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Im gonna kill my XJ!!


NAXJA Forum User
Huntsville, AL
OK, ive been posting 4 the last few weeks. Im trying to pass smog and have replaced darn near everything (bruised my credit card bad). Here is my latest problem. New fuel pump and filter here, the smog tech says I am running rich. I decide to check my fuel pressure regulator again, it is 25psi, it was 30/39 with the vacuum off. I replace the regulator, no change. Other than the obvious like a leaky fuel line what could it be. No leaks. Oh yeah 5 new fuel injectors too, they didnt have the last one in stock. Maybe a frag would help? Boom!
Oh yeah, 88XJ. 4.0


fuel pump
fuel filter
pressure regulator
3 new injectors, 2 not too old, 1 orig
plugs, rotor, cap, wires, coil
water pump, not too old 3 core rad, new thermstat, new aux fan w/ adj therm
manifold temp sensor, TPS sensor, ox sensor
some other stuff I cant remember right now.
170 Hydrocarbons, needs to be less than 124 at 5mph, 104 at 15 mph, carbon monoxide is a little high too, forgot the number. Had a diagnostic run, all sensors appear to be working properly. New cat, high flow good expensive one, was checked before and after cat, cat is working like it should. Levels too high going into cat.
That last fuel injector might be the culprit- I had many similar issues with mine, and it was ONE fuel injector.....so I would wait until you have the last injector replaced, and also verify that your coolant temp sensor (drivers side, lower part of engine) is reading properly- a simple digital voltmeter can easily determine its calibration. That sensor tells the Renix computer that the engine is warm enough for "closed loop" operation....good luck!!

Bret S Gray
1990 XJ Laredo
I checked it , looks good according to the FSM. Why is my fuel pressure low??? I havent had this many problems since I was married.
This morning I decided to bypass the ballast resistor for giggles. Wow, the fuel pressure went from 25 to 34/42 no vac.. it used to be 31/39 or so with the ballast. I measured the ballast and it is 1.1 ohms as it should be. This is bizzarre, kinda like doing plumbing, you touch one component and everything goes wacky.
More bizzarre stuff. Now the pressure is steady at 25 PSI with the ballast bypassed and 20 with the ballast, vacuum or not. The fuel pump is drawing 4 amperes without the ballast. I took the rail off the motor and jumpered the pump so I could look for leaky injectors, no leaks. At this point I think I have some problem with the new fuel pump. Looks like I'll be dropping the tank for the third time, oh no! There are no external fuel leaks.