Considering looking at a '99 suburban. Current owner claims the timing chain was recently redone along with new plugs & wires. Says it turns over, sounds like it wants to start, but won't stay running. Says his mechanic thinks it's a bad plug or wire. I'm wondering if it means the timing chain replacement was not done correctly. Concerned as the owner has put some money into it and is suddenly ready to sell. It could be frustration or it could be that he "suspects" a more costly problem. I've never owned a GM of this vintage so looking for any advice or likely causes. Especially something that could be diagnosed easily and/or with a cheap part.
Put a timing light on it first.
Then do a compression check.
Check that the wires are installed correctly, as in not crossed up.
That will tell you if it's in the timing components. A 350 with a bad plug wire will run on 7, or even 5.
Assuming it never ran right after the job, I'd assume his "mechanic" put the chain on a tooth or three off. It's easy enough to screw up, as you have to slap the gears and chain on simultaneously, no tensioner.
Did the chain break, or just get loose? If it broke was there any check for bent valves? I think SBCs are interference.
Kenny_McCormic wrote:
Assuming it never ran right after the job, I'd assume his "mechanic" put the chain on a tooth or three off. It's easy enough to screw up, as you have to slap the gears and chain on simultaneously, no tensioner.
Did the chain break, or just get loose? If it broke was there any check for bent valves? I think SBCs are interference.
Those are my concerns. Sounds like it won't start immediately following the timing chain replacement. Not sure if it broke or was loose. Will try to find out more from him tomorrow.
Take a fuel pressure gauge with you. If those CFI things don't have 60 psi cranking, like if they have 55psi, they will not start without a shot of ether. Really.
And if whoever did the chain managed to get a small block Chev wrong, don't trust that the wheels are tight.
Wasn't there an issue with that vintage and having to sync the distributor and crank sensor in the computer somehow? I seem to recall swapping out a distributor and having to haul it to the dealership for 10 min with their scan tool to get it to run again.
I have a '96 1500 with the Vortec 5.7L, and I imagine yours is the same motor. The only thing I've had keep it from starting has been the fuel pump (twice in 16 years) and the crank position sensor. The cps sounded like the chain jumped when trying to start, backfiring through the tbi.
If it has sat for a while, the spider injector system in these motors really hate ethanol, and will plug up easily if they sit. With any kind of mileage, they get old and brittle anyways, and won't maintain fuel pressure.
Streetwiseguy wrote:
Take a fuel pressure gauge with you. If those CFI things don't have 60 psi cranking, like if they have 55psi, they will not start without a shot of ether. Really.
Cannot be stressed enough. The "spider" fuel injection is VERY PICKY about its fuel pressure.
I'd also be curious if the distributor was stabbed in correctly. If it has the central port fuel injection (and JEEZ I cannot remember the GM acronym for it) and it has a flat-cap distributor, the distributor does not set timing (that is done with the crank sensor under the timing cover) but it does have a cam position sensor in it. Get the distributor off and the engine won't start.
Y'know, forgetting to put the crank trigger wheel back on would also prevent the engine from running...
If it kicks but doesn't run, and especially if it kicks and bucks against the starter, and it has the flat cap, replace the cap and rotor. They are wear items with a shockingly short lifespan, the caps like to arc internally or just plain wear out. Buy two new sets from NAPA, they last the longest, and keep the second set as a spare since they always seem to act up at the worst times. Lifespan 20-50k miles. Don't cheap out here! I've replaced brand new cheapo junk because they wanted to save a few bucks by going to Autozone or Rock Auto. (And don't use the new screws, unless you want to break the plastic distributor housing)
racerfink wrote:
If it has sat for a while, the spider injector system in these motors really hate ethanol, and will plug up easily if they sit.
Never seen it happen. The only issue I've seen besides the odd injector failure has been the fuel pressure diaphragm leaking, which causes severe rich running/misfires on two cylinders (3 and 5 I think, the diaphragm is over the passenger side and the intake is shaped like a mini crossram).
The only real "sitting causes problems" problem I've seen is that if you let an old 4L60 sit long enough, like 5-6 months, the torque converter drains out and you lose a couple quarts of trans fluid after it overfills the trans and dumps out the vent.
a few weeks ago, my 97 Chevy just decided to die at 60mph... it almost tried to restart a couple of times, but it was dead..
long story short, it was the coil... $42 at NAPA..
Looks like I won't have to figure it out. Owner sent me a text that it was sold.
