Diesel Engine "Surging" or "loping"

[Jerry/MT]

Nothing like surgery to take you off-line at the tractor and the internet

(Original question was about engine surging on a Branson 3510H (year=2010). Engine rebuilt and injector pump replaced 200 hours ago (under warranty)

I changed the fuel filter - it didn't have a lot of crud. Also changed air filter, since it was quite dirty.

After changing the fuel filter I primed the system - or thought I did. I opened each nut (flared pipe), one at a time.I cranked it until bubbles stopped, and tightened the nut. The difference in how the engine ran was insignificant.

Ignoring Einstein's advice, I tried the same thing again hoping for a different outcome.

The next time I opened each nut more - one at a time - and cranked. I got a feeble spray squirting out if each fuel line. I was expecting a flow of diesel.

QUESTION: is this the right way to bleed it?

When I started the engine, it started easily (all things considered). It runs without surging. Too soon to celebrate! Moving throttle handle 1/2" either "faster" or "slower" made the speed move instantly to 500 or 2100. Not slowly, instantly: before I could count "one thousand-one" either way (faster or slower), the speed flips between minimum and maximum.

Sorry Einstein, but I did it again. Now it runs mostly smoothly (very slow and small fluctuations) but has very little power.

By the way, I'm sure the dealer drained the fuel: the fuel gauge has been wrong all the time, ever since.

1. I idled it several minutes and then ran it at 2100 for several minutes. It runs runs smoothly, but it has "no" power. At 2100 lifting the bucket slowly almost kills the engine.
2. I backed the tractor up a small incline and ... it kills the engine.

Since bleeding makes a difference - but not enough difference, I assume that there is some blockage or remaining air bubbles.

What should i try next?

The fact that it idles throughout the rpm range but won't run under load implies a fuel delivery issue. Most commonly this is cause by a blockage at the tank strainer, the fuel filter head, or the fuel filter itself. You changed out the fuel filter so that isn't the problem. Remove the fuel cap, open the line at the tank out let and use compressed air to blow back through the tank strainer. If you get a temporary reprieve from the symptoms then you've found the problem. Bacterial sludge can form in the tank due to water in the fuel. Water can get in there from normal condensation and you'll need a biocide to kill the bacteria. Sea Foam won't do it. If there is a clog, you have to drain and flush the crud out of the tank or it will be a recurring problem. Keeping the tank as full as possible can help reduce water accumulation. If treatment with compressed air does not work, check the fuel passage in the filter head to make sure it is not clogged.

Generally bleeding the system consists of bleeding at the filter head , bleeding the pump, and then bleeding the injector lines ( not the injectors themselves). You owners manual should tell you how to do this for your specific model.. If you don't have access to one, I can give you some general instructions.

 

[artfull dodger]

I agree on a fuel delivery system problem. Had one tractor have a crack in the line inside the tank, would stuck little bubbles of air into the line when the fuel was below the crack. Bacteria crud blocking the pickup screen will do it to. I also recommend Power Services (white bottle) in the fuel, helps with cold weather gelling, raises the Cetane number a bit and helps with other stuff. I also keep thier orange Diesel911 in my tool box just in case(its for fuel already gelled up). Does the tractor have a lift or pusher pump that feeds the injector(high pressure) pump? A failed or weak lift pump will starve the injector pump for fuel at higher rpms, but run fine many times at low rpms, just lack power when it needs to. Many times the injector pump can pull its own fuel, but not enough to run well or even keep the injector pump safe ie the Dodge 24valve with the VP44, a failed lift pump quickly kills the expensive VP44 main injector pump. Good luck. Mike

 

[Soundguy]

Ditto on fuel obstruction.

These things are just fuel powered air pumps..

 

[artfull dodger]

suck squeeze bang blow

 

[Soundguy]

....go diesel go

 

[Chlawson]

Mine was doing something similar but was a little low on power. The actual fuel lines were clogged. I had to take the inline filter out and blow the lines out with an air hose.

 

[PJ The Kid]

Its is possible algae problem, we have had that issue at work and now have to add algicide (sp.) to out 10k underground tanks. If that is the issue, you will need to thoroughly clean the tank and ALL lines. I don't think it is a governor issue as it is fluctuating, most gov. issues will just let it die without trying to catch themselves. Possibly pump timing or (depending on pump design, not familiar with this machine) an advance issue, Is the pump loose on the bracket at all? If you are getting small improvements every time you bleed the system, I would look there or look for somewhere the system is sucking air.

 

[THennessy]

I am no diesel expert, my deceased brother maybe was, but I know common issue on gas/ diesel generators on RVs/ stationary equipment is the electric fuel pump. On gas, intermittent/ failing operation of pump causes surging, dying and hard start/ no start/ no restart until cooled. All this in gas engine as symptom of float bowl level being low. I know in diesel that electric "Lift pump" often feed the high pressure mechanical pump that feeds injectors. If tractor gravity feeds fuel to high pressure pump, ignore this/ but if electric pump used, consider electric pump and rubber low pressure fuel lines as possible culprits. I know every engine requires free flow of fuel to the metering device/s vs restricted. I also know most/ all diesels have water separator/ filter. Have you drained and checked that? and if electronic controls in engine, does it give error codes thru flashing light. If so, get the book/ chart to read the codes?

 

[THennessy]

Its is possible algae problem, we have had that issue at work and now have to add algicide (sp.) to out 10k underground tanks. If that is the issue, you will need to thoroughly clean the tank and ALL lines. I don't think it is a governor issue as it is fluctuating, most gov. issues will just let it die without trying to catch themselves. Possibly pump timing or (depending on pump design, not familiar with this machine) an advance issue, Is the pump loose on the bracket at all? If you are getting small improvements every time you bleed the system, I would look there or look for somewhere the system is sucking air.

One issue about algae in fuel is that it only grows in the water that is in the bottom of the fuel tank/ fuel bowl, but once grown, fuel movement can cause it to break loose and move in the fuel itself and clog filters, jets, nozzles. Algae can also lock down moving parts like needle/ seat, or solenoids/ plungers.

 

[THennessy]

I do now see this post is 9+ years old, but OP did not post final resolution? HERE IS ONE youtube that may help some/ others, and there are several other videos on diesel engine surging: