• Steel Soldiers now has a few new forums, read more about it at: New Munitions Forums!

  • Microsoft MSN, Live, Hotmail, Outlook email users may not be receiving emails. We are working to resolve this issue. Please add support@steelsoldiers.com to your trusted contacts.

Runs rough and black smoke on initial start

incorporatedbyinference

Member
Steel Soldiers Supporter
38
56
18
Location
Mission Kansas
Today I pulled my Mep 802 a out of the garage for a little exercise. My start procedure was a couple 5 second cranks using the dead crank. Then primed for 45 seconds. When I turned to start, it fired up running rough w black smoke. After about a minute I shut it down. Right away gave it another start, idle was much better but still rough. After shutting it off and starting again it ran smooth. I read through tm 9-6115-641-24. Chapter 3 didn’t address my issue. Filters are all new w fresh fuel. The generator is an 09 w 650hrs. Has anyone had a similar issue before?
 

Icesythe7

Active member
147
223
43
Location
Indiana, USA
Today I pulled my Mep 802 a out of the garage for a little exercise. My start procedure was a couple 5 second cranks using the dead crank. Then primed for 45 seconds. When I turned to start, it fired up running rough w black smoke. After about a minute I shut it down. Right away gave it another start, idle was much better but still rough. After shutting it off and starting again it ran smooth. I read through tm 9-6115-641-24. Chapter 3 didn’t address my issue. Filters are all new w fresh fuel. The generator is an 09 w 650hrs. Has anyone had a similar issue before?
Just sounds like it was cold is all, black smoke is unburnt fuel most diesels do this at startup especially after not running for a bit or when in cold temperatures until it warms up a bit, all my gensets do it when cold (MEP-803a, MEP-831a, MEP-016d) as does my truck (11 6.7 powerstroke), generally do to feeding it fuel to get it up to speed yet the speed isn't coming up as fast (due to thick oil/not enough air etc) so the unburned fuel has to go somewhere.
 
Last edited:

incorporatedbyinference

Member
Steel Soldiers Supporter
38
56
18
Location
Mission Kansas
I’ll check into that. It just seemed odd that turning it off and then restarting 3 times would clear the issue. The idle didn’t change at all while warming up all be it was less than 2 min.
 

Ray70

Well-known member
2,552
5,759
113
Location
West greenwich/RI
I'd agree with LITD that you could have a slight leak in 1 of the injectors or possibly also could be a leak in one of the metering pumps allowing a little fuel to drain back creating an air pocket in the injector line.
This can cause the "Good" cylinder to struggle a little and smoke until the air is completely worked out of the offending cylinder.
Either way the good news is that it clear itself quickly.
I would just keep an eye on things next time you run it.
Out of curiosity, how long had it sat since you ran it last?
 

incorporatedbyinference

Member
Steel Soldiers Supporter
38
56
18
Location
Mission Kansas
Maybe 5-6 weeks. The generator was bought at auction 3-4 months ago. I replaced all the fuel lines and filters. Started up and load tested. There was some noticeable dark smoke at near 100% load. I ran some sea foam through it with a good 3 hour run. The smoke at full load went away.
 

Ray70

Well-known member
2,552
5,759
113
Location
West greenwich/RI
Only a leak in the injector pintle / nozzle itself can cause fuel to drip into the cylinder when shut down.
It may not cause any noticeable issue while running after heated up, but definitely isn't the best scenario for your engine.
A leak at the copper washer would cause a very slight loss of compression pressure, but won't cause fuel to drip while shut down and the compression loss is virtually undetectable except for possible some bubbling around the injector if it's wet with water or any fuel.

If the issue continues I would remove the exhaust manifold so you can see which cylinder is smoking.
Swap the injectors and see if the problem follows the injector or not.
 

incorporatedbyinference

Member
Steel Soldiers Supporter
38
56
18
Location
Mission Kansas
what is the consensus opinion on the best place to source oem injectors? Is it possible to source parts to rebuild origional injector? For the sake of minimal downtime id like to replace both injectors. but then rebuild the problem injector for my own education. The rubber lines off the rail had cracked and I replaced both 4” hoses securing with hose clamps. Could this affect the leak I’m experiencing? Thanks for any input.
 

Ray70

Well-known member
2,552
5,759
113
Location
West greenwich/RI
The injectors can be disassembled and cleaned. One test would be to remove the injectors and turn the hard lines off to the side and reattach the injectors.
Crank the motor and look at the spray patterns. there should be 4 fine sprays coming out radially from the tip of the injector.
If it isn't a super fine spray mist and more of a squirt or a drip, the injector is bad.
If there aren't 4 sprays coming out, the injector is bad.
The bad thing is that other than cleaning, rebuilding isn't that practical.
I've never found a good source for replacement nozzles / needles and the pop pressure is adjusted using thin shims inside the injector to alter spring pressure.
Not exactly the most user friendly design.
I've used the cheap Chinese injectors before. They worked in a pinch, but not one of them ever had the pop pressure set exactly to spec. they were always a few hundred PSI too low.
I'd test yours first, then clean or replace with OEM if a problem is noticed.
Try testing using the machine's metering pumps.
If you want to pop test them I can do it if you can't find a local shop to test for you.
 

incorporatedbyinference

Member
Steel Soldiers Supporter
38
56
18
Location
Mission Kansas
Pulled the 802 out of the garage to start and run again. Inspected the high pressure lines for anyt loose connections no finding any. With it being a week since the initial run. Same procedure a couple 5 sec turnovers at the deadcrank. 30 sec of prime then ignition started up just slightly rough. Tried to let her warm up and smooth out for a couple minutes. Wasn’t happening. Turned it off. Waited 15 sec. Then it started up smooth. Ran it for 4-5 hours switching between 3 4 and 5 kw loads. I ran hotshots secret diesel extreme in the fuel. There was a light rain and while switching between voltage readings the needle went to zero. I was still operational. Switched the dial position several times gauge still not working I gave it a flick w my finger and it started reading again. When visually looking over things I noticed a difference in appearance w the 2 injectors one had minuscule disturbance of the engine paint that was applied to the engine. The other one had more paint missing with a little diesel grime. Could this be my problem injector.
 
Last edited:
32
7
8
Location
California
Sure Sounds like a faulty injector to me , That may be why i recommend everyone have a back up complete engine for parts or replacement of entire engine , Parts from Onan no matter which country you order them from are SKY HIGH . I have 7 REBUILT ENGINES IN CRATES . Just saying .....:)
 
Top
AdBlock Detected

We get it, advertisements are annoying!

Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website like our supporting vendors. Their ads help keep Steel Soldiers going. Please consider disabling your ad blockers for the site. Thanks!

I've Disabled AdBlock
No Thanks