I have a 03 blazer that cranks but wont start. When i turn the key to run, the fuel pump comes on for a split second (not the full prime). The fuel guage is also on empty and my code reader tells me to turn the key to run (even though it is). No dtc's. If i keep turning the key to off and run, after 10-15 min the pump will come on for the complete prime cycle, the fuel guage will come back and the code reader will work. This also happens sometimes if i just leave the key in the run position. I hooked up a test light to the connector at the pump and it does the same thing. Also swspped fuel pump relays. Car drives fine once it is started. Any help would be appreciated. Thank you.

 

Sounds like a flaky ign switch.
What about the panel warning lights? Check the underhood block for any relay or Circuit breaker for ign or vcm.

I dont have your year diag's but in mine there's no relay for the VCM. Fact it comes on eliminates a fuse blown. And the VCm as far as I can tell does not affect the fuel gauge, otherwise I might suspect bad vcm.

 

I agree on the ignition switch issue. Check out the link in my signature below my sig image. Run through the outputs from the ignition switch under the steering column and make sure that the various circuits make good connections (ie. very, very low resistance) when they are supposed to.

 

Thanks guys. Ill check it out tomorrow after work and post back.

 

So i cant seem to find a wiring diagram for my ignition switch anywhere. Does anyone know where i could find one?

 

The link in my signature applies to a 2003 as well.

 

Thanks a million!

 

Kyle takes great care of us!!!

But you guys who have bad ignition switches and are tempted to use relays (refer to end of thread) need to understand that a relay must have a 'clean switch' to drive it. If the switch contact is already burnt/flaky, reducing the current through it usually, not always, makes it worse.

The answer there is to drive the relay through one of those good contacts. Making sure to document it for the future so you dont drive yourself crazy with your own mods.
- yeah..I know.. 'as IF'

 

So i finally put an ignition switch in and the problem is still happening. Any suggestions? Thank you.

 

Did you test the old ignition switch before jumping into the replacement?

Maybe you have an intermittent connection somewhere or a ground problem... During the no-start condition, do you have spark? If not, take a look at the thread below for some ideas on where to look / what to check:

No-Start - Engine Cranks OK - Ignition System Diagnosis