Rainy day no start

[Rbarcroft]

my 2000 chevy astro won't start on wet or rainy days. does any one have a clue. plugs, wires, cap, rotor, coil allgood

[old_master]

Originally Posted by Rbarcroft

....plugs, wires, cap, rotor, coil all good....

You'll find that one or more of those parts are not so good afterall! Those are the most common parts that can cause a no start condition with high humidity. What brand and part number of parts are you using? How old are they and how many miles on them?

[Rbarcroft]

The problem is that this started more than a year ago and all those parts have been replaced. I know that sometimes that you can get bad parts from the supplier. but how do you check to see if they are bad? also someone said that it could be a faulty temp sensor that does not allow enough fuel to enter to start when cold. There is no arcing between coil wires or other ignition sources so I tend to believe they are ok. I do not know the part numbers etc.

[old_master]

The ECT, (Engine Coolant Temperature) sensor is located next to the thermostat housing and can affect starting if it's out of calibration. Keep in mind it is not affected by humidity. If you have access to a scan tool capable of monitoring live data, the ECT and IAT, (Inlet Air Temperature) sensors can be compared when the engine is stone cold. They should be within 2 or 3 degrees of each other. The comparison does not tell you which sensor is faulty, only that one of them is out of calibration. If they are within specs, don't bother replacing the ECT sensor.... save your money and time.

Without an ocilloscope, eliminating the possibility of faulty ignition parts can be a challenge.

If you're experiencing a problem with hard starting, no start, or rough running when damp, usually, not always, the ECM will set a DTC, (Diagnostic Trouble Code) and the SES, (Service Engine Soon) light will be illuminated. The most common DTC to be set under these conditions is P0300 however, any P0300 series DTC can be set. If the SES light comes on, either flashing or continously, and any P0300 series DTC is set, it's a dead give away for secondary ignition faults.

These engines can be very fussy when it comes to secondary ignition parts: plugs, wires, distributor cap, rotor and ignition coil. Here's a thread that addresses aftermarket distributor caps and rotors and the importance of using AC Delco ignition parts on the 4.3L engine: http://www.automotiveforums.com/vbul...44#post6100044

Something else to check:
When the engine is shut down hot, under certain atmospheric conditions, condensation can form on the underside of the distributor cap. There are 2 small holes in the distributor housing base that allow for ventillation. If the vent holes become clogged, moisture will accumulate and can give the symptoms you're describing and possibly set a P0300 series DTC also.

[Wmurky]

ok sounds like you got clogged distrbutor vents with new cap & rotorl it will run fine untill damp weather sets in, soon it will run just like before look at the cap it wiil be corroded. be careful taking the cap off, this is a BS setup should have been clips, the distributor base & shaft housing is plastic the screw ears will breakoff the base,due to heat fatigue.plastic for critical engine parts is BS. i had to replace my distributor due to broken screw ears on the base.

[2000 CHEVY 4.3]

***This is a TRUE compliment to this posting!!! It may very well save you countless hours of frustration, time and money- THANK YOU!!!

PROBLEM- 4.3 WON'T START IN DAMP WEATHER-


***csamford
07-19-2007, 05:18 PM
I finally got it fixed, it turned out to be the distributor, after all of that, It may have been the cam shaft position sensor, which is attached to the distributor, All I know is that after sticking a new one in, it fired right up after sitting for almost 6 months, I still don't know how it went out overnight, however it was freezing when it went out, maybe the cold??? I was getting fire but it was "double sparking" etc... as I stated before, really weird, but I am super happy to have it fixed.


PROBLEM- 4.3 WON'T START IN DAMP WEATHER-
CAUSE- WATER DROPPING OVER TIME BETWEEN HOOD AND DISLODGED RUBBER DAM ONTO FIREWALL FALLING DIRECTLY ONTO DISTRIBUTOR CAP AND WIRES-
RESULT- CAUSES EARLY DISTRIBUTOR CAP CORROSION AND BELIEVE IT OR NOT SHORTS OUT THE ATTACHED CAM POSITIONING SENSOR-
SOLUTION- REPLACE DISTRIBUTOR CAP, ROTOR AND CAM POSITIONING SENSOR- GOOD TO GO!!!!!!

csamford
07-07-2007, 05:53 PM
Sorry for the lenghty post and misspellings, but I figure the more information I can give the better someone can help me.

,
2002 Chevy
72,000 miles
4.3 L. Vortec V6
Won't start, turns over but sounds like it is misfiring, (comes to a lurching halt randomly when turing over) OBDII diagnostic code "random misfire in all cylinders

This happened over night, ran perfect one day, nogo the next.

I have replaced recently,
Cap-Rotor
Ignition Module
Coil
Crank Shaft Position
Spark Plugs & Wires

I did all this about a month ago, all to absolutely no progress

My wife towed it to a shop & had it diagnosed,(she thought it would be a quick, cheap, fix lol) (I was fishing.... go figure)

They came back with "Spider Injectors & Assembly" (and a estimate of about $2,200) She had it towed back home.

I bought a fuel pressure tester & it was slowly loosing fuel pressure after the key was turned off. (I assumed it was leaking out of the spider assembly somewhere) Also it turns over & sounds correct (no misfire) if you disconnect the spider injector sender unit on top of the intake.

I bought an entire running engine out of a totaled vehicle (everything matches up great & I checked casting numbers to make sure it would be interchangeable)

Last week I took the intakes off & swapped the spider injector sender unit & all of the spider injectors, got it all put back together and I still have the same problem. However it holds fuel pressure after the key is off, (jumps to about 60psi w/ key on, but stays at 50psi overnight w/ key off.) so I guess they were leaking but not the cause of my problem

Today I pulled all of the plugs out, replaced them, disconnected the fuel & cleaned out the cylinders from all of the previous cranking, & I was checking spark before I put the plugs back in, I noticed that the #1 cylinder would fire twice on some strokes & only once on other strokes with absolutly no pattern (that I could discern) I checked #4 & it appeared to be fireing correct (once per stroke) I then checked #6 it would fire similar to #1 (twice sometimes) I thought this was wierd so I swapped the coil & ignition w/ the ones from my other engine (again) & had the same result, I figured it was some wierd vortec stuff I proceeded with putting it back together. With no fuel connected I tried to spray carbcleaner in the intake while turing it over it still would not start, sounded like it wanted to a few times, tried it with the air cleaner (mass air flow etc..) hooked up & with out, same result.

Like I said I have an entire engine sitting in my garage, but I don't know what direction to go,

I am pulling my hair out over this one, can anybody give me some advice.

Thank You for your time,
Cody Samford
Cdn4Evr
07-18-2007, 01:11 PM

Cody, Have you ruled out the ECM? I believe it sends the signal to the moduale. Not sure what colour wire to test, a manual would tell. I have a posting for a vortec no start with a TBI. I'm leaning that way on mine.
Cheers Stewart

csamford
07-19-2007, 05:18 PM

I finally got it fixed, it turned out to be the distributor, after all of that, It may have been the cam shaft position sensor, which is attached to the distributor, All I know is that after sticking a new one in, it fired right up after sitting for almost 6 months, I still don't know how it went out overnight, however it was freezing when it went out, maybe the cold??? I was getting fire but it was "double sparking" etc... as I stated before, really weird, but I am super happy to have it fixed.

NOTE: CHECK DISTRIBUTOR IF YOR SPARK LOOKS ERRATIC

Thanks, this board is great I have been reading quite a bit since joining