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It could be leaking past the regulator, if its not seated in that radium housing correctly? Maybe a torn o-ring or something? If the pump can supply enough pressure/volume to overcome the leak plus the regulator that would explain how it makes a "proper" 3 bar, but drops instantly but without a giant puddle of fuel.
I got nothin' for that 60psi reading wile running though, that don't make no sense. Unless you have the 4 bar one in there, but that just raises a whole bunch of other issues...
Originally Posted by aidandj
Although I'm still not 100% sure what the problem is.
Pressure when priming: ~44 psi, about on the 3 bar mark (then needle drops after prime)
Pressure when running with vacuum line attatched: ~46psi , 3.2 bar (Shouldn't it read lower, not higher?)
Pressure when running with vacuum disconnected: ~44psi, 3bar
Pressure when running the pump with test mode: ~44psi, 3 bar
I'm not sure if I have a leak. If I do, it might be at the hose/pump side. I'll have to pull the hanger out again which is fine just to be safe. It has also been the hottest day this season if that means anything for fuel temps. Everything up front on the rail and sensors haven't been touched during the pump install. I'll double check the AN fittings on the tank. All that would have to be this weekend then.
What I don't get is why it no longer holds pressure after prime (there's a check valve on both the pump and the fuel filter) unless it's just bypassing to the return. Then why it started to read 60psi under operation. Either way, this is making me nervous enough to just swap FPR's.
Yarr. And if there is no puddle, then its either in the tank or bypassing into the return at the regulator.
Mine drops, but not instantly. DW200 punp + Fulelab FPR FWIW. It does take a while to bleed back into the tank but I've never waited around to see how long it takes.
Ok, I think it makes sense. I'm still second guessing the FPR right now. As a thought experiment:
Assumptions:
- Everything is sealed fine
Observations:
- Sustained pressure after prime
- Higher than normal running pressure (4bar)
New Observations:
-No sustained pressure
-Slightly higher than normal operating pressure (hair above 3bar)
Now if there where a leak, assuming the rest of the lines outside the tank are fine, could this pressure bleeding and drop off after prime be answered by
1) The hose on the pump leaking, as though not tightened enough, the extra pressure found a path to eject some fuel, resulting in relieved pressure
2) The FPR is damaged allowing more fuel to bypass to the return
My notion is the FPR because it didn't seem like it played well with the pump initially. Then the pump just demanded more. This might be a limitation of an OEM style regulator cap. Or it could be I suck at tightening clamps. Or anything in between on the high side. Either way, I'll have to check it all and I went ahead and ordered a FuelLab 353 Mini.
Last edited by psyber_0ptix; Apr 10, 2017 at 03:39 PM.
Lastly, anyone out here using an internal 3.5bar map sensor? I had been going back and forth with Brain but he's done quite a lot for me with this VVT/knock/sequential thing I don't want to keep pestering him. I'm not confident in soldering on the MapDaddy 4 bar myself and the MPX5700 is just way more than I need. I'm supremely terrible with electronics. I'd feel more comfy wiring the AEM 3.5 Bar to a spare analog input, but didn't know if this was the way to go.
Yesterday I pulled everything apart to install new injectors, and repair the threads on the fuel rail mounts. Flyin' Miata supplied M8x1.25 x30mm bolts which had initially chewed up the leading threads. This was a bit tricky with everything open and I was worried that the tap was not gliding as smooth as it could be, and was cross cutting existing threads. Turned out OK and I had overnighted 40mm length bolts from McMaster-Carr. I'm feeling a lot better about it now. I also got new oring and cushion hardware from Flowforce but ended up forgetting the rail spacers. I didn't have time and was running out of daylight, but with the new injectors, everything seemed to fit a lot better. I rewired the injector harness with one that Raisin sent and it cleaned up the wiring quite a bit. This is the first time I didn't break out the soldering iron and just used weather sealed butt connectors because I'm starting to get jaded from the wiring work. I hope this doesn't bite me in the end. I also re-wired the VVT solenoid because I found insulation to be eroded and was grounding on the manifold. I tried to separate and isolate the Cam/Crank bundle from the old CAS wiring but ran out of daylight and it was tucked further behind the head than I could reach in the given time frame. At this point the car started again and I ran to the local store and got electronic connector cleaner. Cleaned all the ECU plugs, and all the engine related plugs and then dielectric greased everything once it was dried.
Luckily it started today. I'll try to revisit this wiring when I replace the FPR.
Tweaked ID1300 injector settings, but I think the deadtimes are going to be off until I get the fuel pressure stable. Still fired up but I found that it starts easier mid priming than waiting for the pump to stop....probably because fuel pressure drops after that. I had checked the top of the pump hanger in case the pressure line was leaking, everything is sealed up great with no smell of gas. Also no leaks under the car. If there is a leak and it's not the FPR bypassing prematurely, It's gotta be the hose between the pump and hardline in tank. Both the pump and my fuel filter have check valves, so I'm still inclined to think it's on the low side of the fuel system (FPR to return) that's bleeding off pressure.
On the way to the parts store I curbed an unseen island next to a cross walk. It follows a median, where there's a cross walk, then an island juts out. The curb is eroded from where others have done the same since there are no markers or reflective batons to identify it's protrusion into the intersection. I couldn't see it at night, probably cut sharper than I should have, and made a stupid mistake. Bent two wheels. Ordered replacements to be overnighted as well as two new tires. Things have been tough lately.
The throttle body feels more sticky than ever. It doesn't return to full closed until blipped. I think I just need to adjust that throttle stopper and back off the IAC bypass screw to just let it hang open more. It's getting annoying having intermittent high idle / high AFR (16:1) just because it's stuck reading 1-2% TPS
Action Items: Water pump/Timing Belt
Clean up spark/fuel wiring
FM Fuel Rail Flex Sensor
New Throttle Body Flex sensor wiring
Install new Oil Press/Temp, EGT, Wideband/Flex gauges New parcel shelf cover
ID1300 injector install with new orings and bushings
Retapped threads to mount fuel rail because Flyin' Miata supplied 30mm length bolts which chewed things up
Fix Coolant Leak after thermostat housing Find a new home for the Oil Catch Can
DW300 fuel pump install with feed through and upgraded relay/wiring
New map sensor
Replace two bent wheels and tires due to bad curb chomp
New FPR
Oil Cooler
Under tray + Ducting
DYNO TIME + E85
Last edited by psyber_0ptix; Apr 12, 2017 at 10:03 AM.
Go figure you get close to completion of your to-do list and more fail happens adding to the list. Glad to see you chugging along and ironing out all of these issues! LMK when dyno time happens, id like to come out and enjoy
It was a pretty sad moment. Right in my blind spot as I was making the turn and my heart stopped because I didn't know what was going on. I thought I got T-boned.
Anyway, I'm just a bit jaded from doing so much on this car, I still need to wire a new map sensor and replace the FPR to see if this solves my weird over pressure issue. Then I need to stop for a while.
Helping James with some things this weekend. I'm more worried about the leakdown and pre-dyno shake down next week. That'll determine if dyno is go for the following week.
Replaced the FPR. Pressure is way more stable and consistent. It still drops pressure. I'm going to buy some submersible fuel hose from parts store and investigate the tank. I've tightened down everything in the engine bay that I could think of. No smell of fuel otherwise. No signs of fuel on the ground.
I had a spare 6UL kickin it as a foot rest. The front wheel was replaced, tire was still fine (above post). Waiting on two more 6UL, one to replace the rear and the second will be another spare. I guess I didn't need to order two more tires. That's $300 I didn't need to spend, but hey, I can make a running spare, and have another tire on hand for nails and ****.
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