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Strange fuel pressure issue E85

Old 03-12-14, 01:06 PM
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Angry Strange fuel pressure issue E85

I just recently put a new E85 setup on my car and since I've changed over I'm having a fuel pressure issue under load. I would appreciate your help on this matter.


Fuel System:
Bosh 044 pump inline -6 line welded on to stock pickup 70 micron SS sock ( changed to Walbro 485 same thing) (real Bosch 044 confirmed)

Large bulk heads on pickup 10 gauge wire to chassis ground and wired to Haltech PS1K relay. I've also tried wiring to battery directly no change

-6 SS 90 fittings welded on to stock pickup for feed and return line

1/4 Mocal vent (tested ventilation by unscrewing cap and doing a log no change)

Feed line -6 Teflon coated line to inline -10 micron SS filter brand new to SS hard lines in factory location (changed inline to larger filter no change)

-6 Teflon line to Earl's fuel Y block this is where my SS fuel pressure sensor in mounted (changed fpr sensor no change)

-6 line Teflon coated to feed primary KD rail and secondary KD rail anodized, EV14 1000/2200cc (Teflon lines replaced same thing) (injectors have been re flow tested and cleaned same thing)

Aeromotive FPR new diaphragm a1000 -6 (changed FPR no change)

Return line -6 Teflon coated to hard line -6

Alternator rebuilt high amp with new regulator constant 13.6 Volts under load no change. Tested voltage while under load at relay reads 13.0 volts.

I'm all out of idea's and options...

I had a shop flow test since I know it's a volume /restriction issue and it passed in the rear and middle but not in the engine bay. I had him replace the Teflon lines in the front thinking it was a kink in the line. He also found a fitting that was reduced from hard line to Teflon line in engine bay changed that no change.


Here is a picture of the log middle of the map is under load. Fuel pressure drops to 42psi from 52psi the lowest point at 5,900rpm, 13.6 volts and 13psi manifold pressure. Fuel pressure starts dropping at 5,200 rpm you can also see under normal driving the fuel pressure is erratic.
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Not my car but normal fuel pressure on dyno:
Name:  Logwithfuel_zpsb449ecad.jpg
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Thank you in advance
-Jonathan
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Old 03-12-14, 03:46 PM
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Which sensor are you using for the fuel pressure? How does your fuel pressure looks while the car is at idle?

I am having similar problems with the fuel pressure readings, and oil pressure readings; both readings are taken from AEM brass sensors to a haltech PS1000.

In my case, a mechanical gauge shows steady pressure!
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Old 03-12-14, 04:00 PM
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The fuel pressure sensor is the AEM stainless sensor it bounces around by about 5psi between 36-41psi. Mechanical gauge shows steady pressure but does the same thing under load drops fuel pressure.
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Old 03-12-14, 04:17 PM
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the closer the sensor is to the rails the more likely you are going to pick up on the harmonics of the injectors opening/closing. if the sensor can be moved to the middle of the car or closer to the pump it might not be so erratic, or a filter could be installed inline before the sensor(an orifice, a restrictor to muffle the signal. cheap sensors have no filtering and the readings will be jibberish).

that said once you muffle the signal i'm sure you will find you're just hunting a witch. once you smooth it out if it then still doesn't follow your map lines then you can look at why. the sensor should still be after the filter so a restrictor or different sensor would be a better choice.

Last edited by RotaryEvolution; 03-12-14 at 04:25 PM.
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Old 03-12-14, 04:27 PM
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I was also thinking because the sensor is installed on the Y block is why I have an erratic pressure. Most people install them on the fuel pressure regulator.

Picture of the Y block the -6 fitting were welded on
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Old 03-12-14, 04:30 PM
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that's a possibility, the fork in flow paths would make that spot possibly the worst location to log pressure from.
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Old 03-12-14, 04:31 PM
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I created the same post in another thread here is another post to my issue.

Originally Posted by mach.80 View Post
I had the EXACT issue.

My fuel system is way overkill with a SX fuel pump good for 1300 hp -10 line from tank to injectors.
I had a 100 micron pre pump and 20 micron post pump.
I removed the element from my 20 mic post filter and there was a noticeable increase in pump noise(back to normal)
and it resolved the fuel starvation issue.

For some reason the E85 has a film that develops in the fuel system and clogs the fuel filters.
I cleaned the filters with methanol and noticed some weird stuff settle at the bottom of the container.
Now I'm just running the pre filter and I'll just keep an eye on the injector filters every once in a while.

So even with a pump that runs about 130 Gallons/hr it could not pump the volume through a 20 mic filter.
So for a smaller pump and a 10 mic filter it could be impossible for the pump to do it's job.
As an added note, my filter started to rip holes in the stainless steel element, proving to me that
the pressure between the pump and the filter was extremely high.

I do want to give Johnny at J-Tran Studios props for discovering the issue based on expertise.

My advice, temporally ditch the inline filter completely and let me know if it resolves your issue. It did for me.

Cheers,

Joe
Awesome man.. one of the shops pulled the element out and did a test looking at the digital gauge no log he said it went pig rich so they thought they found the issue too small of a inline filter replaced the inline filter to a larger assembly but it was the same thing.

The weird thing the filter JEGS Billet 40 micron was dirty and looked to be strained as you mentioned. I ran the same filter on my Evo X, E85, 400whp no issues but it's not a rotary.

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Old 03-12-14, 04:33 PM
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I thought the same thing. I was more concerned about the fuel pressure dropping, I have a mechanical liquid filled gauge mounted on the FPR that mirror's the sensor under load.
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Old 03-12-14, 04:38 PM
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well it's difficult to see anything with the logs provided, it could still be a starvation issue but smoothing out the data would be a good place to start.
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Old 03-12-14, 05:00 PM
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Cleaner log but an older log. I can also send out the log file.Name:  Mylatestlog_zps5bf8b0af.jpg
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Old 03-12-14, 05:02 PM
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Thank you guys on all the help...
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Old 03-12-14, 06:07 PM
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This is what my filter looks like.

Aeromotive 12604 Aeromotive In-Line Fuel Filters - Free Shipping on All Orders @ JEGS

Your filter just might not have enough surface area. That, plus the fact that a fuel pump is very
sensitive on the inlet side of the pump. They work good pumping, not so good sucking.

For example, in the jet, each engine driven fuel pump is good well over 5000+ lbs/hr.
But without the electric boost pumps in the on position, the plane is unable to provide proper fuel pressure over 25000 ft.
The engine driven pumps just have trouble sucking fuel through 50 feet of line, and needs help to get the fuel up to the engines.

Once, not too long ago after switching to E85, a small bit of rubber hose got sucked into the inlet
port of the filter. It was too large to get past the opening of the AN fitting. as the fuel tried to squeeze by
it made erratic noises from the pump and the fuel pressure fluctuated -10 psi.
I wasn't sure if I was going to be able to limp it home, but I did. And lo and behold once removed everything was back to normal.

Joe

OH! How much horsepower are we aiming for? Over 400+ to the wheels I'm guessing??
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Old 03-12-14, 06:15 PM
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Remember I changed to the larger Aeromotive SS inline filter like picture below and a Walbro 485 pump w/sock the same issue:

I'm on the Bosch with 70 micron SS sock and JEGS Billet 40 micron inline filter again:

Here are the filters I was using the inline I used with stainless element and the sock is stainless 70 micron mounted on bosch 044.

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Old 03-12-14, 06:37 PM
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I plan to pull the inline filter element out and log. I just realized they are both 40 microns which is a lot of filtering, the last shop installed the Aeromotive but they put back in all my old parts when it didn't work.

Here is a 10 micron SS filter
F-10 Inline Modular Fuel Filter
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Old 03-16-14, 08:17 PM
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I pulled out the inline filter element and it's the same thing Has anybody heard of anyone running the fuel lines separately to the fuel rails and both into the FPR and having issues? This is the only thing I ran differently from before.

-J
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Old 03-16-14, 09:34 PM
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going back to basics.. choose another spot to reference the fuel regulators manifold pressure signal from .. make sure it is not a purge or partial vacuum port
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Old 03-16-14, 10:06 PM
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Originally Posted by bumpstart View Post
going back to basics.. choose another spot to reference the fuel regulators manifold pressure signal from .. make sure it is not a purge or partial vacuum port
Yes I don't know what else to do. The manifold pressure signal is coming off the back of the manifold.

I've also set the fuel pressure at a Static 60 with no manifold pressure plugged in and it was the same. This is why I figure it's a restriction/volume related issue.

This past week all the Teflon lines were pulled off to check for restriction no issues with lines.

My next step besides running the fuel lines like factory is to bypass the lines with a -6 hose.

Thx
-J
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Old 03-17-14, 09:39 PM
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Any other suggestions?
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Old 03-17-14, 10:12 PM
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i was thinking you have fuel going up the ref line ( but doesnt explain why it fails same in a static test )

maybe the reg hat has some fuel in it already ?

Last edited by bumpstart; 03-17-14 at 10:14 PM.
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Old 03-17-14, 11:43 PM
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I rebuilt the FPR when I redid the fuel system pulled it apart to double check it, and it was perfect.

I changed the FPR to make sure and it didn't change a thing...
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Old 03-18-14, 06:46 AM
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have you put a mechanical guage and put it on a dyno to see if it matches your sensor?
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Old 03-18-14, 02:35 PM
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and have you done a physical volume test to see if the pumps are putting out their rated amount? this should be done at the pressure where your issue is starting to show up at, not a static test without the regulator working.
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Old 03-18-14, 10:40 PM
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A very knowledgable rotary builder/ tuner recommended that I run-8 y into -6 at rails This is for pump. And probably less power than what your looking for... Unless I misread are u running single -6 feed? If so is that large enough for e85?
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Old 03-18-14, 10:55 PM
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I would put it on the return line instead of the feed line or take it right off the FPR.
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Old 03-20-14, 12:32 AM
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Originally Posted by rx72c View Post
have you put a mechanical guage and put it on a dyno to see if it matches your sensor?
Yes this how I found out I had an issue it does the same exact thing they only difference is I don't see the fluctuation.
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