rear return system questions

[jjump59]

Took my 70 GTO to the tuner, FAST XFI, aeromotive A1000 inside Ricks tank, Aeromotive return style regulator mounted at tank and Aeromotive filters. Everything is plumbed with -10 for feed and -8 for the short return. Right away he told me it would not work the way I had it, he was concerned about the fuel going through the regulator, he thought the regulator would be a restriction that would cause the engine to starve for fuel. He recomended putting an additional -10 hose using t-fittings at the inlet and outlet, bypassing the regulator to help feed the engine. Have you guys had any problems that required this kind of fix?

Second question concerns no fuel at rails during restart, I have to let the pump run two or three times before the car will start. it seems that the fuel is returning to the tank and not staying at the rails. kind of stinks having to turn the key on and off three times before it will start. any easy fixes here? maybe a check valve of some type?

thanks for the help guys.

[GetMore]

You may need a check valve to keep the fuel from draining back to the tank. I don't recall hearing about this being an issue, but you never know.
It might also be a case of vapor lock. Since there is no return near the engine the heat gets to soak right into the fuel lines, possibly boiling the fuel. This is why OEMs (usually) had the regulator on the return line, so the pump could push fuel through the lines and clear any vapor.

Now, as for the regulator, I don't know how the Aeromotive ones work, but I thought that the return style regulators work by restricting flow to build the pressure to the proper level. I think you would T the regulator off the feed line so it can bleed off the excess pressure.

[MonzaRacer]

Ok reasone regulator wont work is its not regulating properly. Your regualtor should be after the injectors, the pressure deadhead shou;ld be at the injectors. if your regulating it before the injectorsd it wont work unless its setup returnless.
Not good, you need the the regulator, right after the injectors. Dont forget you need a relay on fuel pumps, the 2 second prime before start, and an oil switch to let it run after cranking.
Oh and yes you should not have to do the repeated crank, it does mean you may have to figure out how to install a check valve (ooppss antidrainback valve).

[The WidowMaker]

i hate to disagree since im still researching this topic, but ive found A LOT of cars running your same setup. from the tank to the pump to a regulator close to the tank then one line returning to the tank and the other dead heading into the rails. a bunch of cars were running the regulator after the rails on the power tour and built up too much heat in traffic. theres no reason to circulate fuel through the engine compartment and then put hot fuel back into the tank

here is a link to the same topic on lateral g

http://www.lateral-g.net/forums/showthread.php4?t=19070

and here is what i drew up. no consideration to placement of parts, and there would be a t after the regulator getting fuel to both rails.



Tim

[68Formula]

Put a fuel pressure gage on it at the rail and monitor the fuel pressure after you shut it off. See how much you have at the time you try to restart it. If it drops off quickly, either you don't have a checkvalve in the system or it's not working.

If it goes up, your checkvalve is working, but you probably have vapor. Try enrichening the the hot restart map if possible (sorry not familiar with that ECU). If the regulator is adjustable, you could also at more pressure to see if that cures it. Due to the distance from regulator to rail, you'll have a slight pressure drop across the system.

[camcojb]

Ok reasone regulator wont work is its not regulating properly. Your regualtor should be after the injectors, the pressure deadhead shou;ld be at the injectors. if your regulating it before the injectorsd it wont work unless its setup returnless.
Not good, you need the the regulator, right after the injectors. Dont forget you need a relay on fuel pumps, the 2 second prime before start, and an oil switch to let it run after cranking.
Oh and yes you should not have to do the repeated crank, it does mean you may have to figure out how to install a check valve (ooppss antidrainback valve).

well, I guess the last 5-6 cars I've built don't work...............

Jody

[camcojb]

Took my 70 GTO to the tuner, FAST XFI, aeromotive A1000 inside Ricks tank, Aeromotive return style regulator mounted at tank and Aeromotive filters. Everything is plumbed with -10 for feed and -8 for the short return. Right away he told me it would not work the way I had it, he was concerned about the fuel going through the regulator, he thought the regulator would be a restriction that would cause the engine to starve for fuel. He recomended putting an additional -10 hose using t-fittings at the inlet and outlet, bypassing the regulator to help feed the engine. Have you guys had any problems that required this kind of fix?

Second question concerns no fuel at rails during restart, I have to let the pump run two or three times before the car will start. it seems that the fuel is returning to the tank and not staying at the rails. kind of stinks having to turn the key on and off three times before it will start. any easy fixes here? maybe a check valve of some type?

thanks for the help guys.

get a new tuner. Also, I have no problems on re-starts with it plumbed the same as yours. It's likely in the tuning. I do not have a valve or anything to hold pressure, and when the key is turned on I have full pressure in less than a second.

Jody

[thedugan]

get a new tuner.
Jody

jody knows his stuff, if he says get a new tuner. then get a new tuner

[streetk14]

Ok reasone regulator wont work is its not regulating properly. Your regualtor should be after the injectors, the pressure deadhead shou;ld be at the injectors. if your regulating it before the injectorsd it wont work unless its setup returnless.
Not good, you need the the regulator, right after the injectors. Dont forget you need a relay on fuel pumps, the 2 second prime before start, and an oil switch to let it run after cranking.
Oh and yes you should not have to do the repeated crank, it does mean you may have to figure out how to install a check valve (ooppss antidrainback valve).

I'd have to disagee as well. This is how the 99 Vette regulator/fuel filter is set up. The regulator/filter is mounted near the tank at the back of the car. There is then a short return line to the tank and a single feed line to the rails. Most cars being built right now are this way as well. It reduces evaporative emissions and reduces heat build-up in the fuel tank from recirculating hot fuel that was in the rails back to the tank.

All of the new BMW stuff I work with has a single feed line to the motor. The fuel is returned at either the fuel filter (that has a built in pressure regulator) located under the driver's seat area under the car, or inside the tank in the newest models.

I am also having problems on long drives when it's hot out with my traditional 2 line fuel system on my camaro. When cruising, a lot of fuel is being sent up to the rails, getting heat soaked and going back to my fuel tank. I'm running an early C5 regulator located on the fuel rail. After a long drive, I can hear the pitch of the fuel pump change and the car loses power under heavy acceleration about 4000 rpm. I found my fuel tank to be very warm and this was causing my fuel pump to cavitate. I will be re-designing my fuel system to have a single feed line with the regulator near the tank.

[streetk14]

Oh, and +1 on the fuel pressure guage. Check to see if pressure is bleeding off excessively. Some drop is normal, but if the pressure is dropping to zero quickly, you have a problem. The check valve is usually located in the fuel pump.