Low fuel pressure, cant find leak!

[Chad1993]

Hello all, to start I have a 1995 Mitsubishi Eclipse GSX. I just bought a new Walbro 255 hp just a week ago. After getting the walbro in, I had a fuel leak at the fuel filter (trick flow) O ring. I put a new O ring in and voila! Fixed it. Was reading 43psi while the vacuum was off, steady too. Wasn't jumping around. I could rev it and it would go up in pressure as it should. That same night my slave cylinder went out and I let the car set a few days. After getting the slave in, I started it. Took a minute to start then I was only reading 30-34psi and it was bouncing around. I give it some gas and the need descends to 20psi. So there is a leak somewhere. I checked injectors, fuel pump, fuel filter. Nothing wet on the floor. The white female plug for the fuel pump had some gas seeping out, but I don't think it has anything to do with fuel delivery. I took the fuel pump assembly out and checked to see if the O ring came off the pump. NOPE, still in tacked. I even tried to blow though it and it held . I'm not sure what to do next. Thanks!

Also I'm running braided lines. 6an

 

[GST with PSI]

Easiest way to find a leak is to activate the fuel pump using the test terminal. This way, you can listen for leaks without the car running. It is also safer, since leaking fuel anywhere is a serious fire hazard. Be sure to take precautions not to cause sparks when applying voltage to the fuel pump test terminal.

On an unrelated note, this is also how I set my base fuel pressure. I activate the pimp via the test terminal, and get the AFPR close to the pressure I want. Then you can fine tune it while the car is running.

 

[dsmspick]

I bet you have an AN fitting not sealed all the way. Mine did the same thing and leaked from several places. Just needed to tighten them up. So look at all of them and feel around for gas even small leaks cause pressure loss

 

[Chad1993]

Thanks for the quick responses! I'm headed home to check that out. I'll try to listen for leaks, but that walbro is so loud! Lol

 

[BogusSVO]

Pull the vac line to the FPR and see if it is wet or smells like gas.

 

[Chad1993]

I just checked the fuel pressure with the car off through link, and it holds pressure perfectly. So I drove it and it leaned out at 2psi. I smell nothing do not see anything, or hear anything. Other than the walbro whining. The vacuum hose doesn't smell like gas either.

Fixed, fuel filter backwards...

 

[Chad1993]

I'm baaaack! With another fuel related problem. I'm running steel braided lines and earl fittings btw. After I got that fuel filter reversed the way it was suppose to go I was able to boost all day long (I wasn't). A few days had passed and it started to lean out again during boost. So I checked the lines and I had another leak, very minor. So I got that fixed and voila! Fixed. About a half of a day passed and back to leaning out again under boost. Just like 5 pounds. This time I couldn't find the "leak". I turned on the pump via link and found no leaks. Was at a steady 43psi on the afr. When the car is running the needle jumps from 38-39 very rapidly thus telling me there somewhere is a "leak" because when there was no leak, it stays constant. No needle jumping at all. I checked the AFPR for fuel on the vacuum, it was clean. I went back and put new Teflon on all the treads. Fuel pump, both sides of fuel filter and the fitting on the fuel rail. No change. And no smell of fuel. Now you all may be saying it's the o ring on the pump or could be the fpr diaphram. I do not think that is the problem. I think it is because of my steel braided lines leaking so minor I can't tell until boosting, and by that time I can't check because I'm driving. I was wanting some opinions on a new fuel line. I was thinking of just going to the parts store and getting some 3/8 fuel line hose and run it from the pump to the filter. Opinions? I can drive the car all day, until I push the gas more than 60% or trying to boost and it leans out to --- on my aem wideband. Thanks in advance!!

Anyone?

 

[Chad1993]

Deleted braided lines, fixed problem.