2001goldGTP Posted June 27, 2013 Report Share Posted June 27, 2013 My 90 cutlass has developed a mis fire. its not always constant. I believe it has something to do with lowish fuel in the car, 1/2 to a 1/4 tank. Does anyone know where the fuel filter is? I would like tostart there since there is no raw fuel smell coming out the back iI have ruled out a dead coil pack or stuck injector. Quote Link to comment Share on other sites More sharing options...
94 olds vert Posted June 27, 2013 Report Share Posted June 27, 2013 Fuel filter is under the car in the centerish area of the vehicle and in front of the tank. Quote Link to comment Share on other sites More sharing options...
2001goldGTP Posted June 28, 2013 Author Report Share Posted June 28, 2013 yeah felt dumb when i got down and it about hit me in the face. filter was dirty, that happens after 23 years, anyway, i still have the mis Quote Link to comment Share on other sites More sharing options...
2001goldGTP Posted July 22, 2013 Author Report Share Posted July 22, 2013 ok so i still need help here, changed the fuel filter, no improvement, changed the spark plug wires, no improvement, i change the spark plug out with OE ac delco ones a couple months ago. Any more suggestions? It comes and goes as it pleases. most times it runs fine, but at least once a day it will start a mis and last 5-50 miles Quote Link to comment Share on other sites More sharing options...
l67ss Posted July 22, 2013 Report Share Posted July 22, 2013 Check ur fuel pressure ot could b a weak fuel pump or relay pump Quote Link to comment Share on other sites More sharing options...
GM Guy Posted July 23, 2013 Report Share Posted July 23, 2013 If you can describe the misfire further it can be narrowed down a bit. Such as is it severe or light hesitation, at idle, under acceleration/cruise/WOT? Starting fine? Does it happen again if you shut it off and start it back up? Could be a number of things such as a bad fuel pump as l67ss mentioned, a shorting or sticking injector, overheating coil pack, to a build up of anti seize on the spark plug threads (happened to me from regular coating during plug installs on aluminum heads). Quote Link to comment Share on other sites More sharing options...
2001goldGTP Posted July 24, 2013 Author Report Share Posted July 24, 2013 If you can describe the misfire further it can be narrowed down a bit. Such as is it severe or light hesitation, at idle, under acceleration/cruise/WOT? Starting fine? Does it happen again if you shut it off and start it back up? yes, all the above . doubt its an over heating coil as it can happen with in seconds starting in the morning. As far as fuel goes the exhaust smells fine, and no smoke. I had a coil pack die when i was in high school. There was smoke and the smell of raw fuel. Not this time. It can be just a slight miss to violently shaking the car. If i can get it to rev high the shutter goes away but the miss is still there. The injectors where changed 40ish k ago. could it be the timing chain? It only has 156k on the chain Quote Link to comment Share on other sites More sharing options...
GM Guy Posted July 24, 2013 Report Share Posted July 24, 2013 A few things to try assuming your fuel pump is not to blame... double up on some water eliminator for the fuel as the ethenol mix can build up water over time, pull the wires for the crank position sensor and check closely for any cracks in the sheathing. I got a misfire on my Z where they cracked and would periodically touch and cause a stumble. Clean the connectors on the harness, CPS, and ECM recepticals, your grounds and the remote positive terminal. Do an ohm test on the coil packs for the heck of it and the ECM. Doubt it has anything to do with the timing chain as it would be constantly running rough, would need to be jumping teeth and would eventually cause the valves to hit the pistons. Probably good to change it in the near future with that many miles on it. Quote Link to comment Share on other sites More sharing options...
2001goldGTP Posted July 25, 2013 Author Report Share Posted July 25, 2013 Found the issue, msd coil sometimes fires sometimes doesnt. This pisses me off and is the second msd coil that died on me. The first one only lasted a year. Good old stock ones will be going back in. Quote Link to comment Share on other sites More sharing options...
2001goldGTP Posted July 26, 2013 Author Report Share Posted July 26, 2013 Update, that was not the issue, coil pack changed, still acts exactly the same Quote Link to comment Share on other sites More sharing options...
AL Posted July 26, 2013 Report Share Posted July 26, 2013 ICM, it commands the spark and if its not sparking, perhaps its not getting the command to Quote Link to comment Share on other sites More sharing options...
2001goldGTP Posted July 29, 2013 Author Report Share Posted July 29, 2013 Spark has been ruled out, i was going to use a noid light to check on the injectors but it appears i have to take the intake manifold off to get to them. Im not prepared for that i need new gaskets. Also, how would i test to make sure the injector itself is good? I have a stock set from my 01 gtp, will those work in the 90? Just to diagnose the problem. Quote Link to comment Share on other sites More sharing options...
Crazy K Posted August 2, 2013 Report Share Posted August 2, 2013 Use a multimeter in the ohm setting. your injectors should be between 11 and 12.5 ohms. you must get injector from another 3.1 multiport, the injectors in 3100's and newer cars are different fuel ratings. The next 3.1 car I bring out will be tuned to use a different set of injectors, as those 3.1 injectors sure get flaky with age. I have plenty of ford yellow tops, or even 3100 injectors, but they cannot be used without tuning, though they do directly fit. Quote Link to comment Share on other sites More sharing options...
2001goldGTP Posted August 5, 2013 Author Report Share Posted August 5, 2013 I put a fuel pressure gauge on it, i have 39psi static after sitting for a day, and 33-34 psi at idle. Bad pressure regulator? The injectors were changed 55k ago not sure if that helps. Quote Link to comment Share on other sites More sharing options...
2001goldGTP Posted August 10, 2013 Author Report Share Posted August 10, 2013 Replaced the fuel pressure regulator last night. Seemsto have fixed the issue! Quote Link to comment Share on other sites More sharing options...
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