TheJeepaholic

Hello everyone, this will be my first post on the website.

So i own a 88 Jeep Cherokee Limited 4.0 Manual. Which i believe these are Renix engines. The whole thing is in rugged condition anyways (Not suprising, i only paid 300 bucks for it) The thing can start without the clutch being held in...scary.. and the radiator doesnt operate unless i flip a switch that someone jerry-rigged into the cab.

So now onto the problem:

At first it would reach normal operating temperature and then do this annoying "lunge" or "Bucking" thing while it is being driven. it'll do it constantly too, about 5-6 times in a row (buck-buck-buck-buck-stall) and if i try to start it afterwards, itll either stall out immediately or it will allow me to drive it about 5 feet forward before the bucking begins again. If i let it cool down for about 20 minutes before trying to start it again, it works OK for about 5 minutes, until it reaches normal temp. then the problem continues.

Everyone says its the fuel pump, but i hear it prime just fine every time i start her up. i replaced the spark plugs and did an oil change on it and now it can stay running for a little while longer before the problem starts over again. ill be putting about $300 into it on the 1st of november and i was just curious if anyone knows what i should try replacing first?

cpnwrench

ok, here is whats goin on.


fuel pump, is truly an issue, coupled with a "old" fuel filter, this will INDEED cause the "bucking" you are getting. be advised, my fuel pump went after 280,000 miles, amazing? truly. but here is the down side.... when it failed I was far from home, big charge for tow. regardless, got NEW pump motor/strainer assy. ONLY. (if you are decent with a wrench, you don't need to buy the whole assy, just motor and strainer.) you see, the original pump when I removed it, well, the strainer/sock/tank filter/whatever u wanna call it (the thing which attaches DIRECTLY to the intake orifice on the fuel pump motor) HAD COMPLETELY DISINTEGRATED !!!!!!!!! (280K is a lotta miles!). now, you may "hear" the pump trying to prime, etc, but if the strainer is gone/broke-off/detached... stuff will block the motor orifice and eventually the pump will burn out. Hence the replacement being required.
DO YOURSELF AND YOUR WALLET A FAVOR,,,,,first change fuel filter, then see if symptoms abate.(check below paragraph or testing).. 8 bucks at O'reilly/Autozone


Secondary Scenario::::: you say you can "start the Jeep without the clutch being held in"????? YIKES! ! ! !


Slave cylinder nearly shot... do yourself a favor, near the brake booster in the engine compartment, there is a small container which looks like a reservoir for an additional brake master cylinder. this is the SLAVE CYLINDER reservoir for the clutch. use a baking baster (turkey baster), suck all the black fluid out of the unit. fill with CLEAN bake fluid. run the car through 10-20 miles of different shifting scenarios, then remove fluid again and refill. if this does not help, then slave cyl is goin bad ( on my jeep it is internal to the bell housing next to the clutch/pressure plate assy. (big job). I got like as I say 280k on mine, so I know whole unit assy has to be replaced soon, especially since temps are droppin.


but from what you are describing, it seems like fuel delivery issue, might even be fuel pressure regulator..... there should be a what looks like a tire valve stem on your fuel rail (atop the intake manifold [driver-side of engine], with car off, press in with a golf tee (careful, dont get yer face too close!!!).....if you get a mere trickle, fuel pump bad or filter clogged for sure. then turn ignition to start, but not engage the starter (run, pos #2, Pos # 3 engages starter). check the pressure again with the golf tee, if you get a quick burst out of the valve stem, pump/ filter is workin ok, so might be clutch or fuel pressure regulator/injector(s) fail..many different posts for those on the forum......


good luck, keep us posted here!


cheers


cpnwrench