sup guys, been gone for a while and have not had my yukon for a couple months now. original motor went bad and left my dd out of commisson since then. ended up buying a used motor for about $500 bucks and did a fresh rebuild on it. long story short, the motor is now finished and in the truck. my only problem is that it has fuel, fire, but does not have the balls to turn over enough to hardly hit a lick! all my grounds are good and tight, valves are adjusted to spec, and from what i know the dizzy is correct referring to rotor being faced toward #1 cylinder? i'm hoping that someone can please tell me that they've at least had this problem before or know the solution because i have to get this truck back on the road asap! the 99 yukon is a 5.7 vortec 2wd thank you in advance.
Stuck at the end of my project!!
- Thread starter 99'Yukon
- Start date
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SunlitComet
OBS Jedi-Do Good
if it is not strong enough to crank look at the condition of starter, battery and power supply cabling.
inspected starter after hooking trans back up, then installed. will check all power supply and grounds again in the morning. the battery was fully charged until trying to crank soo much. eventually threw it on the trickle charger and called it a night. think i also might have soaked the spark plugs in gas, so idk if i will need to replace those or not. oh yea, is there a possibility that the timing chain could be off a couple teeth or something of that nature? 
SunlitComet
OBS Jedi-Do Good
if you replaced engine yes you might have not set the dizzy back in right. put the engine at #1 tdc and check the position or rotor in relation to caps #1 internal location.
Yukon420SEL
Member
Crank positioning senor?
SunlitComet
OBS Jedi-Do Good
yes, a non functioning crank sensor circuit can create a no start condition too.
---------- Post added at 08:53 AM ---------- Previous post was at 08:39 AM ----------
try an use this and perform as much as you can.
Engine Cranks But Does Not Run
Circuit Description
The diagnosis for an engine that cranks but does not run must have three elements present before proceeding with the diagnostic table. The following conditions must exist:
If no trouble is found in the fuel pump circuit or the ignition system and the cause of an Engine Cranks But Will Not Run has not been found, check the following conditions:
Afterwards, reinstall the VCM and check the circuit. Replace the VCM only if the circuit is still inoperative.
An intermittent may be caused by any of the following conditions:
Test Description
The numbers below refer to the step numbers on the diagnostic tables.
2. If the engine starts, the problem could be intermittent. Basic engine mechanical problems, the Vehicle Theft Deterrent (VTD) system (if equipped), and poor connections could cause a no start condition.
3. This step will determine if the cause of the no start or start and stall is related to the VTD.
4. If the signal is over 2.5 volts, the engine may be in the clear flood mode which will cause starting problems.
5. If the engine coolant sensor is below -30°C (-22°F), the VCM provides fuel for this extremely cold temperature which will severely flood the engine.
6. Voltage at the spark plug is checked using the J 26792 spark plug tester tool. No spark indicates a basic ignition problem.
7. This test will determine if there is fuel pressure at the fuel injection unit and holding steady.
8. Use the J 34730-375 injector test lamp in order to test the injector circuits. A blinking lamp indicates that the VCM is controlling the injector.
---------- Post added at 08:53 AM ---------- Previous post was at 08:39 AM ----------
try an use this and perform as much as you can.
Engine Cranks But Does Not Run
Circuit Description
The diagnosis for an engine that cranks but does not run must have three elements present before proceeding with the diagnostic table. The following conditions must exist:
- the battery must be adequately charged
- the engine cranking speed must be sufficient
- there must be an adequate amount of fuel in the fuel tank
If no trouble is found in the fuel pump circuit or the ignition system and the cause of an Engine Cranks But Will Not Run has not been found, check the following conditions:
- Perform the Fuel Injector Coil Test.
- An after-market Vehicle Theft Deterrent system could cause a start then stall or a no start condition.
- Fouled spark plugs
- An EGR valve stuck open
- Water or foreign material in the fuel system
- A grounded or intermittently grounded Ignition Control (IC) signal circuit
- Restricted exhaust system
- Check the following ignition components:
- A grounded tach circuit
- Worn distributor cap
- Worn distributor rotor
- Check ignition wires by lightly spraying them with water in order to identify intermittent no starts
- Cylinder valve timing
- Loose or broken timing chain
- Low compression
- Worn camshaft lobes
- Bent or burned intake or exhaust valves
Afterwards, reinstall the VCM and check the circuit. Replace the VCM only if the circuit is still inoperative.
An intermittent may be caused by any of the following conditions:
- A poor connection
- Rubbed through wire insulation
- A broken wire inside the insulation
Test Description
The numbers below refer to the step numbers on the diagnostic tables.
2. If the engine starts, the problem could be intermittent. Basic engine mechanical problems, the Vehicle Theft Deterrent (VTD) system (if equipped), and poor connections could cause a no start condition.
3. This step will determine if the cause of the no start or start and stall is related to the VTD.
4. If the signal is over 2.5 volts, the engine may be in the clear flood mode which will cause starting problems.
5. If the engine coolant sensor is below -30°C (-22°F), the VCM provides fuel for this extremely cold temperature which will severely flood the engine.
6. Voltage at the spark plug is checked using the J 26792 spark plug tester tool. No spark indicates a basic ignition problem.
7. This test will determine if there is fuel pressure at the fuel injection unit and holding steady.
8. Use the J 34730-375 injector test lamp in order to test the injector circuits. A blinking lamp indicates that the VCM is controlling the injector.
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well tried a new cam and crank sensor tonight and to no avail still no start. have perfect fuel pressure, but still think it might be in the timing. probably going to go ahead and take the water pump and harmonic balancer back off so i can get to the timing cover to inspect the chain. i feel like i have really tried everything besides that, and can only hope its off a tooth or two. i dunno what it could be if the tiiming chain isn't off. kinda starting to get worried here guys 
SunlitComet
OBS Jedi-Do Good
whoa, whoa, whoa. timing chain? what happen there? you thinking you did not line up the alignment marks on the otherwise key sprockets? i would remove the left valve cover and dizzy cap and see if you cant see if everything is synced visually. btw when you put this thing back together how did you do you valve adjustment?
---------- Post added at 12:08 AM ---------- Previous post was at 12:06 AM ----------
oh, also dont forget every time you pull off the timing cover you have to put a new one back on.. wait did you put a new one when you rebuilt it?
---------- Post added at 12:08 AM ---------- Previous post was at 12:06 AM ----------
oh, also dont forget every time you pull off the timing cover you have to put a new one back on.. wait did you put a new one when you rebuilt it?
