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Bogging/Backfiring/Dying

bdahlg

NAXJA Forum User
Location
Waltham, MA
91 4.0 laredo

Driving home from work today. Stopped at a light, light turned green, stepped on the gas, gets up to speed and then starts sputtering really bad. Turn into a parking lot, open the hood and rev the engine at the throttle body. It was normal and engine sounded fine. Got back in, said f*ck it, and tried the journey home on the highway.

Couldnt get above 35; intermitant full power and acceleration but mostly bogging sputtering. It finally died on me on the side of the road. Got it towed home.

Battery was shot, so I put in a new redtop. Same problem. Took a long time to start up which it has been doing recently, then I just listened to the idle, which was really rough and irratic: high then low on the verge of stalling, then normal. It cycled like this.

I looked under at the back near the fuel tank and noticed bubblilng leaking fuel comin from one of the metal lines out of the flange for the fuel pump. Only leaked while running, not when it was shut off.

Is there air getting into the fuel line and causing it to act like this? I'v elliterally never had a mechanical problem like this within the 7 years I've owned it and has been very well taken care of by myself.

PLease help!!! I need to get to work and can only borrow my gfs car for tomorrow!
 
Yeah, sucking/pumping air along the fuel lines to the injectors--they don't squirt air worth a damn.

I repair the known issue first, might as well pull the pump assembly and check the condition of the rubber lines from the top of the pump to the flange.
 
Also make sure the vapor canister is venting. Check the gas cap.
 
What and where is the vapor canister? Why the gas cap? That had been the problem on my dad's grand caravan and was the first thing he told me to check too. I pulled it off, waited a few seconds, then popped it back on. Tried restarting it and nothing, then the battery died.

There is a visible crack at the flange on teh fuel pump assemtbly; on the metal nipple where the rubber line goes into the tank. Can I just throw some epoxy on there or should I shell out some clams for a new assembly?

thanks
 
The EVAP, vapor or charcoal canister is mounted on the firewall, passenger side of the engine.

Fuel vapors from the tank are captured there until they are fed into the intake by the EVAP purge solenoid.

The fuel cap can screw you up as it is supposed to permit air to enter the tank as fuel is pumped out to equalize the pressures.

Me, I would pull the pump assembly, disassemble it, and try to braze/weld it up after cleaning it of all fuel residue.
 
Bought a new NAPA gas cap at lunch. If it still does it, I'm dropping the tank and taking the assembly out. However, I do not have the time to weld/braze anything. Prob buy a new pump or go find one at the junkyard if I find time. Anyone have a good replacement I can get FAST?

I recently cleaned the throttle body and IAC, less than 500 miles before this happened which was last sunday. I made the mistake of cleaning it with carburetor cleaner and not TBC.

Would this have something to with it or is this coincidental? I read that it was bad to use carb cleaner but I don't know why.

Regardless, I'm starting with the known problem first: leaking gas.
 
Some carb cleaners are formulated TB safe--should be marked on the can.

Check around your area--radiator shops, muffler shops, metal fabrication shops--all of those should be willing to braze/weld that while-u-wait for chump change, you just need to disassemble the pump and sender and clean up any flammable fuel residue, essentially just take it in stripped of everything.

You could try some kind of fuel resistant sealer but it won't last.
 
Got the pump out and I brought it to work (driving my gfs dinky civic in the meantime.)

Going to try and have it brazed at lunch, as there is a metal fab shop right by my work in Woburn that has two nice lifted XJ's parked in front of it everyday, a 2-door RENIX and a 97-01, so hopefully a fellow jeeper can help me out for cheap!

Wonder if its anyone on here...

Oh and btw< I bought a new gas caop yesterday from NAPA and it helped out a little bit; now it idels fine and revs smoothly in neutral.

But when I tried to drive it, when I give it a lot of gas, it starts sputtering and losing power... I don't get it
 
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Got it soldered for $20. Threw it in this afternoon, she started right up, idled fine, tiook for a test drive for about 5 minutes, ran perfect, idled better than she ever has.

The optima makes the thing crank faster than I can remember! the battery definitely was on the brink of not being able to hold a charge, so it wasn't a total waste, and I'm very happy with it.

In the process I also met an entire group of XJ'ers that have the itch maybe even worse than I have. Plus, they own a metal fab shop and I have a hookup whenever I need anything welded.

Next is upgraded cables from 5-90 and my IPF housings should be here tomorrow. I'm excited
 
Glad you got it done.
 
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