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No Start & loss of power


Ric_Mag

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I checked the injectors anyways and went ahead and cleaned them out. They all held pressure and sprayed 3 strong jets.

When I turn the key on I can hear the pump turn on for the 2 seconds and when I crank it the car just cranks. It doesn't sound like its actually trying to fire until I've gone through the motions about 4 times. At that point I get some firing and then it dies out. When it finally does start it'll idle for a few seconds then die out. It took about 10 minutes to get the truck started this morning.

Lately when the truck is running it will bog down at low rpms and when I give it a lot of gas I can hear some back firing.
 


RonD

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It reads like fuel is OK

So just Compression and spark are left

Liquid gasoline can't be ignited by a spark, yes the movie guys get that wrong, lol
Only gasoline Vapor will ignite by a spark, fuel injectors spray liquid gasoline.

Compression is needed to heat the gasoline so it is vaporized enough to be ignited by a spark plug.
When engine is cold you need at least 120psi compression to get enough gasoline vapor to start the engine.
Once engine starts then hot cylinders will vaporize the gasoline as it enters, but on cold engines you need that compression or you will get a No start
Continued cranking will add a little heat(friction) and more oil to the rings to increase compression slightly which can be enough for a cold start.

Compression isn't an intermittent thing, like spark or fuel can be, you either have it or you don't.
4.0l SOHC engine should have 170psi compression
It also has 3 timing chains which could cause lower compression should they slip a bit
You should test 1 cylinder on EACH bank(side) of the engine, just to take compression off the table or find out now that it is the problem so you don't waste time and money on anything else.

Spark
Check for 12volts at Coil Pack with key on, the red wire, it should match Battery Voltage, 12.3 to 12.8 volts
Also check voltage on that red wire when someone is cranking the engine
Shouldn't drop below 10volts.

I assume your Battery Light works, comes on with the key, and then goes off after engine starts up, meaning alternator is working and electrical system is now running at 13.5 to 14.9volts
If alternator/charging system is having a problem then lower voltage will cause spark to become too weak at low RPM and engine will die
 

Ric_Mag

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I did a compression test already and had steady 168-170 on each cylinder. I'm going to check the voltage on the distributor like you said in the morning and go from there.
 

Ric_Mag

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Tested the coil pack and I was getting 12.2 volts with the key "on", and it quickly dipped to 9.44 then rose to 10.5 while cranking. During this time I checked the Schrader and found absolutely no fuel coming out when I depressed the core.
 

RonD

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Your battery looks like it is 5-6 years old(12.2volts), time for a new one, but not the issue.
New battery is 12.8volts, 12.5v 3-4 years old, when it gets down to 12.2v it can only hold 50% charge, on a warm day :)

No pressure in the fuel rail is the issue
Cycle key on and off 3 or 4 times to see if pressure builds up
 

Ric_Mag

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Cycled the key 4 times and didn't see any fuel come out when I depressed the Schrader valve core. Cranked the truck 4 times and on the fourth it started and stayed running. When the truck started it ran at ~500rpms for about 10 seconds then went up to 1200 for a few and back down to normal idle.
 

Ric_Mag

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Drove the truck around a bit today and checked the Schrader as soon as I shut off the truck and no fuel was present. I was looking for a loaner fuel pressure tester to see when I lost the pressure and to check pressure as the truck was on. Couldn't find one but found a store I could get one from tomorrow and will post numbers then.
 

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