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Topic Review (Newest First)
08-29-2014 05:42 AM
Drew in Houston
Originally Posted by Slabonator View Post
cut the hose that connects directly to the fuel pump
Is the problem the same regardless of tank level?

There's actually some neat engineered things going-on with the fuel pump assembly and the way that it's positioned that aren't immediately obvious. When things are right, that basket assembly should be continuously overflowing inside the larger tank, keeping the entire pump submerged and fed regardless of the level in the tank.

Which hose did you cut?
-Check that the fuel return line feeds back to the inside of the assembly for sure. If that's the line that you cut and the fuel is going into the larger tank instead of keeping the fuel can in a state of continuous overflow, that may be a problem
-Check that the 3rd line is still feeding that strainer looking assembly attached to the bottom of the fuel can, if that's the line that you cut, same thing. That little assembly on the bottom with the fuel can is actually an eductor pump driven by that 3rd line going to it from the tee, the eductor scavenges fuel from the larger tank whenever it's available. The fuel pump maintains operation during temporary low tank level turns/acceleration by running off the fuel that's maintained in the can, and then that little eductor fills it as possible when the fuel sloshes back past it.
08-29-2014 05:02 AM
Originally Posted by Cark View Post
You should have openSID? Run through there and see if you are getting excessive "mifi's" (misfires) and make sure your air request and air achieved are very near one another. You can also see if there are any OBD codes stored that aren't setting of a CEL.

You are running 93 octane too I hope?
Forgot to check the mifi - will do tonight. Car garbles when coasting in 3rd.. not sure if that is synonymous with backfiring. Here's what I'm getting at idle for AIRr and AIRa:

Always running 93 octane. As for the fuel pump - I replaced mine about 3 months ago due to some mice chewing the wiring (see

One thing I had to do when changing out the fried pump was cut the hose that connects directly to the fuel pump - it was hard as a rock and I couldn't pull it off. So, that hose is now shorter.. perhaps I damaged it in the cutting process and it isn't pulling enough fuel?

*edit: Was scanning through my old fuel pump thread and found this:
Originally Posted by oliversexpedition View Post
Might want to clamp the fix on the lines just to be sure. There is a fuel rail valve that you can measure fuel pressure with a standard gauge. I also would swap in a new/know good DI and plugs if you haven't already.

There is a chance that you could be hitting fuel cutoff/leaning out depending on which pump/injectors/airflow/intercooler, etc.
My money is on a damaged fuel pump line, as that problem started immediately after I swapped mine out.. I'll troubleshoot the above advice. New (used but reliable) DIC was installed about a week after I did the fuel pump.
08-26-2014 08:27 AM
mike saunders Ditto on the fuel pump check. There's a pressure port on the T7 rail that will enable you to check it fairly easily.

I'm in the same boat myself, but will need to do the prehistoric flow test....grrrrrr...
08-26-2014 05:29 AM
Saabeh Fuel pump may be dying? Give Mike a call, he'll sort it out.

This doesn't explain the hesitation or lurching forward, but you will lose some performance in the hot summer temperatures.
08-26-2014 03:39 AM
Cark Stock Aero's recommend octane 92+. When tuned, you definitely don't want to run anything less than 93. Yes Trionic will adapt, but you will definitely notice a decrease in performance with lower octanes.
08-25-2014 11:45 PM
Snowcat77 trionic will adapt so you wont have any obvious knocking running lower octane, but it wont run as well and running 93 gives you better fuel economy that makes up for the extra cost.

i dont know if that should throw a code or not though you need to get it read.
08-25-2014 06:20 PM
pisani01 don't mind me for entering but wanted to ask I have 01 9-5 aero acting sort os the same but my cel comes runs good just something isn't it true you have to run 93 octane?
08-25-2014 08:43 AM
Cark You should have openSID? Run through there and see if you are getting excessive "mifi's" (misfires) and make sure your air request and air achieved are very near one another. You can also see if there are any OBD codes stored that aren't setting of a CEL.

You are running 93 octane too I hope?
08-25-2014 06:19 AM
Loss of power at higher speed.

'01 Aero Wagon, 5 speed, Mike D tuned. 201k

Highway overtaking speed has taken a dip in performance. Around 65-70 when dropping into 3rd or 4th from 5th gear and accelerating hard the car hesitates, learches slightly and accelerates at less than full boost.

1st-3rd gear heavy acceleration either from a standstill or roll I don't experience this - it still moves like a bat out of hell. Only when moving at already established higher speeds does the car lack gusto.

I replaced all my vacuum lines and put fresh spark plugs in (NGK BCPR7ES) over the weekend. Didn't make a difference. A friend of mine experienced similar with his '06 Aero and said the ignition coil was the culprit, despite no check engine light.. Any ideas? My only other guess is that it's been running rich.. so maybe the throttle body needs a clean. (Sooty exhaust pipe..)

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