5.7L vortec no spark

mikebrsa · Feb 7, 2011

I just installed a 96 vortec 5.7L in my jeep. It has a painless wiring harness and is mated to a 700r4. we have hooked everything up are getting 12+ volts to the coil and coil control module but are getting no spark. I am sure it is something simply but cant find out why it doesnt get spark. any help is appreciated. This is Matt O.'s old motor

KILLERB468 · Feb 7, 2011

have the ign module checked at vatozone

kid rok · Feb 8, 2011

Disconnect the alternator and try it. Ya it sounds weird but it happend to me, fix, control modual. Also check oil pressure it want send a spark if theres no pressure.

1TONZR2 · Feb 8, 2011

the motor hasnt ran since MattO had it in his buggy. I thought about the oil pressure switch as well. how can we get the oil pressure to come up? while cranking it, the oil pressure gauge does not move at all.

kid rok · Feb 8, 2011

Either it's clogged, no oil, or the pump gear is not working. Do you have oil in the valve covers?

yankster · Feb 8, 2011

Distributor fully seated? Would cause both symptoms.

mikebrsa · Feb 8, 2011

is there any way to check the module myself?

1TONZR2 · Feb 8, 2011

it has oil...not sure if there is oil at the valve cover. distrib. was never taken out.

mikebrsa · Feb 8, 2011

Well called autozone and asked if they could test the module they said yes bring it up and we will check it out, so I uninstall it take it to them and the guy then tells me sorry our machine is down. so i leave and call advance auto the guy that barely speaks english said they had a machine to test the module so i drive up there and their machine is not set up and he advises me to go to the store 10 miles down the road their machine is up and running. so i drive to that store and it is 2 girls working the store by themselves and neither one know how to use the machine. But at least they tried reading the directions and testing it unfortunetly they and i couldn't figure it out. so now i have to wait until tommorrow until they guy that uses the machine is in.

grcthird · Feb 9, 2011

^^^ This really kinda pisses me off. I work part time for Advance and there is no excuse for an employee to not know how to use that module tester. With that being said, those testers are not always accurate. I tested one a while back that showed it was bad. My store didn't have the part but another Advance close by had it. Customer had the module tested there, his old one tested good on their machine and the new one outta the box tested bad. :dunno:

I would say try to find a known good one off a running truck and swap it in before spending a benji on a new one.

Edit I'm looking at the diagram from the factory and the it shows the oil pressure switch cutting the fuel, not the spark.

1TONZR2 · Feb 9, 2011

wow, I cant believe I didnt see that before. I knew that the relay was energized by that switch.....we have fuel. :****: we were chasing (well, they were...I was at home.LOL) the wrong side of things. DEEDADEE :wtflol:

Mike said the coil and module were tested good.........now what?

mikebrsa · Feb 9, 2011

it could possibly be my crank shaft position sensor, it is missing the rubber weather seal and fits kind of losely. I did however in testing the spark today got a little to comfortable holding the spark plug and got shocked but couldnt get it to spark again. it has sparked a couple of times but it was very weakly every time.

grcthird · Feb 9, 2011

Sounds like you found the problem, fix that crank sensor and see if it runs. If the gap between the sensor and the reluctor wheel is off it won't send the ecm a signal (or a correct one anyway). :dblthumb:

1TONZR2 · Feb 11, 2011

well, that was not the problem. Mike is going to pick up a new cap/rotor and borrow a good ign. control module/coil off a buddies truck(if he still has it) to check that stuff. We are at a loss at what else it could be. I hope one of those things fixes the problem, I know he is getting tired of working on it! :****: we are supposed to be going on a ride next weekend, so this thing needs to be running....STAT!

mikebrsa · Feb 12, 2011

well i replaced the cap and rotor, coil, crank position sensor and still no consistant spark, I am borrowing a ign. control module tommorrow hopefully that is it. It sparks on occassion but not enough to fire the motor. any suggestions are appreciated.

5.7yjuggy · Feb 12, 2011

mikebrsa said:
I just installed a 96 vortec 5.7L in my jeep. It has a painless wiring harness and is mated to a 700r4. we have hooked everything up are getting 12+ volts to the coil and coil control module but are getting no spark. I am sure it is something simply but cant find out why it doesnt get spark. any help is appreciated. This is Matt O.'s old motor

are you getting fire out of the coil? or just no fire at all

1TONZR2 · Feb 12, 2011

none at all..other than the occasional spark.

kmcminn · Feb 13, 2011

Is everthing grounded good?

RobbyBobby · Feb 13, 2011

hold one athe spark plugs up to your tongue and get somebody to crank the engine......if it don't knock yer ass to the ground then you prolly need a new coil in that fawker