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Discussion Starter #1
I’m running into a strange problem that I have never seen before when the fuel pump primes the fuel system the pressure just builds each time the fuel pump primes. When I first turned the key it primed up to 60psi then I turned the key off then back on then it went up to 100psi or at least that’s how I high my gauge would read. This fuel system was fine before I had to make a couple changes to it. I’m installing an IRS in my fox body and ran into a problem with the hard lines hitting the IRS so I had to cut them and I added -6 an fittings to the hard line to run steel braided hose up to a aeromotive fuel filter that I had to add since the factory fuel filter got in the way.



I have the fuel filter going the right direction and the lines from the pump should be connected right. The car has a pro-m fuel pump hanger and I checked there site to verify the connections are right and it all looks good. The fuel pressure sensor is close to the fuel rail so I know the pressure is at least getting to the fuel pressure regulator. I also tried to unplug the fuel pump and run the car to bleed off the pressure but the pressure stayed high and didn’t go down at all. I thought there might be something in the lines at the fuel rail so I pulled the fuel rails out of the car but they are all clear. The only thing I don’t know is if there is something in the regulator. I have a kirban fuel pressure regulator in the car and I’ve always have good luck with them.

The only thing I thought of is could air in the line get trapped and cause the system to pressurize and not flow past the fuel pressure regulator? But I would figure trying to start the car would relieve pressure in the system. I also wonder if I should have taken the gas cap off the system to allow air to escape from the system when starting it. I didn’t have to do that when i replaced all the fuel lines but who knows. I’m going to put it all back together tonight and tomorrow now that I know the fuel rails and lines are clear. I also got a new fuel pressure regulator just in case there is something wrong with the one I have right now.

If anyone has anything they think I should try or look at let me know.
 

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Discussion Starter #3
The return seems fine I thought the problem was at the regulator when I disconnected the return line at the fuel rail there wasn't any gas. So I thought there is either something in the feed line plugging it after the fuel pressure sensor or the regulator is bad. I pulled the fuel rail and there was nothing in it. I sprayed brake cleaner through the feed with the fuel rail off the car and it was blowing through the feed fine. I did put a new regulator on the car just in case. I took the original one apart and I could find anything in it or anything wrong with it. The fuel pressure regulator is really basic just a diaphragm with a heavy spring above that pushes down to restrict the fuel flow.

I got the new regulator, fuel rails and intake back on the car and all hooked up last night since everything looked clear. I just need to hook up the lines from the fuel rails to the chassis hard lines. I'm going to drop the tank again double check to make sure everything is hooked up fine then check to make sure the return flows fine and just try again to see if its solved with a new regulator.
 

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put the return line in a gas container redo the prime

what happens?

why drop the tank, now? makes no sense until you do above
 

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then you could put power to the pump for 1 min exactly

then weigh it,,,,,,,,,and you can calculate the true flow at that PSIG

handy
 

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Discussion Starter #7
Here's what I know now got everything hooked back up and turn the key pressure built and nothing came out of the return into my gas can. If disconnect the pump and crank the engine the pressure doesn't go away. Before I hooked everything up I was able to blow air through the return line into the gas can I had put on the end of the chassis hard line. So the lines after the fuel rail are clear on the return side. Since I'm reading fuel pressure that should tell me the fuel is at least making it to the pressure sensor.

My guess right now since I was able to blow air through the feed line of the fuel rail that if there is a clog in the line it would have to be right after the regulator before it goes to the into the fuel rail and to the injectors. Even if one of the cross over tubes was blocked fuel should still be able to travel across the other cross over tube. The other things is if I disconnect the fuel pump and crank the engine the pressure stays the same it doesn't go down so nothing seems to be getting to the injectors.
 

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Discussion Starter #9
The system is plumped like a factory system. I have Pro-M fuel hanger with a 255lph pump running into a Aeromotive fuel filter then into the factory hard lines that run to the front of the car. The hard lines run into a Russel fuel line kit that replaces the metal lines that run to the factory fuel rails. The line for the feed line goes into the factory fuel rail connection that runs to the fuel pressure regulator. Then the return runs from the fuel rail to the hard lines then back to the tank. The fuel pressure sensor is right at the connection between the hard lines and the Russel fuel line that runs to the fuel rail.

I disconnected the line from the pump and put it into my gas can and the fuel passes through the filter fine. I then connected the from the filter to the hard lines and put my gas can at the end of the hard line and gas passed through fine. Since I have -6 an connections on my feed a return hard lines I connected them together in a loop and put my gas can at the end of the return hard line and the gas passed though fine. The only thing I can't test is the fuel rails.

Here's the parts in the system.

Fuel hanger
High Flow Fuel Pump Hanger for 1986 – 1997 Mustangs
Fuel Filter
Aeromotive Fuel Filters 12347
Fuel hard lines
Feed line
SVE Mustang High Performance Fuel Line Kit (86-93) - LMR
Return line
Mustang 1/4" Return Line For Factory Hoses & Connections (86-93) 5.0 MUR1017SS
Russel lines to the fuel rail.
Russell Mustang -6 AN Stainless Steel Fuel Line Kit (86-93) 651104
Fuel pressure regulator
Kirban Mustang Adjustable Fuel Pressure Regulator - Billet Aluminum (86-93) 5.0/5.8 5005

This fuel system was working in the car for the past year. The only change I had to make is removing the factory fuel filter and part of the hard line since they ran into the IRS cradle. The section in the picture in my original post is the only thing that changed. Here's some picture I have of some of the fuel system.













This last picture is how it was with the factory fuel filter.

 

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way too much typing

your post says

My guess right now since I was able to blow air through the feed line of the fuel rail that if there is a clog in the line it would have to be right after the regulator before it goes to the into the fuel rail and to the injectors

so which is it

be brief

pump>rail>inj>reg>return

like that?
 

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Discussion Starter #12
way too much typing

your post says




so which is it

be brief

pump>rail>inj>reg>return

like that?
I figured it out I'm stupid I had the connections swapped on the fuel rail. After seeing your last post I realized what I was doing wrong. That's what I get for not marking everything before I take it apart like I normally do.
 

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cool

BTW, in your last pic, is that an exhaust pipe just below the fuel lines wrapped in heat shield?
 

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Discussion Starter #16
Yeah the tail pipe was wrapped that picture was from when I first installed the tail pipes on the car. I realized it was to close to the fuel line since it only had a little over an inch gap between them so I wrapped the tail pipe where it goes over the axle. Thanks for your help getting the fuel issue solved.
 

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Discussion Starter #18
Its all coming out now with the IRS install the fuel lines are going to be allot further away from the tail pipes with IRS exhaust and the placement of the fuel lines and filter. It was the one thing I had planned on correcting if I kept the live axle.
 
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