Hello,

I'm reasonably certain I'm about to experience a failure of some sort of in the starting capacity of my 06 H3 Base. I'm coming up on 90k, and I'm noticing the engine moves a significant amount in the engine bay during start up. At idle, and under gas, it doesn't move very much, but at startup it rocks significantly.

It seems like it's having a harder time starting, and it when it does start, I can feel the vehicle shake. Occasionally the RPMs will sit around 1600 for awhile, before dropping down to a more normal 6-800. Today, I parked, got out, locked it, unlocked it, got back in, and tried to start it again, and it wouldn't start. Power was good, and I could hear the starter trying just as it normally would, but the engine did not start. Several hours later, I tried it again, and it worked just fine. I've come to understand this could be part of the security system, but I've had the security system (or something similar to it) not release the key, or give any power to the vehicle for 10 minutes before. So I don't think that was it. I understand it could also be the fuel pump. I noticed before I started it, I heard the pump, then it stopped, then I heard it again. I haven't keep sufficient data to know if that's unusual or not. I understand it may also be related to something called a coil pack? My urge is to just buy a new starter, however if there is a different source to the problem, I would prefer to identify it.

Possibly unrelated, recently, my CEL came on indicating either low coolant, or a failing thermostat. Temp gauge sits around half way, and my ScanGauge pegs the regular temp around 180-190F....which doesn't seem that high to me...I bought a new thermostat, but haven't installed it. I cleared the code about a week ago, and it hasn't come back yet.

Regarding electrical. I haven't noticed anything out of the ordinary. Battery reads ~12.6/14.3. Regarding modifications, I have an aftermarket stereo, and a 600W amp.

MAF sensor was cleaned back in January. At the same time, oil was changed to Royal Purple 5w30.

Does anyone have any suggestions as to which items to prosecute first, methods of prosecution for those items, or suggestions of items I may have missed? Any input is appreciated.

Thank you,
-qui

 

is it the original battery from when it was made? good chance it is and that could be the problem. i just replaced my battery that was the original. i had 120k on it. even though your reading 12.6/14.3 volts it could still be a bad battery. mine said the same thing. with the engine off it read over 12 volts and when it was running it read right around 14 volts. the problem is that when you turn the key to start the truck it sucks alot of power from the battery. just because it says 12.6 doesnt mean that it actually is holding that charge long term. it could very easily be dropping below 12 once the starter is engaged therfore not giving it the proper juice to start.
basiclly the battery is on its way out and needs replacing.

 

Thank you for your response. This is the original battery from when I bought it, but I'm not sure how long it's been there. I will likely end up replacing it. From previous experience with (dead) batteries, I noticed the frequency of the sounds caused by the starter would lower and slow significantly, before eventually stopping. In this situation, it made the noises at the same or similar rate to what I would normally expect. With this information in hand, do you still feel it is a failure in the battery?

 

no other codes? keep an eye on, and check/top off coolant.

remove & thoroughly clean that TB!

check air filter & seal... clean the maf again if needed.

get a new ignition switch, install it, and that will correct your security lockout/no start.

GL

 

Update:

When I go to start the hummer, with the key turned to just before it starts, three lights come on. These lights are are CEL ( no codes or pending codes), the battery, and the picture of a car with a padlock. Also, I've noticed the driving voltage according to scan gauge is 14.0-14.2. It just dropped to 12.2 when I parked and turned it off and it has since combed up to 12.4 ( about 5 mins)

Additionally, the second time I started it this morning, the fuel pump didn't sound very eager. If that makes any sense...

 

the batt is ok,generator is ok. voltage tells that,its normal.

 

the voltage will jump up like that while its running, its just the alternater doing its job. those lights will come on prior to start once the key is turned and then go away upon start. I would try a new battery and then go from there. being as its probably the original battery from when the truck was made its time for a new one. it will only take about 10 min to put a new battery in and wouldnt hurt to have a new one.

 

the batt is ok,generator is ok. voltage tells that,its normal

want a simply batt check?,,,put yours in sombodys car for a few days,,like trade them,,,

 

I went ahead and put a new battery in. We'll see what happens.

After the battery, what would be the next place to look?

 

Your battery is in the normal range when the vehicle is off. I see nothing that points to a bad battery. Follow what Hummerz said. A dirty throttle body will make it run rough at different times. That is where I would start. You had the battery tested and it tested good. I wouldn't buy a new battery. THos e are not signs of a bad battery.