ITB Install - Fuelling Leak/Problem

[KMoore68]

Hi,

I am testing my ITB install and I am leaking some fuel and I'm struggling to figure out what the problem is.

My fuelling setup runs as follows

Tank -> Fuel Pump -> Fuel Filter -> Rail 1 -> Rail 2 -> FPR -> Return to Tank.

I have a leak at the line between Rail 2 and the FPR. I have replaced the AN fittings on the hose and still it is leaking in the same spot. I also have a leak coming of out the last injector on Rail 2.

If I pull the FPR, it doesn't seem as if there is anything in the return/output port.

I have an AME 25-302BK FPR with a Gauge on it and the gauge doesn't move at all.

I'm at my wit's end, any ideas?

[winders]

Not enough info....

Post a bunch of photos of the various pieces of the puzzle...including fittings...FPR...rails....etc.

[75 911s]

On your FPR, you're going from rail 2 to the High Pressure inlet port (1 of 2 on the AEM) correct?

The Outlet port is at the bottom and goes back to the tank. The AEM is set to 40 PSI out of the box.

It sounds like you have pressure at the end of the line at the FPR, it's causing it to leak out of the last injector and the rail to the FPR.

Like Winders said, post some pics and explain how you have the FPR installed.

[KMoore68]

Here are some pics, the first pic is with the fuel return coming from the bottom of the FPR. I unhooked this and ran the fuel pump and no fuel was coming out of this outlet.



The second pic is with the return on the second input port, it is still leaking

[TimT]

The return definitely goes to the bottom port.. Even though it says its preset at 40 psi, you need to try and adjust the pressure

What does the pressure gauge indicate when the fuel pump is running?

Re-reading your original post, you need to adjust this.. the adjustment screw looks like it is backed all the way out, which equal maximum pressure.. Which may prevent by-pass at all..

loosen the lock nut, screw in the adjuster a bit , turn on the ignition/fuel pump and see what happens..

[al lkosmal]

1st pic shows the return connected to the return port. When the fuel pump is running, what is the pressure reading at the FPR gauge? If it is over or under 40 psi, use the regulator to adjust it per the above post....if it is pegged at 100psi and the regulator cannot regulate the pressure down.....your return is blocked...

Note: If there was fuel pressure and you removed the fitting from the return port and no fuel came out...... the regulator may be afu.

[Jeff Alton]

My suggestion, and how we plumb our ITB engines....

Get a dual in single out Regulator. From your filter connector to bank 1 rail with a T fitting. Route from Bank 1 inlet over the fan to Bank to inlet from the T. Then have both rails enter the regulator. Adjust pressure as required.

Pardon the quick/poor arrow applications...

Cheers







Cheers

[winders]

Jeff,

That parallel system is not required on a lower power street system. In fact, it's not needed on a 450 HP race engine setup. An in series setup is just fine.

Your suggestion is complicating solving the problem.

[KMoore68]

After spending a bit of time with it, I believe I have corrected the fuel leak issue for my fuel lines.

In case anyone has a similar issue in the future, I was connecting the Russell 8AN Female fittings to the Female fuel rails via a male to male adapter.

The adapter has a longer end and a shorter end, the shorter end has an O ring on it. I had this adapter reversed for my leaks and had the O ring into the Russell fitting, once I switched it and I had the longer end going into the Russell fitting, it sealed 100%.

I also switched injectors to see if it was the injector or something else. It turns out the injector isn't able to seat correctly.

Two steps forward, one step back ... making progress though!

[KMoore68]

OK, so all of the new fuel connections are holding pressure, the gauge is working but the issue I am having is the return to the tank is leaking.

Here is my setup, I was going to try and add an O-ring to see if it will seal better, any ideas?

[75 911s]

The problem is likely that you have a mismatch in the AN adapter to the stock return line. The stock fuel lines are tricky, they use oddball (here in the US at least) M14-Convex 37 degree fitting. Check out Gordo's post here for an explanation of the flare types.

[winders]

The Germans don't use AN lines.....you will need an adapter.

[Showdown]

The Porsche fuel line fittings are cohline and you’ll need an adapter- washers and o-rings won’t cut it. I’m not sure if anyone makes a cohline to AN fitting so you may end up with several adapters which isn’t ideal as it introduces more points of failure and leaking.

Best option is to have the fuel return line remade with an AN fitting on one end and the original cohline (to tunnel) fitting on the other- or just replace all the fuel lines with AN stuff.


Sent from my iPhone using Tapatalk

[montauk]

I bought new tank to engine fuel lines from Len last year. I sent the engine compartment ones back to him last week to have male AN6 fittings installed for my ITB conversion. They should be here tomorrow. He makes great stuff.

You can reach out to him via email.
https://forums.pelicanparts.com/members/22236.html

[KMoore68]

I did reach out to Len about fuel lines however in doing some research, the web-site batinc.net has a fitting that looks like it should work.

I believe it is AF14AN6 which maps a concave M14x1.5 female to AN6 male adapter.

Has anyone tried that type of adapter?

[montauk]

Originally Posted by KMoore68

I did reach out to Len about fuel lines however in doing some research, the web-site batinc.net has a fitting that looks like it should work.

I believe it is AF14AN6 which maps a concave M14x1.5 female to AN6 male adapter.

Has anyone tried that type of adapter?

Sorry Kevin, I don't know if that will work or not. The Porsche stuff is odd.

I just got my modified fuel lines from Len. He put AN6 female fittings on the engine side of my supply and return lines. It was only $70 for both plus shipping. I have lines that I know won't leak.

I still have to decide on a fuel filter. I think I'll go with a canister type so I never have to take the lines apart to change it.