1992 Ford Tempo doesn't work in the rain. (Yes I am serious)

This post was posted in two parts on a ford enthusiast forum so bear with me.

I have a 1992 Ford Tempo 4 dr GL. It has about 146,000 kms on it.

Anyways…recently I’ve been having problems with keeping the vehicle running during the rain. It’s quite annoying. I will describe to the best of my ability what exactly happens here.

Firstly let me say that the problem comes and goes but has an absolute correlation with the weather. When it’s sunny or even overcast the car runs fine, however when it is raining or just finished raining the car has issues.

What happens, is that when it is raining or has just finished raining, the car will start but will not idle properly. It runs really rough. My car idles at about 764 rpm but in the rain it varies wildly. I will hold the gas pedal steady at about 1000 rpm and even with my foot steady the revs still oscillate between about 800-1200 rpm. While this is going on the car shakes madly and will often stall, requiring restart.

Once on the road, the engine propels in fits and starts and does not accelerate evenly even with the pedal being held steady almost as if not enough fuel is getting to the engine. However, I’m sure this actually is not the case because the car works fine when the weather is sunny.

My best guess is that this is some type of wiring problem, because if it was a fuel line problem it doesn’t seem to make sense that it only occurs in the rain.

That was the first part.

Here’s what I added today:

So…I did some work on the car today…I really don’t know what the problem is but I will eliminate possibilities one by one until I either find the problem or can afford to have a mechanic figure it out for me.

I disassembled the windshield water drainage system, i.e. that black plastic bit where the wiper stocks are. I unscrewed the black plastic bits but couldn’t figure out how to get the windshield wiper arms (the arms not the wipers) (I’m not that dumb…lol) off. So instead I went under the hood and removed the black foam rubber bit that covers all that drainage stuff. The drain holes for the windshield water seemed okay on the upper part.

On the passenger side of the car, there appeared to be a drain with what looked like to me, a bizarre design.

Instead of lets say sloping the metal slightly so that the water ran through the drain, the drain (if it was a drain) had the metal around it raised by about two inches, and it had two covers to prevent larger crap from falling in, and at the bottom the last “filter” was a sponge.

I was tempted to pour water onto the sponge to see how well it drained but then I thought I don’t really know with 100% accuracy whether this is actually a drain or not, and if it’s not, pouring water down there might either create a new problem or make the existing one worse.

Does anyone know if this is indeed a drain or not. The location of said “drain” is on the passenger side, underneath a black foam thingy at the top of the hood (ie the end of the hood furthest from the bumper and closest to the passenger seat)

I should have taken photos, I didn’t think about that though at the time.

Anyways, there seemed to be no obvious drainage problems from the windshield which I thought might be getting into some wiring.

Assuming this is a drain I can test the drain out, though I will just remove the foam bit and leave the black plastic exterior pieces in place (it’s not necessary to remove them to access this piece)

So…yeah…no obvious windshield/roof water running onto wires around the top of the hood as far as I can tell.

Also for the record since this caused me no shortage of grief today, how does one remove the wiper arms?? It appeared impossible!!


-Big Bad Bill

This problem is usually caused by problems in the secondary ignition system; plug wires, distributor cap, etc.

Replace the spark plugs and wires if it has not been done recently and also check inside of the distributor cap for moisture.
Any engine warmth at all can attract moisture inside the dist. cap. It’s the same thing like you might see on a sweating house window.

Try spraying the dist. cap down with WD-40. Some Fords of this era were equipped with a rubber boot that encapsulated the distributor cap. This helped to prevent moisture entering the cap.

Thanks, for the help, I already have a brand new set of plugs hogging up my driver side door panel cubby so I can replace those for free!! I might do that first, and check the distributor cap, the plug wires will wait for now.

Once again, this is classic symptoms of bad secondary ignition components. Of all the parts involved, the spark plugs are the least likely to cause these problems. I strongly encourage you to not skimp on this and replace the cap, rotor, and wires too. Dielectric grease is also a wonderful thing for this problem too. You can use it to seal your plug boots and also to create a nice seal along the bottom of the distributor cap to prevent that moisture from getting in there and causing problems. If you are really and truly cheap, you can also narrow down the specific part or parts by spraying around with a spray bottle of water to find out what part or parts malfunction when wet. When you do this, don’t touch the wires, cap, or anything you get wet unless you want to know what 40,000 volts feels like.

… the plug wires will wait for now.

The are the most likley cause. They are also cheap. Don’t buy the fancy designer wires buy OEM type.

I agree with the others about checking the plugwires. Try checking the wires by looking at them at night with the engine running. See if you can spot any weak spots in the wires that are arcing to ground. Try spraying the wires with a spray bottle filled with water and see if that changes things.

It’s not that I am really and truly cheap more so that I am really and truly unemployed…

Hi thanks for the reply’s:

I took off my distributor cap and checked for moisture etc, there was none inside it. Because I am a total idiot (sigh), I forgot to write down the firing order (did I mention I was an idiot?) and couldn’t get the car to start again. After several unsuccessful guesses, I went to google, and Google helped me out. I learned my car fires 1-3-4-2. Anyways I managed to put it back together, and get the car working again.

I then decided that in the long run $30 wasn’t that much…and replaced my spark plug wires. I didn’t see any cracks in the rubber while replacing them but I didn’t look really closely. The new wires make a big difference when starting the car and it idles WAY smoother (& at slightly higher rpms) too!!! I think that whether this fixes my problems or not, the spark plug wires were a good investment.

Now my plan is to wait for the rain, and see if I actually solved my problem or not.
I will let you know when the rain comes!!

See if wetting the car with a hose invites the problem to show up. You can selectivily moisten areas one at a time to isolate the problem area. Try the spray bottle method described in a earlier post with underhood items. Your car doesn’t know if the moisture is from a cloud or a spray bottle.

Or I could get a car wash…I kinda need one…I think I’ll do that.

Since you saw such a dramatic difference in performance with the new wires I suspect that the trouble you were having will be gone now.

While it is something that is often overlooked or taken for granted, you should always check the spark plug gap before installing the new plugs.

The plug gap does have an affect on plug wires and an excessively wide gap may cause arcing from the plug wire that would normaly not be present otherwise.
Aged spark plugs in which the gaps have widened will do the same thing.

This is also rough on ignition coils and modules.

Okay, so I replaced my spark plug wires…as I said a while ago. Today it rained, I nervously stepped outside to start the car and see what would happen on a test run.

The car worked great over the 10 mile Or thereabouts) test run. The engine started easily, the idles were smooth and the car kept running and I could change gears (it’s an auto so I mean from R to D) without having the car die.

I guess the issue was the spark plug wires, since that was the only part I ended up replacing.

Thanks a lot Cartalk community!!!