Humid

[Gaston53]

I have a Blazer 1996 with a 4.3, I wonder if anyone knows what could cause the motor to be very hard to start when humid outside or just after it sits for a little while on a rainy day. And would just replacing the wires, cap, rotor and plug would cure this annoying problem ?

[old_master]

You're probably on the right track. Hard starting, and rough running with high humidity is usually caused by faulty secondary ignition: Plugs, Distributor cap, rotor, plug wires and ignition coil. Best to use AC Delco parts, they cost a little more but well worth the added expense.

[Gaston53]

Originally Posted by old_master

You're probably on the right track. Hard starting, and rough running with high humidity is usually caused by faulty secondary ignition: Plugs, Distributor cap, rotor, plug wires and ignition coil. Best to use AC Delco parts, they cost a little more but well worth the added expense.

OK Thanx I will start with the basic and let you know later how it turned out.

[blazer8696]

Same issue here. Hard to start when humid and runs rough until driven 100 or so miles. Some bangs from the exhaust when attempting to start. After that all OK. Eventually the check engine light goes out all is great until the next humid weather.

Some history: The same problem occurred several years ago when the Blazer had about 134,00 miles on it (the engine was replaced at 96,000 with a Jasper).

The toy code reader stated cylinder 1 misfire and sometimes random cylinder misfire.

Visual inspection of cap and rotor revealed they were a mess. To me the contacts on this 134,000 cap didn't look good. I replaced the cap, rotor, plugs & wires and all was better until a few months ago.

Now 151,000 on the clock and symptoms are the same as last time except the code reader shows multiple cylinder misfire. I pulled the cap and it looks perfect and dry. I also removed and re-installed all plug wires which also looked like new. There are lots of bangs coming from the exhaust when attempting to start.

As I need to go through emissions real soon I'd really just like to get the thing running well enough to drive it to a pro for service.

My automotive repair experience is all from the 70's & 80's. I'm not afraid to tackle a big job but in my non-automotive work I often need to clean up after a DIYer so I don't want to make anything worse.

[old_master]

DTC's in the P0300 series are usually caused by faulty secondary ignition: Ignition coil, distributor cap, distributor rotor, spark plug wires and spark plugs. Use good quality parts. These engines are fussy with plugs, use AC Delco only.

[blazer8696]

Thanks, I'm somewhat suspecting coil but not through any real diagnosis. The Blazer sits for long periods, sometimes weeks, without being driven. Yesterday it would not start after a snowy and rainy week. The coil and the bits around it were wet. Distributor cap and rotor (relatively new) were dry inside and out.

After about 2 hrs with a drop light warming the coil area it was dry and fired right up.