350/454 TBI Injectors

[pomai]

I couldn't get the fuel pressure to go lower then 19 psi, even after exchanging springs and cutting the original stock one, 2 times. No matter what I did the psi stayed the same.

I disconnected the return fuel line from the TBI and tried to blow into it with my mouth and had a very hard time, so I wandered if there was a problem with the return side of the fuel system being restricted in any way, possibly causing the injectors to supply to much fuel and maybe causing the psi to stay the same no matter what springs I installed. So I connected another fuel line from the return side of the TBI and stuck the other end into a gas can and when I started the engine, the idle went right up to 2000 rpm’s. Any ideas on what happened or why the rpm's went up when I did this?

Thanks,
Ed

 

[4X4HIGH]

I couldn't get the fuel pressure to go lower then 19 psi, even after exchanging springs and cutting the original stock one, 2 times. No matter what I did the psi stayed the same.

I disconnected the return fuel line from the TBI and tried to blow into it with my mouth and had a very hard time, so I wandered if there was a problem with the return side of the fuel system being restricted in any way, possibly causing the injectors to supply to much fuel and maybe causing the psi to stay the same no matter what springs I installed. So I connected another fuel line from the return side of the TBI and stuck the other end into a gas can and when I started the engine, the idle went right up to 2000 rpm’s. Any ideas on what happened or why the rpm's went up when I did this?

Thanks,
Ed

Did fuel come out of the line and into the gas can when the engine started? It should have and if not then there is something wrong with your fuel pressure regulator. Did you remove the regulator at all and if so did you put it back together correctly?

 

[pomai]

Did fuel come out of the line and into the gas can when the engine started? It should have and if not then there is something wrong with your fuel pressure regulator. Did you remove the regulator at all and if so did you put it back together correctly?

Yes, fuel did come out and the idle went up to 2000 rpm's and coul'nt come down.

should I have been able to blow into the return line easily?
why did the idle go up like that?
I removed the gas cap before I blew into the return fuel line.

I'm installing a Aeoromotive fuel regulator but I wanted to find out what is causing the fuel pressure to stay at 19 psi
I wondered if there was a problem with the return side of the fuel system being restricted in any way, possibly causing the injectors to supply to much fuel and maybe causing the psi to stay the same no matter what springs I installed.

 

[4X4HIGH]

Yes, fuel did come out and the idle went up to 2000 rpm's and coul'nt come down.

should I have been able to blow into the return line easily?
why did the idle go up like that?
I removed the gas cap before I blew into the return fuel line.

I'm installing a Aeoromotive fuel regulator but I wanted to find out what is causing the fuel pressure to stay at 19 psi
I wondered if there was a problem with the return side of the fuel system being restricted in any way, possibly causing the injectors to supply to much fuel and maybe causing the psi to stay the same no matter what springs I installed.

No, you should not have been able to blow into the return line.

I have no idea why your RPM's went up.

Do you have an adjustable fuel pressure regulator?

 

[eagle mark]

Yes you can blow through the return line after the TBI regulator, most times. compressed air will go right through. If this is blocked up the return pressure goes from 0 to whatever... if it raises 3 lbs the inlet side goes up 3 lbs.

I've never seen injectors taken apart. But what very few people know until now is that with the help of a injector cleaning machine with flow tester you can adjust flow. Haven't you ever looked at the top of an injector? It's got an adjustment and then is lock tighed! I wouldn't doubt all TBI injectors are the same except the setting...

There's no reason to run a regulator! If you doubt the fuel presure than use a fuel pressure gauge or mount one permanent. I don't care what the books say (9-13psi) if it's not 13 psi it's not right! Although the later big blocks do run a higher presure but I forget what it is?

 

[4X4HIGH]

Yes you can blow through the return line after the TBI regulator, most times. compressed air will go right through. If this is blocked up the return pressure goes from 0 to whatever... if it raises 3 lbs the inlet side goes up 3 lbs.


There's no reason to run a regulator! If you doubt the fuel presure than use a fuel pressure gauge or mount one permanent. I don't care what the books say (9-13psi) if it's not 13 psi it's not right! Although the later big blocks do run a higher presure but I forget what it is?

My bad, i thought he was trying to blow into the return line on the injector pod not into the return line going back to the tank.

YES, you should be able to blow into the return line leading back to the gas tank.

You MUST run a regulator of some sort otherwise the engine WILL NOT run.

 

[eagle mark]

My bad, i thought he was trying to blow into the return line on the injector pod not into the return line going back to the tank.

YES, you should be able to blow into the return line leading back to the gas tank.

You MUST run a regulator of some sort otherwise the engine WILL NOT run.

OK My bad, there is no reason to run a regulater other than the one in the TBI unit!