s2000Junky

Hey guys, to the point, i'm running a adjustable AEM fpr and aftermarket 340 fuel pump. I noticed on my fuel gauge today that the idle pressure has changed from my pressure setting to run proper afr and is now about 90psi and I cant lower the fuel pressure via the AEM fpr any lower then 60psi, which is where I use to have it set btw. The car seems to run ok although the afr does do some irregular things once in a wile and seems to be leaner then id like. I noticed the Philips screw on the oem fuel regulator/damper thingy is pushed out, I assume due to the high pressure now realized. I thought that was strange and screwed it back in and ended up breaking the screw, luckily I had a spare regulator to replace with and learned my lesson. I am a bit confused at whats going on here, why the pressure changed by itself and is so high, but fuel enrichment to the motor seems to be lacking. The only thing I can think of is I developed a blockage somewhere in the fuel system but I don't know how or where to look. I'm hoping one of you guys have had something similar happen, or and had some ideas as to troubleshooting this.

Thanks guys!

s2000Junky

Update: I removed the AEM adjustable FPR and installed the OEM one to see if the pressure would drop back to 43.5. It does not. Still idling at 90psi! With engine off, ignition on, the pressure holds at 80psi. With all off, the pressure in the rail holds at 70psi right now, but this seems to change whenever it wants. Ive looked at it later and its moved down to 60psi or so.

realblag

Are you sure your pressure gauge is still functioning correctly?

s2000Junky

Its about 3 weeks old, So I would assume it is. Not sure how I would be able to test it, other then possibly hook up an air compressor to it which I don't have. So I'm going to assume its showing correct pressure based off how the car seems to be responding to the pressure fluctuation readings. The car has had issues with running lean periodically for no reason in the past, just a random afr sweep or chugging when idling, and I'm starting to think the larger fuel pump I just put it may have exacerbated that. I'm wondering if I might have a collapsing or kinked fuel line somewhere, that would be my first thought. Any thoughts are welcome.

chris_barry

Connect the outlet pipe of the regulator to a hose and run it into a container. Block the original return hose to stop fuel running out of it.

Idle the motor and check pressures. If its back to normal you have a blockage on the return line.

Use a large container as something like 5 litres/minute will come out of the regulator.

fluid filled pressure gauges can start to read too low when the get hot if there is no significant bubble in the gauge (the glycerene expands pushing against the pressure of the fuel). This is not your problem but worth remembering.

s2000Junky

Thanks for the troubleshooting tip here, I appreciate it!

**My gauge is not fluid filled just fyi, but good to know.

s2000Junky

Ok I have an update, I performed the test with removing the return line from the fpr and ran that into a gas can and checked pressure on my gauge, it did not move from 90psi. (I forgot to cap of the exposed end but no gas came out and I don't know if that would effect the outcome of the test) So I removed the gauge from the rail and it did stick at 30psi under no pressure. So the gauge is not reading accurate, however I was surprised to see the gauge still read the same pressure during the test as if the return hose was still connected to the system. Should it not be much lower? Should it have been closer to the 30psi the gauge reads under little to no pressure? The stream coming out of the hose looked like a good stream, not under high pressure particularly though, just uniform and the velocity like a garden hose. Could I still have a pressure issue somewhere else in the system, or does this seem like just a faulty gauge? I'm surprised that I'm having an issue with a 3 week old Automotive gauge, thing cost $40. Could high pressure surging f@#ked it up? I just hate chasing my tail, not sure what to do at this point other then replace the gauge and see if the same issue repeats. Thanks for your input.

zeroptzero

You can get a fluid filled gauge for an extra $10, dry gauges are known to fail or read inaccurately after a short while. I'd try a new gauge.

I think adding a higher flow fuel pump on the stock fpr naturally gets you higher fuel pressure settings, but you should have been able to bleed some of that down with the adjustable fpr. Maybe it is a combination of a faulty fpr and fuel gauge ?

s2000Junky

Thanks for the input.

Yeah I don't know, Realstreet recommended and sold me the non fluid filled gauge so that's what I got. I think i will be calling them Monday for return.

chris_barry

gauge is stuffed. Look around the garage as the ones in foot operated tyre pumps often have the similar thread. Borrow one from any appliance that reads the right range. Only use a generic pressure gauge for short term testing as they are not designed for gas and would probably explode and leak fuel everywhere if you left it installed long term.

With the return line disconnected it should read whatever the pressure regulator is set at. The reason for running with it disconnected is that if there is a blockage in the return line the fuel pressure would rise to the max that the pump can supply which is typically around the 70-90psi range.