Expert: Robert Summers - 11/27/2007

Question
QUESTION: My 95 blazer has no spark; installed new coil and ignition module. Still no spark. I sit possible it could be a bad Crank sensor? What else should I check? Also fuel pump doesn't come on after ignition is on. Do you know what relay in the glove box is for the fuel pump and where is this fuel pump test connector located? Is it possible these two problems could be related?

ANSWER: Hi Chad... fule pump should come on for three seconds when key turned on, if not it defaults to the oil pressure switch and comes on when you have enough oil pressure...fuel pump relay should be marked on the fuse box lid...test connector should be near brake booster.check for power at the relay and at the fuel tank...the should also be a fuel pump fuse. no spark could be bad crank sensor or bad cap and rotor. check for ign referance at the dist if good look at the cap and rotor. if none look at crank sensor.hope this helps

---------- FOLLOW-UP ----------

QUESTION: Thanks a lot for your help! Ok I verified the fuel pump works when I put 12vdc to it. I am getting nothing to the relay when I turn the key on, fuses are good. Upon checking out if ecm was sending signal I noticed that the ecm was not getting any power. Ecm fuses are good so I figure I have a broken wire somewhere. Do you know the routing of the wires? And I assume the ecm gets 12V.

Thanks again

Answer
Hi Chad.... if you back probe the plug on the computer you will need a wiring diagram of the plug and see if you have power on the input for the ECM could be 5 v or 8 v the diagram should tell you which... if no power trace that wire back to the panel and see where the open is in the circut.... hope this helps