Question I have 2002 GMC savana 4.8L V8 that I just did a Tune Up. I replace all 8 Coil and spark plug because according to my OBD2 scanner (ACTRON) says multiple misfiring. After I did all that. I started the truck and it start perfect. I turn it off and proceed to ERASE the check ENGINE LIGHT. After that I started again and it won't start anymore. I put the key on ON position and the only lights that lid up is the Check Engine and Battery. I check the battery connection is fine. I check for spark on all spark plug and it's fine. I Also check the fuel pressure valve it sprays a lot of fuel and I can hear the fuel pump turn. The truck feels like it want to start but it just quit after. Am not sure what else I should check now. Can you give me some advice? Thanks
Answer Hi Albert,
Your vehicle needs three things to run. First is compression then fuel then spark. If your fuel pump is working and you have fire at the plugs. One of two things might have happened. Either the plugs you installed were wrong and popped a hole in the pistons, hopefully not what happened. Could also be plugs somehow got could with fuel. You can take plugs out and check the end of the plugs to see if there is damage. Other than that the timing could have jumped. Possible but highly unlikely. Do a compression test. Let me know what you find out. Thank you.