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fuel system troubles
Chrysler Dodge, Plymouth, Jeep, Eagle, etc info/talk (rec.autos.makers.chrysler)
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#21
 
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Re: fuel system troubles -
02-25-2007
, 06:51 AM
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Dipstick wrote: I know from experience that an intermittently failing/failed fuel pump (low pressure) on a '96 will not set a fault code in 1000 miles of drive/die/restart/drive highway travel over 2 plus days. Every dealer within 600 miles of here knew exactly what the problem was, but none was sure enough to replace the pump if they couldn't make it quit while they had the pressure gauge hooked up. Never did set a code. Also never quit with a gauge in place :-) As you say, IF you get a code from fuel pressure, it will be a secondary code not directly tied to the pressure itself. That's really interesting, because it is obviously getting too much fuel, so much so that it cannot burn it. I know the spark plugs are working because I pulled the wires off and watched the sparks jump to the tip of the plug, meaning that there is spark in the cylinder. I listened to the injectors clicking, meaning that they are operating properly. So the problem is either too high fuel pressure or an injector that doesn't close all the way. The resistance on the injector coil is correct. I guess I need to buy a fuel pressure gauge, unless somebody can think of another problem that would cause excessive fuel delivery WITHOUT setting a computer code. |
#22
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On Sat, 24 Feb 2007 21:32:37 -0600, Robert Reynolds <robbie (AT) kcnet (DOT) com wrote: bllsht wrote: It won't set a mixture code if the fuel pump just 'up and quits'. It also won't set a code if the pressure is only slightly high or low. With gas pouring out of the tail pipe, it will NOT set a code because it'll likely never achieve closed loop and can't know what the mixture is doing. It will, however, definitely set a code if the pressure is off far enough that the PCM can no longer correct the mixture. If it's misfiring, it 'should' set a misfire code. However, if the battery has been disconnected and the adaptive numerator has not been relearned since, misfire detection will be disabled. It would also be disabled if the engine is operating outside the normal paramaters that misfire detection occurs in. OK, this is interesting because the battery has been in and out a couple of times as I worked on basic tuneup items. If disconnecting the power would disrupt normal codes, I'm starting to think it may be something more obvious like an oxygen sensor. Stop right there. Now, before you start thinking again, go back and read what you quoted. Now, tell me where I said disconnecting power would disrupt normal codes. That's right, I didn't say that. I said MISFIRE DETECTION would be disabled if the PCM hasn't relearned the adaptive numerator since the battery was disconnected. OK. Resume thinking and take it to somebody that knows what he's doing. |
#23
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So which is it? A few posts ago, you said "It won't set a mixture code if the fuel pump just 'up and quits'. It also won't set a code if the pressure is only slightly high or low." Now you say it WILL cause a code to be set. I say you are wrong. It can't cause a code to be set because it isn't monitored. Any codes that are set are the result of follow-on symptoms, which could be caused by any number of things other than fuel pressure. Fuel system rich or fuel system lean are nice codes, but they are not the same as fuel pressure high and fuel pressure low. On Feb 25, 3:32?am, bllsht <nos... (AT) dot (DOT) net> wrote: My last post obviously went over your head. While fuel pressure is not monitored, it WILL cause a code if it's high enough, or low enough, to cause the PCM to determine it can't keep fuel trim within spec. The resulting code would be 'Fuel system rich' or 'Fuel system lean'. Yes. Fuel pressure alone WILL cause a code to be set. On 24 Feb 2007 18:03:11 -0800, "Dipstick" <SSTE... (AT) aol (DOT) com> wrote: Fuel pressure alone will not set a code. It can't set a code because it isn't monitored. If out of spec pressure persists long enough, the resulting symptoms 'may' eventually set a code of their own. And maybe not. On Feb 24, 7:18?pm, bllsht <nos... (AT) dot (DOT) net> wrote: It won't set a mixture code if the fuel pump just 'up and quits'. It also won't set a code if the pressure is only slightly high or low. With gas pouring out of the tail pipe, it will NOT set a code because it'll likely never achieve closed loop and can't know what the mixture is doing. It will, however, definitely set a code if the pressure is off far enough that the PCM can no longer correct the mixture.- Hide quoted text - - Show quoted text - |
part is bad. If you have a fault code for a map sensor/TPS sensor or
anything else does not mean those parts are at fault. It simply points you
into a direction of the problem. A fuel system rich or lean does not condemn
the fuel pump but points you in the direction of the problem. NO THERE IS
NOT a fault code that simply says fuel pump is bad. Just like there is no
fault code that says 02 sensor, TPS MAP and so on are bad....
Glenn Beasley
Chrysler Tech
#24
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bllsht wrote: It won't set a mixture code if the fuel pump just 'up and quits'. It also won't set a code if the pressure is only slightly high or low. With gas pouring out of the tail pipe, it will NOT set a code because it'll likely never achieve closed loop and can't know what the mixture is doing. It will, however, definitely set a code if the pressure is off far enough that the PCM can no longer correct the mixture. If it's misfiring, it 'should' set a misfire code. However, if the battery has been disconnected and the adaptive numerator has not been relearned since, misfire detection will be disabled. It would also be disabled if the engine is operating outside the normal paramaters that misfire detection occurs in. OK, this is interesting because the battery has been in and out a couple of times as I worked on basic tuneup items. If disconnecting the power would disrupt normal codes, I'm starting to think it may be something more obvious like an oxygen sensor. |
part is bad. If you have a fault code for a map sensor/TPS sensor or
anything else does not mean those parts are at fault. It simply points you
into a direction of the problem. A fuel system rich or lean does not condemn
the fuel pump but points you in the direction of the problem. NO THERE IS
NOT a fault code that simply says fuel pump is bad. Just like there is no
fault code that says 02 sensor, TPS MAP and so on are bad....
Glenn Beasley
Chrysler Tech
#25
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Just because you get a fault code for a particular part does not mean that part is bad. If you have a fault code for a map sensor/TPS sensor or anything else does not mean those parts are at fault. It simply points you into a direction of the problem. A fuel system rich or lean does not condemn the fuel pump but points you in the direction of the problem. NO THERE IS NOT a fault code that simply says fuel pump is bad. Just like there is no fault code that says 02 sensor, TPS MAP and so on are bad.... Glenn Beasley Chrysler Tech |
#26
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On Sat, 24 Feb 2007 21:32:37 -0600, Robert Reynolds <robbie (AT) kcnet (DOT) com wrote: bllsht wrote: It won't set a mixture code if the fuel pump just 'up and quits'. It also won't set a code if the pressure is only slightly high or low. With gas pouring out of the tail pipe, it will NOT set a code because it'll likely never achieve closed loop and can't know what the mixture is doing. It will, however, definitely set a code if the pressure is off far enough that the PCM can no longer correct the mixture. If it's misfiring, it 'should' set a misfire code. However, if the battery has been disconnected and the adaptive numerator has not been relearned since, misfire detection will be disabled. It would also be disabled if the engine is operating outside the normal paramaters that misfire detection occurs in. OK, this is interesting because the battery has been in and out a couple of times as I worked on basic tuneup items. If disconnecting the power would disrupt normal codes, I'm starting to think it may be something more obvious like an oxygen sensor. Stop right there. Now, before you start thinking again, go back and read what you quoted. Now, tell me where I said disconnecting power would disrupt normal codes. That's right, I didn't say that. I said MISFIRE DETECTION would be disabled if the PCM hasn't relearned the adaptive numerator since the battery was disconnected. OK. Resume thinking and take it to somebody that knows what he's doing. |
taking my van to an "expert". I'll admit that I have a lot to learn in
life, and I'm not scared of car maintenance. So you can take your
arrogant attitude somewhere else. If you can help, that's great because
that's why we're all here.
How does the computer know there is a misfire? Does it read the
activity of the coils? I know my engine is misfiring because it has
poor power and will not idle. I also know that the ignition system is
not misfiring because I pulled the wires off the plugs and watched the
sparks jump to the spark plugs. So I'm assuming there wouldn't be a
misfire code anyway.
What would be helpful is to know what other conditions might cause
excessively rich running without setting a code. I looked for vacuum
leaks but didn't find any. Any other suggestions?
#27
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bllsht wrote: On Sat, 24 Feb 2007 21:32:37 -0600, Robert Reynolds <robbie (AT) kcnet (DOT) com wrote: bllsht wrote: It won't set a mixture code if the fuel pump just 'up and quits'. It also won't set a code if the pressure is only slightly high or low. With gas pouring out of the tail pipe, it will NOT set a code because it'll likely never achieve closed loop and can't know what the mixture is doing. It will, however, definitely set a code if the pressure is off far enough that the PCM can no longer correct the mixture. If it's misfiring, it 'should' set a misfire code. However, if the battery has been disconnected and the adaptive numerator has not been relearned since, misfire detection will be disabled. It would also be disabled if the engine is operating outside the normal paramaters that misfire detection occurs in. OK, this is interesting because the battery has been in and out a couple of times as I worked on basic tuneup items. If disconnecting the power would disrupt normal codes, I'm starting to think it may be something more obvious like an oxygen sensor. Stop right there. Now, before you start thinking again, go back and read what you quoted. Now, tell me where I said disconnecting power would disrupt normal codes. That's right, I didn't say that. I said MISFIRE DETECTION would be disabled if the PCM hasn't relearned the adaptive numerator since the battery was disconnected. OK. Resume thinking and take it to somebody that knows what he's doing. First of all, I'm trying to learn something here, rather than just taking my van to an "expert". I'll admit that I have a lot to learn in life, and I'm not scared of car maintenance. So you can take your arrogant attitude somewhere else. If you can help, that's great because that's why we're all here. How does the computer know there is a misfire? Does it read the activity of the coils? I know my engine is misfiring because it has poor power and will not idle. I also know that the ignition system is not misfiring because I pulled the wires off the plugs and watched the sparks jump to the spark plugs. So I'm assuming there wouldn't be a misfire code anyway. What would be helpful is to know what other conditions might cause excessively rich running without setting a code. I looked for vacuum leaks but didn't find any. Any other suggestions? |
#28
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Has the compression been checked on the cylinder in question? |
Here's a bit of additional info, which I realized I hadn't covered yet.
I only recently acquired this van, and I did some basic maintenance to
it such as the belt and the plugs and wires. When I pulled the plugs
they all had gasoline on them, not just the #2 and #4 that I mentioned
before. The only difference between these two and the rest is that
when I pull the wires off of them there is no change in the engine,
meaning that they are not producing any power. The rest, although too
rich, are contributing to the engine's power, which is shown by a drop
in performance when I pull the wires.
This is why I became suspicious about the fuel delivery system. But it
seems like more of a universal problem rather than something having to
do with 2 and 4, because they all are wet with gasoline.
#29
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So which is it? A few posts ago, you said "It won't set a mixture code if the fuel pump just 'up and quits'. It also won't set a code if the pressure is only slightly high or low." Now you say it WILL cause a code to be set. I say you are wrong. It can't cause a code to be set because it isn't monitored. Any codes that are set are the result of follow-on symptoms, which could be caused by any number of things other than fuel pressure. Fuel system rich or fuel system lean are nice codes, but they are not the same as fuel pressure high and fuel pressure low. On Feb 25, 3:32?am, bllsht <nos... (AT) dot (DOT) net> wrote: My last post obviously went over your head. While fuel pressure is not monitored, it WILL cause a code if it's high enough, or low enough, to cause the PCM to determine it can't keep fuel trim within spec. The resulting code would be 'Fuel system rich' or 'Fuel system lean'. Yes. Fuel pressure alone WILL cause a code to be set. On 24 Feb 2007 18:03:11 -0800, "Dipstick" <SSTE... (AT) aol (DOT) com> wrote: Fuel pressure alone will not set a code. It can't set a code because it isn't monitored. If out of spec pressure persists long enough, the resulting symptoms 'may' eventually set a code of their own. And maybe not. On Feb 24, 7:18?pm, bllsht <nos... (AT) dot (DOT) net> wrote: It won't set a mixture code if the fuel pump just 'up and quits'. It also won't set a code if the pressure is only slightly high or low. With gas pouring out of the tail pipe, it will NOT set a code because it'll likely never achieve closed loop and can't know what the mixture is doing. It will, however, definitely set a code if the pressure is off far enough that the PCM can no longer correct the mixture.- Hide quoted text - - Show quoted text - |
#30
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i'm not saying it can't happen, a rich condition but i have never seen that with a failing pump it has always been a lean condition with a failing pump bllsht wrote: On Sat, 24 Feb 2007 21:32:37 -0600, Robert Reynolds <robbie (AT) kcnet (DOT) com wrote: bllsht wrote: It won't set a mixture code if the fuel pump just 'up and quits'. It also won't set a code if the pressure is only slightly high or low. With gas pouring out of the tail pipe, it will NOT set a code because it'll likely never achieve closed loop and can't know what the mixture is doing. It will, however, definitely set a code if the pressure is off far enough that the PCM can no longer correct the mixture. If it's misfiring, it 'should' set a misfire code. However, if the battery has been disconnected and the adaptive numerator has not been relearned since, misfire detection will be disabled. It would also be disabled if the engine is operating outside the normal paramaters that misfire detection occurs in. OK, this is interesting because the battery has been in and out a couple of times as I worked on basic tuneup items. If disconnecting the power would disrupt normal codes, I'm starting to think it may be something more obvious like an oxygen sensor. Stop right there. Now, before you start thinking again, go back and read what you quoted. Now, tell me where I said disconnecting power would disrupt normal codes. That's right, I didn't say that. I said MISFIRE DETECTION would be disabled if the PCM hasn't relearned the adaptive numerator since the battery was disconnected. OK. Resume thinking and take it to somebody that knows what he's doing. |
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