60 Series Detroit Diesel Help Needed

[dodgemain]

I am looking for some help with my M916A3 I purchased over the summer. It has a 60 Series Detroit diesel engine that is hard to start and idles rough. If I can get it to start it runs very rough at below 500 RPM. After sometime the RPM will climb by itself to alittle of 500 RPMs. The engine shakes, knocks, and just sounds bad. It does smooth out when over 1000 RPM. I already changed the fuel filters. Do you think a bad fuel pump could cause this? It only has 5k miles so it's hard to believe it has bad injectors. Any thought or suggestions greatly appreciated. Thanks

 

[73m819]

Sounds like it is sucking air

 

[Floridianson]

What codes is it throwing? Power on engine off push / hold the button down buy the lower panel drivers side and read the flashing engine light. Count flashes and then decode. I will pm my cell number .https://www.steelsoldiers.com/showt...C11&highlight=Detroit+60+series+trouble+codes

 

[Floridianson]

Sounds like it is sucking air

Have not heard what the out come from Op but yea could be air. The TRS sensor can cause lots of starting trouble. I carry both SRS and TRS new sensors in truck with tools. Also pressure check valve on the return fuel system line on back of head.

 

[dodgemain]

I have been busy with work. Hoping I will have time this weekend to work on the truck. Will have an update for you next week. Thanks for the help.

Have not heard what the out come from Op but yea could be air. The TRS sensor can cause lots of starting trouble. I carry both SRS and TRS new sensors in truck with tools. Also pressure check valve on the return fuel system line on back of head.

 

[Hammer]

Also pressure check valve on the return fuel system line on back of head.

This causes the leak down issue when sitting that makes it really hard to start, and the first minute or few to run SUPER rough. But it would smooth out 'some'.
Air getting into the system is the easy answer.
Sensors should show up on codes though.

 

[gunsgreg]

As others have said the codes are the place to start. Overall what a good power plant though...

 

[wrenchturner6238]

You should check the fuel PSI; there is a restricted fitting in the back of the head. If the fuel psi is low; you may have to replace this. it is a specific size hole in the fitting to keep up the fuel psi. you can modify the size of the restriction to boost HP but if outside the range things go down hill. If you do have to work on this it is a good idea to remove the check valve that is connected in the return and loop the hose so it is above the head because the check valves do mess up. If looped above the head it will hold the fuel in the head. Normally though the rough running would go away after running a while unless it keeps getting air in the fuel. I think i found a few problems with filter head and normal hose problems. I would take the return line off the tank and run it in a bucket of fuel ( you will have to put you hose down in the fuel to notice bubbles) to check for air in fuel ( you should get almost no bubbles in the bucket if no air) this would be a first step if the fuel psi is low and then go to the restricted fitting. The restricted fitting is tough to get to in this model of truck .

 

[Floridianson]

If what they call the restricted fitting or check valve is bad is good to be a skinny country boy. Also manual shows a check valve to prevent drain back when filters are changed after secondary filter. I was just trying to see how many pumps of the fuel primer it takes after my truck has sat for a week. Don't know if it shows the true condition of my system but the primer gets solid after 5 pumps. Seems like if the head check valve was stuck open and the OP did not use primer before starting it might cause a hard start. I always prime up the system before starting. Seems like if the restrictor holds correct pressure then the only thing that might happen was something clogging it up then pressure would be higher than normal. Head check valve stuck open drains the head and hard starting.

 

[Floridianson]

You should check the fuel PSI; there is a restricted fitting in the back of the head. If the fuel psi is low; you may have to replace this. it is a specific size hole in the fitting to keep up the fuel psi. you can modify the size of the restriction to boost HP but if outside the range things go down hill.

Don't see how it would boost HP. Seems like it would lower rail pressure if it was out of spec. or opening it up bigger than .086. Looking at my manual the spec was .086 and it can go as high .096 after that replace it. The main thing if you can is keep the fuel tank full to help keep the fuel cooler. Myself when my fuel gage reads just under half a tank I fuel up. Now you could install a fuel cooler might get you a little more. Best thing just have the computer hacked and add some HP. I am happy with my 400 HP just the way she is. I might not have a great top speed with my 4.56 gearing but I can pull hills very well. As for reaching the back of the head I might be able to get my azz up there from the passenger side and coming up from the bottom back side of the Trans. I'm running about 200lb and wish I was back at 175lb. Then I believe I could get to it with out holding my breath. As said send a skinny person and lay on top of the Trans. Now if it was a manual Trans. don't believe it would happen.

 

[wrenchturner6238]

Well we are talking pretty small moves in opening up the restricted fitting and yes once you reached a certain point you would be going backwards and loosing your fuel PSI .
At the time the idea was to get more fuel passing through the head to help get cooler fuel because you start loosing horsepower in your fuel anything over 100*. This was in the early to mid 90's most were not running fuel coolers. We had customers report back to us that once we opened up the restriction some that they were seeing better power; we at that time did not have a dyno to get hard data.
One other thing I did to some was to put a map sensor in place of the boost PSI sensor; the throttle response would improve but the engine would smoke like a Cat when you mashed down on the peddle but if drove correctly you would get the response you wanted but no smoke or lose in MPG.

 

[dodgemain]

Hi,
Finally had time have someone come out and hook a computer to my truck. Ended up being 3 bad injectors. Had all 6 replaced and it running great now.
Thanks