Truck is a 2002 Dakota crew cab with 4.7 L v8. I’ve been having long crank issues, always starts but cranks for several seconds before starting at a somewhat low idle then coming to life and running fine. If running and I shut down it will restarts great if only sitting for a few min, but if sitting for a while 20 min or so, the long crank returns. I did a pressure test at rails and initially got in the 30s which declined after shutting it off. Decided likely related to pump/regulator/filter assembly so dropped the tank and replaced that. However, still having long crank. Pressure is better around 40 psi, but still under spec of 49. Does hold pressure over 30 when shut off for at least several min. Oh, also had a shop which I no longer trust work on it who replaced battery and crank position sensor prior to me deciding to work on it myself and going down the whole fuel pump route. Not currently throwing any error codes. Hoping someone has an idea what to check next.

 

These pumps are extremely notorious for having the backflow valve fail. Also most of the aftermarket replacements are quite bad. Check the entire length of the fuel line for leaks. If that's all 100% dry after running it for 30 seconds or so then you could got one of the many pre failed pumps... You could also try installing a extra backflow valve on the line yourself but that can be a leak source so be cautious. Also put it as close to the pump as can get.

As an alternative you should check your fuel injectors for leaking. They can get stuck partially open and drip into the heads. This is really bad as you'll fuel wash your cylinder walls and burn them up. Pulling the injectors and the rail as one unit and then turning the key to the on but not start position and look for any leaks. Be careful not to get gas on the exhaust or something hot.

 

From a cold start (such as sitting overnight), turn the key to the ACC & IGN position, which is the last position before actual crank. Leave it there for 5 seconds before cranking. Report back on whether it still long cranks or starts immediately.

 

Haven’t quite gotten to first set of suggestions yet, but I can confirm after sitting 24h, turning key to acc/ign position x 5 sec it did still have a long crank, followed by slightly stuttering start before rpms increased to normal idle.

 

Try cycling the key twice before starting, turn it to Run, listen for the fuel pump to stop, off, back to run, when the fuel pump stops the second time, crank the engine.

 

Doesn't sound like a bleed down issue to me, not if it's hard to start after 30 min or so. Might not even be fuel related. When is the last time the plugs were changed? I'd be tempted to pull the plugs and see their condition anyway.... see if they're burning clean or any coolant getting into the cylinders (head gasket).