Trying to help diagnose a car with a few weird issues.
Issue 1;
It is an RSX car with a fuel cell, only about 6 hours total. Fuel pump has been replaced as it died on track, checked everything, and even with power to the pump directly wouldn't turn on, hit it with a hammer, turns on.. replace pump.
Car intermittently had the issue again but we can't replicate it at the shop, one thing we did notice was the FP seemed high, around 3.3-3.4, it would also bleed down almost instantly when the pump cut out after the initial power up. We have 2 other RS cars that do not do this, but they are both alum tank.
Thought possibly the supply/return are flipped on the output of the cell, but found an original log file from before the pump was originally changed and it seems to do the same thing.
I guess the main question here is, is this normal on the fuel cell cars? the car seems to jump FP everything it's not consuming it, then drop pretty drastic when on the power. The pump could be flowing WAY more than the 2 RS cars we have and the regulator simply can't return fuel to the tank fast enough?
Also unsure if this is a coincidence or part of the issue he occasionally has where the car cuts out and then will never supply fuel pressure again.
Attached a log file showing the fluctuation.
And Issue 2;
This one will probably be easy once we get more info but the car puked oil out the dry tank, completely filling and then overfilling the overflow catch can. We sucked catch can dry and the oil in the tank is at min on the stick when checked per procedure, but the engine also always has oil still visible in the sight glass.
Thoughts are he either changed the oil at some point after it overflowed and forgot exactly what he did, or something is causing the scavenge pump not to properly evacuate the oil, and when it does it jams an extra few liters into the tanks and out she comes.
@zacko - Hi Zacko, I had a look at the fuel pressure log from my brand new (<2hour) SR3-XX on the weekend. My fuel pressure fluctuates in a similar range to yours (drops by around 0.3 bar when under load)... but mine peaks at 3 bar (at lower throttle openings) and drops to ~2.7bar (saw as low as 2.65 bar I think, but mostly drops to around 2.7 to 2.75 bar after extended wide open throttle).
Not sure which one is correct. I would say yours is running a bit high... and mine may be running a bit low.
I think I remember being told, or reading somewhere to aim for 3.1 bar at idle loads...?)
Thanks Rod,
It definitely seems his is excessively high. I also remember reference to 3.0-3.2 being normal range. I think slight elevation should change it since it has a diaphragm inside the regulator that would allow boost to be added. I could be wrong but less atmospheric pressure behind the spring should weaken the setting every so slightly considering we are 95% baro a slight drop of 5% seems reasonable.
For reference I found a log from my car on the same track, (I'm not good enough at RaceStudio to make it in the same order, but it is the same reference and fuel press is the same scale range, but in a different spot)
also considering his excessive pressure drop vs the very conservative RPM usage, makes the problem probably even worse using the full RPM.
Currently short on ideas but we'll have to check out the entire fuel sys again as we can't really think of a cause.
@zacko - G'day Again Zack, I was looking through some data for another reason last ight and while I was doing that took a couple of screenshots of Fuel Pressure from both my cars - the RSX and the XX. Interesitngly they seem different! See below
Here's the RSX data
You can see that the Fuel Pressure ranges from a minimum of 2.8 bar when the engine is revving fairly high (and the throttle is wide open although that trace isn't shown here) to a maximum of 3.0 bar.... so about 200 kpa variation.
Here's the new XX's data (car has only done 2 hours since new)
You can see here that the pressures are reading ~1 bar higher... but I suspect this might be measuring 'absolute' pressure (rather than 'gauge' pressure). So if we assume that's correct, then the equivalent pressure in the XX is a minimum of 2.66 bar. and a maximum of 2.96 bar... so a difference of around 300 kpa
Makes me wonder if there are any major differences in the fuel system (pump, regulator, etc) or engine mapping??
Does anyone know if my assumption about the XX's fuel pressure being in 'absolute' is correct... or are the new cars Fuel Maps calibrated to take 4 bar regulated pressure?? (I need to check what's shows on the AiM dash next time I start this cars engine - I think I remember seeing ~ 3 bar like the older RSX)
