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post #1 of (permalink) Old 01-16-2005, 09:52 PM Thread Starter
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Fuel pressure question

I have a pressure gauge hooked inline with my high pressure fuel pump. When the jeep is running, it doesn't show any pressure, but if I restrict the return line, it will build pressure. I'm wondering since the fuel is returning to the tank so fast if the TBI is getting enough. Should I restrict my return line say with a hose clamp until the gauge reads 15psi like the TBI requires or does it even matter?
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post #2 of (permalink) Old 01-16-2005, 10:33 PM
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Re: Fuel pressure question

It only takes what it needs then dumps the rest to the return line. Dont know what it would do if you blocked the return line.. It may push fuel past the TBIs regulator and make it to rich
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post #3 of (permalink) Old 01-16-2005, 10:37 PM Thread Starter
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Re: Fuel pressure question

i'm not talking blocking it, just tighten a hose clamp up enough to bring the gauge to 15psi.
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post #4 of (permalink) Old 01-16-2005, 10:53 PM
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Re: Fuel pressure question

i thought on TBI the fuel pump only pumped what it needed, and up'd its pumping on demand, as dictated by the ECM.

I imagine that too much back pressure in the system might fry your pump?

are you sure your gage is connected correctly? not to insult your skill of course, but if there was not pressure, then no fuel would be flowing ? if your gage was correct and reading no fuel pressure then your injectors would have no force behind the injection and the fuel would dribble out instead of spray.

i vote that if you donthave an huge lack of power you dont mess with it, ....and if you do, carry a spare fuel pump just in case

can you describe your setup, what TBI on what motor and so on.
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post #5 of (permalink) Old 01-16-2005, 11:00 PM Thread Starter
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Re: Fuel pressure question

there is no pressure because it is flowing back to the tank. If i take a pair of pliers to the return line and squeeze it, the pressure on the gauge comes up. The pump only pumps at a constant, it doesnt'pump more if needed. And its not about power, i'm trying to troubleshoot why my jeep back fires and just runs like garbage. Thanks for the reply.
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post #6 of (permalink) Old 01-16-2005, 11:03 PM
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Re: Fuel pressure question

Sounds like your regulator is indeed bad. It won't send excess fuel to the tank unless it has the pressure it is set at first. Since yours is showing little pressure, it isn't working.
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post #7 of (permalink) Old 01-16-2005, 11:12 PM Thread Starter
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Re: Fuel pressure question

new regulator. the regulator is doing what its suppose to do, use what it needs and send the rest to the tank. I thought it was the regulator at first too, so i replaced it. Then a mechanic told me to do the pliers trick and it works.
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post #8 of (permalink) Old 01-16-2005, 11:43 PM
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Re: Fuel pressure question

Is the timeing out?
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post #9 of (permalink) Old 01-16-2005, 11:53 PM Thread Starter
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Re: Fuel pressure question

probably, but that is not the problem. i've set the timing numerous time to no avail.
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post #10 of (permalink) Old 01-17-2005, 01:34 AM
 
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Re: Fuel pressure question

How does it run when you pinch the return line? Is the TBI unit leaky? I am thinking a fuel pump, maybe.
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