Pontiac Repair: 1994 Pont Bonneville, fuel pressure regulator, crank sensor

Question
QUESTION: I recently asked a question about this car. I purchased the car about 4mths ago. It has been doing well until about 2 weeks ago. It started "cutting out" while driving(not knocking off just a short interruption in the RPM and the alert chime would sound) Then it got to where it would knock off at a stop light or just setting idling (in park) At first I was told that this sounded like a fuel supply issue, and to add fuel system cleaner to the tank, upon doing this it immediately got much worse stalling out quite often. Then progressively improved till it was better so it seemed. Also it will be very hard to start sometimes then others it acts fine (before this started all it took was to "bump the key and it would catch and start) Last night while driving it knocked off several times, and was hard to start many of them and the last time I was in an area where I could really look at the dash when it was happening, I noticed that the RPM fell immediately when the car stalled however the speedometer of course was still reg.ing when the alert chime went off the speedo jumped up and back down and this is the first time that I noticed the alert chime went off 3 separate times in the same occurrence (almost like you had turned the key  off and on) I have tried to describe everything as detailed as I can, if you need more info please ask, I am desperate to get this car running properly again I have a newborn and this is our only transportation, Oslo money is tight. Thank You in advance for any help and advise you are able to give! Daniel

ANSWER: Hi Daniel:

well it sounds like it couls be 1 of 2 things I'm going to "guess" the first thing as a crank sgaft position sensor the fact that the rpm's cut out is a dead give away if there is no RPM signal the engine will die. the crank sensor is what gives the ignition system it's signal that the engine is running. The second idea is a bad fuel pressure regulator it'a mounted on the end of the fuel rail with the engine running pull the vacuum hose off and let the car run for a while and see if raw fule starts to leak out of the regulator if so it's bad. those are my 2 thoughs. good luck :)


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QUESTION: Would the crankshaft position sensor cause an increase in gas consumption and would that cause it to cut out momentarily and then continue to run It doesn't always knock off. I pulled the vacuum hose off and let it run for a while and never saw any sign of fuel coming from the regulator.
Thanks
Daniel

ANSWER: No it wouldn't. If you have 1 or more cylinders misfiring that would cause an increase in fuel consumption. If you chnaged barand of fuel that an do it also Use only 87 octane you will get more MPG on the lower octane fuels.


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QUESTION: On this car I have now changed the crankshaft pos sensor and checked the fuel pressure regulator as you suggested. After replacing the Crank sensor and putting everything back together now I am getting no fire to the plugs I had a diagnostic done and was told that it was either the Crank Pos Sensor or the Cam Pos sensor. would the cam sensor cause the engine to not start at all? and how do I replace it? Are there any other suggestions that you have?
Thanks Daniel

Answer
Okay lets start over. A Cam sensor that is bad will not make it not start. The cam sensor is for misfore diagnostics (94) is a pull a head OBDII system so to speak and the cam senosr is for sequntial injection nothing else. If all you did was replace the crank sensor and it will not start then a few things could have happend. Aftermarket parts stink especially if they are for ignition or injection systems. Al lot of them are "fits all" and there are subtle differences from one year to another just because it loos the same doesn't mean the magic inside is the same. The reluctor wheel could have been damaged on the back side of the crank shaft balancer and if that was damaged it could have damaged a brand new crank sensor. It could have been damaged from an aftermarket part or it was not inatalled correctly on the front timing cover a lot of times corrosion will build up on the dowel pin that aligns the sneor and you put the new sesnor on the corrosion and it's not lined up and you crank the car over and bingo damaged 2 parts. so if it ran before the part was replaced then look at what was done and no place else.