# Hard starting when warm .....sometimes



## jblakeslee (Nov 30, 2005)

1992 D21 Ka24E.......does not want to start up sometimes after it has warmed up....battery and starter are fine, spins the engine easily.....replaced plugs, wires, cap, rotor....when it is running it runs pretty good.....but yesterday I drove 3 miles to the store, turned it off, came out 10 minutes later, it would not start....left it sit all afternoon, then went back, it started but was difficult.

This evening I hooked up a fuel pressure guage....read 33-35 psi static and when eng. running. Disconnected vaccum line to FPR, pressurejumped to 45 psi....reconnected line, back down to 33-35.....all normal. "Blipped" the throttle, and pressue when up just like it is supposed to.

Turned off engine, pressure guage stayed at least 30 psi for 10 or 15 minutes or so until I released pressure.

Those tests tell me pump, filter, regulator, pump check valve are all ok.....

I looked at the temp sensor, the terminals are kind of cruddy. If the temp guage inside the truck is reading ok could the sensor still be bad.....

I have not checked for any codes yet, have to take the seat out to get to the ECM.....check'd the "easy" stuff first...

Thoughts?


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## dvdswanson (Nov 6, 2005)

check for codes, it is a PITA but its worth it. other easy things to check would be the other sensor connectors. and if its dirty, clean them. just because the temp gauge is reading normal doesn't mean the ECM is getting a proper signal or vice versa.


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## SPEEDO (Jun 9, 2003)

might check the air temp sensor, the wires maybe damaged at the sensor..
(mounted on the underside of the air cleaner, on the front)


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## jblakeslee (Nov 30, 2005)

*Thanks*

Thanks for the suggestions, going to check the codes tonight, and will look at the air temp sensor......will just go one step at a time and see what I find..... 

I realized just after I posted, that the water temp sensor (that is hooked to the guage) and the the eng temp sensor are two different sensor's....the water temp sensor could be fine and the temp gauge reading ok, and the engine temp sensor telling the ECU that the engine is too hot.....


Anyone else with any thoughts feel free to chime in.......


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## cwilliamrose (Jul 11, 2010)

Check the distributor. Mine had some fine red dust inside that coated everything. It likely came from the failed bearings. It would start and run well cold but was a real problem to start when it warmed up. I think the timing sensor in the distributor was getting extra heat due to the bad bearings and becoming intermittent. What started as a hard starting problem when warm became a poor running issue when it warmed up. At that point it almost wouldn't start at all. Heat soak made it worse. My fault code was 21 -- "Ignition Signal".........Bill


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## dentedsub (Oct 23, 2007)

SPEEDO said:


> might check the air temp sensor, the wires maybe damaged at the sensor..
> (mounted on the underside of the air cleaner, on the front)


good place to start, these break real easy


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## lastcall (Aug 16, 2010)

How did it turn out?


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## jblakeslee (Nov 30, 2005)

Well....replaced the eng temp sensor....been almost a month...and so far so good....it has not been a problem since........

I appreciate all the help........thanks


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## lastcall (Aug 16, 2010)

Where is that one? I feel in need to change the same thing. Thanks for your help.


Zach


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## jblakeslee (Nov 30, 2005)

There are two "temp" sensors mounted on the passenger side in front just to the left of the valve cover.....sorry I do not have a picture....the first one has a two prong electrical connector on it......that is the eng temp sensor, and sends a signal to the ECM...if it is out of whack....it will tell the ECM the engine is too hot and it will not start.........the other is a single lead water temp sensor that sends a signal to the temp guage mounted in the dash....

Go to Autozone or Advance or any parts store website and look up the engine tem sensor and they will have a picture of it....cost about $18.00 and takes five minutes to replace.

Hope that helps


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