Mustang940E
New Member
Alright- new to this forum, was recommended by a friend and can't seem to find anybody having the exact issue I'm having.... With that said- I picked up a 96 Mustang 940E skid steer with a Yanmar 4TNE84-MS engine in it. When I got it, I went through all filters- from charge to hydraulic to fuel, oil, air, etc.. Also changed all fluids.
First off- if won't start without ether. If I crank it without spraying it, the engine fires and runs for a couple seconds and shuts off. If I give it the slightest whiff of starting fluid it will fire right up and I have full range of RPM out of the motor. This is the case whether the engine is cold or warm. Once running, the hydraulics and drive motors work. However, The machine will stall going uphill with nothing in the bucket if I don't feather the controls just right and go super slow. The machine also wants to stall and does stall when I lower the bucket and curl it back at the same time after dumping a load. Unless the ground is muddy and slippery, the machine won't even spin the (bald) tires on it without stalling. It will still lift over 1000lbs, as i have done with it, and It's still usable to move material and grade, but it's definitely not right, as I have to go super easy on it to keep it from stalling. If it is about to stall and I stop all movement, the engine will catch back up and continue running.
Since I have discovered this problem I have replaced all four fuel injectors, lift pump, and bypassed glass fuel bowl in case it was leaking, all factory parts. Drained fuel tank and ran all new lines, with the exception of the metal ones from injector pump to injectors. I have tried shutting the machine off and pinching the fuel line that goes to the injector pump in case it lost prime for some reason, but it doesn't make a difference. I have also gone through and adjusted the controls for the drive motors so that they are in neutral when the machine starts, as they were creeping before.
I was advised to look into hydraulics and that if there was more of an issue with the engine it would be smoking (which it doesn't) and/or I would not be able to achieve full rpm. So figuring there could be a load somehow on the engine trying to start, I did some tests-
There are two test ports on the machine for the hydraulics- the test port coming off of the charge pump going into valve body, and the other is right before the charge filter at the cold start bypass valve, which bypasses the charge filter and dumps back into the reservoir. The test port coming directly off of the charge pump I can only get to hold steady at 1700 psi without stalling the motor. This is done at full rpm, applying the auxiliary hydraulics. Manufacturer spec according to service manual is supposed to be 2400psi. The test port that is at the cold start bypass is supposed to have 250psi +/- 50psi and I can hardly get a reading on my gauge at full rpm.
I'm wondering if either of these hydraulic issues might be tied into the engine not starting and stalling out while i'm using it, or if there is anything else that I should be looking into to try and solve this problem. I'm really running out of ideas here, sorry for the long read, any thoughts? Thanks
First off- if won't start without ether. If I crank it without spraying it, the engine fires and runs for a couple seconds and shuts off. If I give it the slightest whiff of starting fluid it will fire right up and I have full range of RPM out of the motor. This is the case whether the engine is cold or warm. Once running, the hydraulics and drive motors work. However, The machine will stall going uphill with nothing in the bucket if I don't feather the controls just right and go super slow. The machine also wants to stall and does stall when I lower the bucket and curl it back at the same time after dumping a load. Unless the ground is muddy and slippery, the machine won't even spin the (bald) tires on it without stalling. It will still lift over 1000lbs, as i have done with it, and It's still usable to move material and grade, but it's definitely not right, as I have to go super easy on it to keep it from stalling. If it is about to stall and I stop all movement, the engine will catch back up and continue running.
Since I have discovered this problem I have replaced all four fuel injectors, lift pump, and bypassed glass fuel bowl in case it was leaking, all factory parts. Drained fuel tank and ran all new lines, with the exception of the metal ones from injector pump to injectors. I have tried shutting the machine off and pinching the fuel line that goes to the injector pump in case it lost prime for some reason, but it doesn't make a difference. I have also gone through and adjusted the controls for the drive motors so that they are in neutral when the machine starts, as they were creeping before.
I was advised to look into hydraulics and that if there was more of an issue with the engine it would be smoking (which it doesn't) and/or I would not be able to achieve full rpm. So figuring there could be a load somehow on the engine trying to start, I did some tests-
There are two test ports on the machine for the hydraulics- the test port coming off of the charge pump going into valve body, and the other is right before the charge filter at the cold start bypass valve, which bypasses the charge filter and dumps back into the reservoir. The test port coming directly off of the charge pump I can only get to hold steady at 1700 psi without stalling the motor. This is done at full rpm, applying the auxiliary hydraulics. Manufacturer spec according to service manual is supposed to be 2400psi. The test port that is at the cold start bypass is supposed to have 250psi +/- 50psi and I can hardly get a reading on my gauge at full rpm.
I'm wondering if either of these hydraulic issues might be tied into the engine not starting and stalling out while i'm using it, or if there is anything else that I should be looking into to try and solve this problem. I'm really running out of ideas here, sorry for the long read, any thoughts? Thanks
