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Discussion Starter #1
We get it to crank but not start. We have dropped the fuel tank and replaced the fuel pump, checked the fuses, replaced the cam sensor, replaced the crankshaft sensor, battery is low but we are jumping it and get it to crank but not start. We did a code reading on it and got P0700 but nothing about that has seemed to help. Just put in new spark plugs. Also when hooked to a multimeter we get 12 volts sent to the coils but still no spark. Also checked the compression and its at about 120-125 psi. Also sprayed starter fluid into air intakes and no start, so it's not the fuel. Completely lost! :/ Does anyone have any more ideas?
 

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I'd check fuel pressure at the lines before determining that it is definitely not a fuel problem. System pressure should be 58 PSi +/- 2 PSi.

Might try checking the fuel pump relay as well. Replacing the part would be ~$20.00, PN R4823.
 

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Discussion Starter #3
Yeah we ment to grab a gauge at the store when getting a compression gauge and spark plugs but forgot. Would low fuel pressure cause a no spark?
 

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Not saying that it would cause no spark, but since you've replaced the cam and crank sensors along with verifying that each coil is getting 12V it should be getting spark since you've tested the components up to the last part, the coil on plugs. The only other way you can test for spark at each cylinder is to take the COPs with spark plugs attached out to verify that spark is there.

The only thing that you can't see is the amount of fuel pressure going to the cylinders. It should fire if even one fuel injector is bad, but since it appears that you're getting spark, the only other thing should be is a lack of pressure at the fuel rail possibly cause by the fuel pump relay.

If FP tests fine and the fuel pump relay is alright (not sure if pressure is regulated via PCM or vacuum and fuel pressure regulator on the 4.7) then start testing/replace PCM entirely.

I checked over to see if there were any TSBs for the 4.7 with fuel/spark and not any pertaining to your symptoms. There doesn't seem to be any TSBs for the PCM either.

Go hereTSBs and use "tech" and "tech" as login and password to scour through any TSBs. Might try earlier and later build years as well.
 

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The 12 volts to the coil is simply potential until the PCM grounds the coil. The coil driver is in the PCM. It does not mean the PCM is bad however. Without the proper inputs the PCM will not allow spark to occur. How are you determining no spark?
 

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needing help on a 2004 dodge dakota 4x4 4.7. i get a error code of 3 blinks on the odometer no bus. all my dash lights are on but my dodge will not crank at all. what could be causing this? Thanks
 

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The "no bus" message means your communication network has been taken down. This can occur due to defective module(s) or wiring.
 
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