Return line clogged/restricted?

[Gnx6]

The fueling on my car seems to be all over the place, one wot blast it's rich, then lean and so on. I had heard from somebody that there is some kind of a restrictor fitting in the return line as it goes down the front of the block and it is known for corroding? Does anyone have a photo of it's location? Second question is has anyone come up with a way to unclog it besides replacing all the line? My clue that this was happening was when I had to do my smog check a few weeks ago. I could not get the accufab regulator to dial down below 39 psi with the vac line off.

Thanks!

 

[TurboTnZ06]

One time I had a leaking rubber hose that someone had installed to attach the fuel pump to the harness in the tank. The symptoms of that were pressure to start it but then it would die with low pressure when it bled out of the hose back into the tank.

 

[Scooter3800]

What are you using for a fuel pump?
I know with the Denso pump (Toyota Supra) it flows too much for the stock return line. The lowest I can get my fuel pressure is around 48-50 line off. But as soon as you get on the gas a bit (no boost) the fuel pressure drops to where it should be ~43 psi. FWIW

 

[bmackinnon]

The fueling on my car seems to be all over the place, one wot blast it's rich, then lean and so on. I had heard from somebody that there is some kind of a restrictor fitting in the return line as it goes down the front of the block and it is known for corroding? Does anyone have a photo of it's location? Second question is has anyone come up with a way to unclog it besides replacing all the line? My clue that this was happening was when I had to do my smog check a few weeks ago. I could not get the accufab regulator to dial down below 39 psi with the vac line off.

Thanks!

Sounds more like the reg may be bad/sticking. A clogged return would never cause a lean condition.... rich yes, lean no. Maybe the diaphram in the reg is leaking? Any fuel apparent when you remove the vac line? I think you can order a rebuilt kit for the accufab... I would tear it apart and have a look.

 

[ESP Products]

I'm not familiar with any restricter valve in the return line. Your description is that the fuel pressure is up and then down. So it's not consistant. If that is the case, I would look into the 1- Fuel Filter 2- Fuel Pump 3- Fuel Pump wires 4- Fuel Reg. If you had a restriction it would be all the time.

Hope this helps you.

 

[Gnx6]

The car has a Racetronix fuel pump with hotwire. I'm not sure if the Fuel pressure is varying, only speculating from O2 readings.

Let me try a different angle. If I set my fuel pressure to 45 psi with the regulator and there is a restriction in the return would this affect the regulator setting? Then if the corrossion breaks free the pressure drops slightly. When I say lean the 02's were 720. They were 785 just the previous blast and the car had not been shut down. Then when I park the car (usually a month at a time) the corrossion accumulates again and regulator and restriction alter my fuel pressure again. So the next time I go out the car is rich?

Car has extender chip with Translator Plus

 

[salvageV6]

That "could" happend but as previously mentioned it will only run rich with a clogged return line.

Under the power steering pump there is the transition from rubber to metal that is most definately a clog and restriction point, not a restriction fitting per se though, just a bad design.

You need to put the gauge on it and see what happens during driving and idling on different days.

I used a coat hanger or similar steel or iron wire to clean mine out years ago, frozen smegma crap in it.

Drove for almost week with about 60psi. at idle too.

It was a tad rich.

 

[scot w.]

I just went through this very same issue on my personal car.

The fuel pressure was completely inconsistent and I had to add a bunch of fuel at WOT. I replaced the filter, I replaced the filter sock on the pump, I replaced the fuel pump, Replaced fuel pressure gauge, I sent the acufab regulator of to acufab and had it rebuilt, IT STILL DONE IT!! When I gave the car gas just sitting in the garage my Fuel pressure gauge would go down at acceleration... Red Armstrong told me over the phone that it was my return line. YEP, He was 100% right!

I went and picked up a 15 foot roll of rubber gas line and just for the test I ran it from the fuel rail along the outside of the drivers side and down to the return line of the pump, started the car, Gave it gas and the gauge went up like it should, WALA! Fixed..

At least my fuel system is completely new now!

SW.

 

[V8killR4U]

What are you using for a fuel pump?
I know with the Denso pump (Toyota Supra) it flows too much for the stock return line. The lowest I can get my fuel pressure is around 48-50 line off. But as soon as you get on the gas a bit (no boost) the fuel pressure drops to where it should be ~43 psi. FWIW

I'm experiencing the same thing, but im being told my problem is the AccuFAb FPR. That it will not adjust below 44-45 lbs with line on or off......Anyone else experience this. Ive replaced everything except the return line which i feel is the issue, guess ill just have to get one put in....

 

[salvageV6]

Take the return line off and plumb in some clean shop air at 60 psi. or so.

If you don't hear it flow whoose/whistle nice into the tank sender it's gotta be a restriction somewhere.

Then you can hunt it down where the joints are, well one joint anyway that splits the pipe/hose into 1/3 and 2/3 of the system.

 

[84BuickGNYorkPA]

Return fuel line restriction ? - TurboBuicks.com
I went through the same thing follow my link above.

Chuck

 

[V8killR4U]

OK...........you'll find this interesting.

The connector that plugs into the alternator came loose while looking under the hood. Voltage drops and voila FP drops down to like 35 lbs......

Previously the FP would not drop below 44 lbs line on or off didnt make a difference...So with connector unplugged fuel pressure acts normal like it should. Plugged in and voltage up, FP will not drop below 44lbs.

What would cause this....what do i need to check for.....is there any way to decrease the voltage going to the pump so i can adjust the FP how its should be?

 

[V8killR4U]

I just realized i posted on the wrong thread, sorry....

TTT