I have a 1993 YJ with 2.5L 5sp that I just rebuilt the motor due to a bad valve leak from PO overheating the engine. Initially when I purchased the jeep the codes stated it was a fuel injection problem and the engine sputtered and lost power once warmed up. Compression test showed 30 psi on #1 piston which lead to rebuild. Now I have everything back together with all new radiator, water pump, thermostat, exhaust, O2 sensor, fuel pressure regulator, alt, and both block and thermostat temp sensors. Engine runs and sounds 100% better, but after 10 minutes I get the same symptom of no acceleration and it backfires and dies. If I turn the key off it fires right back up and runs good for another 10 minutes or so. The ECU is throwing no codes and today I found the return fuel line where it comes out of the tank has been cut! Would this cut line cause all my troubles, I'm asking because of where its cut I would have to drop the tank just to splice into it. Should I just replace the fuel pump while the tank is down or just splice the cut hose to see if it fixes the problem. Fuel Filter is only three months old so I don't think that's the problem. I get the right fuel pressure at the fuel rail, but it doesn't hold the pressure once the engine is turned off it drops to 0. Where should I go from here?
07-14-2013 04:21 PM
You should definitely replace the fuel pump, the filter, and probable the regulator too. There is a check valve built into the pump and another one in the regulator, that is supposed to hold the pressure for you. It obviously isn't doing so. The pressure should be holding over 20 PSI for at least 1/2 hour. That and the return line is definitely part of the prob. Your fuel system is basically marginal --- it has the pressure but can it keep up when you are on the gas, is the question. So check into all the stuff I mentuioned. Its cheap insurance for a new engine.
07-14-2013 04:31 PM
Thanks for the help I was heading down that path just wanted some input before I started thought maybe the crank position sensor might also be the problem but I think your right I'll start with the fuel problem then move on. By the way the jeep is a 1993 but the motor is from a 1995 I'm thinking they use the same fuel pump right?
07-14-2013 05:20 PM
Yeah the fuel system is the same from 1991 thru 1995, all models.