My afr:s has been going leaner day after day. I have been running on stock lines, stock filter removed and at engine bay an6 from hard line to 10 micron filter to aem fuel rail and siphone drilled. I have stock wiring+ better wires with hobbs switch (kicks around 10--12psi).
I have been running e85/ron98 mixed (3/4 e85 and 1/4 ron98) to keep the afr:s at 12 or below (around 540-570whp virtual dyno).

Some weeks ago I put new mixed fuel in and the car started to run leaner at wot. I thought that the e85 was real summer blend e85 (it can be between 70-85) . So I had to modify the fuel tables richer.
Last week I replaced the oem fuel hose/tube from pump hanger to the hard line with -an6 hose and was hoping to get some more fuel but the result was opposite. It was about 0.2-0.4 afr leaner. The fuel light was on, so I thought the pump didn't get enough fuel so I put some more fuel (same mixture) in there but it didn't help. I thought that something was wrong with my 3/8 fast lock- an6 hose -5/16 fast lock line and swapped the oem system back. Now it's running even leaner. so my better an6 fuel hose wasn't the problem.

My Evo is running fine on idle and cruise but when on wot it's running lean now (12.4 - 12.8). All I can do now is to check the fuel filter and the oem hard line. I already replaced the stock fpr.

Is there any way to check the fuel pressure valve on this 450 pump? Maybe it's open all the time and the pump is not flowing as it should when pushed. Or is the pump just dying? It has been running about 5000 miles.

 

Are you mixing that much fuel without a content sensor? That is asking for trouble IMO.

 

Yes, I know. It's calculated E65 LOL. I don't run crazy boost/timing at the moment (31 psi tapering to 27psi at 7000rpm and 8 degrees timing).

 

..
A calculation may get you close on the first tank but on refills its going to be off.

Why risk your investment over buying an inexpensive sensor /gauge?

 

So AFR changes after adding fresh Ethanol + Gas mix, not knowing the actual ethanol content but you think it's hardware related?

Get a flex fuel sensor.

 

After -an6 fuel feed line it was still going leaner. I put a little more ron98 in and checked how the afr gauge reacts. It went richer, so the afr gauge is doing fine.

So, the problem could be the fuel pump, the fuel filter or the injectors. At the end of last summer, I swapped to a good brand European 10 micron E85 compatible fuel filter and it has max 2500 miles on it. I opened the fuel filter housing and there was the problem. The stainless steel filter had some kind of glue at the end and it has started to dissolve. I was able to remove the end cap with my fingernails! I got white stuff on my hands from the filter, it was like dry car wax.

I called the seller of the filter and the case is now open. And the injectors will be checked and cleaned and I was suggested to clean the fuel lines with clean pump gas. so I have to pump the old gas out and put some fresh 98ron in and pump the lines clean. I already opened the fuel pump housing and the tank looks good and the fuel pump sock looked fine. If I keep this pump, I will put a new sock on it.

 

I got the results about the injectors and they were dirty, as was expected. They were flowing around 1100cc and they were cleaned and flow about 1450 again.

Now I should empty the tank.I already pumped out all the fuel I could without the return/siphon system.
I will try to push air into the return line while powering the pump. I hope I will get the other side of the tank empty this way. Has anyone tried, if it works?

 

All clean now and my Walbro450 is working fine. As mentioned, the problem was with the bad, not e85 compatible fuel filter and the injectors were dirty because of the junk coming from the filter.