius types, not those 90 degree sharp turn types, even on the return line.

Ive always seen the regulator at the firewall but why mount it there and have to run a return line all the way back???....seems counter productive to have to run 2 lines with more changes of leakage. Any NHRA rules that prohibit the regulator from being mounted in the rear of the car?
 

·
Registered
Joined
·
1,013 Posts
Ah-OK?

lol

Now thats an explanation...Holy Bat Goggles. Im still trying to wrap my head around that one...

Thanks.

I get head pressure is downward from a Volume of fuel in tank above.

I appreciate the help with routing and securing with heat protection, also what areas to avoid.

Nice to see ya, and thanks for the heads up.
 
1 - 20 of 23 Posts
Top