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Dirty Fuel ? or Something Else ?


Matt

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Good Day All. This is very strange. I just came back last week from an extended business trip that I used my car for. I also went away right after that for the holiday weekend. The car was perfect, engine smooth and powerfull. Yesterday, Tuesday was my first day back to work and lunch time I fueled up with about 10 gallons of Sunoco top grade fuel.That gave me about 3/4 tank full. I'm getting better milage with this stuff . I drove the car home after work and went to a few stores, about 15 min of driving, all was fine. Last night I went out and 10 min. into the ride I noticed my Tach was jumping from like 650 to about 1500, the needle was bouncing back and forth very fast and the engine felt only a little bit rough. The engine was in no way reacting like the tach was. I stoped for 5 min to get a coffee and when I restarted it the same thing was going on. When I took off the engine was bucking and stumbleing and holding back when I pressed on the gas pedal. I pulled over and shut the engine and restarted it but that did not fix anything. I drove it home and it cleared up a bit. it felt fair under heavy exceleration but at idle the tach would bounce around a bit and it was running a bit rough. This AM I drove it to work, about 6 min out it began the same thing. When I got there I checked all plugs around the Distributor, vacume hoses and anything I could get my hands on. I test drove it again and for a few min it was OK at normal driving and Ok wile jumping on it. When I got it back to work and let it idle the tach began to jump like crazy again. The needle was bouncing around from idle to like 1500 or so. The engine was stumbleing just a bit, not reacting like the tach at all. If it was the engine would have been going crazy bit it was not. So is this a tank of bad fuel? (water or dirt) or the ignition module? or the computer? or just a bad connection someware? O-My just when all was so good. I'm hoping it's water in the fuel. It's acting like there is water in the fuel BUT would the tach jump like it is?? I'm not sure. I ran the car about a total of maybe 40 min after fueling up to the point when this started to happen. What do ya think guys? Thanks.

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Break time I put on the fuel pressure guage and PSI looked good. I used the button on the side and let fuel out into a glass jar and let it sit. I do NOT see any water in jar of fuel. I am stumped now.

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I figure something is breaking down, SO, since I have a spare GM ignition module I will put that in lunch time and see what happens. The engine seems to run ok under higher RPM, if I can get it there, but at idle is when it messes up. I do not know if this is typical of a module going bad but I will swap it out and see what happens

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So lunch time I replaced the ignition module and ran it up to temp and drove it for a wile. It seems to be fine now but I am not 100% on it yet. I can not believe that module was the problem. It seems nothing was that easy so far with this car so I do not believe that was it. Only time will tell now. I will put money on it that on the way home it will act up, I just do not have the faith in it yet.

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So it seems I was right, not to trust it that is. The ride home from work was fine, the engine did not stutter once. I thought just maybe the ignition module was the problem and I was glad I replaced it with the original GM from the old distributor, well remember the bet against it I took? I would have one that bet. I just got back from a 15 min outing and sure enough out of the blue the engine acted up. I was doing about 30 MPH headed for a red light, it changed to green and I pushed down on the gas pedal and she bucked and held back a bit then the engine took off. This time I did not notice the tach go crazy. So what the heck is it? It is just funny that this all started with in 40 min of getting fuel the other day. I'm starting to think that just because I found no water in the fuel that I drained out from the fuel rail today does not mean that there is positively no water or dirt in it. So does anyone have any thoughts on this problem or do I head for yet another computer.

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Check for codes. Check your FPR for moisture at the vacuum hose.

Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life.

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Matt,

It is very suspicious that it happened right after a fill up. Just to rule out water in the tank add a can of gas dryer or iso-somthing-or-other alcohol (someone will know the correct name).

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Hey Larry. It is very strange, the car was so good up till that fill up. The gas dryer may be a good shot. I would need the propper info on exactly what to put in. I would not want to hurt any thing. Maybe somebody has the info.

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Hey Larry. It is very strange, the car was so good up till that fill up. The gas dryer may be a good shot. I would need the propper info on exactly what to put in. I would not want to hurt any thing. Maybe somebody has the info.

Any isopropyl gas line anti-freeze/moisture remover will work fine - it is commonly available at gas stations. Iso heat is one brand. The isopropyl gas line moisture remover will not harm the fuel system components. The label should state how many gallons a bottle will treat.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Thanks Kevin for the info. I will pick up some in the AM. This is so frustrating, I thought all was going good till this event.

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Hey Mike, How ya been doing? No codes and the hose is dry.......

Good Matt, we were just speaking about you recently, someone asked how your were doing.

Kevin has a good idea with the dry gas, maybe with all of this rain you got some water on that fill-up... Let us know how it goes. Other than this problem how has she been running?

Here was that post, sonjaab was how you were doing

http://caddyinfo.ipbhost.com/index.php?showtopic=6172

Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life.

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Mike I got to tell ya it has been like a new car. I have been just thrilled with it. I used it for business two weeks ago for about 5 days and it was flawless. Then we went away for a few days before the holiday weekend into the holiday weekend and it was just perfect. I was sorry we were not around to meet up with you wile you were around for the wedding you had to go to. I hope you had a great time. The only thing I was worrying about was keeping the car towels clean to keep her shined up. I was cleaning the tires and wheel wells and keeping her all shiney. Boy that was great!!! No mechanical problems was a blessing. I still have that suspension code but it feels like it's working fine so no biggie for now. Then yesterday I bought 10 gallons of Sunocos best from a station I'v gone to in the past. That was all she wrote, 40 or so min later all heck broke loose. I would bet they do not sell much of the #4 grade gas, most buy the # 1-2 & 3rd grade. You know what happens when you do not move a lot of it, I bet moister set in. Well I'm gona hit the rack early tonight, or something like that, Anyway; You guys have a good night and lets see what happens on my ride in to work in the AM. I will pick up the gas dryer and keep my fingers crossed. Later guys.

Matt

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Matt,

I had exactly the same experience with my 92 sls.Thought it was bad gas tried dryer,no good -changed a number of parts.Problem persisted,but like you describe it was intermitent.I ended up tapping on the computer and it would go away-tap again and it was back.$95 for a new computer and the car is like brand new.

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Back when I had many problems with the car I ran into another problem that "was" with the computer. It would run smoth for about 20 - 25 min then all of a sudden it would kick and buck and not take the fuel. I would slip it into neutral and shut the engine and then restart it and it would be fine. I droped the computer to the floor to tap on it when it did this and just tap it to try and make it happen but it would not do it. Also there was not one code showing any problems,just like this time. It seemed that when it got hot it would have its problem. The key was that it would clear up after shutting it down and restarting it. I replaced the computer and it has been fine since. I did put in a used computer though so it's possible it is having a problem.

" OK GUYS, I will call the place that I got the computer from about 3 weeks ago and see if I can get another one". Also note; So far not one of the 3 gas stations I hit on the way to work had any Dry Gas or the like, Bad time of year I guess..

I hate this feeling I have now, it's like tunnel vision trying to figure out this problem with my car again. I have to stay focused wide though or I may miss something.. Well, now to my job problems, later guys...

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I am glad she was running good up until now.

Get the dry gas at a Pep Boys, Auto Barn or equivalent, gas stations don't usually have it... Good Luck, Mike

Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life.

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Good Morning Mike, I did not sleep to good last night. I thought I was getting Numb to these car problems. LOL. I have my parts shop bringing me the fuel dryer and a new fuel filter, the one down under the frame. The stuff should be here with in the hour. I"m also making arrangements to have another computer droped off( just in case) What the heck right? I have a customer, BBL. Matt

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Just a quick up date. The fuel filter and dry gas arrived. I swaped the filter and put in the dry gas. I then drove it for a few blocks to shake up the mix. I will not know the results till tonight I think. I will use it lunch time but that is still to early. Next I cut the old filter open with a hack saw. I thought to my self (HOLY CRAP) this was not replaced with the new engine like I was told. I showed a few other mechanics here and all agreed it is very old and in bad shape inside. The out side looked pretty good so it was deceiving. Lets see what happens now......

Matt

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So much for that box of goodies you so well prepared yourself with..... I hope you have found the problem, you will eventually. I am very happy it has been running good however. Mike

Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life.

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Yes my " Box O Parts" went to good use, just ware I do not know!!! It was nice when it was running good up to a few days ago now. I got word that the fellow ware I got the computer from has none to swap me with in case I feel it's the computer again. That was a good price too, I hate to have to buy another one for more money then the last one. O Well. Back to work. Later.

Matt

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Yes my " Box O Parts" went to good use, just ware I do not know!!!  It was nice when it was running good up to a few days ago now. I got word that the fellow ware I got the computer from has none to swap me with in case I feel it's the computer again. That was a good price too, I hate to have to buy another one for more money then the last one. O Well.    Back to work.  Later.

                        Matt

I would just buy a new one and get away from it, its less than $100 and you can eliminate the possibility alltogether, this way you are "thinking" it "might be" the PCM... Eliminate it. Mike

My DAD drummed into my head, if you are going to do it half-assed, don't do it at all...... he has cost me lots of money but he is right

Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life.

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It's just about 10:30PM, I'v been trouble shooting since 7 PM. I drove the car till it began to run rough. It took a long time this time. It usually begans at a light at idle, it starts to miss and vibrate and the tach jumps a lot. Then if you boot it and run it hard it clears up for a wile. I was starting to think the new fuel filter and dry gas I put in today was starting to do the trick. I was starting to think that maybe I did get a tank of bad gas a few days ago, after all the problem started with in 45 min driving time of the fill up.. When it began to run rough tonight I shut down fast and pulled out the replacement PCM I put in a few weeks ago and put in the old PCM to see if this new problem would go away . Earlyer today I took it off its mount and lay it on the floor so the swap would be fast. If you remember with the old PCM in, the engine would run good for about 20 min till the PCM got warm and then the engine would Kick-Buck-hesitate and almost shut down, then I would restart the car and the problem would go away.When I put a new (used) PCM in that all went away. I thought if I put in the old one when this new problem started and the problem was gone then I could say the replacement PCM is bad too. Well that did not work!! . Well wouldent you know it, it did the same thing as the replacement PCM. I thought I could narrow the problem down by useing the two PCMs to see what was doing what. Now that they are doing the same thing I still do not know if it was a tank of bad fuel or not. ( any body have any dynamite?) I was going to follow Mikes idea, just put a new PCM in and forget it. I called my parts shop and they said 85 bucks with the old one. So now am I supposed to think that both PCMs are bad and just replace them any way?? Could I have another bad PCM, it is 12 years old. What if it is bad gas.??? What the heck should I do ???? You know how a boat is a hole in the water to through money in, well thats how I feel about this car now. Mike, those 4 ropes and a big tree are getting closer. What kind of flowers grow best in a Seville??? I;m very confused now, and tired. Guys Please give me your feed back. I will be back in the Am from work. Bare in mind that Tuesday at 2PM I fueled up. I put 15 gallons into a tank that had about 4 or 5 gallons in it. I use Sunoco Ultra.(94 oct I think) It took 5 min back to work and 10 min to home. Then that evening about 10 min from home it began to run terrible. Catch ya all later.

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Where is Guru when you need him? Anyway, I think you have proved that it is not the PCM. Odds of both being bad are slim. No codes stored? Plug wires good? Routed properly? Maybe try the snapshot mode next time it occurs?

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There are no codes at all and everything is new. Remeber all was just rebuilt. It's been running super, a true dream up to tuesday...

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