18" bandit problems

[imagineero]

Hi all,
Going to give a buddy a hand trying to get his chipper going tomorrow, it's the 4cyl 140hp perkins turbo diesel, 2006 model. He bought it from new and has kept up with the servicing but it does have a lot of hours on it.

Lately its started losing revs when chipping. Not by much, just enough to stop the rollers feeding. It's intermittent and no logic or rhythm to it - happens whether tanks full or empty, under load or not, but does seem to get better when warmed up. Not always though. It only slows down for a brief second, then picks up again. This has been going on for a couple weeks but getting worse.

We're suspecting fuel problems so going to try draining and flushing the tank, checking fuel hoses for leaks, changing filters. Any way of testing the fuel pump? Testing the injectors is probably beyond our abilities.

Any other ideas what might be causing this? It sure does make chipping a pain :-(

Thanks,
Shaun

 

[treemandan]

Check adjustment of throttle cable. Make sure when hand lever for the throttle is set in high detent the rpms match recomended autofeed rpms as per repair manual.It only has to be off a hair to stop auto feed. There are two detents for the lever, the idle and the run.

You can also adjust the computer to allow autofeed to work at lower rpms but I wouldn't unless I was in a pinch and was working the stop bar. You can disable the autofeed and work the stop bar too but I think all you need is a slight tightening of the pinch bolts on the end of the throttle cable. Also make sure you are actually setting the hand lever for the throttle in all the way into the high detent. I have notice some people just throw the lever up and its not quite dropped into the detent.

On mine the autofeed is set to come on at 2700, at 2699 it don't. Lubrication of the throttle cable and lever is important on these things too.

 

[no tree to big]

does it smoke at all when doing its thing? we had a chipper, believe the same motor but in a 15", that did the reving thing and would smoke pretty good too we ran 100 gallons of fuel through it atleast when it was f'd up cause we already had two chippers in the shop and had to deal with it... it turned out it had water in the fuel. it had a fuel/water seperator and I drained it like every other day but it still acted up even with having so much fuel run through. I think they drained the tank and completly emptied the lines and added new fuel and it was fixed??? what I dont understand is how the water even got in there or why it wouldn't have eventually gotten used up with so much use

 

[squad143]

I'd start with the fuel filter.

 

[MarquisTree]

Electronic throttle? All of our chippers 2003 and newer have throttle switches not cables.
Had an issue similar to urs with our oldest Woodsmen, the throttle switch was worn out
Same machine around 5k hrs had some weird loss of rpms and some smoking, it was high pressure fuel pump.
don't adj your auto feed to mask an issue, it can help u get thru a day or two but def not a solution.

 

[imagineero]

Thanks for all the good advice guys, we futzed around with it for a day but nothing seemed to help. My buddy took it in to a guy who specialises in the control modules and he sorted it pretty quick. The problem had something to do with the glow plugs/power supply/sensor. Apparently the computer was sensing that the glow plugs weren't hot, so it made the injectors flood the engine. At least thats what the electrician said. He did a temporary re-wire to get around it and parts are on order.

Shaun

 

[VA-Sawyer]

Sorry, but that doesn't make any sense. The glowplugs are only used during start. They have nothing to do with how it runs!
Rick

 

[imagineero]

yeah, didnt make any sense to me either. I havent looked at the schematic though. I'm only hearing it 3rd hand, but my interpretation of it was that there is a sensor which decides whether the engine is warm or not, and if not yet warm it leaves the glow plugs on and sends more diesel down the line. The sensor went south and decided the engine was always cold which screwed the power supply for the glow plugs and kept the engine permanently overinjected. Will see if I can get a bit more info on it.

Shaun

 

[VA-Sawyer]

That makes even less sense, diesels don't have a throttle plate to reduce airflow like a gas engine does. They get full airflow even at idle ( turbos get more airflow at higher power so they can add more fuel), so any 'extra' fuel will simply produce more power, ie make it run faster. Too many people want to think of diesels as running lean or rich like gas engines, but that doesn't happen except at the high end when you are injecting more fuel than there is air to burn it. That is why tubo diesels can produce so much more power.
If that is truly what the mechanic said, then he doesn't understand diesels.
Rick

 

[imagineero]

Sorry mate, I guess you must be right and the guy who got the machine running perfectly again doesn't know what he's talking about. I'll let him know next week ;-)

Shaun