Fuel Pressure Regulator plumbing

Hoping one of you GRM'ers have experience with AEM adjustable fuel pressure regulators. I bought their universal AFPR for my V6 MR2 project. I'm getting tons of fuel through the return and no pressure to the engine.

The only thing in the instructions about the ports:

"b) The two inlet ports are tapped with a 9/16-18 thread. The fuel pressure gauge port is tapped with a 1/8-27 NPT. c) The outlet port is located at the bottom of the fuel pressure regulator. It has a 9/16”-18 thread. You may purchase a 7mm barb fitting from AEM part number 25-390."

So here's what I've got, based on my interpretation:

1. Supply from pump. 2. Outlet to engine. 3. Return

Anyone else run into this? Seems like maybe the return and supply should be switched, but directions don't read that way.

Thanks!

"two inlet ports" to me does not mean a supply and return.

is this specifically mentioned as a return style regulator? there is a difference. like you're blowing straight through one supply port through the other back to the tank

nope. other side is supply to engine. you have the barb in the wrong place. its all in the sentence structure. since they mention the return barb fitting right after they mention the bottom outlet port, it implies the return is at the bottom, which is aligned to my aeromotive one which looks identical. switch 2 and 3.

-J0N

Somthing is wrong here. For a system with a return I think it should be hooked up as follows

The fuel should come from the pump to the rail.
A line then goes from the rail to the FPR Then the line goes from the FPR back to the Tank.

Your FPR has two inlet lines. On V6 and V8 motors they some times will take a line from each rail back to the FPR.

I would block off one of the Inlets (#1 or #3) and run a line from the fuel rail to the other one (#1 or #3 in your photo depending on the one you blocked off)

The return line that goes back to the tank should be connected to #2 on eh bottom of the regulator.

So you can understand how this work.

Fuel is pumped to the fuel rail and then goes to the regulator. The regulator restricts the flow out of the fuel rail by restricting the flow back to the tank. Thus creating pressure.

It is not intuitive at first as logical you would probably assume that you want to put pressurized fuel in to the rails when in fact you want to restrict the flow out of the rail back to the tank to create the pressure in the rail.

Make sense?

jm thunderbird turbo wrote: nope. other side is supply to engine. you have the barb in the wrong place. its all in the sentence structure. since they mention the return barb fitting right after they mention the bottom outlet port, it implies the return is at the bottom, which is aligned to my aeromotive one which looks identical. switch 2 and 3. -J0N

I think this would work as it would put constant pressurised fuel at rail but the return fuel is circulating through the FPR and not the rail. I do it the way I noted above as it keeps the fuel circulating through the rail providing a constant supply of cooler fuel from the tank available to the injectors. What ever the injectors wont take is sent back to the tank. This helps to prevent the fuel in the rail from boiling causing vapor lock.

In reply to dean1484: True, but if hes dead set on a return-less rail (which for most applications where engine temps remain under 220F and under-hood temps remain under 350F, it should work just fine), thats how id plumb it. i understand the concern for fuel boil, but c'mon double bowl carbs don't boil fuel till 2 minutes AFTER the head gasket blows... :P

-J0N

Yep, 2 and 3 look switched to me. Every regulator I've seen that looks at all like that design has the return opposite the adjustment bolt.

Wow...thread delivers!

The reason I did this is that the 1MZ-FE V6 I'm using is returnless, requiring a fixed 50psi, whereas the MR2 fuel system is return-style. On the donor car ('97 Avalon,) the FPR is integrated into the fuel tank.

I have a spare return-style fuel rail off an earlier Lexus 1MZ-FE. To use this FPR in your first scenario, dean1484, I think I would need to switch to that rail. Then, I would need to remove the stock vacuum-referenced FPR and crossover pipe from that rail and replace with two -AN banjos and t-fitting. That's about $60 in AN stuff, but has the advantage of possibly cooler fuel.

For cost reasons, I'll try what jmthunderbirdturbo suggests first, as it's just about free.

I'll report back.

Thanks!

I have the 2GR-FE installed with the non-return fuel rails. If you look close you should be able to figure the way I did it. The return is out of the bottom and a little harder to see.

Super clean, Scott. Thanks. What chassis is that?

In reply to Tyler H:

Lancia Scorpion

Scott_H wrote: In reply to Tyler H: Lancia Scorpion

Oh. I've driven one of those on top of a 93 MR2 NA. ;)

I can't imagine the V6 in there. Good times.

Tyler H wrote:

Scott_H wrote: In reply to Tyler H: Lancia Scorpion

Oh. I've driven one of those on top of a 93 MR2 NA. ;) I can't imagine the V6 in there. Good times.

Did you get your headers from Marc L?? Small world..

Update. Swapped my return and feed connections and voila! Steady 50psi at the rails now.

Thanks!

Cool. Post some more info on your V6 MR2 when you get it up and running.

T.J. wrote: Cool. Post some more info on your V6 MR2 when you get it up and running.

I'll add it to my garage as soon as it makes it out of the garage under its own power. Build thread is here:

http://www.mr2.com/forums/v6-owners-group/Toyota-MR2-79169-1mz-fe-swap-progress.html

Update and more uncertainty on the fuel system. Got the car running when I posted in July and I've been cleaning up a few odds and ends since then. I never let it run more than 5 minutes due to the noise.

After I let it get warm in the driveway, the fuel pump begins to slowly get noisy after about 10 minutes. It's quiet at startup, then gradually starts screaming. It's a new Walbro 255lph. If I turn off the car and immediately restart it, it is silent and then gets loud over the course of 90 seconds or so.

I suspected that the pump was outflowing the return in the AFPR, backing up and vaporizing/cavitating, based purely on intuition and no experience with custom fuel systems. I put a larger orifice in the AFPR and thought that did it, but it started to get loud after 12 minutes yesterday. Also, my fuel pressure guage was steady at 50psi, but now bounces several times per second between 47-57 with the larger orifice.

It is a 'whinebro,' but I've had that same pump in an MR2 and it wasn't ever this loud.

Anybody else run into a similar issue? Taking suggestions, otherwise I should have the car driveable tomorrow and we'll see what happens.

Took the car for a drive today. It is bogging down when the engine is loaded, about 4krpm. Certainly seems to agree that the fuel system is struggling. I'm going to blow some air through the return line to make sure it is unobstructed.

I verified that my pump came from an authorized Walbro reseller. This thing sounds like it is screaming for its life. Possible that it is just bad, I guess.

I know this is an old thread but did you ever find out what was causing this problem? We are having the same issue with our MK1 MR2 with a 1MZFE. We run it for 40 mins or so and the fuel pressure is erratic, the rpm stumbles at 4k, and the external pump whines. 15 mins or so off and she'll run another 45 minutes fine. We are running an in tank supra pump to a surge tank. An external to the rail. Both pumps are 255lph. There is an FPR on the return side of the rail. It returns to the surge then a return back to the tank.

Yeah...the chassis donor sat for a few years. There's no smell quite like 5+ year old fuel. I drained the tank before I began the swap, and then it sat for another 6 months or so that it took me to do the swap. In that time, the inside of the tank flash rusted and was clogging the pick-up sock with a fine rust sludge. Ended up using the Eastwood fuel tank sealer kit and that took care of it.

Moral of the story -- check the inside of a tank that's been out of service for a while, and it's better to store it full of fuel. It was fine when I drained it, and totally flashed over with rust 6mo later.

The whining (at least in my imagination) is when the pickup is clogged enough that the pump gets hot, cavitates, and then starts getting vapor lock. I'd recommend pulling cutting open the fuel filter and checking for rust. Dropping the fuel tank in an MR2 without a lift and with a big v6 stuffed in the back ranks right up there with one of the E36 M3tiest jobs out there. Good luck!

Question: Why are you running so much fuel pump? I went back to a stock turbo pump. The 1M isn't very thirsty.

Edit: Here's proof that 1MZFE engines don't immediately asplode as soon as they hit a race track. This one was from a spry, 232k mi Avalon.

Hey Tyler, I know this is an old thread, but I have a 86 MR2 which I have put a 1MZ-FE in and am now about to get the fuel regulator installed. I have the Aeromotive version, which will be plumbed just like your car was. I also have the returnless fuel rail line with the plastic fuel line. What did you do with the plastic fuel feed line on the fuel rail? I would like to convert all to fuel injection hose with proper fittings but am not sure how best to transition to the fuel rail?