Dodge Nitro Forum banner
61 - 80 of 99 Posts

·
Registered
Joined
·
68 Posts
I'm "listening" for your results! I just had a tune up a few weeks ago. Now, I'm getting more extended cranks than I ever have. EXACT SAME SCENARIO.
 

·
Registered
Joined
·
147 Posts
So far so good. Starts normally every time. Pull the plugs, on one the center porcelin will be dark brown, that's the cylinder to change injector on.
 

·
Registered
Joined
·
147 Posts
Every time. It would crank even longer when I parked for a few minutes, then restarted to move again.Got concerned that it wouldn't start a few times.
 

·
Registered
Joined
·
147 Posts
Update, I now occasionally get a long crank time again. The truck has 150k on it, but the motor was replaced with a reman about 20k ago. I assume long block with all external accessories used, including fuel system. I may just replace all injectors if problems persist. I will check fuel rail pressure to verify it is within specs.
 

·
Registered
Joined
·
147 Posts
Finally got around to checking fuel pressure. 65psi with key on, stays there at engine start, so fuel pump good.
BUT, pressure drops off quickly after shut down.
Generally the truck starts fine when cold, but has issues when shut off and restarted after 5-10 minutes.
I considered the possibility of a bad fuel regulator, (located within the fuel pump assembly) but it shows none of the symptoms of that, ie; black smoke, fuel out the tailpipe, deceleration issues, not running smoothly or stalling.
However, there is also an anti drainback valve located within the in tank fuel pump assembly, which I believe is the culprit. If the injectors were bleeding fuel into the cylinders that quickly, there would be black smoke upon startup, as well as misfiring due to fouled plugs. New fuel pump assembly is over $200, but if that cures the problem, then that's what I need.
I will update.
 

·
Registered
Joined
·
68 Posts
Oh Lordy, I'm still listening! You're the only one coming back with your trials. There has never been a solid solution. I have no skills to "fix" anything. But I have followed, researched, taken it to the shop, had a sensor changed, prayed it will start, recorded it, cussed, talked to a top GM mechanic. Because with mine it is so random that when you think that it is fixed and it doesn't do it for months and doesn't show a code it is impossible to figure out. One time I left it at the shop and they cranked it over 50 times and it never did the extended crank.Waiting for your update...
 

·
Khaki Nitro Nut
07Lifted,4X4,6sp-man,3.7L
Joined
·
30,657 Posts
Finally got around to checking fuel pressure. 65psi with key on, stays there at engine start, so fuel pump good.
BUT, pressure drops off quickly after shut down.
Generally the truck starts fine when cold, but has issues when shut off and restarted after 5-10 minutes.
I considered the possibility of a bad fuel regulator, (located within the fuel pump assembly) but it shows none of the symptoms of that, ie; black smoke, fuel out the tailpipe, deceleration issues, not running smoothly or stalling.
However, there is also an anti drainback valve located within the in tank fuel pump assembly, which I believe is the culprit. If the injectors were bleeding fuel into the cylinders that quickly, there would be black smoke upon startup, as well as misfiring due to fouled plugs. New fuel pump assembly is over $200, but if that cures the problem, then that's what I need.
I will update.
That is actually a tad bit high 58 Psi ± 5 Psi is the standard, but not terrible. And totally possible the gauge is just a bit off.
The pressure should not drop more than 10 psi after shutdown in 5 minutes. If it does then it is pump or injectors.
 
  • Like
Reactions: Nitrogen

·
Registered
Joined
·
147 Posts
Yes, that's the other reason I think it is in the fuel pump assembly. Either the regulator or anti drainback valve, or both. This way I'll at least eliminate that possibility. Truck has 150k on it, probably due anyway.
I did replace one injector, due to it fouling the plug, and causing hard starting. That threw a code and caused a miss. That's why I don't think it's the injectors. It bleeds off to 0 almost instantly. If it was dumping that much fuel into the motor that quick, it would cause hard starts and black smoke.
Bosch pump from Rock, over $150 cheaper than local stores, due 12-23, hopefully I can get motivated to get on it over the long weekend, and know for sure, heck can't go anywhere or have people over, might as well get something done, right?
 

·
Registered
Joined
·
147 Posts
Ok, got the fuel pump replaced, no change. Still doesn't want to start after sitting for 5-10 minutes.
This is really weird. It starts right up when cold, or when warm if I shut it off and restart within a minute or so. But let it sit warm for over 5 minutes and long crank time?????
No smoke, no miss. Is there some kind of temp sensor that could do this?
I tried hitting the accelerator when long cranking, it maybe started faster, but went to high rpm right now.
 
  • Like
Reactions: Nitrogen

·
Khaki Nitro Nut
07Lifted,4X4,6sp-man,3.7L
Joined
·
30,657 Posts
Did you do the leak down test?
 
  • Like
Reactions: Nitrogen

·
Registered
Joined
·
147 Posts
Which leak down test? Fuel rail pressure dropped to zero within seconds. Don't know why cylinder pressure or radiator would matter.
I'm wondering if there's a sensor which is getting heat soaked after a couple minutes which is causing it. As I said, it starts right up cold and if it doesn't sit too long.
When I get a chance I'm going to test if I'm getting spark after 5 minutes of sitting.
If it was injectors dumping fuel, I think I would have problems all the time, and upon restarting within 5 minutes it would miss and blow a puff of black smoke.
BTW all O2 sensors are new, and the one is a different part number.
 

·
Registered
Joined
·
15 Posts
hi there guys, i have a 2007 nitro r/t,...... in the last couple of months i notice something pretty weird and very annoying. When i first star the nitro in the morning every is normal, it starts normal, all is good for now...., but almost after every ride of more than 30 minutes when i shut it off and start it back on it kept crancking more than usual, and it does it with the remote starter too....,
i have been looking all around for similar problems like this but havent see anything yet....., any help, any info on this pleaseee....!!!!
Thanks to allll!!!
Good Morning
I have same problem with starting I
Found out there is a one way check valve
In the fuel tank that is part of the fuel pump
Assembly only way to fix is put in new
Dodge fuel pump which keeps pressure
At the injectors at the correct pressure
Bad check valve on the fuel pump the pressure leaks down
That is the reason for the long cranking and no start right a way pressure has leaked down
Good luck Hope this gets helps
And new fuel filter also
 

·
Registered
Joined
·
147 Posts
Thanks for trying to help, but if you read back 3 posts you'll see I already replaced the fuel pump assembly, thinking that check valve could be the problem. Didn't fix it.
I even key on to allow the pump to run a few minutes before starting, no change.
 
  • Like
Reactions: Nitrogen

·
Registered
Joined
·
5,343 Posts
personaly i would try and jump start the engine, just to see if the extra Amps make a difference,
 

·
Registered
Joined
·
147 Posts
It's not a battery problem. The motor starts quickly cold, when the battery is taxed harder.
This is only an issue when warm, after sitting for 5 minutes or so.
 

·
Registered
Joined
·
5,343 Posts
i don't think it's a battery problem, but maybe an elecrical problem, just thinking of trying things members haven't tried, this "no start when hot" issue has been around on the forum since day 1, appart from the fuel relay bypass (which some members have had success) there has not really been any other solutions,
it's just something i personaly would try, in the hope the extra Amps give something electrical a little extra kick,

and before anyone says your not supposed to jump start these modern engines, i know, but i would still try it,
 

·
Registered
Joined
·
147 Posts
It's almost certainly a fuel issue. The rail pressure drops within a second or two after shutdown. I want to install a fuel pressure gauge on it and see what the pressure is when the hard start occurs.
Since it only happens for me after sitting about 5-10 minutes, (starts great cold, under 5 minutes after shutdown, or if it sits more than 30 minutes) I was leaning towards an electrical item getting heat soaked and causing it.
It could still be an injector leaking down, even though I get no smoke, miss, or rough idle upon start.
I did a lot of research last night, and have come to a couple other possible other issues.
Vapor lock, I'm going to try insulating the fuel line.
Crank or cam position sensor.
TPI. Which might also fix my hard shift at light throttle.
Already replaced the O2 sensors.

One other thing I'm going to do is get a scanner, leave it hooked up and see what readings I get when the problem occurs.
 

·
Registered
Joined
·
147 Posts
I tried something different today. When it didn't start immediately I pushed the accelerator pedal to the floor and released it, while it was still cranking. It started right up. I will have to try that a few more times to see if it continues to happen.
I know there's no accelerator pump like in a carburetor, the only thing the throttle does is open the throttle plate to allow more air in.
So I'm wondering why that shot of fresh air caused it to start better. MAP sensor maybe?
The weird thing is that if an injector leaked down leaving raw fuel in the motor causing the no start, why doesn't it affect it within the first 5-10 minutes? One would think the fuel would evaporate in 10 minutes, and not be a problem.
 
  • Like
Reactions: Scar0
61 - 80 of 99 Posts
Top