Fuel Pressure keeps changing on its own . . . help!

[snowmansdsm09]

A 1994 Eclipse stock hood fell on my hand today @ work so I'm gonna keep this short and simple!

I have a 2g Eclipse GST - I installed my full throttle FPR 2 months ago, and set it @ 42.
I just changed out the PITA fuel filter and put in RC 550cc's. It seemed to raise my pressure up about 3-5psi on my FPR gauge.

So i set it back down to 42psi again, couple days later its back up to 46psi.

Any clue whats going on? I know this has to be a simple fix.

Thanks in advance !



( my psi is w/ vacuum line pinched/off )

 

[snowmansdsm09]

Should i go drive the car down the highway for 20 mins and then try resetting it?
Maybe i set it when the car wasn't OP. Temp? I dont think that would matter though... would it?

LMK someone...

 

[oldman]

Instead of pinching the vacuum line, remove it completely. Pinching it might result in trapping the pressure/vacuum. Did it hold pressure for the whole three months before you installed the filter and injectors? If so, check for leaks as well. Did you use new injector o-rings and lubricate it well? Did you use new crush washers for the filter?

 

[snowmansdsm09]

Having stock 450cc's in there and running my boost pretty low, i never really payed attention to the fuel pressure until i installed the 550's and turned boost up to 17psi.

Yea i used brand new injector o-rings and lubricated them good.
I didnt use new crush washers for the fuel filter though, but im about 99% sure its not leaking, nor are the injectors.

I really hope its not the fuel filter, that was the biggest PITA...

I'm gonna let the car warm up to OP. Temp, then completely remove the Vac Line to set my psi.

Thanks for the reply, Let ya know how it works.

 

[David15151]

one more thing i might want to add is if you have the liquid filled gauge like i do the reading is a little off when it gets warm under the hood. Try to check it while its cool each time. And oldman is right about removing the vac line all the way.. doesnt take but 2 seconds.

 

[snowmansdsm09]

Yea well i was being lazy about it. I replaced the line with a shorter one, took it off all the way and set it at 41-42... i'll check it tomorrow to see if it stays.

So far so good though! Guess being lazy dont pay off, even on something stupid and easy as this.

 

[snowmansdsm09]

I have a 255 w/ 550cc injectors and full throttle FPR.

Ok guys, its gotten worse. I have to change my FPR's pressure everytime i need to drive my car now. If I set it @ 43 (w/ vacuum off) it will jump down to 30 the next day.

What could be causing this?

I read something about a fuel pump o-ring? Would that cause this?

My fuel pressure goes up, and down drastically everyday.

I NEED HELP QUICK PLEASE !!!!!!

(BTW - I'm only getting 250 miles per tank of gas....)

 

[oldman]

If you're 100% sure there are no leaks in between the pump and afpr, there can only be two possibilities.

1. Like you mentioned, a ripped/damaged pump o-ring or a defective pump.

2. A defective afpr, more likely the case IMO.

 

[snowmansdsm09]

I thought if my FPR was bad i would have HIGH pressure ?

What all lines could be ripped? Inside the gas tank?

 

[Pure92TSi]

I'm sure you did but did you make sure you tightened down the lock nut really good.

 

[snowmansdsm09]

yea i tightened it real good

I just don't understand why it changes every day?

How can i test my FRP to see if its good?

 

[snowmansdsm09]

Also, I have a new fuel filter...

 

[snowmansdsm09]

I also ready something about air bubbles getting in the lines??? I dont see how that would change the pressure up or down so much but if that is a possibility would that be from a torn line inside the gas tank?


I'm thinking its either the o-ring or a line somewhere in the tank if thats possible.

Can someone let me know exactly what lines near the fuel pump i should look at...
Maybe ones that are prone to messing up.

I dont wanna have to buy a new FPR or fuel pump just to see if thats whats wrong w/ my fuel system.

 

[snowmansdsm09]

Check valve on fuel pump???

 

[snowmansdsm09]

I just checked my Injectors, FPR, and Fuel Filter. I did not see, feel or smell any leaks.

I really need some help w/ this....

 

[oldman]

Settle down Beavis.

First, I would pull the pump and replace the o-ring and see if it helps, make sure you lube it well before installation. After that, I don't know what else to tell you except for trying out a known good afpr.

 

[snowmansdsm09]

I'm gonna check out the o-ring @ the fuel pump this week... i'll update after that.

 

[snowmansdsm09]

Well after taking the fuel pump apart many times, I finally found out what was going on by blowing thru the high pressure, copper line off the pump.

The o-ring kept slipping over the spacer just a little bit which caused a leak of pressure.
I tried installing the pump a few different ways, and saw that it sealed 3 different ways.
One way would seal it completely, other way would seal half way, or it wouldn't seal at all.

Now I know your supposed to put a little oil on the o-ring, but thats what kept making it slip over the spacer.

Well all my problems are totaly fixed with the fuel pressure issue, thanks god