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01 Dodge Dakota 4.7l v8, 150k
If the truck sits for more then 10 minutes, upon starting it, I have to crank on it for awhile. Maybe 5 or 6 secs. It will then usually start, however, if it doesn’t, I stop for a few seconds, and start again, and it will fire up on the second go around. Upon it starting, the engine lets out a puff of black smoke, and you can smell gas. It runs rough for a second or two before it clears up. It almost seems like the engine is flooded. It does always start, and the truck seems to run great. I checked for codes, no codes. I’m thinking I should start with a fuel pressure test? See if the fuel bleeds off quick?
I looked at some live data from my simple scan tool I have, and everything looked “normal” (at least to me) except my LT FTRM 2 is showing -14%. So my thinking is maybe I have an injector that is stuck open? Maybe the fuel is bleeding off an injector, and that’s why I have the long start and maybe that’s why the rich condition exists?
Am I thinking through this correctly? Looking for some confirmation or redirection. Other then the fuel pressure test, where should I start from, knowing what I know.
Thanks for the help
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A fuel pressure reading is a good place to start. This will tell you lack of fuel
or possible over fueling.So i checked fuel pressure. KOEO pressures around 44/45, engine running it’s 48/49. Service manual says it should be 49 +/- 5psi…so I think I am good there. I was able to isolate the injector side and fuel pump side of the system. Thing is, they both lost fuel pressure over time. The injector side lost about 25psi in 15 minutes(45psi to 20psi), the fuel pump side was similar in that it also lost pressure, but at a slower rate 15psi in 15 minutes. Thoughts?
The injector side shouldn’t lose any pressure at all should it?
The fuel pump side should bleed down slowly overtime correct?I’m getting confused about what you mean by fuel pump side and injector side. The way this system works, the fuel pump pushes the fuel in a constant loop. There is a check valve in it that only allows fuel to head to the rail which allows the fuel rail to stay pressurized and not just bleed off every time you shut off the truck. The fuel flows into the injector rail and on the return side a regulator is placed which will not allow outward flow until its preset pressure has been reached. After leaving the regulator it flows back to the fuel tank.
Now obviously the system is not perfect, and some bleed down will happen over time. This is why the pump turns on for 2 seconds when the key is first turned to the run position. After that it turns off until the vehicle receives a signal from the crank position sensor telling it that the engine is turning over and more fuel will be needed.
The flooded condition you seem to describe when trying to start it coupled with your fuel pressure bleed off means that the fuel is ending up in your intake manifold. Either you have a leaky injector or a bad fuel pressure regulator. Try taking the vacuum hose off of the regulator. Do you see any wetness? Then run the engine with the vac line off and watch for a minute. You will see if it leaks fuel, which would be drawn into the intake and along with bleeding your rail pressure would flood the engine. If the regulator is working properly without leakage, you would need to be checking injectors. If I recall correctly, this fuel rail isn’t too hard to pull out. I would get some small Dixie cups and put one under each injector. Pressurize the rail and watch. You know you are losing pressure within 15 minutes so its not going to take long to see which one is dripping. Be sure to replace all the injector O-rings before you reinstall the rail and lubricate them with some silicone spray so they do not get damaged during installation.
The systems on these trucks are different than normal. The fuel system on the truck does not contain a separate return line like you would traditionally expect. You have a fuel line running into the fuel rail and that’s it. The pressure regulator sits on top of the fuel pump, so their is no way to access it, unless you drop the tank and pull the pump. (I’ve attached a pdf from the service manual that notes this, just so we don’t get stuck on how the system works)
Trying to test the regulator as you suggested isn’t an option. I wish it was that easy. You are right though, pulling the injectors wouldn’t be hard at all, and I should be able to tell quickly which one(s) are leaking once pressurized. My next thought, is given the age and mileage of the truck, (2001, 150k miles) should I just replace the bad one(s) or should I being looking at just replacing all the injectors at this point anyways?
Ok, with a returnless system that changes things and brings us on the same page. Makes sense to me now with your earlier post.
These injectors are pretty good in my opinion. I really don’t see pattern failures out of them that would make me want to throw a whole set at it for one being bad. Its not like a Ford COP ignition coil where once you see them failing you toss a new set at it. If you only see one leaking, just give it one. If more than one, might think of just doing them all. Its your call. This is a pretty easy one to go back into if you have to, so were another injector to fail down the road its not like you have to pull half the truck apart to go back in.
Returnless systems can be a pain to test, but they have been good at stopping pump failures since the pump only runs just enough to keep the rail pressurized. Have that system in my girl’s Camry and the guys at the Toyota dealer told me the things are practically bulletproof. They don’t even stock them as they don’t see them fail.
Thanks for the information. That is good to know. As you suggested, I plan on pulling the injectors, pressurizing them, and try to determine if any or which ones are leaking. I plan right now, to just replace the injector or injectors that are leaking and call it good. They are easy to get to, so If I have to get back at them, it really isn’t that much work. I’ll report back what I find, and hopefully find the cause of my long crank.
So I pulled the injectors and found that cylinder 8 injector was leaking. Pulled the plug on it, and it was wet. I replaced the injector and put a new set of plugs in since I was already there and the old ones looked shot. I also put new o-rings on the bottoms of the injectors before I put them back in.
Truck fired right up, but now is running really rough. It’s stumbling on itself, and wants to die at idle. Of course its not throwing any codes, but the live data shows it is running super rich….like – 33%. Where do I go from here? How do I determine what’s gone wrong?
If thats a positive 33% then your adding fuel. see you just pulled the injectors
I would suspect a vacuum leak on the O ring injector. With either carb spray or
a spray bottle with water spray all the injectors with the engine running. This video
should help.http://www.ericthecarguy.com/faq/solving-automotive-performance-issues?start=3#CheckforVacuumLeaks
Disconnect the battery for 10 minutes. While waiting the 10 minutes, take this opportunity to clean the battery and terminals so they are nice and shiny, then make sure they are tight when reconnected after the 10 minutes. See if that helps. Why am I suggesting this? To clear the fuel maps out of the computer memory.
It is a negative 33% (-33%). It sounds like one of the injectors is firing off like a machine gun at idle. Is it possible I got a bad injector or the wrong injector? The battery was disconnected while I was changing everything. Any reason to unplug the battery again?
[quote=”Brink5″ post=135627]It is a negative 33% (-33%). It sounds like one of the injectors is firing off like a machine gun at idle. Is it possible I got a bad injector or the wrong injector? The battery was disconnected while I was changing everything. Any reason to unplug the battery again?[/quote]
Nope, no reason then. Those are the details I didn’t know since I am on my side of the internet and can’t see/hear the vehicle. If the injector is rapidly opening and closing then it isn’t getting proper control. It is possible that the injector is the wrong one or is defective. I would doubt it is defective though, as it would probably just not open. The computer sends the signals to open/close the injectors, so it is a control issue. If the injector is the incorrect model, it could be responding incorrectly to the commands from the computer. Do you still have the leaking injector? If so, swap it back into place and see if that control issue goes away and it fires normally. Also, your leaking injector could be rebuilt for about $25 instead of replacing it. There are online places that do it, and there may be a local injector shop in your area.
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