Engine Fuel pump?

[Bearlyrunnin]

Need some expert advice..

I have a 83 CJ7 AMC 258 i6 / 4.2l with Chrysler fuel injection

I drive it here n there on the weekends and it’s been running fine.
Until The other day I went for a drive and it smelt really badly of fuel. I come home and find that my supply line was leaking, fixed it and was fine. Til I looked back and the tail pipe had smoke coming from it.

I changed the map sensor, runs a little better but still smokes.

I got a pressure gauge turned it to accessory mode, it builds pressure to 31psi, then I turn the vehicle off and it dies down to zero quickly.

I did the usual check of the regulator, pinched off the return hose and it still dies to zero. I turned the engine on and it built pressure again, unhooked the vacuum line to the regulator and it builds to 42 as it should.

So regulator should be fine? So I have my wife turn the vehicle on, I pinched off the supply line and had her turn the vehicle off. Pressure didn’t die at all and stayed at around 32.

Before I dive into changing the fuel pump, could it be the injectors? All of them tick at same speed.

But obviously something is causing too much fuel into combustion.

I don’t see how a bad fuel pump would cause smoke? It does occasionally have a hard time starting. Also sometimes the engine won’t turn off right away after I turn it off, kinda like some diesels.



Any help or input would be great’

Thank you!

 

[NP435]

Oxygen sensor? My old 89 Ramcharger threw black smoke when it killed yet another sensor

 

[TSB8C]

Any error codes? I'm not familiar with the Chrysler EFI. Does it have a check engine light? Any OBD port to read from? A bad O2 sensor or a faulty injector will usually throw a code. I agree an O2 sensor problem could cause black smoke (running too rich). Of course high fuel pressure can also cause it to run rich if it's so high the ECU can't speed the injectors up enough to compensate for it, although your pressure tests seem to rule this out. I also wouldn't suspect the fuel pump causing the black smoke, again since your pressure tests seemed OK (not too high). No losing pressure after shutting down? Maybe something there. But not the rich condition, which I would focus on first. Would be odd for all or multiple injectors to out all at once. But certainly one bad one could cause your symptoms. Pop the plugs and see if one is fouled up or burnt compared to the others. This would identify a faulty cylinder (injector, etc).

 

[Bearlyrunnin]

Oxygen sensor? My old 89 Ramcharger threw black smoke when it killed yet another sensor

So looking at it more further I does seem to be the o2 sensor… now my issue is I can’t get it out, I’m a complete noob when it comes to this stuff… the bolt on the right, if I can get it out can I just hook the new o2 sensor to that? The 02 sensor is way too far into the hole that I couldn’t use any sort of socket. I tried my best but it’s just rounding out.

 

[TSB8C]

That other bolt/plug, if the correct size hole/threads, looks like it could be used as an alternative spot. May have damaged the original sensor too bad now, but they do make special O2 sensor sockets that are 6-point (unlike many 12-point sockets or wrenches) and they wrap around all 6 points of the sensor (unlike a wrench that hits two flat sides only). Even a vice grip plier would not grab as well. You can purchase O2 sensor sockets at most auto parts stores for cheap, or even use their "borrow a tool" service for free (after a deposit).

Link to O'Reilly O2 Sensor Sockets

 

[Patrick]

The exhaust manifold, you don’t think it’s the wrong location for this component…

 

[Bearlyrunnin]

I have the smaller black socket, but the bolt isn’t exposed enough to use it very well, just keeps sleeping. I may try and get the chrome one it might work better.
I was able to get the other bolt out fairly easy, however ended up with this…
Just a hollow bolt and there’s a wall at the back side of that hole. So I have no clue what that hole is even for

 

[TSB8C]

The exhaust manifold, you don’t think it’s the wrong location for this component…

Really should be mounted in the exhaust pipe after the manifold, similar to being in the collector at the base of a header. How tough to drill a hole and weld a threaded bung into the exhaust pipe itself?

 

[NP435]

I have the smaller black socket, but the bolt isn’t exposed enough to use it very well, just keeps sleeping. I may try and get the chrome one it might work better.
I was able to get the other bolt out fairly easy, however ended up with this…
Just a hollow bolt and there’s a wall at the back side of that hole. So I have no clue what that hole is even for

You do know the o2 sensor has wires coming out right? not just a bung on the manifold? Look at the new sensor and then look for where it is in the exhaust stream.

 

[TSB8C]

You do know the o2 sensor has wires coming out right? not just a bung on the manifold? Look at the new sensor and then look for where it is in the exhaust stream.

I think he was hoping to use that other hole to put the new sensor in since he can't get the old one out. But after removing that bolt/plug from that other hole, it now appears that hole can't be used for the new sensor. Now back to getting the old one out or finding a different/better mounting location.

Those O2 sensor sockets have a slot in the side to slip over the wires on the sensor, while still providing a 6-point grip on the sensor's "nut" portion. But since the old one is in a bit deep with part of the "nut" part not exposed, and after stripping it a bit, looks like he needs another solution. I recommend looking at potentially drilling a hole and welding a bung in the exhaust pipe itself rather than mounting the new one in the manifold.

 

[NP435]

I think he was hoping to use that other hole to put the new sensor in since he can't get the old one out. But after removing that bolt/plug from that other hole, it now appears that hole can't be used for the new sensor. Now back to getting the old one out or finding a different/better mounting location.

Those O2 sensor sockets have a slot in the side to slip over the wires on the sensor, while still providing a 6-point grip on the sensor's "nut" portion. But since the old one is in a bit deep with part of the "nut" part not exposed, and after stripping it a bit, looks like he needs another solution. I recommend looking at potentially drilling a hole and welding a bung in the exhaust pipe itself rather than mounting the new one in the manifold.

Yes indeed, I replaced 13 of those on my old Ram Charger had to have the tool milled down to get in the flange .

 

[Bearlyrunnin]

I think he was hoping to use that other hole to put the new sensor in since he can't get the old one out. But after removing that bolt/plug from that other hole, it now appears that hole can't be used for the new sensor. Now back to getting the old one out or finding a different/better mounting location.

Those O2 sensor sockets have a slot in the side to slip over the wires on the sensor, while still providing a 6-point grip on the sensor's "nut" portion. But since the old one is in a bit deep with part of the "nut" part not exposed, and after stripping it a bit, looks like he needs another solution. I recommend looking at potentially drilling a hole and welding a bung in the exhaust pipe itself rather than mounting the new one in the manifold.

That’s exactly what I meant, sorry I didn’t explain better.
I think I’m gonna try to mess around with the old one this weekend and if I can’t seem to get it (it’s somewhat hard to work on because it’s literally right under the manifold and id rather not rip everything apart) I’m most likely just gonna go that route and weld in a new bung, make it more accessible. Thanks for the input!

 

[Patrick]

He needs a link to selecting the right location and welding in a bung for sensor. TS, you are good at this, and also to make sure he gets the correct sensor.

 

[TSB8C]

The best position is somewhere between 10 degrees off straight horizontal and about 15 degrees off from straight vertical. You never want it positioned anywhere pointed downhill (less than 90 degrees from straight down) due to crud settling and potentially contaminating it. (See the diagram) It is also best placed in a collector or part of the exhaust where it is "seeing" a combined output of all cylinders on that side of the engine (in a dual exhaust setup). Here's a great shot of an O2 sensor mounted in a header collector just a few degrees above 90 (sideways). In a single exhaust setup on a "V" engine, you can place it after the "Y" part of the pipe where the two engine sides are combined into one pipe.

It is also recommended to mount the sensor no less than 20" from the nearest exhaust valve. If that's not possible, you can space the senor out by using a bung extension or welding another bung over the existing one so the sensor tip is slightly out from the pipe. The sensor will get hot, so make sure it is not too close or touching underbody insulation or sound deadening materials due to fire hazard, or other wires/hoses that could be melted. Since the O2 sensor does not read properly until it reaches operating temp, a heated sensor may be required in environments where it could get wet (tires throwing water on a wet road, etc). I learned that lesson when I installed an O2 sensor in the header collector on a set of fenderwell exit headers and the front tire would throw water on it and screw things up. So a standard Bosche or other 4-wire unit is ideal (2 wires for signal + and - and two wires for the heater + and GND). I simply connected the heater + to my fuel pump relay so the O2 sensor heater was on whenever the fuel pump was running since my ECM wasn't designed for a heated O2 sensor (an old AFI system I scrapped for other reasons).

If a person doesn't have welding skills or access to a welder, they do make clamp-on bungs. You drill a hole in the pipe and then this bung uses two clamps to strap it to the pipe over the hole. Not ideal, but workable.

 

[Bearlyrunnin]

The best position is somewhere between 10 degrees off straight horizontal and about 15 degrees off from straight vertical. You never want it positioned anywhere pointed downhill (less than 90 degrees from straight down) due to crud settling and potentially contaminating it. (See the diagram) It is also best placed in a collector or part of the exhaust where it is "seeing" a combined output of all cylinders on that side of the engine (in a dual exhaust setup). Here's a great shot of an O2 sensor mounted in a header collector just a few degrees above 90 (sideways). In a single exhaust setup on a "V" engine, you can place it after the "Y" part of the pipe where the two engine sides are combined into one pipe.

It is also recommended to mount the sensor no less than 20" from the nearest exhaust valve. If that's not possible, you can space the senor out by using a bung extension or welding another bung over the existing one so the sensor tip is slightly out from the pipe. The sensor will get hot, so make sure it is not too close or touching underbody insulation or sound deadening materials due to fire hazard, or other wires/hoses that could be melted. Since the O2 sensor does not read properly until it reaches operating temp, a heated sensor may be required in environments where it could get wet (tires throwing water on a wet road, etc). I learned that lesson when I installed an O2 sensor in the header collector on a set of fenderwell exit headers and the front tire would throw water on it and screw things up. So a standard Bosche or other 4-wire unit is ideal (2 wires for signal + and - and two wires for the heater + and GND). I simply connected the heater + to my fuel pump relay so the O2 sensor heater was on whenever the fuel pump was running since my ECM wasn't designed for a heated O2 sensor (an old AFI system I scrapped for other reasons).

If a person doesn't have welding skills or access to a welder, they do make clamp-on bungs. You drill a hole in the pipe and then this bung uses two clamps to strap it to the pipe over the hole. Not ideal, but workable.

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I finally got it out, cut the O2 sensor in half heated it up til it was almost red and sprayed PB blaster and put a 22 stubby socket on there and it finally gave.
Replaced it and also reset the computer (atleast I think I reset it, unplugged battery grounded positive and did the headlight trick) and it runs a little better but still smokes, changed the fuel regulator and it no longer has the gas smell.
But as far as why it’s smoking I still haven’t figured out why.
Working on it here n there but still no luck

 

[TSB8C]

Glad to hear you got it out and replaced. So good news and some positive to focus on. I recently bought an entire tank of gas for only $25. Sure, it was in my riding mower, but I'm trying to remain positive. But back to your black smoke issue. Ever get a chance to check the plugs to see if one cylinder is fouled up or burnt more than the others? Checking/comparing plugs could help identify if a single cylinder is the issue or not. A bad ECU or MAP sensor or O2 sensor or fuel pressure issue would affect all cylinders. So checking if they all seem problematic or just one would help narrow this down. If only one plug is fouled up for example, then you could check that one injector or even swap it for another to see if the problem moves.