dykz34 Posted November 19, 2007 Report Share Posted November 19, 2007 Is 45psi at key-on and 42psi cranking normal? I'm trying to figure out why my 93 Z34 won't start. Quote Link to comment Share on other sites More sharing options...
BXX Posted November 19, 2007 Report Share Posted November 19, 2007 plenty normal... Quote Link to comment Share on other sites More sharing options...
dykz34 Posted November 19, 2007 Author Report Share Posted November 19, 2007 What should it be at idle and at WOT? Quote Link to comment Share on other sites More sharing options...
BXX Posted November 19, 2007 Report Share Posted November 19, 2007 Thats obviously the least of your worries older GM fuel pumps and FPRs suck, so expect a fluctuaction anywhere from 42-48 psi on any given testing procedure... You might wanna check spark on all 6, along with injector pulse Quote Link to comment Share on other sites More sharing options...
dykz34 Posted November 19, 2007 Author Report Share Posted November 19, 2007 Thats obviously the least of your worries older GM fuel pumps and FPRs suck, so expect a fluctuaction anywhere from 42-48 psi on any given testing procedure... You might wanna check spark on all 6, along with injector pulse Yes, I know it is. But I was just curious how it compares to my 3800 pump. Do you know the cylinder numbering? IE: is the front bank from left to right 1,3,5? and the rear bank from left to right 2,4,6? Quote Link to comment Share on other sites More sharing options...
joey b Posted November 19, 2007 Report Share Posted November 19, 2007 front bank is 2,4,6 I believe from left to right I'm definate that the even are the front bank. Quote Link to comment Share on other sites More sharing options...
z34Phoenix Posted November 19, 2007 Report Share Posted November 19, 2007 DOHC pressure is fine... i get 45 at key on 40 at idle and 50 when the vac to the FPR is disconnected. and when you say it doesnt start... what exactly is it doing? Quote Link to comment Share on other sites More sharing options...
Turbo231 Posted November 20, 2007 Report Share Posted November 20, 2007 We need more info...doesn't start goes from: A) Doesn't Crank Crank but won't Start Then...if it cranks but doesn't start, check the FP, which you did and seems fine...do you smell unburnt fuel in the exhaust after cranking...try it and run around the back and take a good wiff. If yes...then you're getting fuel and just not getting spark. Of course, if you have an induction timing light hanging around, that will definitely confirm no spark. No spark means 2 things. Either the ICM has failed, or the crank sensor that tells the ICM the engine is turning has failed. Some tests with a volt meter can almost rule out the crank sensor. I have heard it is a popular fail item...but my 3.4L lost the ICM, an easy to change but expensive $200 GM part. Good luck. Quote Link to comment Share on other sites More sharing options...
dykz34 Posted November 20, 2007 Author Report Share Posted November 20, 2007 DOHC pressure is fine... i get 45 at key on 40 at idle and 50 when the vac to the FPR is disconnected. and when you say it doesnt start... what exactly is it doing? Thanks!! That picture is exactly what I need! The car cranks, and really really tries to start. I think I might have gotten the plug wires crossed as I wasn't paying attention when I pulled them off. Quote Link to comment Share on other sites More sharing options...
dykz34 Posted November 20, 2007 Author Report Share Posted November 20, 2007 We need more info...doesn't start goes from: A) Doesn't Crank Crank but won't Start Then...if it cranks but doesn't start, check the FP, which you did and seems fine...do you smell unburnt fuel in the exhaust after cranking...try it and run around the back and take a good wiff. If yes...then you're getting fuel and just not getting spark. Of course, if you have an induction timing light hanging around, that will definitely confirm no spark. No spark means 2 things. Either the ICM has failed, or the crank sensor that tells the ICM the engine is turning has failed. Some tests with a volt meter can almost rule out the crank sensor. I have heard it is a popular fail item...but my 3.4L lost the ICM, an easy to change but expensive $200 GM part. Good luck. The car cranks over just fine. It will even start for a 1/2 a second when spraying starting fluid in the TB but it will not stay running. I will try the cranking then smelling the exhaust tonight - thanks for the tip! I was working on the car on Saturday, put new plugs in, tried starting it, then pulled the plugs and they were dry. If the car was getting fuel, but no spark they should be wet, right? It leads me to a fuel delivery issue based on nearly starting on ether, and the plugs being dry. I wonder if the injectors went bad??? I still have a few things to check - such as the plug wire order and the wiring to the injectors. Thanks everyone for the help so far! Quote Link to comment Share on other sites More sharing options...
Turbo231 Posted November 20, 2007 Report Share Posted November 20, 2007 It leads me to a fuel delivery issue based on nearly starting on ether, and the plugs being dry. I wonder if the injectors went bad??? I still have a few things to check - such as the plug wire order and the wiring to the injectors. Ok...another vote for the crank sensor...if the PCM doesn't know the engine is turning, it will not fire the injectors. (make sense, but a service manual would confirm that - I sold mine long ago). I also think we're dealing with a System issue and not one particular set of cylinders...otherwise, you'd get a lot of half ass firing, kicking, and bucking. Quote Link to comment Share on other sites More sharing options...
GOT2B GM Posted November 20, 2007 Report Share Posted November 20, 2007 crank sensor Quote Link to comment Share on other sites More sharing options...
dykz34 Posted November 20, 2007 Author Report Share Posted November 20, 2007 It leads me to a fuel delivery issue based on nearly starting on ether, and the plugs being dry. I wonder if the injectors went bad??? I still have a few things to check - such as the plug wire order and the wiring to the injectors. Ok...another vote for the crank sensor...if the PCM doesn't know the engine is turning, it will not fire the injectors. (make sense, but a service manual would confirm that - I sold mine long ago). I also think we're dealing with a System issue and not one particular set of cylinders...otherwise, you'd get a lot of half ass firing, kicking, and bucking. What's involved in replacing a crank sensor? Remove crank pulley and replace? Quote Link to comment Share on other sites More sharing options...
Bake82 Posted November 20, 2007 Report Share Posted November 20, 2007 Nope.... jack up car, support with jack stands, crawl under neath the car. It's on the back of the block in the middle. I think a 7 or 8 mm screww holds it in...pul it out. be careful with it tho, they are prone to breaking off. Quote Link to comment Share on other sites More sharing options...
dykz34 Posted November 20, 2007 Author Report Share Posted November 20, 2007 Nope.... jack up car, support with jack stands, crawl under neath the car. It's on the back of the block in the middle. I think a 7 or 8 mm screww holds it in...pul it out. be careful with it tho, they are prone to breaking off. That sounds pretty easy! Do you happen to have a part number handy? Thanks! Quote Link to comment Share on other sites More sharing options...
Chancho Posted November 20, 2007 Report Share Posted November 20, 2007 Check Rockauto.com, they usually sell ACdelco of everything Quote Link to comment Share on other sites More sharing options...
BXX Posted November 21, 2007 Report Share Posted November 21, 2007 I have a brank new one... Wells part, lost the box... $10 plus shipping Quote Link to comment Share on other sites More sharing options...
dykz34 Posted November 21, 2007 Author Report Share Posted November 21, 2007 I have a brank new one... Wells part, lost the box... $10 plus shipping Thanks for the offer - I'll let you know. Will coolant or oil come out when I pull the sensor? Quote Link to comment Share on other sites More sharing options...
BXX Posted November 21, 2007 Report Share Posted November 21, 2007 Some oil, you are supposed to drain it first... Might as well, good time to do an oil change... Quote Link to comment Share on other sites More sharing options...
adam_murphy Posted November 21, 2007 Report Share Posted November 21, 2007 Why would it be a sparking issue if it almost starts with a little ether. If there was no spark it wouldnt act like it wants to start at all, just turn over and crank and crank. I think your onto something though with the whole pcm firing injectors stuff, i thought he should try pouring a small amount of gas into the front 3 cylinders and try to see if it'll fire and run for a second doing it that way, somewhat confirming it has a fuel problem. Big help from you guys none the less Quote Link to comment Share on other sites More sharing options...
BXX Posted November 21, 2007 Report Share Posted November 21, 2007 Pouring some gas in can be very very dangerous... It cant atomize and shoot down the intake like the ether... Why is acts like it wants to start could be the simple fact ether easily detonates.. Have you actually did a spark test??? if not, do it before proceding Quote Link to comment Share on other sites More sharing options...
dykz34 Posted November 21, 2007 Author Report Share Posted November 21, 2007 Some oil, you are supposed to drain it first... Might as well, good time to do an oil change... You're right. I just pulled the front three spark plugs and they are sparking - so I know the coils are good as well as the ICM. Next up is to trace the plug wires to make sure they are in the correct order. Quote Link to comment Share on other sites More sharing options...
BXX Posted November 21, 2007 Report Share Posted November 21, 2007 If the crank sensor fails, you loose spark too... So it's safe to say the CPS is good... I think next you need to check for injector pulse... Quote Link to comment Share on other sites More sharing options...
dykz34 Posted November 21, 2007 Author Report Share Posted November 21, 2007 If the crank sensor fails, you loose spark too... So it's safe to say the CPS is good... I think next you need to check for injector pulse... The car cranks fine, all the plug wires are in order according to the image posted earlier in this thread, and it will fire for a split second on ether. I have to assume it is a fuel delivery problem. How do I check for injector pulse? Quote Link to comment Share on other sites More sharing options...
AWeb80 Posted November 21, 2007 Report Share Posted November 21, 2007 It Is Easy. On A Manual Car. Quote Link to comment Share on other sites More sharing options...
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