davemec

Has anyboby with a 2007 been having trouble with the starter? Mine used to start almost instantly, now it takes between 3 and 4 seconds to turn over and often doesn't start on the first try. I am taking it to get looked at, but wanted to see if anyone else had this problem and knows a fix.

e

dave, are you holding the key to the start position while its starting?
These are resistor based systems so if youbump tothe start position then let off it should continue cranking until it starts. I usually fire up the electronics (run position) then bump to the start position (.5-1.5 seconds)and it cranks 2-3 times then starts. this happens within 1-2 seconds. I'm not saying you cant hold it in the start position while its cranking, i'm just saying its not necessary.
Try putting it to the run position, wait a second then turn to the run position and let off before it starts, does it continue cranking?

Just tried bumping very very short and it cranks than stops with no start. If I hold it counting to 1 then releaseit continues cranking until started.

ZX1100F1

Are you sure about this?

davemec

My problem isn't with the cranking, it's that it either cranks for .5 to 1 second and starts (not a problem), or cranks for 3 to 4 seconds and barely turns over, or cranks till it times out and doesn't start. The problem wasn't there for the first 11 months, then during the 12th month it started getting progressively worse.

ZX1100F1

Dave,
it is usually a fuel system issue that causes extended cranking times before light-off.

I would change the fuel filter and clean the fuel injectors.
You may also want to check the fuel rail pressure and if low inspect the fuel pressure regulator.

davemec

Thanks Dave, I'll let the service manager know to check out the fuel system.

e

yes. but afterI re-read my postI should ofmade myself a little more clear:

Dave stated in the first post that it would take "3-4 seconds to turn over" and I took this as it wasn't engaging the starter.

First off, I should of stated that starter wire does not actually supply the starter with voltage. A resistor is used along withvoltage reference to make the system fire the starter thus me saying "resistor based system."

The actual whole key system is a voltage reference. This means that before the truck will start there is a sequence of voltage and resistance that must be established. The "Starter Reference Wire"has a sequence of things that it does to tell theBCM that it wants to start the truck. If one of the steps in the sequence fail the starter could crank but not start the truck or the starter could not engage at all.

Sequence on the Pink/Black Wire (some call it the starter wire)
Put Key in Clyinder = 12v
Turn key to Accessory/Ignition = 5v
Crank = under 4v (due to resistor being shorted between pink/black and white reference wire)
If these voltages are not within spec, thetruck couldshow signs of a no start whether its starter running or not running.

We went through this problem back in 06when we helping out in creating bypasses for the new gmt900's. We could make the starter engage but not start. This was due to an improper start up sequences which wouldn't fire up the fuel system or trigger the security system.We could make no starter response conditions as well.

I didnt want to get too technical on the first post because its probably something easy like the fuel system causing the problem. I was asking about the holding of the key thing because we were able to make the resistance glitch out in the early 07Tahoes and Avalancheswhich would not engage the starter. Sometimes it would engage as we were releasing the key back to the run position. Bare in mind that these were in extreme wierd cases and after constant on off cycles throughout the day.

If all of your fuel systems, starter and battery check out, it might be worth looking into.

I apologize for not making my post clear..........
e

ZX1100F1

e,
Pretty good; I am impressed and it is clear that you have some of the basics of the starting system down but it is not actually "resistor based", the entire start sequence is microprocessor controlled and since we are on the subject here is a short version of how the system functions:
When the ignition switch is placed in the Start position for at least 0.4 seconds, a discrete 12-volt signal is supplied to the body control module (BCM) notifying it that the ignition is in the Start position. The BCM then sends a message to the engine control module (ECM) notifying it that CRANK has been requested. The ECM verifies that the transmission is in Park or Neutral. If it is, the ECM then supplies 12 volts to the control circuit of the crank relay. When this occurs, battery positive voltage is supplied through the switch side of the crank relay to the Sterminal of the starter solenoid thus cranking the starter motor, once the start timer is activated, the PCM/ECM will continue to crank the starter until either the engine starts or a no start time limit is reached after several seconds.