Diesel Blue Smoke related to Fuel?

Paul007

Member
I got a free Dozer! But it's a Fiat! Weird, but it really works good. So someone had messed with the injector pop off pressure adjustments and it was a bear to start and didn't idle worth a crap. But it didn't smoke a wisp. I made my own pop off checker out of a porta-power and set them all to the recommended 3,200lbs. Starts fine, idles, runs fine but smokes blue. Today I tried cracking the fuel lines while it was running, letting a bit of fuel spray out and the smoking stopped immediately. Tighten the lines and smoking starts. Night and day difference.

The engine oil in the 20 or hours I have used it has stayed ultra clean, cleanest I've ever seen in a diesel. Doesn't seem like a blowby problem. Does the new California diesel fuel smoke blue when rich?

What the heck is going on? I have no checked nor set the fuel pressure, just the pop off pressure.

TIA,
Paul
mvphoto20146.jpg
 
Make sure the fuel system is clean,if there is a priming pump check the gauze filter under the cover,what injection pump has it got.have you checked the pump timing,what model Fiat is it,looks to be a nice dozer.
AJ
 
Thanks AJ. Model is 605CSM, sold under the name Heston. But it's a Fiat. Pump is a C.A.V., whatever that stands for. Does have a primer pump. I have not serviced the fuel filters nor checked the pump timing. It had been regularly serviced and little used before I got it.
 
I am not familiar with that model but I am familiar with the CAV fuel system as it is very common here in the UK,with all rotary pumps a clean fuel system is crucial as there are things like the automatic advance that depend on hydraulic pressure created by the transfer pump [a small vane pump that is part of injector pump],if the automatic advance is not working the timing will be late and can cause smoke,read up on the manual and it will explain.
AJ
 
http://www.solidebolide.nl/downloads/CAV%20Workshop%20Manual%20fuel-injection-pump.pdf

Here is some information on the CAV pump. It's a Roosa design.
 
How much blue smoke?

Our FA 10 exhaust looks bluish against the light but only then with what now passes as diesel here
 
(quoted from post at 03:10:49 05/03/15) How much blue smoke?

Our FA 10 exhaust looks bluish against the light but only then with what now passes as diesel here

It's running in the top photo above. About that much.
 
OK. That is a lot more than ours, where you have to have it against the light. Our oil consumption says it isn't from there.
 
I'm a decent mechanic but fairly new to diesels. I thought fuel related smoke would be white or black. Mine seem to have no oil consumption either, and clean oil. The oil in my old VW diesel pickup is black as night and not a hint of smoke out the tailpipe, fuel from the same source.
 
By the rule of thumb black smoke incomplete combustion,lack of air,white smoke moisture in the fuel combustion area,blue smoke unburnt fuel,bad injector nozzles,nozzles dribbling,bad atomizing of fuel,late timing,does the engine have glow plugs or a thermostart plug in the manifold,if a thermostart check its not leaking fuel in.
AJ
 
The (*&^% operators manual is in Italian, but it does have some kind of heater in the intake, you are supposed to hold the starter switch in the cold weather position for 15 seconds if it's cold outside. I don't know if that is just an electrical thing or if there is fuel connected to it.

Hmm, bad fuel atomization might mean my pop offs are set too low, but cranking them up would make the timing later than it is I think, another symptom you mentioned.

I have to move some dirt today, I will try further diagnosis.
 
Those thermostart plugs in the manifold work by igniting fuel that passes through it,basically there is a fuel line to the plug and a power wire which is connected to a spring like element inside,the fuel is blocked from going through the plug by a ball and that spring,when you hold the key on heat the spring glows and goes weak,the fuel is allowed in and as it goes through the hot spring it ignites the engine sucks in the flame when its cranked over,if the spring is weak or burned out the fuel will pass through all the time the engine is running causing blue smoke,when setting the injector pop off did you test for dribble,pump the pressure up to pop off and hold a dry piece of blotting paper under each nozzle tip for at least 10 seconds before it stains the paper,if it staining the paper in less than that it is the cause of the blue smoke,e.i unburnt fuel pushed out on the exhaust stroke,have a look at your exhaust as it looks askew and the pipe might be closed up a bit causing back pressure.
Good luck
AJ
 
OK I found the thermodingus and pinched the supply hose off with pliers. No help. Had my phone today, check out this video. My arm is just below the camera window. At about 2 seconds I cracked one fuel supply line and let it spray out. After about 5 seconds I cinched it back up. Like I said, night and day difference. The other thing I noticed is when you goose it the smoke disappears while the revs raise, then it smokes again.

https://www.youtube.com/watch?v=hh9vDuS2E44&feature=youtu.be

When I set the pop off pressure I did not check the spray like you said, I just jacked them up until it sprayed out at the right pressure, and made sure it was coming out all three orifices. With the setup I made it would only spray for a second. Today when I first started it up I felt the exhaust manifold and thought the front cylinder was staying cold or cooler than the other three so I pulled that injector completely apart, did not find any dirt, put it back together, no help.

That lack of smoke with the line cracked should tell us something. Happens no matter which cylinder I crack the line on.

Thanks AJ,

Paul
mvphoto20378.jpg
 
OK I read up on how to do that in the manual but didn't have time to try it yesterday. Boy that pump is complicated piece inside isn't it? I had to use the dozer, when first started (about 60F outside) it miss fired some and the smoke was intermittent like Indian smoke signals. Once underway I kept revs high (around 2K) while pushing the dirt and by the time I was finished it was barely smoking and not missing. I wonder if the advance mechanism could be sticking?
 
Yes the fuel injection pump is complicated and it is a specialist job repairing them,setting them up properly etc using complex testing equipment,there are lots of rubbish on forums about diy pump repairs but you never see anything about the ones that are assembled wrong and cause a runaway that's put a rod through the block,reading over your posts again I think you should consider having the injectors reconditioned at a fuel injection shop,injectors nozzles and needles are are wearing parts,if the needle seats are bad they don't shut off the fuel after injection that dribble causes smoke,the whole of the fuel system depends on hydraulic pressure,if there is any restriction in the fuel system such as dirty filters or poor supply from the tank that can cause miss-fire and poor running,if you do want to advance the timing,look at the tag on the pump,there should be an arrow pointing the direction the rotor inside turns,you would move the pump body the opposite way to advance the timing,consider also of working the machine hard for a day to see if it clears up.
AJ
 
(quoted from post at 11:01:57 05/08/15) consider also of working the machine hard for a day to see if it clears up.
AJ

Thanks AJ. I used it again yesterday and it seems to be smoking less. A friend suggested trying some cetane booster as there may be some sludged up fuel in the bottom of the tank.

Most of the job I had at hand is finished and I can live with the smoking for the small stuff I have left to do, I just don't want it to damage the engine.
 
Got the dozer out yesterday after it sat for a month or so. Look at this video. It does not smoke at all at idle but as soon as I raise the revs just a few hundred RPM it smokes like the dickens. Lower it back down and it stops, like flipping a switch. Something it turning "on" when I raise the throttle that makes it smoke. Any ideas? Also note the crank case oil is still full and clean.


https://www.youtube.com/watch?v=R_LFJZN_MRk&feature=youtu.be
 
That looks like the pump automatic advance is not working,you are going to have to bite the bullet and have the pump and injectors serviced at a fuel injection shop.
AJ
 
(quoted from post at 17:10:46 06/16/15) Thanks AJ. Today it stopped smoking after awhile. Could the advance be sticking?

Just a quick update, no more smoke! I was searching online for similar symptoms and someone mentioned algae in old diesel fuel clogging up the pump/advance. Mine had sat for many years before I got it with fuel in it. I bought some diesel fuel additive and with a fresh tank of fuel it seems to have cured itself, used it every day last week with no smoke and even smoother running. Thanks to all who responded.
 

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