QuestionQUESTION: I have a 1999 Chevy Suburban 5.7 "R" and am having a problem. The vehicle will not start. I have checked the spark, timing meaning distributor position, tdc, even took timing cover off and checked chain. Have spark and fuel pump runs the two seconds when turn key. Sprayed hot shot to see if it would help but no good. The odd thing is that is seems like motor gets hung up as I spin motor, and I get air coming back through the intake on consistent strokes. WTF. Please help.
ANSWER: Jason,
Unfortunately, somewhere you have a timing-type issue. Air comes up through the intake when the motor tries to fire with the valves open. Options are: broken valve spring, broken valve, flattened cam lobe, or wrecked cam to distributor gears to start with. (I know it sucks.. I just replaced two valve springs on my wife's 99 burb and my 99 tahoe just started missing a little....) Anyway, I would take the valve covers off and start there. Gaskets aren't much, and it will tell you the most info. Let me know what you find, Good Luck!
---------- FOLLOW-UP ----------
QUESTION: Thanks for the response....
I have checked the compression and it is good with 155-180 pounds all around. I checked for fuel and it is good. I have good spark. I took off timing cover and checked marks and all is good. I checked the distributor gear and it looked knife edged so I replaced it new along with cap, rotor, plugs, wires.
The odd thing is the truck started with the rotor 180 out from timing marks, but it ran really poor, binding when trying to start, and was backfiring hard into intake. When I align the correct way, it will not start and has air going into intake. I found this to be odd that it will run 180 out but not with correct timing. This truck is driving me nutz. I have compression, spark, fuel, and replaced new parts and I am puzzled. Any ideas?
AnswerJason,
Okay, first, when you checked the timing marks, were both the dots at 12 o'clock on the gears? (Sometimes folks put them in with the dots at 12 on the crank and 6 on the cam and it does that.) I'm going to assume that they were in correctly for this though. If it runs a little 180 out, it could be the gears, but it could also be valve adjustment. In my answered questions archives there is a sieries of questions and follow-ups from "Dave" on 350 timing, and this will give you the correct way to set up your valves. Try adjusting the valves, and if the gears are in correctly, it should fix the problem. Good Luck!
