fueling question

[mccarthy69]

car and setup:
1987 bmw 325 (e30)
turbocharged
ms1/extra
16 gallon fuel cell
8an to FI tech fuel pump rated for 500+hp
6an from pump to rail and return
adjustable fuel pressure regulator with gauge

I have finally found some time to get the tune dialed in on my bmw e30 turbo. Starting tuning ve and got most of the cruise and idle dialed in anything less than 100kpa . I started to get into boost however it would start to run lean , i would up the ve value in a few cells in the area (viewed the log) and retest. same thing happened so i adjusted again, and again, and again.. until my values at ~110kpa and ~4000rpm are over 200 in the ve cell. idle and cruise are around 40-80ish. car has 42lb injectors batch fired 3 and 3. duty cycle never went above 50% so i dont think ive maxed the injectors out.

This didn't seem right so i started doing some basic diagnosis, what i found is when i revved the engine my fuel pressure dropped on the gauge. the regulator has a vacuum/boost port which is connected and should increase pressure when revved up however this was doing the opposite. i disconnected that which in theory should just hold a constant pressure, revved up and pressure still drops. made sure there is gas in the fuel cell and there's about half a tank. I figured maybe a bad regulator. i clamped off the return hose after the regulator (should rule out the regulator from regulating pressure) rev it up and still drops pressure. so i'm here to question my setup with the fuel cell and lines or a possible bad pump. Looking to see if anyone else has set a car up like this and had this issue before? i added a picture of an elbow i am questioning and a drawing of my setup(sorry its not that great)

Is this 90 degree elbow 8an too restrictive off the fuel cell?

https://photos.app.goo.gl/855d7tWcsmMk3bMM9

[dsobering47]

Every car I've seen will drop fuel pressure when you rev it... but it depends how much. What is your idle pressure? How much does it drop? What is the max pressure? Are you getting max voltage to the fuel pump to actually output max pressure? What pressure regulator are you running?

[hkv]

your fuel system looks like its set up great based on that diagram. the filter pre pump should be 100 micron and the filter post pump should be 10 micron. make sure the filter pre pump isn't finer than 100 micron. I don't think the elbow off the fuel cell is causing the issue at all.

funny enough I had the exact same issue your experiencing and it was due to a rusty fuel tank with sediment clogging up the fuel pickup. it supplied enough fuel to idle but anything more than that and the fuel pressure would drop and the engine would starve. definitely sounds like a supply issue, is the fuel cell new? I would double check anything you think is suspect.

and by the way to dsobering; a vacuum referenced fpr like the op is talking about does in fact raise the fuel pressure off idle as the engine decreases vacuum. an engine that's set to 58/59 psi for example will usually idle at around 55psi

[hkv]

check your fuel pump wiring/ground and try datalogging or monitoring your fuel pressure while trying to drive

[mccarthy69]

Every car I've seen will drop fuel pressure when you rev it... but it depends how much. What is your idle pressure? How much does it drop? What is the max pressure? Are you getting max voltage to the fuel pump to actually output max pressure? What pressure regulator are you running?

regulator set at 60psi will stay there at idle , once throttle starts to open, pressure drops down to lower than 20psi. I understand that there should be some drop i pressure but 40psi seems too high. also it does this even when the return is blocked ie: the regulator cant bleed excess pressure back to tank.

[mccarthy69]

check your fuel pump wiring/ground and try datalogging or monitoring your fuel pressure while trying to drive

ill double check voltage tomorrow, i had checked amperage and was steady at 11amps at all times. Unfortunately i don't have a way to log fuel pressure, there isn't any fuel pressure sensor to connect to megasquirt , i may get an extension for the gauge so i can see it while driving

[mccarthy69]

your fuel system looks like its set up great based on that diagram. the filter pre pump should be 100 micron and the filter post pump should be 10 micron. make sure the filter pre pump isn't finer than 100 micron. I don't think the elbow off the fuel cell is causing the issue at all.

funny enough I had the exact same issue your experiencing and it was due to a rusty fuel tank with sediment clogging up the fuel pickup. it supplied enough fuel to idle but anything more than that and the fuel pressure would drop and the engine would starve. definitely sounds like a supply issue, is the fuel cell new? I would double check anything you think is suspect.

and by the way to dsobering; a vacuum referenced fpr like the op is talking about does in fact raise the fuel pressure off idle as the engine decreases vacuum. an engine that's set to 58/59 psi for example will usually idle at around 55psi

the fuel cell was bought brand new as well as the fuel pump/lines/filters but the car sits for extended periods of time without running. it is a plastic cell and has a foam insert. perhaps some foam came apart and got into the lines or some other type of contamination from the car sitting. ill double check the filters also.

thanks for all the replies

[hkv]

the fuel cell was bought brand new as well as the fuel pump/lines/filters but the car sits for extended periods of time without running. it is a plastic cell and has a foam insert. perhaps some foam came apart and got into the lines or some other type of contamination from the car sitting. ill double check the filters also.

thanks for all the replies

I would bet that's what the issue is. I didn't think about foam but depending on how old it is its very likely that your foam is degrading and bits of it have clogged up the pre filter. foam is known to break down and clog up a fuel system they say it only lasts several years from what I hear but if you let it sit with old gas for extended periods that's even worse.

[The Dark Side of Will]

ill double check voltage tomorrow, i had checked amperage and was steady at 11amps at all times. Unfortunately i don't have a way to log fuel pressure, there isn't any fuel pressure sensor to connect to megasquirt , i may get an extension for the gauge so i can see it while driving

11 amps seems excessive. Have you asked FI tech if that's what you should be seeing?

[mccarthy69]

I would bet that's what the issue is. I didn't think about foam but depending on how old it is its very likely that your foam is degrading and bits of it have clogged up the pre filter. foam is known to break down and clog up a fuel system they say it only lasts several years from what I hear but if you let it sit with old gas for extended periods that's even worse.

Update on this. I drained my fuel cell and removed it as well as the pump and 2 filters, what I found was some small metal shavings in the cell as well as some pieces of the foam insert from the cell after removal of the main insert, sitting in the bottom. I opened the pre filter and was a few pieces of the foam in the chamber leading to the filter element as well as some bits and pieces in the filter element itself . No sign or evidence that any made it to the pump but I'm sure it caused some sort or restriction . I cleaned everything and re installed . I didnt put the foam back in the cell . Refilled and ran the car , didnt seem to drop as much pressure free revving but I havent taken it for a drive to monitor the results yet.

[hkv]

Update on this. I drained my fuel cell and removed it as well as the pump and 2 filters, what I found was some small metal shavings in the cell as well as some pieces of the foam insert from the cell after removal of the main insert, sitting in the bottom. I opened the pre filter and was a few pieces of the foam in the chamber leading to the filter element as well as some bits and pieces in the filter element itself . No sign or evidence that any made it to the pump but I'm sure it caused some sort or restriction . I cleaned everything and re installed . I didnt put the foam back in the cell . Refilled and ran the car , didnt seem to drop as much pressure free revving but I havent taken it for a drive to monitor the results yet.

good call ditching the foam. heres hoping that was the issue.

[kingclutch]

8an to FI tech fuel pump rated for 500+hp

OP, slightly off topic but it seems youre one of the only people using this fuel pump. What do you think of the pump? I Went with a walbro 255 and the terminal snapped when gently snugging up the lead, had to solder it to get the car running but want to replace the pump. Summit wouldn't replace it for warranty and the quality made me want something else, especially since the fi tech pump is cheaper. thanks

[ForcedFirebird]

8an to FI tech fuel pump rated for 500+hp

OP, slightly off topic but it seems youre one of the only people using this fuel pump. What do you think of the pump? I Went with a walbro 255 and the terminal snapped when gently snugging up the lead, had to solder it to get the car running but want to replace the pump. Summit wouldn't replace it for warranty and the quality made me want something else, especially since the fi tech pump is cheaper. thanks

I have completely abandoned Walbro at the shop after a few failures (almost all of them are clones anymore). Went to Aeromotive where I can buy directly from the manufacturer - they have a drop in solution much like Walbro at a similar price point.