Hello All,

Like to introduce myself, my name is Shayn. [sm=smiley31.gif] I live in Kansas and I have a 94 Dakota SLT 4x4. It has a 5.2L and is basically stock. This was an EBay purchase and I am semi happy with my purchase. I will try to help where I can but this forum is fairly new to me so I will probably be more needy than helpful for the time being. On to the problem!

My Dakota starts just fine every time when it is cold. When it is hot I have intermittent problems which nobody has had an answer for. [:@] BTW I have done the relay splice. After the truck has been driven till the engine gets warm and then shut off (by me) it will frequently NOT start. It does crank and my fuel pump spins up fine. I have plenty of battery and I have tried to swap my relays around to no avail. The strange thing about this is when it happens I hear a very faint high pitched whine coming from my computer. This noise will click off, very faint like a relay contact, after time and then the truck will fire right up. First thought was the auto shutdown relay but that does not seem to help. Second thought was the computer so I pulled it. Heat sinks were filled with mud so I thought the computer was just overheating. Cleaned the heat sinks and the computer is filled with gel so it is difficult to diagnose any electronic issues with the computer. This has seemed to shorten the “won’t start” time but I still have it. If I wait about 5-15min for the truck to cool then it starts no problem. The engine compartment does seem excessively hot after it has been run but I show no problems via my gauges. So what is the problem? My thinking points to an abused ECU but I would rather not buy one to find out if that is my fix. Does anyone know a way to bypass any thermal shutdown it may have? I have read a few posts about bypassing some parts of the ECU but I have no clue what I should do in my case. I have yet to find anyone with this same problem so any info would be greatly appreciated. Sorry for the long wind! Take care and thank you.

 

Do this: next time its having the "doesn't want to start" take a sledge hammer to the ECU. 60 percent of the time it works every time .

Just kidding. No, but really, next time it does this, check to make sure that there is spark getting to the plugs.
Also, I know you said you hear the fuel pump spin up, but make sure there is fuel at the fuel rail.
I know a bad crankshaft position sensor can cause starting problem, but, it doesn't make sense to me that that would be bad because its only hot-starts that are effected.
As far as thermal shutdown, I am not aware of any such feature.
Post the results back.

 

Hard to start when its warm. Been there.

Try looking at your air filter, is it dirty. If it is change it. Another thing to check into would be your engine ground wires. One more thing I would look at is the pick up in the distributor. I have seen one of these go bad and create an issue something like this before on my daytona shelby. I have seen this part itself go bad and never set a code. The pickup doesnt cost too terribly much, I recently bought one for 23 bucks.

Hope this helps.

 

There is no fuel at the rail it seems. Any ideas? BTW is there an easy way to check fuel at the rail? My way seems to be the NOT good way. Thanks

 

Attached are the instructions to test a) fuel pressure, and b) [on the last page] pump capacity.
Pretty much, you can just use the pump capacity test, because this will verify that fuel is available at the rail.

Since you did not say that it didn't have a spark, I will assume you had a spark. If the fuel pump is not putting out fuel, swap the ASD relay and the fuel pump relay. If, after that point, the fuel pump works, and you don't get spark, the relay was bad.

Anyways, let us know how the fuel test goes.

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I have done the relay swap and this did nothing to fix the problem. I suppose it is possible to have all bad relays but I am betting that is not it. So yes spark, no fuel at rail but the pump does spin up no matter the temp. So when the engine gets warm something is shutting off the fuel supply randomly. I need to run through this check again but thus far that is my story.

 

Well, I can tell you the ASD relay is good (because, if it wasn't, you wouldn't be getting a spark!).
Now, if my thinking is correct, if you disconnect the fuel line up front, and turn the ignition to ON (not start), the fuel pump will keep running until a proper line-pressure is obtained (which, since the line is disconnected, will never happen). Bah... I'm gonna go poke around my truck tommorow so I get a slightly better idea of the electrical operation of this.

 

The fuel pump should only run for 2 to 3 seconds when the key is turned to "on" and then shut down if it sees no pulses from the cam or crank sensors. This is a safety feature so that if you get into an accident the fuel pump doesnt keep running and start a big fire. Try a couple of shots of starting fluid into the throttle body. When looking for spark on these newer engines you can get led astray if you see it spark once or twice during the first couple of engine revolutions and then the ASD relay shuts down and no more spark or fuel. The cam, crank sensors can become heat sensitive and also the coil. If you want to experiment, get a can of component cooler at Radio Shack/electronics store, when the engine dies, spray one of the sensors and see if it starts right up. You can test both sensors and the coil this way.
Have you checked the computer for error codes?
You may also have a fuel supply problem that is caused by the pump bearings binding up when they get hot. The problem you are having is sometimes a signal that the fuel pump is on it's way out.

 

Ah... I suspected something like that, because I don't recall ever having the key in the "ON" position (w/o the engine starting) and hearing the fuel pump re-activated (and I know it looses its pressure). Thanks for enlightening me Chump.

 

I will try to check this out this weekend and I will report back. Thank you gents