its worth pulling it off, costs you nothing to check it. It will collapse than go back to its shape, like sucking a milk shake through a straw

Well what happened with me is on the dyno that day we tuned on pump fuel due to injector change. Flipped the switch to also run a E85 tune. We tuned on E85 and turned up the boost, my wastegate was not holding higher boost so we had to shut it down that day. When we did the car had dynoed 409 I believe but that was almost 2 years ago.
I took care of the wastegate issue and then the storm hit and my house flooded ( my car was stored somewhere else at the time anyhow ) .

I never got back to the dyno since then. The car sat from october- July. Last year a few weeks before rotorfest I put a big brake setup on the car. I only drove it 2-3 times if that. Its been stored since October or so again and a month ago I moved it and we have been restoring the suspension/subframe, new fuel and hard brake lines and other stuff.

Next time I get back on the dyno I will have my new fuel lines in place.

 

I can try it see if it makes a difference. I figured I used the Walbro pump and the Walbro sock I was good but you never know.

Wow that's a crazy story, I could never imagine my house being flooded like that your real lucky your car wasn't there.

 

FWIW, was reading on a fuel pump site and they mentioned that in higher peformance apps a dash 6 (or larger) fuel vent is necessary... any possibility you have an occluded fuel vent?

 

I have a Mocal 1/4 vent that's mounted on the pickup. I thought that might be an issue aswell so I loosened the gas cap and did a log it made no difference.



The return line is a -6 as well.

 

The fuel line was replaced with a -8 hose and that seemed to fix the issue. I'm waiting on the log file to confirm for myself and will post, it must have been a restriction in the -6 SS line and not that it needed a larger line.

Thank you all for your help.
-Jonathan

 

So u think it was faulty line and not line size?

 

I believe it was the line with to many bends probably cavitating the fuel. I had a shop make me a SS -6 line that had the same bends and curves as the stock line instead of a straighter line.

Still working on it will post more information when it's completely put back together.

 

On another note I'm not sure If I posted this before I found a 10 micron SS E85 rated inline fuel filter instead of Fuelabs fiberglass 6 micron really large inline filter.
F-10 Inline Modular Fuel Filter

I plan to run a fuel pressure sensor on this inline filter since I heard some horror stories from foreinnovations about E85 fuel being delivered dirty and causing issues on brand new GTR's. From what he said the government is not as strict on the filtering process on E85 as they are with regular fuel..

 

What did u find out?

 

Pistons,

once you finish this fuel system trip you can quit your day job and become a consulting engineer to the auto industry or Penske.

HC

 

ARGH!

I moved the AEM brass fuel pressure sensor from the rail to right after the fuel filter, and the pressure still oscillates at idle like the op described

 

I too have developed a fuel pressure problem.... although mine is preliminary... I'll report back when I get to figuring it out

 

Beck to normal.... my fuel pump socks were gummed up...as well as my fuel filter stainless filter...believe it is a 40 micron

 

Sorry for the delay my fd was on the back burner at the shop. The fuel lines were replaced with -8 and it's still having a fuel pressure issue...

I really don't know what to do now everything has been replaced.

less fluctuation because the sensor is mounted on the FPR currently.

 

Sorry if I missed it ^ but have you checked your filter?Pump Socks? I'm going to be keeping a really close eye on mine...but Also want to get the stainless steel level socks just to prevent corrosion.....or I guess not corrosion but fuel from eating away at the filter element

 

Yes I did it was replaced with a Walbro 485 and sock. I then re-installed the Fuelab SS sock and Bosch 044 after it didn't fix the issue.

I also went to a 10 micron SS inline filter with -8 lines, flow tested the injectors, replaced FPR, re routed fuel lines the stock way and replaced fuel pressure sensor and nothing has fixed my issue.

The only thing I have not replaced is the pickup assembly and fuel rails.

-J

 

I am no expert but if you really have a large fuel pressure dip under a decent amount of boost shouldn't you see some sort of A/R fluctuation to correlate with the dip? Your boost pressure and A/F are rock solid. It looks like electrical noise to me. If you are doing this on a dyno get a mechanical gauge and observe it during the entire run to be sure. If this is real you will see movement with such a large dip even if it is very sudden and fast.

 

I have a couple of questions. Just curious on why you are tuning E85 to an AFR of 11 or so?

Doesn't e85 make max power at an AFR of 7-8 AFR?

http://i72.photobucket.com/albums/i1...Conversion.jpg

Stoich for E85 is 9.765 AFR. That is why people see a reduction in MPG.


I see the reduction in pressure, but I don't see a reduction in AFR. What does your map look like? Is your base map pretty smooth and what does the curve look like? Does the curve just rocket in the area that the pressure drops are occuring? If not, then perhaps you are chasing a ghost that doesn't exist. Your sensor might not be reading correctly. You can't have a nice steady AFR with a nice smoothed map and have pressure act erratically. Have you tried a lower PSI and see if it still happens? Perhaps make a run at 5PSI, or 8PSI, something lower (especially if you can control it with a boost controller and full peddal it). If the pressure is constant there, or if you get a similar erratic reading but the map and AFR's are nice and smooth.....might be nothing to worry about.

 

One would assume he is using a meter that is calibrated for the stoichiometric ratio of gasoline because that's what 99% of the budget meters are setup to read.

This gets into the whole "why you should use Lambda" debate. Rest assured, if his meter is programmed to display gasoline AFR with Lambda of 1 equaling 14.7:1 AFR, when he is running E85 and the meter reads 14.7:1 Lambda is still 1. Lambda 1 of E85, as you stated, is somewhere around 9.8:1 AFR.

Does your head hurt yet? Once you understand you're using a Lambda meter that is calibrated to read AFR for a certain fuel and, if you use a different fuel, the AFR values become irrelevant, you'll understand why he doesn't try to run the engine at 7:1 according to his meter.

 

Any updates?

I am having the same exact problem (on pump gas). I am too using a bosch 044, and a PS1K ecu. With the engine off, 12v to the fuel pump, the static fuel pressure is rock solid, but when the engine is running, the static pressure oscillate by 5-8 psi.

Pressure sensor has been moved to pre primary rail, post secondary rail, right after the fuel filter; all with the same results. Engine off, static pressure is solid, engine running, pressure oscillates.

There's no fuel damper, and a SX pressure regulator, which in theory acts as a damper. I am thinking of buying a marren damper, or two

 

Have you unhooked your vac. reference from the fpr with the engine running to see if the pressure stabilizes?

 

Forgot to mention that, unhooking vac reference to the FPR does not stabilizes the pressure readings. Still need to bypass/remove the pre pump sock filter, and the pre engine filter.

 

where does the return go to in your surge tank?

Seen this?

 

Return line is the OEM return line on the FC3S, going to the factory return port on the tank.

First time seeing the video, thanks for sharing, and adding that to the list of things to check/test

 

Looking at the data log, I have to wonder if there may be constant pressure oscillations as the injectors open and close, and due to the sample rate of the data, it shows up as larger dips in pressure.

If the overall flow was too low I'd expect the readings to be smoother.

Do you have access to an oscilloscope to check the raw output from the sensor? You could compare it to the data log. This may be revealing.

Also you can change the sample rate in ECU Manager.