I have a Dodge Dakota Quad Cab with a 4.7l V-8. The fuel pmp loses its prime if it has been sitting more than a few minutes.I just had the fuel pump replaced after it quit running completely. It also had a vacuum leak that was fixed, but the fuel pump still doesn't hold its prime and the cab smells like gas when it starts. What can be causing this?
Country: United StatesMake: DodgeModel: Dakota SportYear: 2002Engine: 4.7
replacing vacuum line, replacing fuel pump
Your Dakota might actually have a problem with leaky injectors. Hi, my name is XXXXX XXXXX welcome to JustAnswer!.Long crank time after sitting a few minutes can be caused by several things, including loss of fuel system pressure at rest. The difference between simple loss of pressure (bleedback to the tank) and leaky injectors is that the engine will be over-fueled and flooded when leaky injectors are involved. To tell the difference, I let the vehicle sit long enough in a condition that I would expect the problem to occur. If this is a hot engine restart problem, make sure the engine is fully heated.Then pull the fuel pump relay from the underhood fuse and relay panel (called the PDC) and locate the pressure test port on the injector rail, which will be about middle-passenger side.Stuff some rags around the fitting to catch fuel and press the pintle to release pressure. It will go on for quite a bit with a heated engine as the fuel begins boiling as pressure is let off. At some point, the fuel will stop flowing, but you're not done yet. Tap on the injector rail a few times on both sides of the engine to inspire the fuel to boil ONE MORE TIME and then the fuel system will be officially... flat. Remove the rags and place them somewhere that they can air-dry without danger to anything nearby.Now attempt engine start. With no pressure in the fuel system, you should have no sign of life at all now when trying to start up. If it fires even briefly, it shows that fuel had entered the intake air system on its own during the hot-soak, which means one thing... Leaky injector or injectors. Pulling the whole rail while still connected to the supply line is the best way to sort out who's leaking and who's not simply by monitoring the firing tips of the injectors for wetness after blotting them off and rolling the key to the ON position a few times to charge the system. The rail can be lifted only a few inches like this, but it's enough to do this diagnosis.On average, expect there to be two leakers, but the last two jobs I did showed only one bad injector... but they were each leaking pretty bad.While I don't expect your new pump unit to be allowing bleed-back so soon into its life, it's still a possibility especially if this is a problem that began only since the new pump arrived. Watching fuel system for pressure decay with a gauge is of course the best way to check this (and you may have already done so), but if you find that rolling the key to the ON position 4-5 times to prime the fuel system improves your restart performance, it strongly suggests the new pump is at fault.Your in-cab fuel odor could be coming from the exhaust system as excess fuel is pumped out if the engine does actually flood itself while sitting, or it may be from an evaporative hose being left loose, leaking, or even a misaligned fuel pump module seal... hard telling. The evaporative system describes the vapor portion of your fuel system, describing the control, collection and use of liquid fuel as it evaporates within the tank. Liquid fuel leaks are rare on this system, but evap leaks happen pretty often and will eventually turn the MIL on, disclosing a P0456, 0442 or 0455 (small, medium or large) evap system leak. It takes a few days for testing to be completed by the Monitor, so chances are good that if the pump is more than a week old... it's not an evap leak or you'd have a CHECK ENGINE lamp burning by now.Other possibilities for long crank time on restart will involve sensors that are closely monitored by the on-board diagnostics and will typically set a code, turning your MIL on. If your MIL is presently on, let me know.I'll stop there for now and let you get caught up. Check those things I mentioned and be sure to get back with me if you have any questions or problems.Good luck!Ed
The problem of excess cranking to start happens mostly when the engine is cold. It hasn't turned the check engine light on since the vacuum hose was replaced. Leaving the key on for a few seconds and pumping the gas a couple times seems to help, but not always. the new pump has been in for a month or two. It took a while to crank over before and after replacing the fuel pump. I haven't been able to get it in to my mechanic yet, but I'll pass this on to him.
It does sound like a bleed-back problem, which should be pretty easy to diagnose once a pressure gauge is used. Let me know if you have any developments and enjoy the weekend!Talk later,Ed
30-year Dodge/Chrysler exp., ASE Master with L1 certification. Driveability/ combustion specialist