1999 Cat 302.5 mini. SN 4az00094 - Perkins 3013 - 2400 hours on the meter I'm pretty new in the diesel world but fairly capable. So please bear with me, if i need to ask simple follow up questions. When i fist bought the machine (about a month ago) several motor mounts were disintegrated due to an oil leak At low idle it would rattle your teeth out. This caused what i think is the mass air flow sensor located on the air intake system to come disconnected. As a result there was a pretty consistent white smoke and rich fuel small. I taken the entire fuel rail system apart from the fuel pump to the injectors cleaned inspected and replaced. I tested the mist by turning the motor over without the glow plugs in place and have what i think is a very fine fuel mist (i did completely disassemble the injectors clean and replace (next time i'll just but new ones it was not worth the time investment) Replacing the MAF sensor did resolve the majority of the high fuel smoke issue, however it is still intermittently present I read that a faulty coolant temp sensor can potentially trick the ECM into thinking it colder outside and cause it to run rich. The Service Repair manual says the resistance should be as follows: 122 Degrees or less 54 ohms +or- 2 ohms 248 Degrees not less than 15 ohms. My resistance reading are significantly less in both temp ranges. When i disconnect the wire connection to the temp sensor the temp gauges fails to read. A replacement temp sensor is in the range of $70 dollars Us with seems excessive. If replacing this resolves my problem i am fine with the spend. I've investigated buying CAT ET and the connections necessary to do further troubleshooting. I think the ECM is behind the fuse panel under the seat with no obvious open diagnostic ports, so before i go to deep down this rabbit hole i figured I would pick the community braintrust. Is my theory possibly correct that a bad coolant temp switch could could a rich fuel condition?
Have any photos of the engine
First and foremost, there is ZERO control over fuel delivery, timing, quantity, etc on that machine, save for the priming pump and the fuel shutoff solenoid. You can swap sensors all you want and and it will not achieve a change. Secondly, what exactly is running rich? Define the symptoms better. Easy or hard start? Excess cranking? Smoke at idle? Smoke under load? Puffing? Steady? Black, white or blue? Being a 3 cylinder, they all vibrate excessively at speed dial 1, and, as you've discovered, even moreso with damaged engine mounts.
Sorry some of the questions were cut off in the mobile view editing With MAF sensor disconnected a visible white cloud of smoke through my whole property to the point where my wife can smell it in the house. Not sweet smelling definitely fuel rich. Easy starting Minimal cranking to start no glow plugs needed some smoke at idle, smoke increases significantly as rpms go up Steady smoke All white smoke (not sweet smelling) Following maf replacement and injector clean up visible white smoke decreased significantly but does puff under high rpm and heavy loads Last night the sensor i am pointing to below did disconnect again and the smoke returned so i assume i can repro the problem at will
It does appear to me that someone has at least unbolted the top of the high pressure pump could they have monkeyed with the shims or am I just observing normal operating behavior now
This is what I am referring to as the maf sensor, if it helps
Thats the plugged air filter light switch check your are filters if you havent
Try as i might like i am sure you knew, i could not get it to duplicate the heavy smoke in relation to that sensor. It did smoke heavily upon start up (no smoke under low rpm's and then heavy smoke oh hight rpms for several minutes and then it stopped. I tried several more times to duplicate it but could not. I think i got what i was looking for in that (don't bother to replace the temp sensor" and that Cat ET is probably not going to help me here? I'm putting her back together now and will continue to monitor. Thank you for the help.
No et will not help you your in need of a pump and injector tune up/replacement
Most diesels do not "overfuel" in normal load situations, the air is not throttled so the amount of fuel injected IS the only control on engine speed. More fuel, more power and speed if the fuel is more than the load. More speed than the gov calls for, less fuel is injected, that's IT. (a turbo with an aneroid will limit fuel to prevent smoke under high load before there's enough air, that's the exception, maybe some with throttle plates also). Smoke is usually from timing, poor compression, oil burning, air in the fuel, maybe others.
That inj pump looks like it HAS been out..(no paint) and the teeth marks on the shut off solenoid (left side) only fuels that thought.. It’s possible that whom ever did the work on it, bumped the fuel up..?? Look to the right & down of the inj pump.. do u see an adjustment with a cap on it.?? OR any tamper proof laquer on any of the screws.?? Btw, how did u “clean” the injector tips.??
That's a simple switch that when the restriction in the intake system reaches a certain level it illuminates the "air filter restriction" light on the panel. No more, no less. The light comes on when wire 430 Blue is connected to machine frame ground.
This is kinda mean but if you thought that was a maf sensor you might not be as capable as you think with diesel engines. Maybe load a video if it running on YouTube then post a link here?