I've got a Chevrolet van that doesn't run when it's wet out. Earlier mechanic had done some diagnosis and looking around in the wiring harness that goes from the engine to the computer.
Makes me wonder if there is water getting in to the wiring harness, and that's what makes it not run when it's wet.
What's a good way to seal this, to keep water out? Duck tape? Scotch 33 electrical?
See if there's any condensation inside the distributor cap (if you even have one)
Yes, has one. Might be dry weather tomorrow. I'll see if it starts. If it starts, I'll spray water on things till I find what makes it quit.
- . Christopher A. Young learn more about Jesus .
I don't know that I would be looking at the harness itself as much as I would be looking at connectors. Even if water was getting into the harness, each individual wire is (should be) insulated.
However, if there *is* exposed wire(s) in the harness, I'd be more concerned with fixing the root cause than just keeping the water out. If the insulation is breaking down due to heat or age, sealing the harness may help slow that down, but having exposed wires inside the harness is never a good thing.
I don't know if this will happen to your van, but this vehicle was at the dealer, waiting in line to be brought into the shop to have the alternator changed when the alternator caught on fire. I guess he waited just a few hours (minutes?) too long.
Over $7000 to repair the damage. The engine will have to be pulled in order to R&R some of the stuff that was impacted by the fire.
Also check for any corrosion/crud on the coil post or inside the wires.That's why they give you a bit of dielectric goop with new wires Spent months tracking down a miss in the S-10. finally discovered the prob was a loose coil wire connector. (crimped it a bit and no miss)
What doesn't run about it? Does it crank? Normal speed of cranking?
Does it ignite at all?
If it turns over and there is no ignition, the usual source is wet spark plug wires; wet distributor cap, inside or out; or wet ignition coil.
Shops don't want to spend forever on the repair, or worse yet, give it back to the customer and have it not work again, so they just replace all three, and the rotor too.
But if you're doing it yourself, and you don't absolutely have to start the van on a given wet day, you can replace one thing at a time. Buy the parts at a consumer parts store, where you can (check on this) return an unused distributor cap or coil. Pro stores don't like returns on electrical parts, and Pep Boys etc. might not allow it either.
It's also possible that 2 or 3 things contribute to the problem. I found it hard to believe the coil could be wet inside, until after replacing the wires, I replaced a coil and everything was good again, even in wet weather.
Yeah, on a dry day I'd take the cap off and let it dry out in there, but the problem is more likely the spark plug wires if they are 6 years old or more. I guess the rubber covering is porous. Replace them one wire at a time, both ends, so you don't mix up which one goes where.
start by performing in the old days was a tune up.
new sparkplugs, new wires, new cap and rotor. do a oil change. look over everything, probably good to replace the coil.
now while it may not fix it you just did some necessary maintence and elminated a ton of possible causes.
probably good to check the computer for codes.
i had a van that started running rough and hard to start.
finally traced to a failing fuel pump. it got so bad it barely ran. fuel pressure was way too low
Probably condensation under the distributor cap. VERY likely if the vehicle isn't driven daily. The moisture burns off when you drive them daily. Pop the cap off, wipe it out with a towel with some silicone on it. Then spray the wires down with silicone. If you think it's in the harness you can spray the back of the plugs and wiring with clear enamel paint. It will seal the wiring.
Friday dinner time. Just got home. Van started right up. I crawled under and taped the wiring harness under the drivers seat. Now, it won't start. Aparently, I shifted one of the bypass wires, and opened a connection. Tomorrow, I'll go cut off some tape, try to figure out where the new wires go. Reinforce the connections for the new wire. See if it starts. Put more tape on to replace the tape I cut off. Sigh.
Well, at least I have a rough idea where is the problem.
The retired mechanic across the street isn't feeling well tonight. But maybe tomorrow he can come over and help me search out the bad connection. Reinforce the bad spot, and then wrap it again. No plan survives the first challenge, of course. I'm hoping for good. The rest of the van works. One silly connection.
First time it did this, was in the shop for nine days.
- . Christopher A. Young learn more about Jesus .
Thanks, that real world wisdom is priceless.
- . Christopher A. Young learn more about Jesus .
First things first - good spark plug wires. You have the potential for 60,000 volts there - that voltage will leak theough anything that is not perfectly waterproof. New wires with silicone dialectric past in the coil boots and the plug boots (and distributor boots if it still has a distributer)
12 volt wires don't leak appreciably through insulation that is wet or dry. If they are going to short wet, they will short dry too. Low voltage (sensor) connections are working on 0-5 volts - so again, moisture won't short them. If anything, take the connectors apart and clean them. A bit of dialectric grease hear usually won't do any harm either and will keep moisture from getting in and corroding connections. Moisture on low voltage stuff is more likely to cause corrosion and open circuits than shorts. The new plugs we've been telling you to put in for the last 2 years will help too as the wide gap and rounded electrodes of worn plugs requires a lot higher voltage to jump the gap. A good sharp well gapped plug will hold your secondary voltage down around 45000 volts - a lot easier to keep in your wires. Also make sure the cap, if a distributor model, and / or the coil towers are prisinely clean..Thes steps will make even a 6 volt chrysler flathead start with a water hose pointed at it.
CY: Cranks but doesn't start.
CY: Intemittent. No start this AM. Yes start this afternoon. No start after I finished taping up some wiring harness.
CY: I suspect wet wiring harness under drivers seat.
CY: I think the problem is localized. What you write is correct, and thank you.
CY: I've had coils not work when wet.
Mine traces out to the wiring harness under the drivers seat. Got to pull that apart, tomorrow.
- . Christopher A. Young learn more about Jesus .
On a SBC of that vintage, make sure you have a GOOD sistributor cap and rotor - along with the good wires - and be certain your coil is clean and has no cracks. The good caps are the glossy black or light beige ones, not the crappy pourous phenolic brown ones. or black ones with an open rough surface on the inside.
You don't want to use any sealers as all they do is hols water in
So when it fails to start you have no fuel pressure - most likely. When you go to start the vehicle, take off the gas cap. Turn on the key and listen at the filler. You should hear the pump run for about 3 seconds. Then when cranking it should run again.. If you can get your hands on an EFI fuel pressure guage stick it on the service schrader valve on the injector log and watch the pressure.
I didn't try it on ether. But, my gut sense is no fire from the ignition system. Either way, I'm going to hope for dry weather tomorrow (light rain, now) and cut some tape off. Try to find the bad splice connection.
Keep hoping that if I actually find the problem, the van will be OK for a while. I think the splice for the recent wire is the problem.
- . Christopher A. Young learn more about Jesus .
Jesus will fix the problem if you ask him !!! But be prepared to pay a huge repair bill. He aint cheap.
Somewhere around the fuel pump?
About six or eight feet forward of the fuel pump.
Wiring harness under the drivers seat. When the last guy found a bad wire and ran a bypass, he didn't do a good job of the connection and the necessary water proofing.
I violated one of the big rules: When one vehicle (Blazer fuel pump) is needing parts, don't work on the other one. Even some thing simple as tape wrapping wires. Now instead of a van that runs when it's dry, it doesn't run at all. I'm worse off.
- . Christopher A. Young learn more about Jesus .
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