Troubleshooting M1009 6.2l Idle

Have a M1009 with the 6.2L - last week it was very hard to start (acted like it was not getting full) after some time got it to start, then the Idle started to get strange. Sitting with no pressure on the peddle, it would rev up and then get super slow to the point of not wanting to run. I could go in and manually rev it up and get it going again, would run normal for a short time and go through the same thing....sometimes fast and others very slow. It does not seem to be a consistent issue, just on an off...my though is I have a Injector Pump that is getting ready to crap out or an injector that is bad. It appears the IP is a bit costly and time consuming to replace and the injections are far less and a bit easier to fix. I wanted to get the thoughts of the more experienced to see if you think it is the pump or injectors.

Assuming one or both of the above are the case, where would you suggest I get the replacement parts?

Thank you,

TJ

I would lean toward air in the fuel lines first. Air in the lines will cause a poor idle when first started. A common source of a leak is the stock fuel filter base. What is your fuel filter setup, and have you gone through and replaced any rubber fuel lines on it?

That is an interesting idea. My first thought was bad fuel but air is a possibility as well. I did replace the filter about a month ago, but the lines are all original and I am certain could use a replacement. I will start with that. Another symptom that I noticed that I forgot to add - I have a Banks Turbo with Exhaust Temp gauge, most often if I am pressing it I get to around 900 degrees and I noticed I was pressing into 1200....would this running hot also be due to air?

First is your EGT pre or post turbo? Your best case, I believe you want to be running under 1050F... 1200F you are melting your pistons...

High EGT is due to EXTRA fuel.

Hard start your truck, let the idle smooth out (this should happen pretty quickly), shut it off... wait 15 seconds... Restart it. Does it fire right up and run smooth? Then odds are the fuel filter housing is leaking.

Sometimes the angle you park at will effect if the truck has a hard start or not if the housing is at fault... it could make it seem random.

More work, you can replace the line coming off the top of the IP with a clear line, if you see air bubbles you know your issue...

The high EGT is post Turbo. As I rule I try to keep it below 900. Extra fuel, why would that happen?

Several times I started it and it ran fine and then started the fast/slow idle. This happened 2 or 3 times over 3 days, 4th day started to idle correct but still seeing it run hot.

I'm going through similar symptoms on my truck albeit I don't have a turbo or pyro. So far I have replaced my cartridge type fuel filter with a spin on due to a loss of prime issue. My leak was due to the fuel pressure sensor, some people simply eliminate that by tapping the hole and threading a screw and o-ring into it. My issue got better but was not cured. I read around and decided to get rid of the check ball in the housing pressure regulator. It's the 9/16" fitting on the top of the injection pump that the fuel return line connects to. My truck runs great that way but still loses prime slightly. Nowhere near as bad as before. I put a new housing pressure regulator valve on and drove the truck about 20 miles. Great power until the last 1/2 mile to the house. Got home and like yours I was idling kind of low but could rev the truck up. It wouldn't rev up as quickly and was smoking. Shut it off for a minute and it was fine again for a short time. Started acting the same as before so I shut it down and installed my housing pressure regulator without the check ball. Back running great again. I looked at the new housing pressure regulator and sure enough, little rubber specks. From what I've read on here and other sources, the 1985 and older injection pumps have a drive ring in the governor housing that was made of rubber. There was an update around July of 1985 that changed the material and was known as an "elastomer insert drive" to eliminate the problem. The units that were upgraded have a triangular shaped tab stamped "E". Looking at the rubber specks on my housing pressure regulator and lack of the tag tell me mine never received that upgrade. Hopefully that's not your issue but even if it is, you're in the same boat as me and we'll get these trucks fixed soon.

I aint a turbo expert but POST turbo you are running 1200? You are melting your motor, PRE turbo should be a max of 1050 assuming stock 6.2, a turbo 6.5 can run hotter but it was made for a turbo and many things are different to support that higher EGT.

Why would extra fuel happen? Did you adjust the IP when adding the turbo? If you bought it WITH the turbo on it I would turn down the fuel, these motors can NOT smoke like "new" DI motors can, for IDI motors smoke is death (high EGTs). Or as said the pump could also be going bad. Maybe bad injectors (leaking) Extra fuel = crazy EGT's for these motors...

Assuming the pump is good, your idle will screw up due to a fuel leak allowing air in... however if the idle issues started with the running hot issues... I would lean towards IP over fueling... but would of course what you can before looking at a IP replacement ($$$ and pita)... the poster above me has a good thing for you to check inside the IP.

Prior to the issue I would hit 900 with the turbo engaged and between 400-600 running normal. Sounds like I have a few lines and maybe switch to a spin on filter to try. I have looked at an IP, about $600 for the part and what looks like a ton of work!

A question, if I replace the lines how do I bleed them to avoid the air in the line? I assume the same way I would when replacing the filter?

Seeing as your increase temps AND idle issues go hand in hand I would think you have an IP issue or injector(s) leaking...

You can screw with lines and filters but if it was me based off your info here (temps and idle issues happened at the same time) assuming this vehicle can be down for sometime... either BUY or BUILD my own injector tester (this would take you down for just the time it takes to pull each injector and test it ) OR send them out to be checked... places like accurate diesel in MI offer this service... (no affiliation but have used them before and they are very helpful/knowledgeable) if one or more is leaking you could have idle issues / temp (cause... excessive fuel)

Other thing to do would be replace the IP after checking what the other poster mentioned... I would STOP driving it with post turbo EGTs of 1200... you WILL cause massive engine damage.

If you replace the lines, you can open the filter bleeder and put some air pressure into the tank (rag + blow gun) until you get fuel... crank it a few times with the IP pink wire off... and then let her go.

That being said... I really do not think your issue is going to be a line if you did not have the temp issues, yes maybe... but seeing as your temps are sky high, do you see excessive black smoke?

IP replacement is not super bad, but does require pulling the intake, oil fill... for the love god don't drop a bolt else... your pulling the front of the motor...

Edit... a diesel running lean (lack of fuel) is going to run cold... a diesel running rich (excessive fuel) is going to run hot...

I do have a great deal of black smoke.

Injection pump is going out. Take the cover off and look for black flecks, this is the elastomeric governor weight cage drive which has gone bad. Clean it out and it will run better but you are risking failure as the cage now has metal to metal contact and the shavings are really bad for the life of the bearings in the pump.

The high EGT is due to late timing due to clogged outflow check valve causing case pressure to rise. Timing is adjusted using fuel pressure in the timing circuit which dumps to case. With high case pressure, the additional pressure in the timing servo cannot move timing advanced.

Don't worry about melting a piston, worry about valves and the turbine. The black smoke is a dead give away.

As far as the complexity, it isn't bad. First, pull the intake and tape over the ports. Bag and tag hardware, sharpie marks on the manifold etc. Next, pull the injector lines off the injectors and cover the injectors/line openings. Next you need to remove the oil fill tube and grommet. Now you can see the IP gear bolts, 3 of them. Pull them one at at time, rolling the engine with a breaker bar and socket clockwise.

Now for the hardest part, the three fasteners securing the pump. Take your time, IIRC 15mm using a mix of extensions and universal joints. Take the pump and lines off as one unit.

Assembly in reverse, the injection pump flange has a key pin, it only goes on one way. Adjust timing by ear and EGT. Late timing is high EGT, early timing is excessive knocking. Its an IDI, timing isn't all that sensitive.

If it were me, request to keep your core. Longer turn around but better timing assurance.

I did my first swap in the parking lot of the step son's apartment, 220 miles from home using two tool bags. Took me a day.

For some reason you are getting way too much fuel, I would stop driving it before you melt a piston. The issue is not going to be a fuel line, you have excessive fuel for some reason... either bad injector(s) or IP (or both) would be my input.

You could try to adjust the pump down but, if it was working fine and now is not... I fail to see why that would be the reason. But really don't be going over 1000F post turbo...

Keith_J said:

Don't worry about melting a piston, worry about valves and the turbine.

Click to expand...

1200F egt POST turbo on a N/A motor with pistons that do not have oil jet cooling and melt at 1200F...

Explain why NOT to worry about melting a piston.


Unless this was a motor built to be turboed the pistons can not take the heat. The turbo should have no problem taking it, a 6.5 can run 1400 EGT...
Pic is for fun... it is what happens if you drop a bolt...

Thank you all for the feedback - some great information and I have a good plan of attack!

Matt5 said:

1200F egt POST turbo on a N/A motor with pistons that do not have oil jet cooling and melt at 1200F...

Explain why NOT to worry about melting a piston.


Unless this was a motor built to be turboed the pistons can not take the heat. The turbo should have no problem taking it, a 6.5 can run 1400 EGT...
Pic is for fun... it is what happens if you drop a bolt...View attachment 746887

Click to expand...

I gave him a rather simple exploratory wrench spinning exercise, removing the top cover on the IP will confirm if the elastomeric drive ring has gone out. This will cause the high EGT, black smoke and poor running.

High EGT doesn't always mean high piston temperatures. Late injection will cause high EGT without piston temperature excursion as the piston is further from the flame front (remember, diesels have stratified combustion) while the exhaust valve is right next to the precombustion chamber. Modern diesels use late injection timing to raise EGT to regen the particulate filter (burn out) while having the required exhaust gas oxygen to burn the soot. ( also injection after valve opening to use oxidation catalyst to raise EGT).

Proper injection timing results in PRESSURE rise which is how thermal to mechanical energy conversion happens. And post turbine temperature excursion is normal when there is minimal mechanical energy extraction through the turbine. Or in other words, when the turbine is actually extracting power, there is a greater temperature drop.

So yes, using ALL the symptoms of high EGT, poor running idle, black smoke and age, I can say the root cause is a decomposed urethane governor drive ring clogging the fuel return check valve in the top of the injection pump cover.

I still have diesel under my fingernails from my last injection pump tear down. That engine is now running fine.

If you have a bad IP, bleeding the lines after replacing the pump is easy. Charge the batteries first. Leave the fat pink wire disconnected as this will shut off fuel in the high pressure side. Leave all the lines to the injectors loose. Crank the engine for 10 seconds at a time, allowing 5 minutes to cool the starter. Leave the fuel return line off the IP and crank until there is fuel from the pump. Now connect the pink wire and crank for the above schedule until you have fuel at each injector line nut, tighten all 8. Now it should start, it might be rough until all bubbles are gone. Check for leaks and enjoy another 15 years until the IP needs swapping.

I just had to bleed my fuel lines from a motor swap. I would highly advise whats been stated already about pressurizing the fuel tank with air to get fuel to the filter and to the IP. Before you start cranking the motor and instead of cracking the fuel lines at the injectors I took out the glow plugs. This removes compression, relieving some stress from the starter, it also makes for faster cranking and lower temps on the batteries. You should still wait 5 minutes between cranking to give everything a rest(specificaly the starter), keep doing this until you get diesel mist out of ALL of the glow plug holes. Once you have diesel mist you have fuel at the cylinders.