1998 Yukon Starts Fine, Then Doesn't

[mercedea]

Just bought a Yukon 1998 and love the truck however I continue to have trouble with the truck not starting. It is sporadic with this behavior as it does not always happen. Most times it starts fine then others it wont start...have to leave it set for about 15 minutes then it will start fine.

Any suggestions for this?

Thanks

[GM-Tech]

Can you better define "won't start"??

 

Does it crank but not start or does it not crank. Not that you don't know, but this seems to be a difficult concept for customers to grasp. I often have to go into a long explanation just to find out what they mean when they say it won't start.

 

Think of cranking like the old days when one actually had to use a crank to start a Model T. So, cranking means the engine is turning.

[mercedea]

Can you better define "won't start"??

 

Does it crank but not start or does it not crank. Not that you don't know, but this seems to be a difficult concept for customers to grasp.  I often have to go into a long explanation just to find out what they mean when they say it won't start.

 

Think of cranking like the old days when one actually had to use a crank to start a Model T.  So, cranking means the engine is turning.

 

<{POST_SNAPBACK}>

 

 

 

 

Sure. It will not start. It cranks but will not start.

 

Thanks for bringing to my attention the need for clarification.

[GM-Tech]

Have you noticed what the security light is doing when this happens? If you attempt to start it and it doesn't, and you leave the key on, does it stay on or blink? Either of those things would indicate a security system problem. This is not a terribly uncommon problem.

 

Otherwise, you'd need to do a little digging to see if you don't have fuel pressure, injector pulse, spark, etc. So many things can cause a no start and without a bit of diagnostic info, we're really just guessing.

[mercedea]

Have you noticed what the security light is doing when this happens?  If you attempt to start it and it doesn't, and you leave the key on, does it stay on or blink?  Either of those things would indicate a security system problem.  This is not a terribly uncommon problem.

 

Otherwise, you'd need to do a little digging to see if you don't have fuel pressure, injector pulse, spark, etc.  So many things can cause a no start and without a bit of diagnostic info, we're really just guessing.

 

<{POST_SNAPBACK}>

 

 

 

 

Security light stays on after trying to start it. No blinking. Leave the key on it stays on. No blinking.

[GM-Tech]

Security light stays on after trying to start it. No blinking.  Leave the key on it stays on. No blinking.

 

Yep, you have a security system problem. These can be a REAL pain to fix because they're so intermittent. I have one in the shop right now. Been trying for two days to duplicate the problem so I can track it down. I have the whole thing in pieces and I checked every terminal, every connection along the way and I can't find anything obvious nor can I make the passlock voltage vary by even 100th of a volt.

 

Another tech already replaced the passlock sensor to the tune of $400 parts and labor and didn't fix it.

 

In most cases, there's just some extra resistance in a connection somewhere along the path from the sensor in the the ign lock housing to the module buried under the dash.

 

All I can tell ya is, good luck.