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Discussion Starter · #1 ·
Yesterday, I went out to the garage to start up my 96 854t5 after two days of heavy rain, car cranks like made but won't start. Got real close a couple of times, coughed and gave up. Tried all kinds of options with the gas pedal, foot off, 1/4 throttle and then crank, 1/2 throttle and crank, floored and crank. Nuttin but cranks like crazy.<p>The car is in very good shape, all current maintenance is done. Just for WTF, I put a 50 amp starter/charger on the car and try to start, no difference.<p>I then pulled the shift lever out of park and thru the gears a couple of times and tried to start, almost caught but no.<p>I then tried again, but with my foot on the brake pedal, the motor caught and ran real ragged. I tried to tap the gas pedal and the motor stumbled and almost stalled. After idling ragged for a couple of minutes, the idle rpm surged maybe 300 rpm for 15 seconds, dropped back to normal and now the car ran fine. Stopped and started again several times yesterday with no problems at all.<p>This morning, after another night of rain, with my foot off the gas pedal the car just cranked for 15 seconds. I put my foot on the brake and tried again. It caught right away and then ran ragged for about 20 seconds. Then ran fine for the next hour.<p>I am thinking that this is some funky sensor going bad. Any ideas which one or what else might be the cause? I saw this once last fall when the weather conditions were similar.<p>Thanx much.<br>
 

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Re: Car just cranks, only when its real humid (Stormin Norman)

Humidity and Corrosion on electrical connectors could be your problem. <p>The next occurence of this problem, check for ignition spark. Pull off one of the spark plug wires and hold it an eighth of an inch from the engine block (I keep a known working spark plug in my tool box. I connect spark plug from tool box to spark plug wire and place spark plug on engine block for ground. I don't like holding spark plug wires while they are sparking). Have a friend crank the engine. <p>If you have weak spark, then I would clean electrical connectors around the coil. You could have a weak coil. You could have a weak ignitor module. <p>I am a new Volvo owner. I may be wrong about how coil and ignitor module works with Volvo. <p>
 

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Your fuel pump could also be toast. Use a T25 Torx to take off the screw on the plastic cover that goes over the throttle body and take off the schrader valve cover (little blue valve cap) and push the pin in and see if fuel comes out. No fuel= Toast fuel pump. Use safty glasses cause if there is pressure in that line it could get into your eyes.<p>The new coils Volvo installs on their cars are perty dependable.<p>If that isnt the issue, Do what robert said. You also may wanna change your plugs wires, distributor cap and rotor too. ( tune up )
 

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Re: Car just cranks, only when its real humid (Stormin Norman)

I just got a call from the IM, the temp sensor is bad. When cold, it thought it was 250 degrees (!) and set the fuel mixture so lean that it won't start. He also found that the warmer the motor got, the lower the temp reading from the sensor. This means that at temp the motor runs rich.<p>Mebbe my gas mileage gets better now.<p>Thanx to those with thoughts on this problem.
 

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Re: Car just cranks, only when its real humid (Stormin Norman)

Very Interesting!! By any chance did your IM check ECU for Diag Trouble Codes? I would've thought that ECU would've triggered "Check Engine" light for bad readings from Engine Coolant Temp Sensor.
 

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Discussion Starter · #6 ·
Re: Car just cranks, only when its real humid (robert213)

Now why would it be that easy? No check engine lite or any kind of a clue. <p>We have been chasing the source of my poor mileage for over a year, with just one morning commute, I am already seeing an increase in MPG. I wonder how much it will improve.
 

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Re: Car just cranks, only when its real humid (Stormin Norman)

How many engine coolant temperature sensors does our engine have? <p>I am aware of the one mounted under the thermostat. This one sends the signal to the gauge in the dash. <p>I think that the gas mileage of my girl friend's 850 turbo should be higher. Since you didn't notice any problems with your Temp Gauge, this leads me to believe that there is another engine coolant temp sensor somewhere. <p>Would you know the location of the second sensor that your independent mechanic replaced? <p>
 

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Re: Car just cranks, only when its real humid (robert213)

There is only one sensor, near the thermostat. <p>But: Keep in mind that we found this due to problems getting the motor started. Before you do this looking for mileage, you need to attend to more likely candidates:<p>1. Usual tuneup stuff, plugs, rotor, wires, etc.<br>2. Vaccum leaks, lots of people rip all the vaccum hoses and replace with silicone. I did and things did improve.<br>3. O2 sensors.<p>All of the above stuff can be in need of replacement without throwing a CEL.<p>Good luck.
 

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Re: Car just cranks, only when its real humid (Stormin Norman)

Thanks for the follow-up...<p>I replaced the engine coolant temp when I replaced the thermostat in her car last Thanksgiving. <p>I am planning on replacing the items that you listed this summer. <p>
 
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