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#51
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On Sat, 12 Feb 2005 00:31:13 GMT, aarcuda69062
> wrote: >In article >, > Lawrence Glickman > wrote: > > >> > All of these parts are new or re-built. >> >> So what is left over that could be causing his symptom of loss of ALL >> fuel pressure on occasion? > >It could be any of the parts he's already replaced. >The fuel pressure bleeding off at rest can only occur in three >places; >1) Injector (CPI) assembly >2) Fuel pump check valve >3) External fuel line between #s 1 and 2 > >It's not hard to isolate sections of the fuel system to determine >where the leak off is. > >> What would you want to look at next as a probable cause of his >> difficulties? > >If it is fuel starvation or over fueling, it will show up on the >O2 sensor voltage and/or the fuel trim numbers viewed on a scan >tool, I mentioned this to him in a post a while back at the >beginning. He procured a scan tool but went no further with it. >He could have posted the scan data here and myself and a number >of others could have given out opinions of what was there. OK. Myself, I've recorded what should be "normal" numbers for my own engine using a data logger and storing the file(s) on my hard drive for future reference. I've also used my Scantool to record what parameters that reveals: e.g. long term fuel trim bank 1 % = 5.5, 4.7, 1.6, 2.3 short term fuel trim bank 1 %= 0.00, -2.3, 1.63, 3.9 long term fuel trim bank 2 %= 3.1, 3.9, 7.0, 7.8, 7.0, 7.8, 3.9 short term fuel trim bank 2 %= 2.3, 2.1, 0, -.08, -2.3, -3.1 and I am lead to believe, from my readings, that it is perfectly NORMAL on my engine for bank 1 to be quite different from bank 2, although I can't put my finger on the source of that information at this moment. Now goody for me, I can program my data logger to record all of the above values in a continuous stream if so desired, so if I see any MARKED deviation from my baseline reading, I've got a "clue." There are many many other parameters I've recorded for baseline purposes, too many to list here. Point is, I would have reference values to consult. Maybe this is asking too much for anybody to do. >He did mention in one post that his running fuel pressure dropped >to 50 psi, this is 4 psi below the absolute minimum required to >open the poppet nozzles in his CPI system ( pressure >differential) > >He'd be best off with a scan tool with recording capability, that >way he can trigger a recording on a test drive at the moment the >problem occurs, and then review the movie from the trigger point >for anything unusual. Wouldn't he get what's called Freeze Frame? IOW, my data logger has the ability to show all engine parameters it is capable of reading at the moment a malfunction occurs. I've never had the pleasure of seeing this happen, so I can't be more specific, IOW, I can't give you the parameters delivered because it hasn't happened to me =yet=. But if and when it does, I may post for General Information purposes. >It's also entirely possible that it isn't a fuel problem. Could be electrical. Intermittent loss of power to fuel pump, etc. But I'm wondering if that wouldn't throw a DTC. Again, I've never experienced ( on this car ) a malfunction so I can't be more specific. Lg |
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#52
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#53
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In article >,
Lawrence Glickman > wrote: > >If it is fuel starvation or over fueling, it will show up on the > >O2 sensor voltage and/or the fuel trim numbers viewed on a scan > >tool, I mentioned this to him in a post a while back at the > >beginning. He procured a scan tool but went no further with it. > >He could have posted the scan data here and myself and a number > >of others could have given out opinions of what was there. > > OK. Myself, I've recorded what should be "normal" numbers for my own > engine using a data logger and storing the file(s) on my hard drive > for future reference. Good idea. It's always better to know what normal looks like then trying to figure it out once things go wrong. > I've also used my Scantool to record what parameters that reveals: > e.g. > long term fuel trim bank 1 % = 5.5, 4.7, 1.6, 2.3 > short term fuel trim bank 1 %= 0.00, -2.3, 1.63, 3.9 > > long term fuel trim bank 2 %= 3.1, 3.9, 7.0, 7.8, 7.0, 7.8, 3.9 > short term fuel trim bank 2 %= 2.3, 2.1, 0, -.08, -2.3, -3.1 Add the long term fuel and the short term fuel to determine the total fuel correction at that instant, anything over 10-12 percent is cause for suspicion. > and I am lead to believe, from my readings, that it is perfectly > NORMAL on my engine for bank 1 to be quite different from bank 2, > although I can't put my finger on the source of that information at > this moment. Yes, that is true. > Now goody for me, I can program my data logger to record all of the > above values in a continuous stream if so desired, so if I see any > MARKED deviation from my baseline reading, I've got a "clue." > > There are many many other parameters I've recorded for baseline > purposes, too many to list here. Point is, I would have reference > values to consult. Maybe this is asking too much for anybody to do. It becomes a question of whether it is possible. > >He did mention in one post that his running fuel pressure dropped > >to 50 psi, this is 4 psi below the absolute minimum required to > >open the poppet nozzles in his CPI system ( pressure > >differential) > > > >He'd be best off with a scan tool with recording capability, that > >way he can trigger a recording on a test drive at the moment the > >problem occurs, and then review the movie from the trigger point > >for anything unusual. > > Wouldn't he get what's called Freeze Frame? IOW, my data logger has > the ability to show all engine parameters it is capable of reading at > the moment a malfunction occurs. His is a 95 model year, not yet quite OBD2, his system may not have the capability to record freeze frame data, I also believe that he's posted that he's not getting any fault codes, so if no fault is being detected, no freeze frame. > I've never had the pleasure of > seeing this happen, so I can't be more specific, IOW, I can't give you > the parameters delivered because it hasn't happened to me =yet=. But > if and when it does, I may post for General Information purposes. Just booby-trap something. Loose gas cap, disconnect the EGR, pop the purge flow sensor off, etc. > >It's also entirely possible that it isn't a fuel problem. > > Could be electrical. Intermittent loss of power to fuel pump, etc. > But I'm wondering if that wouldn't throw a DTC. Again, I've never > experienced ( on this car ) a malfunction so I can't be more specific. |
#54
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On Sat, 12 Feb 2005 01:43:38 GMT, aarcuda69062
> wrote: >In article >, > Lawrence Glickman > wrote: > >> >If it is fuel starvation or over fueling, it will show up on the >> >O2 sensor voltage and/or the fuel trim numbers viewed on a scan >> >tool, I mentioned this to him in a post a while back at the >> >beginning. He procured a scan tool but went no further with it. >> >He could have posted the scan data here and myself and a number >> >of others could have given out opinions of what was there. >> >> OK. Myself, I've recorded what should be "normal" numbers for my own >> engine using a data logger and storing the file(s) on my hard drive >> for future reference. > >Good idea. It's always better to know what normal looks like >then trying to figure it out once things go wrong. > >> I've also used my Scantool to record what parameters that reveals: >> e.g. >> long term fuel trim bank 1 % = 5.5, 4.7, 1.6, 2.3 >> short term fuel trim bank 1 %= 0.00, -2.3, 1.63, 3.9 >> >> long term fuel trim bank 2 %= 3.1, 3.9, 7.0, 7.8, 7.0, 7.8, 3.9 >> short term fuel trim bank 2 %= 2.3, 2.1, 0, -.08, -2.3, -3.1 > >Add the long term fuel and the short term fuel to determine the >total fuel correction at that instant, anything over 10-12 >percent is cause for suspicion. > >> and I am lead to believe, from my readings, that it is perfectly >> NORMAL on my engine for bank 1 to be quite different from bank 2, >> although I can't put my finger on the source of that information at >> this moment. > >Yes, that is true. > >> Now goody for me, I can program my data logger to record all of the >> above values in a continuous stream if so desired, so if I see any >> MARKED deviation from my baseline reading, I've got a "clue." >> >> There are many many other parameters I've recorded for baseline >> purposes, too many to list here. Point is, I would have reference >> values to consult. Maybe this is asking too much for anybody to do. > >It becomes a question of whether it is possible. > >> >He did mention in one post that his running fuel pressure dropped >> >to 50 psi, this is 4 psi below the absolute minimum required to >> >open the poppet nozzles in his CPI system ( pressure >> >differential) >> > >> >He'd be best off with a scan tool with recording capability, that >> >way he can trigger a recording on a test drive at the moment the >> >problem occurs, and then review the movie from the trigger point >> >for anything unusual. >> >> Wouldn't he get what's called Freeze Frame? IOW, my data logger has >> the ability to show all engine parameters it is capable of reading at >> the moment a malfunction occurs. > >His is a 95 model year, not yet quite OBD2, his system may not >have the capability to record freeze frame data, I also believe >that he's posted that he's not getting any fault codes, so if no >fault is being detected, no freeze frame. > >> I've never had the pleasure of >> seeing this happen, so I can't be more specific, IOW, I can't give you >> the parameters delivered because it hasn't happened to me =yet=. But >> if and when it does, I may post for General Information purposes. > >Just booby-trap something. >Loose gas cap, disconnect the EGR, pop the purge flow sensor off, >etc. That's a good idea ! ;0 I can just disconnect for example the EGR vacuum line or something simple like that while the engine is running so I can see what will be recorded at the moment the MIL is lighted. Good Idea. Beats wondering what and how much information I would get when a DTC pops up. What I mean by that, is I am currently monitoring 4 out of a possible 23 engine parameters. So when a DTC is thrown, I don't know how much information of WHAT parameters will get logged to the chip. This is the perfect way to find out. Lg > >> >It's also entirely possible that it isn't a fuel problem. >> >> Could be electrical. Intermittent loss of power to fuel pump, etc. >> But I'm wondering if that wouldn't throw a DTC. Again, I've never >> experienced ( on this car ) a malfunction so I can't be more specific. |
#55
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"aarcuda69062" > wrote in message ... > In article >, > Lawrence Glickman > wrote: > >> On 11 Feb 2005 09:01:10 -0800, wrote: >> >> >yes it is fuel injection. i just replaced the CPI (injector/spider). >> >> That's probably what is called the "fuel rails" on my vehicle. >> There is one rail for bank 1, another for bank 2, they are tied >> together with a piece of high pressure hose. > > Nope, his set up is different. > Central Port Injection (CPI) Between the bad injectors, stuck EGR's etc doncha just love the vortec? Bob |
#56
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Update.
I double checked my work on the CPI install and found a problem. One of the fuel lines was not all the way in and it was slowly leaking. I oiled (really helped) the lines up real good and made sure it was all the way in this time. I gas fouled all the plugs so I have to change the plugs before I can let you guys know if that fixed it. Also, it is still bleeding off pressure with the key off. It has been going all the way down to 10psi. My current guess is it is the pulsator since it was never replaced. >From what I understand this might not cause problems after the van has been started. I will try and change the plugs before work tomorrow and let you guys know . I might not get finished because it is not the easiest job on that van. |
#58
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I finally got it fixed. I suspect it was the pulsator.
I ended up dropping the tank and replacing the pump, threw out the pulsator and replaced with fuel line, replaced the main gasket and a missing o-ring on one of the fuel lines to the tank. I am not sure if the o-ring was lost when I dropped the tank or some other time. It runs great now. Thank you guys so much for all you help and suggestions!!!!! |
#59
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Fuel pressure issue - 95 Astro - please help
replying to daveg.01, Drewsky wrote:
I have the same problem with my van same model w vin. Did you ever find the problem? -- for full context, visit https://www.motorsforum.com/chevy_tr...elp-35769-.htm |
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