I have a 2002 trailblazer that will start fine in the morning and after it sits for an hour or two, but once i start it and run it for over ten minutes and i shut it off when i try to re-start it, it will crank but won't start. the dealer cleaned the throttle body and injectors, check the fuel pump for presure and it was fine,and they got no error codes?????? I've read that in can be the ignition switch?? any ideas??

Thanks

Juan

Usually the ign switch has other symptoms, when this happens you must check for spark ( not easy) and/or fuel pressure.

On my 06 trail blazer, the ignition switch went out.. It is a know problem with the TB's... My would not crank.. It's not bad to replace, maybe 30 minutes.. Also if you can get it without the long harness, it's under 20 bucks.. That's what I did...

When you turn the ignition on before cranking, can you hear the fuel pump? Also to check for spark, pull one wire off and insert a old used plug to check.. Be sure to ground the plug or you'll become the ground..

Keep in mind there is no " wire" to pull off, this is coil on plug ign. you will need to access the plugs, then pull the coil off, make sure it is grounded then put a spark tester jumper onto the plug and coil and crank the engine, not a quick process as I mentioned.

If their's no spark would this happen this way(intermittent)? I don't understand why it only happens after i run it for a couple of miles but it works fine when it sits over night or for an hour, I'm puzzled????

No way to predict why these things happen this way, all the proper diagnostics must be performed.

Cleaned the throttle body but no change,but i can get it started if i press the gas pedal all the way down while cranking it, but it will rev high for a few seconds when it starts?????

Boy that sounds like a weak fuel pump but not sure.. Although the dealer checked the pressure..

On my sons blazer it wouldn't start also.. When he turn the key on and off 2 or 3 times without cranking it, then it would start.. What that does is cycle the electric fuel pump and insures the right fuel pressure if you have a weak pump. The pump is on a timer when you just turn the key to run, you shuld be able to hear the pump run, then shut off..Then I changed the pump and ran great..

Give it a try.. :smooch:

Again, a scan and some diagnostics are in order, there is no quick answer or shortcut here. Possible throttle control motor or tps issue.

I have the EXACT problem that u do Juan. also my ECT senor goes on and off but i think thats just a bad conenction. let me know if you find out what it is. DOES ANYONE KNOW?

O and i replaced my ignition switch and it did not help at all.

Boy that sounds like a weak fuel pump but not sure.. Although the dealer checked the pressure..

On my sons blazer it wouldn't start also.. When he turn the key on and off 2 or 3 times without cranking it, then it would start.. What that does is cycle the electric fuel pump and insures the right fuel pressure if you have a weak pump. The pump is on a timer when you just turn the key to run, you shuld be able to hear the pump run, then shut off..Then I changed the pump and ran great..

Give it a try.. :smooch:


I tried it and didn't work, im going to have it scanned this week and see if i get any error codes.

I posted another thread about my temp. gauge that stays at 100 and jumps to 210 then back to 100 and stays there, but when the gauge decides to work properly the problems does not exist, can this be linked to the temperature gauge????? puzzled!!!!! and still have no codes.

You have a dash cluster that is going bad, I have replaced at least 50 in the past year alone. If one gauge goes out more are sure to follow. Use it as long as you can,
most rebuilds run at least $ 300.