HELP Trouble with a 2.5L

Hey all,
I just bought this 87 MJ with a 2.5L and FI. I scored it real cheap($400) because it ran real bad.
Here is the trouble. It starts and runs, but runs real rough, like it not hitting on all cylinders. I pulled the plugs and they are all gas fouled. I cleaned them, put them back in and it does the same thing and fouls out the plugs. I checked compression and all 4 are around 100psi. It seems that the FI is dumping way more fuel than it should.
It has new plugs, cap, rotor, wires and other tune up stuff. Cat converter is new(but may be shot soon if I don't fix it).
What should I check? Any suggestions?

Thanks
Scott
87 MJ 2.5L 5sp 4X4

First the compresion is low. It should be about 140-150 psi with no more than a 40psi variance. Did you do a wet test? As for the FI its TBI but you probably knew that. IMSC the computer controls the fuel amount. But I am not sure. Seems like the O2 sensor tells the computer if it is lean or rich but I may be wrong there. AMybe Hoss or Old Man will chime in. They both ran that style 2.5L and know more about it than me.

After a little more investigating I drained the oil and there had to have been at least 2 gallons of oil/gas. I know this could not have done the engine any good, I am sure the bearings are going to suffer big time.
I did not do a wet test, just dry. I figure the compression is low now due to the thin oil/gas and the cylinders are worn.
I think that maybe the injector is leaking while it sits, is this possible? It has sat for a very long time and started up for a minute or two just to have a customer look at it and then walk away. It then sat till the next time.
It also seemed to run real rich.
At this point I would just like to fix the FI problem so that it runs and then when the engine completely wears out I will pull it and rebuild it. I would like to get a one summer of fun out of it before I pull the engine out next summer. BTW it is not going to be a daily driver, just fun on the weekends.

Thanks for your input,
Anyone else?

Scott

I'd have to say that the injector couldn't leak when not running, because the fuel system doesn't hold any pressure when it's keyed "off" like an MPI system. It might dribble a little, but I don't think more than a drop or two. Try changing the o2 sensor, and maybe the TPS and coolant temp sensor also. AFAIK, the comp uses input from these three to set the injector pulse length. Seems like it's been running too "rich" for awhile...
Keep us 2.5L guys posted on your progress, and good luck!
Jeff

Sorry for no update, I took off for the Holiday and just got back last night. I did buy an O2 sensor, but I will have to install it tonight.
Thanks for all the input.

I run the same tbi system. I would start with the injector. Here is a link for a rebuilt one to save some money rebuilt injectors. I have to respectfully disagree with the injector not leaking when the engine is off. Your fuel tank has a pressure cap. Even a little pressure buildup can cause a bad injector to leak. Maybe not fast but the beast hasn't been started much and it has had a long time to leak in. Normally you would burn off the excess in the oil with daily driving. I wouldn't be too worried about your bearings if all you did was try to start it. What you need to do is on a nice warm day look down to see if raw fuel is leaking from the injector. If that's not the case then check to see what happens when you crank it. Put your timing light on the spray pattern to check it. It should look even and misty. Other than that then the cps and o2 would be most likely.