the only code is p0300

littlejoered

2002 4.3l timing problem

Unread post by littlejoered » Tue Mar 16, 2010 3:56 pm

hello i have a 2002 silverado with a 4.3l here`s my problem 2 weeks ago i was turning my truck around and it stalled wouldn`t refire everybody i called said fuel pump so i put a new one in. still nothing next everybody said timing chain. so i started changeing i followed my book it said to put #4 piston on tdc line up timing chain cam gear 6 oclock crank 12 oclock put it back together still nothing called local mechanic he told me if the gears had arrows on them their suppost to be both at 12 oclock so i did still nothing.which way is the right way?i atleast want to have that part right before i take to a shop to figure out. thanks

Meccboy

Re: 2002 4.3l timing problem

Unread post by Meccboy » Tue Mar 16, 2010 11:13 pm

Crank sprocket dot at 12 o'clock, cam dot at 6 o'clock is the correct alignment.

stegar1
Posts: 1
Joined: Mon Jan 07, 2013 4:50 pm

the only code is p0300

Unread post by stegar1 » Mon Jan 07, 2013 5:12 pm

i have a 97 silverado with the 5.7 tbi. i have had a small miss for about a year now and the truck has been hard to start ( 3-5 seconds ave crank) i have had a rare back fire only on start up . i have replaced plugs, wires. rotor and cap. a new tps and fuel pump. the truck just died right after i started driving the other day and has hissed and bogged and back fired but not started ever since. rotor is spinnig and with # 1 at tdc is pointing at # 1 on cap. the coil has bright blue loud spark. all cly have faint or very faint orange spark except # 3( strong) . i am totaly lost. any ideas? :?:

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ProTech
Posts: 651
Joined: Wed Oct 17, 2012 10:08 am

Re: the only code is p0300

Unread post by ProTech » Tue Jan 08, 2013 8:32 pm

It could be the fuel pressure regulator has ruptured inside the upper plenum. This is common and usually causes a long crank before the truck will start up when it goes bad. If you remove the upper plenum (intake) you can see right away if it's been leaking, or have someone turn the key on and watch for it to leak out.

Another common problem on the older 350's that causes a slight misfire is a burned valve in the cylinder head. Normal diagnosis will not be able to check for this, as you will have good spark, fuel pressure, etc. This would require the head removed and repaired, which can be costly.

One thing, though, since you just replaced the fuel pump and now it won't start, I would really recommend going over your work and checking to make sure the fuel pump is still functional. Sometimes you can pinch a harness putting the tank back up and/or a fuel line can kink or break or come off the sender. You should check fuel pressure first, and the spec should be about 55psi with the key on and the pressure should hold steady. If it drops off, that is a sign of a leaking regulator like I mentioned before, or even a bad pump.
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Chevy Silverado Fuel Pressure Regulator Location.
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