930G Sputtering and Cutting Off

Have a 930G here seriel number TWR

She fires right up every time no problem. However intermittently she likes to sputter and/or cutoff. Could be 1 time per hour or 10. Throttle can be any position, bucket can be any position, at idle or while running hard. Seems like it sputters more when you run higher throttle for a minute or so. Maybe a fuel pressure issue?? The injection pump looks relatively new, but we bought the machine at auction and have no known history.

Have replaced all rubber fuel lines, fuel filters and fuel lift pump. Blew air back into the tank to make sure lines were clear. Also inspected fuel tank and fuel looks good and no visible debris.

Thinking injection pump but would like to confirm before replacing. Anyone have other suggestions of possible culprits or maybe the proper way to test injection pump?

Thank yawl for reading.

While checking/cleaning have you looked for any small screens (not sure there are any on the 930G, need to check) that are located inside banjo bolt fittings (for example).?
Also have you drained any water and sediment that might have accumulated in the fuel tank.?

Had a 950G with debris stuck in the primary filter head

Haven't come across any screens yet, but I haven't been looking for them. All the rubber lines we replaced just slide on with clamp so no banjo fittings have been pulled. I'm gonna check the filter housing connections like Jonas 302 suggested and I think they are steel lines with fittings so maybe there will be a screen. I dunno if catparts.com diagrams are that accurate but there do not appear to be screens on that picture.

We been wondering if it might be electrical because the fuel filters and tank all looked so good, no water or sediment. Its almost like it shuts the fuel off sometimes and othertimes shuts it off for split second causing the sputtering. Like a fuel cutoff solenoid energizing for a second. But then we keep going back to fuel because after running high throttle for a bit she tends to sputter or cutoff more regularly, like it's a lack of fuel pressure.

Wastepro said:

I'm gonna check the filter housing connections like Jonas 302 suggested

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You should. They are famous for getting plugged with small particles. IIRC the head of the water separator has to be removed and worked on upside down to get access the the internal passages.

Wastepro said:

We been wondering if it might be electrical because the fuel filters and tank all looked so good, no water or sediment.

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So you did drain the tank then, or at least opened the drain tap for a few seconds.?

Does it make any difference to the symptoms how full of fuel the tank is.?
i wonder if there could be something floating around inside the tank that under certain circumstances is getting sucked up against the fuel pickup tube.? That would not show up when the water/sediment was drained.

Would it be possible to temporarily tee into the line somewhere between the secondary fuel filter and the injection pump and install a pressure gauge in the cab somewhere convenient.? Then when the engine starts to act up the operator or mechanic can see what the fuel pressure is doing.

Nige said:

You should. They are famous for getting plugged with small particles. IIRC the head of the water separator has to be removed and worked on upside down to get access the the internal passages.
So you did drain the tank then, or at least opened the drain tap for a few seconds.?

Does it make any difference to the symptoms how full of fuel the tank is.?
i wonder if there could be something floating around inside the tank that under certain circumstances is getting sucked up against the fuel pickup tube.? That would not show up when the water/sediment was drained.

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We didn't drain the tank from the bottom, will do so today. We pulled the pickup to inspect the tank visually and blow out the pickup lines because I was concerned that a piece of debris was floating in the tank and clogging the lines periodically just like you suggested.

Doesn't seem to matter how full the fuel tank is. We are going to dig into those filter housings today or tomorrow and Ill post back.

Did you replace the fuel tank vent?

Mike85 said:

Did you replace the fuel tank vent?

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No but I did try running it without the fuel cap with no luck.

I had had similar and different problems with those. Check out the thermal fuse kind of thing on the right side of the of the engine.
Use the search block for 930G. All that info may still be there.
Nige is a great resource. I appreciate him.