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V6 vortec 4.3 has a hard time starting on humid rainy days


Brandon87

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I have noticed that about every humid rainy day my truck has a very hard time starting. When the key is turned into the on position I can hear the fuel pump turn on. The truck will crank and try to fire up. I noticed that if I gas it while trying to start it, it will start up as long as I keep reving it up and then after it runs for a minute everything seems fine and it will stay idling with no problems at all. Whats going on guys? I have some ideas but need your opinions before i go blowing money.

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Would also indicate a weak fuel pump or fuel pressure regulator, cycling the key would let the pump run and build pressure before starting. Try this next time turn the key on but don't start leave the key on for about 10 seconds then start, that would point to a weak fuel pump if the truck starts fine and idles.

I have tried turning the key on for more than 10 seconds and it does no good but If I cycle the key 4 or 5 times it seems to start up good every time. I have been thinking that maybe it is the fuel regulator because several of my truck problems seem to point to the regulator like anytime I accelerate 0 to 10 mph my truck shutters and shakes for a few seconds, I read somewhere on google about regulators causing this issue. Last month I was under my hood and noticed that the hoses that connect to the regulator were all dry rotted so I replaced them. Is there any sure way of testing a regulator?

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We have all the big auto part stores here. I Ordered the one off of ebay because it was a good deal for $15. I knw maybe I should have ordered better quality but I'll give this cheap one a try and if it acts up then ill just go get one down at auto-zone. When I get this cap should I use some kind of conductive grease like the spark plug stuff? maybe it will help with corrosion?

 

I never used anything inside a cap.

 

Dielectric grease is non-conductive. It is used on spark plug boots to help seal out moisture, and also prevent the plug wire cap from sticking to the plug. The grease helps keep the wire on simply due to vacuum. The wire cannot vibrate off because the boot will not let air into the space between the end of the plug and the actual socket of the wire.

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that is good to know, I will check the screens when I put the new cap on. Thanks for sharing that

 

Keep in mind that the screens were put there initially to keep stuff OUT of the distributor. Stuff like spiders. Never checked, but is a spider web conductive?

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What ideas do you have? You have the most information and experience with what is happening, maybe your thoughts will help gives us a better idea of what is happening.

 

Generally, hard start in wet conditions, is caused by ignition problems. Plug wires to be more precise. No idea what your engine has for ignition system, does it have distributor? If it does, check out the inside of the cap for any carbon tracking. Same for ignition rotor, take it off and look under it for any black marks.

 

Next time it is humid, rainy or in whatever condition you need for the engine to be hard starting, and wait till after dark. Open the hood, disconnecting any under hood light, and get someone to start engine. Make sure it is very dark around the engine, too dark to see is best. Look for any halo or sparking from plug wires. If they are causing the issue, you will be amazed at the light show. The more humid the better.

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What ideas do you have? You have the most information and experience with what is happening, maybe your thoughts will help gives us a better idea of what is happening.

 

Generally, hard start in wet conditions, is caused by ignition problems. Plug wires to be more precise. No idea what your engine has for ignition system, does it have distributor? If it does, check out the inside of the cap for any carbon tracking. Same for ignition rotor, take it off and look under it for any black marks.

 

Next time it is humid, rainy or in whatever condition you need for the engine to be hard starting, and wait till after dark. Open the hood, disconnecting any under hood light, and get someone to start engine. Make sure it is very dark around the engine, too dark to see is best. Look for any halo or sparking from plug wires. If they are causing the issue, you will be amazed at the light show. The more humid the better.

 

I tried this method the other night and I seen no sparking at all jumping off of the wires, I even misted the plugs wires and the distributor and ignition coil with water to try to get it to act up but it didnt phase the engine at all. I took the distributor cap off the other day and all of the points under the cap were corroded up so i scraped them clean. What are the signs that a distributor needs completely replaced?

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I would start with distributor cap and rotor. Bet they are corroded up.

 

I checked the distributor cap the other day and all of the points were corroded up so I scraped them clean and the hard starting problem still exist.

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I tried this method the other night and I seen no sparking at all jumping off of the wires, I even misted the plugs wires and the distributor and ignition coil with water to try to get it to act up but it didnt phase the engine at all. I took the distributor cap off the other day and all of the points under the cap were corroded up so i scraped them clean. What are the signs that a distributor needs completely replaced?

 

I wil take the cap back off and look closer for any black marks, distributors are new to me and I had no idea what to look for beside corroded contact points

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Well that's exactly how it was when I had that problem with my 98 5.7 and all I did was change the cap and rotor. I would have to hold the gas pedal down until it cranked and then keep holding it until the stumbling went away. What happened was moisture was able to get in the cap and on the contacts of the rotor and distributor. Prior to that I had changed the entire distributor just because it was old and in bad condition. A few months or longer was when I had that same problem that you're having and the cap and rotor I bought was AC Delco to make sure it was good quality. How old is the main distributor? I'm thinking moisture is still getting in there.

 

I have only owned this truck for like 2 months so I am unsure how old the distributor is, It still has the original spark plug wires and had very fouled up crusty spark plugs so I kinda am assumeing that who ever owned this truck before me never really did much maintnance at all, so It might be fine to just say that its the original distributor. I dont know how long a distributor can last but my truck has 164 thousand miles.

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Pumping the gas pedal does nothing on a fuel injected engine. You could have just held the throttle open a bit while trying to start it.

I think you have a truck that does not know it is cold outside. When it is colder, it requires more fuel to start the engine. If you have a scan tool, on next cold morning, check and see what temp the ECM thinks it is outside via the ambient air temp sensor.

I dont have a scan tool. I will go down to my auto zone and see if maybe they have a scanner in their loan a tool program. I really need t figure this out before the snow starts to come in next month here in indiana.

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I would not look at replacing the distributor, not likely to fail so badly that replacement is necessary. Take the rotor off the shaft after the cap is off, and look at the underside of the rotor. At the very centre, look for any discolouring or rainbow colours. Chances are very good that the cap and rotor have never been changed, I would swap them out, they are a standard maintenance item.

 

To get your own version of Aurora Borealis under the hood, the humidity needs to be just right, and wires need to be leaking. Having worked at a Chrysler dealership for a length of time, saw more than my share of hard start when humid (dodge had a very bad reputation for slant six being hard start wet, even spitting under the engine would make it damp enough to make it hard to start) and would impress the hell out of customers when we would find a car in for repair that would perform for us.

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I just ordered a new cap and rotor set on ebay, I heard bad things about after market stuff but I just figure its worth a shot especially since it has a 1 year warranty. After I put this cap on, is there anything I can do to prevent future corrosion?

 

EBay warranty is not really of any advantage. Don't you have any of the big name auto parts stores around? Most will carry AC Delco ignition parts, or Echlin, Standard, maybe BlueStreak. Standard is likely the largest aftermarket manufacturer around, and makes most of the in-house branded parts.

 

What you want to get is the heaviest weighing cap and rotor. Some of the crap out there now is unreal how long they don't last.

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Keep in mind that the screens were put there initially to keep stuff OUT of the distributor. Stuff like spiders. Never checked, but is a spider web conductive?

 

Yep, spider man had conductive webs so I'm pretty sure every domestic spider is the same. lol

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I noticed that this morning it was about 38 degrees and my truck had a hard time starting like usual but this time I cycled the key on and off several times and it started right up with no problems at all. I didn't even have to give it gas. Idk whats going on but someone told me that maybe it was the throttle position sensor. anyone have any imput on that?

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