Ok everyone..need assistance. I have been battling this on/off start issue for months. My 2000 old body style Z71 with the 350 vortec..there are times it starts and runs fine then times when it cranks without starting and produces the P1351 code..I am throwing money into this in an attempt to cure the problem but it keeps surfacing. I have changed the fuel pump, fuel filter, coil, ignition control module, battery, fuel pump replay, complete tune up six months ago, distributor was changed two years ago, alternator two months ago..and the issue still comes back. It is my only vehicle, divorce happens, and right now I cant afford a second. I want to make sure that if the problem is the crank position sensor it would NOT produce the P1351 code, correct? I am to the point of simply having it towed in the next time this happens want to avoid that if possible. Does ANYONE have any insight/suggestions on this?? Possible distributor cap/rotor? But thinking that if there are times it starts and runs great it cant be the cap and rotor... Thanks!

 

P1351 is a pretty common problem to occur. As I just read, your ICM was replaced fairly recently. Be sure to check all your power and grounds for the module. Also be sure to check Fuel pressure with the key on, then disconnect the injectors, and crank the motor for 5 seconds. See what the pressure is while cranking. After that, plug the injectors back in and check fuel pressure while running. It should be around 60 while the key is on, then drop down a little while cranking, then after the engine has started it should pop back up to around 60 again. If it doesn't do that, maybe you have a leak somewhere in the fuel lines.

 

The P1351 code generally indicates issues with an abnormal voltage within the Ignition Control Module (ICM) or Ignition Diagnostic Monitor (IDM). The process of the ICM or IDM is very complex, but the most important component to note is that it reacts to the engine data to send a signal that ensures combustion happens at the right time. Have you checked these components?