Motor dies under high rpm heavy aux load

bigboytoy · Nov 3, 2019

I have a high flow T300 ... with a trencher attachment engine running at 1600 rpm on high flow or not it runs normal in the air or in the ground ... when I ramp up the rpm to 2000 it will run 5 seconds then cough, drop rpm, drop pressure, and die unless i release the aux (trencher) ... if I have released the aux the engine will stumble smoke and stumble a little more and then it will get back to 2000 rpms running smooth.

Delmer · Nov 3, 2019

You seem to be going at this from two directions, so one thing to watch for: when it first starts to stumble, is there any dark or even visible smoke? If there's no smoke, I'd look at fuel supply issues first.

How about trying to climb a hill in top speed, can you get it to do something similar? The brush hog should be a good comparison too, don't bother with the post hole digger, not enough flow to do it.

Vetech63 · Nov 3, 2019

Guess I better read better. I thought this was losing hydraulic capacity. What Delmer said ^ X2

bigboytoy · Nov 3, 2019

I am changing all engine filters and oil just for good measure. there is smoke when the engine is choking/stumbling ... I got no hills to try it on... but if I do too quick of a 90 degree rotation I can stall the machine... next week i with hook up the brush hog it is high flow type with drain line ... I also have a tiller that does great on high flow ... just to see if they also can cause engine to stumble... thanks for the ideas!

bigboytoy · Nov 3, 2019

guys it could be engine or hydraulics in my mind... I don't have what it takes test GPM flow out of aux ... engine starts and run fine usually, glow plugs work, starts when its cold...etc I am just trying to keep an open mind... solve easy cheap things first by just buying and changing out.

Junkyard · Nov 3, 2019

How many hours on the machine?

From the engine side of things I’d be looking at fuel filters and air filters first. Next I’d make sure there’s no fuel line restrictions or trash in the tank. Does it have a mechanical or electrical fuel pump? Either could have a screen that’s full of trash and starving when under full load.

Hydraulics could be a case drain issue with that particular attachment, a relief issue, a flow issue with a coupler or hose. I’ve also seen the computer set wrong as far as flow type and it will flat kill a machine. One of our drill rigs had issues and I finally discovered somebody had been messing with the computer and had the darn thing setup in hammer mode and not full power mode. It would dang near kill the machine.

Food for thought.

bigboytoy · Nov 3, 2019

so the smoke indicates fuel is present .... then load is too great? but I get 5 second of it running normal before it chokes ... hmm any thoughts? I kill aux so engine does not die... once i gets it back up to speed i get another 5 second then it chokes.

machine has 2800 hours on it I don't think there is any flow type options.. i have a gauge on charge pressure and it is at 390 but simply drops when it chokes at same rate as engine dropping rpm ... I got all new filters on the way to try

Ronsii · Nov 3, 2019

Did this used to work? and just now started doing this stalling thing?? or did you just get the trencher and now it stalls??? Sorry

but it's not real clear in your post... cause it sure sounds like too much flow for the attachment.

Delmer · Nov 3, 2019

Yes, if you have smoke present, then there's fuel present. You say "cough and choke", that sounds like sputtering to me, an overloaded engine should not cough, choke, sputter or misfire. It should get louder, and only rougher as it gets into the lugging range. So if an engine is rated at 2,800 RPM max speed, then it lugs down to 2,000 it's going to be louder and rougher sounding, and at 1,600 RPM it will shake worse, but it shouldn't sputter anywhere in that range. That sounds like air in the fuel to me, not enough fuel (low pressure) will slow the engine down because each injection stroke is lacking fuel (more or less evenly). Sputtering is one injector gets fuel, and then an air bubble comes through and nothing happens until the air is passed, and it runs again.

Start with the fuel filter, this has nothing to do with oil, probably nothing to do with the air filter. If the fuel filter doesn't change anything, then look at the rest of the fuel system, tank to pump especially.

funwithfuel · Nov 3, 2019

Why don't you stick to one thread?

bigboytoy · Nov 3, 2019

very good feed back guys thanks.... this trench is a new attachment for my machine .... I will change all filters regardless ... I understand and am familiar with the heavy load sound and I am not getting that ...it seems to just sputter/choke and drop in RPM ... it has a mechanical fuel pump ... i see a air bleed port on filter hmm besides checking for air it could be a good location for a fuel pressure reading. thanks it will take me a week to get back with some answers,due to a leak needing parts.

bigboytoy · Nov 5, 2019

correct me if im wrong... if the gear pump has low output = less load on engine

DEMLONE70 · Nov 5, 2019

What are the specs of trench ?

thepumpguysc · Nov 5, 2019

A gear pump.?? only 1 I know of is in a DripTroit engine..

bigboytoy · Nov 5, 2019

the trencher is good with 15-44 GPM

bigboytoy · Nov 5, 2019

whats are the symptoms when turbo charger fails?

funwithfuel · Nov 5, 2019

Black smoke, low power, intake pipes suck closed in extreme cases

bigboytoy · Nov 5, 2019

I capped off hydraulic leak ..started engine warmed it up ran it wide open it did 2500 rpm it ran for 5 seconds and started choking without a load... I never run it that high until I got this trencher ... so I am thinking restriction in the fuel line... weak fuel pump...?

Nige · Nov 6, 2019

bigboytoy said:
... so I am thinking restriction in the fuel line... weak fuel pump...?

Personally I would go looking at all the connections on the fuel system first. This sounds like a classic case of a fitting somewhere (often on the inlet to the injection pump) that has a fine screen in it - said screen being plugged up with sh1t......

bigboytoy · Nov 6, 2019

Nige... sounds like a good idea ... I will go through all lines and replace pump and filter ... the only pain is the feed tube from the tank, it would be very difficult to remove, tank would be difficult to clean, air blow back is all I can think of... maybe create an electric pump filter and back to the tank idea, then let it eat for a while....

Motor dies under high rpm heavy aux load

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