Why won't my ruck start when it rains?

Asked by Samurai_334 Apr 03, 2011 at 11:02 PM about the 1997 Dodge RAM 1500

Question type: Maintenance & Repair

When we moved from Denver, Colorado to Lancaster, SC last June, our 1500 wouldn't start  when it rained or in the mornings when there was heavy dew. In the afternoons, after it warmed up and dried out, it started fine. If I put it in the barn and covered the hood with a tarp and a blanket, it started  more reliably. I don't have the problem on dry days, and never had it in Colorado. Temperature is not a factor. Mechanics don't seem to have a clue. They want to replace plugs and wires and so forth. But it runs smooth. I don't think bad plugs are the problem. I thought it may have something to do with the thinner air in Denver, but that doesn't seem to raise any eyebrows with the mechanics.

17 Answers

33,345

try replacing your coolant temp sensor, its the master sensor when the engine is cold, also you may have to replace the MAF/baro sensors, worst comes to worst take it to a dealer and have them flash the computer it may have lost its ability to relearn new environments

6 people found this helpful.
1,485

Could be moisture in your distributor.

16 people found this helpful.
215

if your coil has a crack or an opening it may let moisture in also your map sensor may act up due to a drop in pressure this could also cause surging

12 people found this helpful.
180

I've had this same problem for3 years.Finally found it . Replaced the ignition coil and it's started ever since, even in wet weather outside.not the coil wire but the ignition coil itself. Cost about 45 dollars and only took about 20 or 30 mins, ThankGodIt'sFixed!

18 people found this helpful.
200

We have this same problem....changed the coil and the distributor cap. Did not fix. Changed the intake temp sensor. Did not fix. Why would coolant sensor fix this? Could it be the wires?? Help.

15 people found this helpful.
80

yeah , im grinding my teeth, i changed distributor cap ,distributor rotor ,new wires ,plugs were done last year and she still gives me a hard time ....

8 people found this helpful.
70

Husband's truck did the same thing. Mechanic changed the wires, spark plugs, distributor cap and rotor, good 1week. It ended up he changed the ignition coil and that fixed it! Ten minutes and $27, thanks to a post here!

7 people found this helpful.
130

2003 Dodge Ram van 5.2l. I purchased one with the no start when wet problem no start . Checked the obvious and then as I was tracing wires I found small puddle of water in the crank sensor on top of motor. It mounts on passenger side. I dyed it off with dryer and it started. I the man played with the wire that goes into sensor as it was running and touched motor and felt a slight volt charge to finger . I moved the wire around were they go threw the gel into sensor and van stalled. I removed sensor and cut open and found rusty wire and moisture. Installed new sensor and filled the little indent with rtv sealant so water does not sit there to gravity bleed into sensor. After rtv dried I wet it with hose including entire motor and no spuddering and starts up every time.

13 people found this helpful.
20

2015 chrysler van battery just dies overnight. have a lemon lawyer for state of Maryland now

2 people found this helpful.
40

Mine ended up being moisture inside the metal sleeves that surround the plug wires. I pulled and checked all plugs and sealed the very bottom of the plug with dielectric grease, also greased the inside of the boots well. A way to check if this is the culprit is to wait till the truck dries and will start, then shut it off and take a garden hose and wet both banks of cylinders. If it wont start this is the issue.

4 people found this helpful.
200

Happening again bad - left me to switch to my ford LOL ; will try the crank sensor

1 people found this helpful.
30

Mine was the ECM located on passenger fire wall gets damp when weather changes. Put a blow dryer on it and it started!

3 people found this helpful.
80

After years of this same problem I finally glued down the L shaped seal on the cowl above the ecm that came loose years ago but I saved it, Has been starting ever since,raining now and just started it again,started perfect. Hope this is the fix,before it wouldn't start in any rain or wet snow, even misting.Unbelievable

4 people found this helpful.
130

I have the same issue going on with a 98 v8 1500, I replaced the distributor cap and rotor spark plugs and asd relay it's started up after I reset the computer, but today it's raining went out to go start the truck it started really rough then stalled out and will not start, please someone help me with this. Im ripping my hair out

13 people found this helpful.
80

I was wrong still won't start after 2 days of rain! Time for a new "Chevy" !

4 people found this helpful.
10

no start after rain/ high humidity - checked ecm connections , the plug in closest to the passenger side was visibly wet inside and out, dried off with blow dryer - started fine

1 people found this helpful.
10

Same problem here with my '01 RAM 5.2L Sport, cranks but wont turn over when rainy or humid. Started when I had Cam sensor replaced...TWICE, within a month. That was 3 mos ago. Fed up, damm truk! Now I just wait for sunny days : /

1 people found this helpful.

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