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Thread: running lean at the top end????

  1. #1
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    running lean at the top end????

    I had my car Professionally tuned last week and there is a problem with getting enough fuel when rpm's are up (over 3K) Tuner said flow was dropping by about 30 percent. needless to say he set it up to run a little rich so every now and then I get a nice pop- explosion in exhaust - probably gonna blow my cat out the tail - pipe lol.

    I have a boyd tank with their aeromotive pump, everything else is stock, ie injectors, rails, controller, etc. my tuner thinks it may be the piece of hose between the pickup and the pump, he thinks it may be non submersible fuel line and that it has swelled up and is constricting flow. Before I remove my seats, belts, back panel etc I was wondering if anyone has had this issue? I cant remember if I put that small short piece of hose in or if it came made up in the boyd tank?????????? if I did it, I suppose I could have put the gates injector hose there but am not sure if that's submersible. any input is appreciated, it may be something totally different.

    thanks,
    Doug

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    The pump has a filter sock on it's end. The assembly sits nearly on the bottom of the tank. When I'm tuning and the motor is lean, I'll add fuel in the tune and if the AFR doesn't get richer then I have a fuel delivery issue. Either the pump system isn't supplying enough or I've reached 100% duty cycle on the injectors.
    Wayne Presley www.verycoolparts.com
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    Senior Member STiPWRD's Avatar
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    I have the same tank and pump and recently took a few pictures of the pump assembly. Mine came assembled inside the tank from Boyd. The reason I took it out was to see the bottom of the pump inlet because I was considering putting in hydramat, also to siphon out year old fuel.
    IMAG1856.jpgIMAG1855.jpg

    I'm curious how much boost your running? And if everything is stock then why did you need a tuner? A few other things can cause a lack of fuel such as a bad injector, fuel pressure regulator not hooked up to a vacuum reference, clogged fuel filter, kink in the fuel hose, etc...

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    My Boyd tank was supplied with non-submersible fuel line. It also came with an Aeromotive pump that wouldn't put out enough fuel even to run at idle. My tuner tested it on the bench and found low fuel flow. He didn't have much good to say about Aeromotive, but I presume there are a lot of them out there working fine. Boyd sent me a new Aeromotive pump, but I had already replaced it with a Walbro and of course replaced the fuel line as well. All works well now, but as Doug said above, it was a major pain to sort out the problem.

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    Quote Originally Posted by idf View Post
    My Boyd tank was supplied with non-submersible fuel line. It also came with an Aeromotive pump that wouldn't put out enough fuel even to run at idle. My tuner tested it on the bench and found low fuel flow. He didn't have much good to say about Aeromotive, but I presume there are a lot of them out there working fine. Boyd sent me a new Aeromotive pump, but I had already replaced it with a Walbro and of course replaced the fuel line as well. All works well now, but as Doug said above, it was a major pain to sort out the problem.

    Yep, my problem exactly. Finally got her fixed and wow! Power galore, really makes you grin. No more pop in with the exhaust either. I had a Boyd tank also, with the aero motive pump, not sure if the hose was submersible or not, I called Boyd they said it was but I swapped that out when I changed the pump out to a walboro. My tuner said he has seen issues with the aero motive pumps. My tuner is going to touch up the tune now that it is getting all the gas it needs. Something else to note about the Boyd tank..... The rubber gasket that gets sandwiched between the aluminum already looks like it is falling apart, like it wasn't made for gas. I am going to call Boyd about this tomorrow to see if they have a replacement material that is going to hold up better.

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    Sorry to say, I still have the issue after: still running lean at the top end. the real problem is it is intermittent and there aren't to many things that cause it to go lean. I have done some things to see if they were issues but to no avail.

    installing walboro pump
    swapping dampeners
    swapped out the fuel hose in my boyd tank
    checked for vacuum block -
    There are a few other fuel parts I changed also

    running:
    stock rails
    stock turbo
    stock injectors
    walboro pump
    boyd tank
    pro tuned

    the only time I can get repeatability is when I drive for around a half hour, then it starts running lean when boost goes over 0. if I keep my foot out of it and the rpms under 3000 it runs fine. it also starts fine.

    to complicate things it runs awesome up to a half hour or so.

    Has anyone had a problem like this, to me its related to heat but I am not overheating anything that I can tell, my oil temp is around 150 at the pan and doesn't go over 180.

    What is heat doing? and to what parts? sensors?

    thanks for any input.

    Doug

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    Senior Member STiPWRD's Avatar
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    This sounds like a fuel pressure regulator issue. Fuel pressure is supposed to increase under boost to compensate for the extra air. It could be that you have a bad vacuum reference to your FPR or the FPR itself has gone bad. If you install a fuel pressure gauge and monitor it while driving, that should tell you if fuel pressure increases with boost.

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    Quote Originally Posted by STiPWRD View Post
    This sounds like a fuel pressure regulator issue. Fuel pressure is supposed to increase under boost to compensate for the extra air. It could be that you have a bad vacuum reference to your FPR or the FPR itself has gone bad. If you install a fuel pressure gauge and monitor it while driving, that should tell you if fuel pressure increases with boost.
    I am going to need to check my files but I am pretty sure my tuner put a new pressure regulator in. The car runs great under wot until things heat up (after about at least a half hour)

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    Quote Originally Posted by dougkirkbride View Post
    I am going to need to check my files but I am pretty sure my tuner put a new pressure regulator in. The car runs great under wot until things heat up (after about at least a half hour)
    Is your FPR stock or aftermarket? I also have the Boyd tank and Aeromotive pump and I've noticed the stock FPR has a hard time keeping up with the increased flow of the new pump (at full power) so I'm planning to upgrade my FPR. Also, I assume you're running the stock fuel controller? This was designed for the stock pump and isn't meant for the higher current of your aftermarket pump so it could be having an issue providing enough power at WOT.

  10. #10
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    I'd replace the Aeromotive fuel pump
    Wayne Presley www.verycoolparts.com
    Xterminator 705 RWHP supercharged 4.6 DOHC with twin turbos

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    Quote Originally Posted by STiPWRD View Post
    Is your FPR stock or aftermarket? I also have the Boyd tank and Aeromotive pump and I've noticed the stock FPR has a hard time keeping up with the increased flow of the new pump (at full power) so I'm planning to upgrade my FPR. Also, I assume you're running the stock fuel controller? This was designed for the stock pump and isn't meant for the higher current of your aftermarket pump so it could be having an issue providing enough power at WOT.
    I am running a new subaru "stock" FPR and yes the stock fuel controller.

    But everything works fine till about a half hour of runtime.

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    Quote Originally Posted by Wayne Presley View Post
    I'd replace the Aeromotive fuel pump
    I have I am running the walboro now.

  13. #13
    What size walbro are you running on the stock controller? I know they can't handle much more then a 255.

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    Quote Originally Posted by redfogo View Post
    What size walbro are you running on the stock controller? I know they can't handle much more then a 255.
    I am running the 255HS walbro.

    Question: does anyone run the pump 100%using battery power and a relay and skip the fuel controller? what issues might this create? due to the fuel controller having a heat sink on it and my issue seems to be heat (last night it was 90 degrees out and it only took 15 minutes to act up, before when ambient was 60 it would take about a half hour to create a lean condition) I think maybe its got something to do with the fuel controller.

  15. #15
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    Quote Originally Posted by dougkirkbride View Post
    I am running the 255HS walbro.

    Question: does anyone run the pump 100%using battery power and a relay and skip the fuel controller? what issues might this create? due to the fuel controller having a heat sink on it and my issue seems to be heat (last night it was 90 degrees out and it only took 15 minutes to act up, before when ambient was 60 it would take about a half hour to create a lean condition) I think maybe its got something to do with the fuel controller.
    I tried this and (I suspect) my stock FPR couldn't handle the pump running at 100% while idling - it ran but my AFR was very rich. I'm going to install a pressure gauge and aftermarket FPR to try and fix the issue. Make sure you use the proper gauge wire for the max current your 255 pump will pull. I think I got some 10ga from home depot for my 340. Ran the wire from the battery to pump with fuse and relay in between (so I wouldn't have to manually switch on the pump each time). Your fuel controller overheating sure sounds like a possibility. You can try measuring the temperature of the heat sink while driving or monitoring fuel pressure.

  16. #16
    I looked for the model year of your donor and didn't see it. You are being pro-tuned, so this is an outside possibility, but there was an issue (early in the tuning cycle for EJ engines in the US) with the transition from closed-loop to open-loop in the fueling system. I'd ask your tuner what they are doing to smooth out that transition (I remember it being an issue around 3K on boost).
    818SC chassis #206 EJ207 2.0L VF37 twin scroll || Cusco type RS 1.5 LSD || Wilwood pedal box (firewall attach) || Wilwood superlite front calipers
    BUILD Phase 1: 6/6/2014 car delivered || 5/24/2015 first start || 6/7/2015 go karted || 4/20/2016 hard-top-topped || 10/25/2016 registered || 11/18/2016 inspected & complete
    BUILD Phase 2: 3/8/2017 EJ207v8 || 5/29/2017 re-first re-start || 7/17/2017 re-assembled with race car bits

  17. #17
    I know a lot of folks hard wire there fuel pumps without having any kind of problems. The only problem is the pump running 100% at all times and you might burn up the pump sooner then later. The pumps in the 818 isn't the most fun to get to with fixed racing seats so I didn't want to deal with it. If your over heating you can get an after market fuel pump controller. I like my DCCD fuel pro it works great and other Subaru folks are using it with great luck.

    https://www.dccdpro.com/product/fuelpro/

  18. #18
    Senior Member STiPWRD's Avatar
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    Quote Originally Posted by redfogo View Post
    This looks interesting, how did you wire the 5V demand signal?

  19. #19
    http://redfogo.com/index.php/wiring/

    Fuel Pump controller (https://www.dccdpro.com/product/fuelpro/)
    Here is their install guide as well-->https://dccdpro.com/main2/wp-content...LPro_Guide.pdf

    Note: I’m running a DCCD fuel pro since I have a Walbro 450 pump.

    VW:
    ECU demand signal. This wire is needed for the DCCD pro ECU pin.
    LgR:
    Wire is just a 12V line to inform ECU the controller is alive. Connect to DCCD fuel pro with the GR(pump relay) line and Infinity box power line.
    BW:
    Connect the DCCD Pro supply Negative/ground line. This is the ground to the pump
    I removed this line altogether and used the wire directly from the pump connector so I had a B color wire to my DCCD fuel pro.
    BOr
    Connect to DCCD Pro Positive Supply line. This is the power for the pump
    I removed this line altogether and used the wire directly from the pump connector so I had a BR color wire to my DCCD fuel pro.
    BY
    Deleted since I have no fuel pump relay.
    B
    Deleted. But you will still need some kind of ground wire for your DCCD fuel pro.
    Last edited by redfogo; 05-18-2017 at 10:02 PM.

  20. #20
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    Quote Originally Posted by mikeb75 View Post
    I looked for the model year of your donor and didn't see it. You are being pro-tuned, so this is an outside possibility, but there was an issue (early in the tuning cycle for EJ engines in the US) with the transition from closed-loop to open-loop in the fueling system. I'd ask your tuner what they are doing to smooth out that transition (I remember it being an issue around 3K on boost).
    I have a 2006 WRX wagon donar when it heats up, 3000 rpm seems to be the breakpoint where it starves and sputters.

  21. #21
    If I remember correctly, around 3K was where the open to closed loop fueling transition was for stock tune; or more correctly the delay between switching tables would catch out the car with the stock tune.

    The typical fix was to 0 out the delay between switchover.

    I would expect the tuner to have already done that, but it's one of those things.

    Apparently, it's easy to test for this by comparing the MAF voltage with the stumble. The magic number is 2.5 volts @ MAF. If the stumble occurs there it's indicative of the fueling table transition (closed to open table) being the problem:

    http://www.iwsti.com/forums/ecu-tuni...osed-loop.html
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    818SC chassis #206 EJ207 2.0L VF37 twin scroll || Cusco type RS 1.5 LSD || Wilwood pedal box (firewall attach) || Wilwood superlite front calipers
    BUILD Phase 1: 6/6/2014 car delivered || 5/24/2015 first start || 6/7/2015 go karted || 4/20/2016 hard-top-topped || 10/25/2016 registered || 11/18/2016 inspected & complete
    BUILD Phase 2: 3/8/2017 EJ207v8 || 5/29/2017 re-first re-start || 7/17/2017 re-assembled with race car bits

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