niscur29

I'm stumped at the moment and could use the forum brain power to figure things out. Sorry in advance for the long read.

Car is a 240sx with an iron LS2, LSA blower setup (adapters), longtubes and LS9 cam. Currently running a PatG base tune and we are just getting into the back and forth logging/adjusting when I am seeing the fuel pressure drop substantially when any load is given and it breaks up before it ever gets into boost. Wideband shows completely leaned out as well when this happens. Cruising around/idling car runs perfect.

Current Fuel Setup everything bought new except the feed line:
Stock LSA Rails (single 6an IN deadheaded)
Deka 60lbs
6an Feed/Return
Magnafuel Boost Referenced FPR with return right before the rails
AEM 380lph pump sitting in an aeroflow 3qt surge tank
Denso Supra Lift pump from tank to surge.
XRP Space Saver 100 micron filter between lift/surge tank
XRP Space Saver 10 micron filter between AEM/FPR
Pump voltage while running is about .5-.75 V less than battery/alternator and it is hardwired directly to the positive terminal of the battery via a relay.
FPR is set to 58 psi without the vacuum line attached.

Today I picked up some 6an Caps to test each circuit out.
Test 1: Cap FPR Return line
With the return capped the pump/rails held 100psi without any leaks after the pump is keyed on.
Test 2. Cap FPR Return and Rail Feed
Same as above held 100psi without issue.
Test 3: Both Uncapped
With the rail/return both uncapped the pressure will drop immediately after the first prime of the pump from 58psi down to 20 within seconds.

So far I have taken everything apart. FPR looks fine internally and no gas in the vacuum hose. The 100 micron filter was spotless. The AEM's internal screen was spotless. The 10 micron filter was completely black and cruddy(stainless mesh) which is alarming because the car has about 1hr of total run time mostly idling and 2 miles worth of actual driving. No leaks that I could see in the braided lines under the car. I never had this issue with the supra pump hardwired running through a fuel lab (albeit much larger filter) and the vette regulator when NA.

After seeing the fuel filter I immediately though it may be a restriction even clean its much smaller than the filter I ran previously. Its element is only .75" diameter by 3" long. However I'm also thinking I may have a bad fuel pump. The 380lph should be enough pump for what I'm running.

Thoughts?

niscur29

AS a follow up to my own thread LOL...

I redid the AEM hard wiring and switched everything over to 10ga with a 30amp circuit breaker much like the prefab kits on the market. Since my battery is in the trunk I also hardwired both the ground/power to the batt vs just the power like before.

I also removed the XRP 10micron filter and replaced it with a fuelab 10 micron what was about 4x bigger. Once I turned it on it immediately sounded better (stronger) and the FPR was no longer bleeding pressure like an open wound and was actually showing a higher pressure than before. Once I adjusted it back down to 58 it held steady and ran great. The boost referencing works now and no more cut out as RPM's build and it idled/reacted better at the pedal. So I'm going to say that the XRP filter was the primary culprit being to small to actually meet the flow requirements of the pump.

Needless to say once dat BOOST hit......now its pissing oil at WOT due to excess crankcase pressure. Fix one thing onto another LOL.

stevieturbo

I'll never understand why people want to use tiny piece of **** filters for an EFI system that is so reliant in high flow.

Filters like that have no place anywhere on an EFI setup

ScottyBG

Do you have your clean side of your PCV being fed by the port on the throttle body, as the factory PCV setup does? If you do that could be the problem it can pressurize the crankcase, and oil pan. In the case of a turbo build it will push the oil back up your drain line from your turbo and could damage the seals in your turbo. I've seen more than 1 build where that has been done.

niscur29

I had installed check valves on both the clean/dirty sides which is probably what caused it since my catch can was clean from the check valve stopping the crankcase from venting. Corrected everything last night and Ill give it a drive today.

Floader

iTrader: (32)

Subed, I have about the same setup going into a square C10. Like to know how yours turns out PCV wise.

niscur29

I redid the PCV system on the car and took it out on Saturday. Removed all check valves and tried to plumb it as close to a standard LSA setup as possible. Since I'm running the LSA blower, both the TB and blower body (pre rotors) never will see boost and I never should hav had check valves there to begin with. Current set up as follows:

Valley Cover to Blower Body (pre rotor) run through a catch can on the way.
Both Driver/Passenger Valve Covers to TB pre throttle blade.

This time my catch can had some oil in it, albeit a minor coating and pooling at the bottom edges of the can. Did notice during WOT throttle a puff of smoke again however there was not the massive mess that was present last time. Doing some digging I found two definite leaking spots.

1. Looking from beneath right after I got back I finally noticed the 02 sensor wire had oil residue on it which made me look up above the transmission/rear seal line based on how I secured the harness. Turns out I overfilled the PS reservoir and ATF (Nissan PS rack) was flowing quite easily down the driver side valve cover right down the side of the block at the back.

2. The Passenger side valve cover gasket definitely leaks. I replaced the grommets when I put the blower on thinking that was my leak source from previous lightly coated covers. However from the underside looking up I could see oil on the underside of the coolant sensor (aftermarket gauge) on the passenger head and oil on the threads of the unused bolt hole next to it.

Oil pressure never dropped (43.5 psi hot idle) and increasing fine with rev's. And the dipstick shows very little oil loss. The flywheel had no oil on the backside (ran some qtips across what I could access through the two side covers and squirting a little brake cleaner in the slot between the pan and bell housing flowed back out clear.

Fueling wise the fuel system ran perfect, with the new filter, greatly reduced pressure bleeding after initial key on and the correct 1:1 rise and lower idle pressure when under vacuum. Now I just need Pat G to adjust the tune to tweak some minor drivability issues at low/part throttle.

Floader

iTrader: (32)

Thanks for the update. I hope to have mine wired up in a few weeks.