3rd Gen vs 1st Gen Starting

[JHylton]

Just bought an '06 SLT about three weeks ago... 52K miles, mint condition, stock - no mods... also am original owner of a 91. 5 with 170K+ miles. My question: Are the newer 5. 9s harder starting than the old ones? The 91. 5 will bump start... every time... you just barely touch the key and it lights up. I swear, you can just about breath on the key, and that baby is up and running... The '06 cranks quite a bit... . 4 - 6 seconds... cold start or warm start... . a hell of a lot more than Old Brownie does. Is this common? I don't know a lot about the history of this '06, CarFax didn't report any problems.

 

['strokeThis_'07]

Yep. 4-6 seconds is a bit long, mine usually takes maybe 2-3 roughly, depending on temp obviously. If it's routinely hard to start, even in warm temps, injectors may be on the way out.



Everytime I hear a VE or P-pump, but especially the VE, it just cracks off immediately.

 

[JHylton]

Realizing that anything mechanical can go TU at anytime, does that sound/seem an unusually short life (52K) for injectors? My old one has a VE pump, I believe... . mechanical all the way... . never had a bit of trouble with any of the whole major engine assembly... . Your 6. 7 swap sounds interesting. One of my mechanic buddies just dropped a 5. 9 into a late model 1500... Also have another friend who has been pestering me for a couple of years to buy my 5. 9... he wants to drop the drivetrain into a Chev Suburban... ... . I told him that was a down right sacrilige.

 

[cerberusiam]

A well tuned 12V almost always fires on the first piston up. Its the way they work with a jerk pump.



The CR is a different beasty. Injectors are not fired by pressure they are fired electronically by the ECU. In order for that to happen the ECU needs to know where in the cycle each cylinder and cam shft lobe is, and what the rail pressure is. All things being good, it takes several revolutions to synch the crank and cam sensor to find TDC on the cylinders and build the required 3000 psi of rail pressure to start the injection event. Usually its the 3rd or 4th piston up that fires first.



Knowing that, you can see where there are multiple areas that can cause a slow start, crank sensor, cam sensor, rail pressure via CP-3 or LP and injectors. The injectors return fuel constantly for cooling so if the rail pressure does not build fast enough, no fire. If the crank\cam sensros do not synch immeditely, no fire. It will default fire off the crank sensor if the cam sensor does not synch but that means a long crank, anywhere from 5-8 seconds.



My truck has lways fired on a slow 2-3 count (1001, 1002, 1003) and is running by 3. I have seen others it is a 4-5 count and they have always been that way since new. Generally a slow 3-5 count is normal. Longer than that could mean issues.



Manual trucks seem to consistently take longer. Not sure why but they do. The auto trucks are usually the fastest starting.



Hope that helps give you a a starting point for the differences.

 

[JHylton]

Thanks much for the explanation. Got lots to learn about the CR system. Not knowing all the acronyms and what they mean is challenging, as well. CP-3 and LP are new terminologies I don't have knowledge of yet, either... but that is one good thing about this forum... an abundance of information, knowledge, and the willingness by good folks to share.

 

[AH64ID]

CP3 is the high pressure injection pump that supplies the rail with pressurized fuel, and LP is lift pump, which is in the tank on your 06.

I think my truck takes about 1-2 seconds to fire, but my dads 06 takes about 2-3. Maybe I'll time it one of these days.

There was a TSB for long cranking, TSB 18-003-06, you may see if it has been applied to the truck. It took my dads 05 from a 5-6 count to a 2-3 count.