Starting Issues

[Bradell86]

Hopefully someone else here has experienced the same issue that I have been having for about the last 5 months. I have a 2015 1500 5.7 and when starting the truck the engine will turn over almost immediately with very little cranking from the starter, but the idle is so low for a few seconds that the truck will sometimes stall if you do not give it any gas. If the truck has only sat for a few minutes or has sat overnight, it will start normally with no issues. It has only died a few times, and will always restart, but usually with an extended crank and requiring me to give it some gas to turn over. Once the truck is started and idling normally it runs with absolutely no issues. earlier this year I did have to replace the starter for a no crank no start issue, and a few months after that I had to replace the fuel pump control module for a crank no start issue. A friend suggested cleaning the throttle body, which I did, but it did not change anything. I am not getting any codes to point me in a direction. Does anyone have any ideas?

 

[Fast69Mopar]

Hopefully someone else here has experienced the same issue that I have been having for about the last 5 months. When starting the truck the engine will turn over almost immediately with very little cranking from the starter, but the idle is so low for a few seconds that the truck will sometimes stall if you do not give it any gas. If the truck has only sat for a few minutes or has sat overnight, it will start normally with no issues. It has only died a few times, and will always restart, but usually with an extended crank and requiring me to give it some gas to turn over. Once the truck is started and idling normally it runs with absolutely no issues. earlier this year I did have to replace the starter for a no crank no start issue, and a few months after that I had to replace the fuel pump control module for a crank no start issue. A friend suggested cleaning the throttle body, which I did, but it did not change anything. I am not getting any codes to point me in a direction. Does anyone have any ideas?

What year is the truck?

Which model?

Which engine?

Is it the 2015 RAM 1500 5.7 HEMI from your profile?

 

[Burla]

Run a bottle of redline si-1 full strength. Theory your fuel/air mix is off a bit, when cold your idle is tuned high meaning it is pumping more fuel then when the engine is warm. Just maybe that will clean up injectors for ya, doesn't hurt to try and side benefit this cleans the isht out of combustion chamber. Before you think you can do the same thing with a bottle of techron, I assure you cant. Read this thread, product and dose count the most when using a cleaner.

Since giving it gas always fixes it, then gas is the issue, also move up to 91 octane if you haven't already.

 

[CanuckRam1313]

^^^ Solid Advice Here!

 

[Bradell86]

What year is the truck?

Which model?

Which engine?

Is it the 2015 RAM 1500 5.7 HEMI from your profile?

I guess I should have included that information. It is the 2015 Ram 1500 5.7. I edited my original post to include that information.

 

[Daw14]

Might want to inspect your intake manifold bolts , they tend to loosen . 108 inch pounds 8mm or 5/16 socket

These should be checked yearly if you drive average miles.

 

[62Blazer]

So you never have the issue if you turn off the truck and it only sits for a few minutes before restarting (the engine at full operating temp). And you also don't have the issue if it sits overnight (engine fully cooled). Meaning you only experience this issue if it sits for a few hours or so? Try to figure out about how long it sits before you start seeing the issue. Also, look at what the engine temperature shows right after you start it and have this issue. If this is what is going on, it sounds like an issue when the engine is half-way warm.
If you really want to figure this out you need to do some diagnostic work. Starting with a good scanner that reads live data. The first thing I would look at are sensor parameters under the conditions where the starting issue occurs. Throttle position, MAP, O2 sensors, engine and ambient temp sensors would be good places to start as they can affect how an engine runs and are dependent on the temperature. Those items basically are acting like the choke on older cars and lawnmowers and such. Everything may be working at the extreme engine temps (full cold basically is full choke, and full hot is no choke), but a bad signal may be causing the "choke" not to be quite right at that mid level engine temp. And yes, I know fuel injection doesn't really have a "choke", but just trying to get my point across that the ECM will adjust the fuel and other parameters when starting the engine based on the temps.
I did not say to go out and randomly start replacing sensors and throwing parts at it......that's called firing the parts cannon.

 

[Bradell86]

So you never have the issue if you turn off the truck and it only sits for a few minutes before restarting (the engine at full operating temp). And you also don't have the issue if it sits overnight (engine fully cooled). Meaning you only experience this issue if it sits for a few hours or so? Try to figure out about how long it sits before you start seeing the issue. Also, look at what the engine temperature shows right after you start it and have this issue. If this is what is going on, it sounds like an issue when the engine is half-way warm.
If you really want to figure this out you need to do some diagnostic work. Starting with a good scanner that reads live data. The first thing I would look at are sensor parameters under the conditions where the starting issue occurs. Throttle position, MAP, O2 sensors, engine and ambient temp sensors would be good places to start as they can affect how an engine runs and are dependent on the temperature. Those items basically are acting like the choke on older cars and lawnmowers and such. Everything may be working at the extreme engine temps (full cold basically is full choke, and full hot is no choke), but a bad signal may be causing the "choke" not to be quite right at that mid level engine temp. And yes, I know fuel injection doesn't really have a "choke", but just trying to get my point across that the ECM will adjust the fuel and other parameters when starting the engine based on the temps.
I did not say to go out and randomly start replacing sensors and throwing parts at it......that's called firing the parts cannon.

It really is a strange issue. I would say 99% of the time when the truck sits overnight or just for a few minutes it starts normally, however even if it has sat for a 9 hour work shift, it will typically still have the starting issues, so I can't say that engine temperature is a consistent factor. What I have found is if I lightly press the accelerator when starting, the idle stays level and the truck doesn't bog down. The crank time will still be very short though. My wife drove it yesterday and described the crank like not keeping your key turned long enough in an older vehicle. I've had the thought that it could be ignition related, but I feel like the instances would be way more random if it was.
I am definitely not in favor of throwing parts at it. I've been waiting for the issue to get worse or to throw a code to point me in a direction, but so far the severity hasn't changed much.

 

[Slinge]

wonder if you key on and off a couple times before trying to start would change anything ?

 

[Bradell86]

wonder if you key on and off a couple times before trying to start would change anything ?

I have tried that many times. I thought letting the pump prime before starting might help, but it doesn't do anything.

 

[62Blazer]

If the issues occur after 9 hours I would fully expect the engine to be completely cooled off. It's just weird that the issue happens after sitting for 9 hours but doesn't happen after sitting overnight. How many hours does the truck normally sit overnight between starts? I just can't think of anything that would cause issues after sitting 9 hours, but doesn't regularly cause issues after sitting maybe 12-14 hours overnight?
If you had a fuel leak down issue or the fuel pump wasn't strong enough to get enough fuel going (i.e. having to give it some throttle) after 9 hours, there is no reason it would be any different after sitting 14 hours? I can understand it restarting fine shortly after you turned it off because the fuel lines are still pressurized.

 

[Bradell86]

If the issues occur after 9 hours I would fully expect the engine to be completely cooled off. It's just weird that the issue happens after sitting for 9 hours but doesn't happen after sitting overnight. How many hours does the truck normally sit overnight between starts? I just can't think of anything that would cause issues after sitting 9 hours, but doesn't regularly cause issues after sitting maybe 12-14 hours overnight?
If you had a fuel leak down issue or the fuel pump wasn't strong enough to get enough fuel going (i.e. having to give it some throttle) after 9 hours, there is no reason it would be any different after sitting 14 hours? I can understand it restarting fine shortly after you turned it off because the fuel lines are still pressurized.

Most nights it sits for 12-14 hours between starts. Your thoughts are mine exactly. It definitely seems like a fuel delivery issue, but for as long as I have had this going on, I would have thought I would have had some issues while driving or idling. I have scoured the internet looking for answers, but it seems like I am the only one who has ever had this problem. I have considered doing a warranty replacement on the fuel pump control module just to eliminate that as the culprit, but when that went out it would only crank and never attempt to start.

 

[Tominator223]

Changed the air filter lately ?

 

[LaurensN]

I'm having a similar issue for over 2 years now and it's getting worse. Mine would have an extended crank when it's sitting for an intermediate amount of time or start with low rpm and die. I'm still trying to figure it out though.. I'm thinking leaky injectors. When it's only been a short period the injectors have not leaked enough fuel to cause issues. When it's intermediate enough fuel has been leaked and there is not enough air for combustion, pressing the gas would introduce more air and start the engine. And when it's been a long time I would guess enough fuel has evaporated so it becomes easier to start again. Just a thought as I'm not sure how to test this. Changed the FPCM, replaced the battery, bypassed the fuel pump relay, tried priming the pump, cleaned the TB, checked the bolts, used 93 gas. All no change.

 

[Tominator223]

Laurensn. You can pull the spark plugs after it sits awhile , if 1 or more is wet or smells of fuel strongly you found the injector in question.