HELP! Jeep problem driving me bonkers!

[quads]

Hey Quads have you ever checked timing?? chain could have jumped a tooth.


JIM

I wondered that too, but according to the Chilton manual it has timing gears like the old straight 6 engines.

With all of you guys' help, I think I have it narrowed down. I took the fuel return line off the pressure regulator and it never returns a drop of fuel to the tank, even at idle. With my luck it's the pump that is bad/weak. I was trying to avoid tearing the rusty old gas tank apart, but I guess I should have just assumed it would be whatever is the hardest to fix and started there! HA!

 

[mayhem]

Not sure where the tank is located, but on alot of trucks its easier to just pull the bed off to expose the tank and you can get right at the pump.

I had a 77 Oldsmobile 98 Regency as a winter beater when I was a lad...it had similar issues, though the sputtering got worse with WOT then half...turns out the gas line was rotted in one spot and I was sucking air periodically. Something else to look for anyway.

I bet its the pump though.

 

[tjnamtiw]

Did anyone mention fuel filter??? The fact that it stumbles at part throttle sounds like the throttle position sensor. Hook a resistance meter to it after unplugging it and slowly open the throttle with engine shut off. Hopefully you have a meter with a needle to see if it changes steadily.

A collapsed cat converter could do it too. Put a vacuum meter on intake manifold. Vacuum should go down as revs go up. If it doesn't, cat is plugged.

 

[begreen]

Hey Quads have you ever checked timing?? chain could have jumped a tooth.


JIM

I wondered that too, but according to the Chilton manual it has timing gears like the old straight 6 engines.

With all of you guys' help, I think I have it narrowed down. I took the fuel return line off the pressure regulator and it never returns a drop of fuel to the tank, even at idle. With my luck it's the pump that is bad/weak. I was trying to avoid tearing the rusty old gas tank apart, but I guess I should have just assumed it would be whatever is the hardest to fix and started there! HA!

Please be super careful if attempting to do this. An empty fuel-tank has the potential to be a serious bomb.

 

[quads]

FIXED! Thanks everybody for all your help! I am in your debt. And the winning failed part was........or wait, maybe I should just let everybody guess? No, it was a weak FUEL PUMP! Now why the engine would level out at wide open throttle, is beyond me, just one of those mysteries I guess, but now that it's fixed it certainly has power at wide open throttle, which it never had before.

It needed the new crank sensor, because that immediately cured the hard starting problem. It needed the new throttle position sensor because that cured the up and down idle problem. I did replace the fuel filter, plugs, wires, cap, and rotor, which it probably all needed anyway. The only thing I bought that it didn't really need was the ignition coil. And considering I got a quote from a garage to replace the fuel pump for $600, I think I did pretty good. It took me the better part of a week to fix it, but the garage had a waiting list of two weeks.

I bought that truck brand new off the showroom floor 20 years ago. It really looks like crap now, all rusted out and I have hit two deer with it over the years, but it has never ran so good even when it was new as it does right now! Unless it's just been running that bad for so long that my old brain has forgotten. I can honestly say one thing though, I'm getting too old to be leaning over hoods and rolling around under trucks all day anymore...

Now tonight, I become a Chevy owner again. A neighbor from a few miles away (almost all of my neighbors are a few miles away) heard about my plight and I was complaining that I needed a spare truck, and he has offered me a pretty good deal on a little Chevy truck, a few years newer than the old Jeep truck. I haven't been a Chevy owner for at least 25 years, and this will be the first used car I've bought in that long too. I'm not even sure how to register a car in Wisconsin anymore. Maybe my neighbor will know.

Anyway, thanks again for all the help! I'm tickled pink to have the old truck running up to snuff again, for now...

 

[quads]

Oh, and I forgot to mention that the fuel pressure regulator was bad, stuck shut, and I think that's what killed the fuel pump by building up too much pressure all the time.

 

[vvvv]

FIXED! Thanks everybody for all your help! I am in your debt. And the winning failed part was........or wait, maybe I should just let everybody guess? No, it was a weak FUEL PUMP! Now why the engine would level out at wide open throttle, is beyond me, just one of those mysteries I guess, but now that it's fixed it certainly has power at wide open throttle, which it never had before.

It needed the new crank sensor, because that immediately cured the hard starting problem. It needed the new throttle position sensor because that cured the up and down idle problem. I did replace the fuel filter, plugs, wires, cap, and rotor, which it probably all needed anyway. The only thing I bought that it didn't really need was the ignition coil. And considering I got a quote from a garage to replace the fuel pump for $600, I think I did pretty good. It took me the better part of a week to fix it, but the garage had a waiting list of two weeks.

I bought that truck brand new off the showroom floor 20 years ago. It really looks like crap now, all rusted out and I have hit two deer with it over the years, but it has never ran so good even when it was new as it does right now! Unless it's just been running that bad for so long that my old brain has forgotten. I can honestly say one thing though, I'm getting too old to be leaning over hoods and rolling around under trucks all day anymore...

Now tonight, I become a Chevy owner again. A neighbor from a few miles away (almost all of my neighbors are a few miles away) heard about my plight and I was complaining that I needed a spare truck, and he has offered me a pretty good deal on a little Chevy truck, a few years newer than the old Jeep truck. I haven't been a Chevy owner for at least 25 years, and this will be the first used car I've bought in that long too. I'm not even sure how to register a car in Wisconsin anymore. Maybe my neighbor will know.

Anyway, thanks again for all the help! I'm tickled pink to have the old truck running up to snuff again, for now...

plugged gas filter makes the fuel pump work harder?

 

[quads]

plugged gas filter makes the fuel pump work harder?

The gas filter was the very first thing I replaced. As far as I know, the old one was original! But, I could blow through it just as easily as the new one. With the pressure regulator stuck shut, that pump had to be working it's guts out because no fuel was returning back to the tank. The pump had to be at full pressure all the time.

Just picked up a used S10 Chevy a little while ago. Old Mrs. Quads is already in love with it!