IH 684 surging

[vezult]

I was doing some mowing with my IH 684 tractor, and about 30 minutes in, I noticed my engine sounded as if it was it was slowing slightly, and then it dropped off noticeably, and started to "surge" then back off, then rev, then back off, etc. I stopped, stopped the cutter, and it evened out. I continued on, made another round, and it was fine for a bit, and then it returned, and got increasingly worse. I drove it back to house and turned it off.

On the face of it, it sounds like a fuel problem. I've got half a tank of fuel, fuel filters have been replaced quite recently, and I mowed for several hours on the same tank of fuel just this past weekend - no problems whatsoever.

Also recently, I drained and replaced the coolant in this tractor. This was prior to its use this past weekend. I mention this because it was a recent change. My thermostat didn't show any high temp (I assume it works). Is this behavior that could be explained by overheating? That seems unlikely to me to be related...but what do I know?

Anyway, any trouble shooting advice?

Assuming fuel:
* The fuel itself (contamination?)
* Tubing (flow)
* Filters
* Injector pump
* Injectors

Any other possible culprits?

 

[Dieseltech]

Make sure the flow AT the injection pump is good with the inlet banjo removed from pump. Any restriction from tank to pump will upset the hydraulic governor inside. Might
be the fuel cap vent is plugged, no fuel out if no air can get in.

 

[tractorsam]

Once the fuel gets to about half on those tractors any
blockage in the tiny balance line between the two sides can
cause in to run out of fuel with the gauge still showing half a
tank. Refill your tank and see if your problem goes away. If it
does remove and clean (after draining the tank) the small line
that goes from one side to the other across the back of the
tractor.

 

[caterpillar guy]

I probably work backwards to most. I start at the tank and check flow then go to the next line split at the filters and so on. I would look for dirt in the bottom of the tank in the fitting or the cross over line Also if the valve is fully open. If all these check out good then change filters again if the spin ons just do as normal. If it has those stupid glass bowls with the short filters check your rubber gasket is in the right place and not stopping fuel flow. If it is starting hard check for leaks at thos filters if it has the filters with the glass bowls. this would leak as well as could be the surging and hard starting.

 

[JimB2]

Hi same as other posts but I start with a clean bucket and remove the fuel line where it comes into the first fuel filter on the front right of the engine, let it drain into the bucket for at least 45 seconds,
the fuel flow should be the full of line, if not the problem is back in the tank, usually on the outlet at the bottom right tank gets blocked with debris. The left side is the return line and the equalizer
line between the two sides, like one of the other posts said if this line is blocked it will use all the fuel out of the right side and there will be fuel in the left side.

Very common problem on the IH 74/84/85/95 series of tractors.
If you require service manuals the European IH 74 versions are posted at link below, the 684 is just one version newer with a few changes from 674.
Manual 674

 

[vezult]

(quoted from post at 09:28:53 03/17/21) Hi same as other posts but I start with a clean bucket and remove the fuel line where it comes into the first fuel filter on the front right of the engine, let it drain into the bucket for at least 45 seconds,
the fuel flow should be the full of line,

Sorry, I'm not sure I understand the last bit. Are you saying that fuel should be filling the full width of the line, not draining, with a gap at the top curve of the tube? Just want to make sure I understand what you mean.

 

[vezult]

(quoted from post at 04:43:40 03/17/21) Once the fuel gets to about half on those tractors any
blockage in the tiny balance line between the two sides can
cause in to run out of fuel with the gauge still showing half a
tank. Refill your tank and see if your problem goes away. If it
does remove and clean (after draining the tank) the small line
that goes from one side to the other across the back of the
tractor.

Would it make sense to remove the fuel gauge on the right hand side, and look into the tank? If it's not being equalized, then the fuel might be significantly higher on the left side vs. the right, correct?

 

[JimB2]

It should run out at a constant rate, not slow down to a dribble. The rate will depend how much fuel is in the tank, the more fuel the more pressure.

 

[vezult]

(quoted from post at 19:46:41 03/17/21) It should run out at a constant rate, not slow down to a dribble. The rate will depend how much fuel is in the tank, the more fuel the more pressure.

Got it. Thanks.


Thanks to everyone for the advice! Really appreciate it. I'll see what I can figure out this weekend.

 

[vezult]

Thanks everyone. I think I have it resolved...we'll see.

I tried starting the tractor this morning, and could not.

I disconnected the fuel line at the filters, and was getting no fuel. I checked the same line back at the tank, and seemed to get plenty of output there.

I checked the equalizer line between the tanks and got good flow there. I disconnected the line from the tank to the filters at both ends, and used an air compressor to blow out the line. I couldn't see both ends at once...so I'm assuming I blew out some gunk.

Hooked the line back up to the tank...no flow. Nothing. I still don't understand quite that. The only thing I can think is that there just wasn't enough fuel in the right side of the tank to push fuel the whole way to the filter. Tractor was parked so that the front end was slightly elevated, and so was the right side, so that might have simultaneously ensured there was less fuel pressure, and a harder push.

Anyway, so I just put more fuel in the tank, and then it worked. I bled the line and filters, and it started fine, and I ran it for several hours with no issues.

Anyway, while I believe it is fixed, I suppose I'll see for *sure* if it is fixed when I get back down to half a tank

Thanks everyone, for all the advice!