87 gn won't start, new motor

T

tyson

Member
Joined
Jan 26, 2003
Put a new motor in my GN, can't get it to start. Has about 40 lbs of fuel pressure, gets spark, has injector pulse. I have pulled out the cam sensor about 5 or 6 times and reinstalled it with the caspers tool.( I think have it right)
It wasn't getting spark so I installed a new crank sensor and it started getting spark. My tps wasn't reading so I replaced it and now it is reading within correct parameters. It spits and sputters slightly almost like it wants to start but is out of timing. I am at a lost. I'm not sure if the crank sensor is set correctly. I just gapped it with a credit card, but it did fix the spark issue so I was assuming it was ok???? I thought maybe I fouled the plugs in the process but when I pulled one out it looked fine but did smell of gas bad. I unplugged the fuel pump and cranked it for awhile to clear out the gas but it still will not start. The only mal code it has thrown up is # 15( I think) which is coolant temp sensor low. ( it is low on antifreeze right now) Can the crank sensor be out of adjustment and still get spark, can the cam sensor be bad but still signal the injectors?
 
You said you had spark and fuel correct? If you have spark, crank sensor should be good. You also tried to set the cam sensor a few times, have you followed the directions properly? Have you checked your firing order? Are all your intercooler hoses and pipes hooked up? Try resetting the chip.
 
U don't do a new engine start up w/ antifreeze in the cooling system.
Spitting could be the cam sensor off location...
 
Sounds like your off on your cam sensor I know your anxious to get her started but i would try it one more time.
 
I'll get out there tomorrow and try turning the cam sensor a little. Yes it is getting spark and fuel.
Chuck, I should have said another engine, it is not a "fresh rebuilt" motor. Just one with way lower miles.(thanks)
 
While setting the cam sensor make sure the dot at the bottom of the sensor is pointing the passenger side fender and the wires at the top of sensor pointing towards the drivers side headlight. I've made that mistake of not checking that in the past and just dropped the sensor in and encountered lots of backfiring while trying to start the engine. When I said to disconnect the maf I assumed the cam sensor was installed correctly and wanted to make sure your maf was not defective.


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well I went back out a pulled the cam sensor and went through it again. I am about positive I put the dot correctly etc. I did get it to almost fire this time. I ended up turning the sensor about an 1/8 of an inch at a time, locking in , unplugging the orange ecm wire to reset the ecm then trying to start again. Did this for over an hour. ended up turning the sensor clockwise until the wires were about at the 9 0'clock position. It came real close to firing then my battery started dying. Seems the more clockwise I went the better it reacted. I will let it charge over night and try it again. I did put a new 204/214 flat tappet cam, lifters, and heavy duty valve springs in it. Not sure if that would change things or if I pulled a dumbazz and got the cam gear off a tooth???
 
The orientation of the cam sensor wires and ears mean nothing. The reason you hear about making sure it's clocked right it to keep the wires from being folded over and pulled tight and to keep from rubbing a hole in the 'S' hose.

What scares me is that you've been cranking and cranking and cranking with a new flat tappet cam. If I were you, I would seriously consider pulling the intake and rejizzing the lifter faces and cam lobes.

Also the low coolant level won't though a low temp code. I'm starting to wonder if you have a flaky engine harness and that's what is causing your running problems.
 
Pull all of the plugs, you need to get the fuel out of the cylinders. Unplug ecm, crank a few times to clear the cylinders. Install NEW plugs, reconnect ecm, crank it a few times, do not hit the gas pedal. If it does not fire after a couple of tries, stop and troubleshoot. Continuing to crank it over without making changes will just fill the cylinders with fuel again.
VERIFY you are starting on TDC when you are installing the CAM sensor, easy to be 180* out.
If you are unsure of the cam being installed correctly I would tear it down to check.

Bryan
 
make sure your spark plug wires are hooked up right to the coil i just put mine back on and it didnt fire but once i got it right it fired right up double check
 
photo.jpg
 
Well two plugs weren't firing. I replaced the coil pack( same one that was on my other motor don't know why it decided to crap out), bought new plugs but no one in town has plug wires so I ordered some. They are supposed to be in tomorrow ...I'll update
 
i read that you used the casper cam tool, and that you pointed the dot , but then you went twisting it , twisting as far as 90 degrees

that is not how its done an could cause a backfire on the wrong cylinder could damage the motor

did you set the crank at 25 degrees after top dead center of #1 compression stroke? (not TDC)
that means establish that compression is building on #1 piston (remove plug and using a compression tester hose or finger feel for pressure build) and then continue rotate the timing mark on balancer 1.45" past the 0 degree mark on timing indicator (dont turn back crank if you pass the mark because of the chain slack .go back 1/4 turn and try again). then using the casper tool adjust so light on casper tool just comes on when twisting counter clockwise , then lock down the sensor bolt

the instructions are at http://www.vortexbuicks-etc.com/cam_sensor.htm
unless the sensor is defective (loose spinning reluctor , sheared roll pin ) and you have confirmed the cap works (if casper tool led goes out and then lights when setting it works)
once the base is set thats it ..leave it alone , if it doesnt start .... leave the sensor alone and look elsewhere
 
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