My 5.2L engine starts but won't run.

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Kollie2263

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5.2L
I bought this 1999 Dodge 1500 from a friend 5 years ago because it cranks and begins to run, then quickly dies. It will start but will not continue to run. I have replaced the fuel pump, fuel filter, fuel pressure regulator, the throttle body and the fuel injectors. I am still having the same problem that I had when I bought it. Help please with any help you can give. Thanks so much.
 

pacofortacos

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Well it is most likely losing fuel pressure or spark or injectors aren't being told to fire. - determine which and let's go from there.



By chance has the PCM been changed out? If so did someone get one with theft on it by mistake? I think that was possible in 99 but not 100% sure.
 
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Kollie2263

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I just ordered a new PCM from "Blue Streak" on ebay and gave the VIN number to match it to my truck. The pressure is good and there is plenty at the fuel rail. Spark is also good. I talked with a local mechanic that says he has seen this before and had a customer, just yesterday buy a new PCM, which solved their problem. I have to wait for delivery, then I will update my results. Thank you for your response.
 

pacofortacos

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It could be a bad driver in the PCM on that cylinder. I am not one to condemn a PCM quickly, however your truck does have a few years on it and it is possible.
 
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Kollie2263

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I installed the new ECM, a new Crank sensor, a new Pick up sensor, a new Rotor cap and Rotor, and a new Ignition Coil. I did the key on for 5 seconds, (because of the new ECM), per the instructions, to help the ECM, identify my trucks electrical components and co figuration (without starting the engine) at least 5 times prior to attempting a 1st start. It did fire up and ran ,but irradically, with a lot of shuttering. But as I attempted to apply the gas pedal it increased in RPM, then died. That was its longest and only run. All spark plug wires are in the correct order as well. What the heck is next? It's almost a new truck, electrically and fuel system! Help please.
 

pacofortacos

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Has the distributor ever been moved?
Have you changed the MAP or TPS sensors?
 
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Kollie2263

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The distributer has not been moved as far as I know. It wasn't moved during the "Pickup" removal or installation. And it wasn't moved for the "Distributer Cap" and "Rotor" exchange. I have not replaced the MAP or TPS sensors. Do you think these can be related to my problem? Can you briefly explain about the TPS, since it remains in "Park" at start up. Thank you for your feedback!
 
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Kollie2263

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I have purchased a Throttle Position Sensor and have yet to install it. My mistake on assuming that TPS had something to do with "Transmission", my mistake. It's been a long day and my mind is tired. Sorry.
Have you seen instances of these two causing this problem before?
 

pacofortacos

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I doubt it is the TPS, MAP maybe or hose to the MAP.

It would be easy to fix looking at it with a scanner that does live sensors, but hard over a keyboard.

I was just wondering if the distributor was turned and it was out of sync.
 

Oliver Closehauf

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Ok back up for a second, will it run on starting fluid? Even a motor with no fuel pump will run if you can get fuel to the cylinders and the spark is in time. I've used the PVC line to feed gas into the intake long enough to show the engine ran before buying it.

See if you can get it and keep it running on starter fluid for 30 seconds.
 
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Kollie2263

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I replaced all of the sensors in the throttle body and it still behaves the exact same way! I tried opening the throttle manually and spraying starter fluid into the throttle body intake. It starts and runs until the starter fluid is burned up. So no ignition issues are present. The fuel rail has pressurized fuel in the rail because I can remove the cap on the pressure relief Schrader valve and there is a strong burst of spray there as well! Is their a particular relay that may be malfunctioning and causing the new pump to operate intermittently? I'm a decent mechanic and also a Licensed Aircraft mechanic but this is a true "head scratcher" at this stage and with so many new parts replaced! Any other suggestions? Check previous thread messages for the list of parts replaced. Thanks again for ANY other helpful ideas.
 
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pacofortacos

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There is a fuel pump relay and/or ASD relay. But instead of guessing, can you put a gauge on the schrader valve and actually read the fuel pressure?
 
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Kollie2263

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I don't have one here. I might be able to rent one from AutoZone of O'Reilly's. I'll have to look into it. It is a brand new "Bosch" fuel pump and pressure regulator. I hear it activate with every key turn. Could a "crimp" in the fuel line to the injector rail cause the same issue? Just thinking outloud. Lol
 

pacofortacos

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Sure if it is restricting fuel and that should show up with a pressure gauge.
I have used AC gauges before to test lol. Old junk ones that I didn't care about.
 

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