I got the car tuned, but I had some hunting. So, I put a brand new fuel pressure gauge on the passenger side port. The fuel pressure "hunted" between 10 and 30lbs. YEOW!

I went to the clear fuel lines and saw with my own eyes that the fuel was not a steady flow, but was going full to empty on the left clear tube, which goes to the FPG over Cylinder #1. It is really easy to see the tube empty, then fill up again, and coincides with the hunt at about 1000 rpm.

Checked the fuel pump in the front trunk and it sounded OK, but am I seeing a failing pump?

I checked the new hoses from the pump to tank and pump to engine and back and the tee, and it is all routed correctly. TPS is absolutely set right, and the ECU is on click 11, with a small (1/2 turn) bleed setting on the throttle body screw.

WTF? Is this how a fuel pump fails when it isn't a sudden thing? Slowly losing it by varying the actual fuel it can deliver? Or am I missing something obvious?

I have 1/4 tank on the gauge, because I filled it myself.

Steve Gaglione (my bud from the 70's in NJ and the main reason I am 57 and still messing with 914's) and I have been pulling our hair out on why this car won't take a load, and hunts at idle when points/timing/triggers are all great and set right. It looks like fuel flow. The FPG on the driver side seems to be correctly set.

I actually have a bit more hair than Steve at this point, but after months of weekend work, duh, I found something no one suspected, I think!

HELP! Am I close to being right?

Thanks!

John
avidfanjpl

Check the screens in the fuel tank (IMG:style_emoticons/default/idea.gif)

[quote name='qa1142' date='Apr 23 2010, 02:36 PM' post='1308232']
Check the screens in the fuel tank (IMG:style_emoticons/default/idea.gif)


That means taking OUT the fuel tank, right?

I had it empty when I changed all the hoses, and believe me, it ran out like gangbusters when I yanked all the old hoses and only had 2 gallons in the tank.

New fuel filter too.

THANKS!

J

Sounds like it's not getting prime. Could be bad pump. Is the pump mounted below the bottom of the tank or is it elevated? How much fuel is in the tank? The pump could be forming a venturi in your tank and sucking air.

His fuel pump is located up inside the front trunk. I believe near the lower side of the left wheelwell.

Steve is right. It is below the tank in the front trunk on the rubber mount. The pump sounds a little labored. I am thinking it is the pump. Seeing that clear tube just run dry is a hoot.

I will check all hoses tomorrow for the 3rd time, then yank the pump and send it to AA. At some point this thing just seemed to start acting up after I changed all the hoses.

I did have a twist in the center hose and that may have made the pump fail. After I fixed the twist, it ran better, but this thing is definitely hunting.

I was thinking of replacing it anyway, so as long as I don't ruin the new one, I am OK with that.

Sold a couple of synthesizers today to pay for the pump and maybe new Yokohama's for the June Autocross. I can't seem to find Falken Azenis in stock and the Yoko's are 205/60-15 not 50's

And they probably stick better, right?

Thanks!

J