Coming here to hopefully get some help on this. Sometimes this thing busts right off, sometimes it’ll crank for 30 seconds and not start. It will do both when engine has set for 3 days, or even if its ran for 3 hours, shut it off, try to start it right back and it’ll either start right up or not start at all. I have changed all the filters, checked pressure in diag mode and with a manual gauge. It’s 20 while cranking, 31 when it starts running. I have put a new check valve return T in, all new hoses and clamps, new primer housing, iv checked the tank and the suction tubes in the tank. No fuel in the oil. No codes in the computer. I have pulled both crank and cam sensors to ohm out but don’t know the specs on the sensors, but both are around 3500ohms. I’m still thinking a sensor is going bad or electrical, any help would be great.
Welcome to HEF Scramblerman ! Let's start with the machine's serial number, please. Have you tried a clear line (make a vertical loop) in the fuel return circuit to watch for the presence of air?
Thank you sir! I have and there are no bubbles/air at all. Machine serial pe4024r101928. I may have just figured out the issue. There are chaffed wires on the ecm plug, the further plug to the front of the machine on the ecm, 3 black wires and 2 red ones.
Sorry that is the engine serial. The machine is 1T0323DKVOG231831
So I take that back, I put the clear hose back on the return to double check, there are really small bubbles. Not the whole time running though. And the engine will miss a little every now and then
If you scroll to codes, there are none, even in stored? The bubbles and the miss coincide? If you have an infrared temp gun, shoot exhaust temps while it is missing to see if we can determine a colder cylinder. Be aware that the cylinder difference between the center cylinders will be considerably higher than the front and back cylinders. Post the results. Many hours on this machine? Post a picture of the machine's serial plate. That number does not come up. 2500-3500
There are no codes in stores or active. It’s really more of a sputter, and only does it for a split secound, but I will get the readings. It bubbles almost constantly, so no to coinciding. It actually bubbles a more than I originally thought. 1000 hours on machine.
Are the bubbles something you think will show in a photo or video? If you place a clear line (capable of handling 30+ psi) between the final fuel filter and the inlet to the block, and there is no air there, then the only place for air entry would be either the injectors or the injection pumps.
I have red fueling and i feel like they would show in a video, I will try. My place is to put a clear hose on suction before lift pump and after the final filter to see where it’s coming from. Hopefully I find it there and it’s not the pumps lol
Bubbles in line Temp on each cylinder starting from accessory drive cylinder 1 is 207, 2 is 125, 3 is 292, 4 is 298. I also put a clear hose after water separator and had zero bubbles. So to me it’s either the supply fitting in block or what you said about injectors/pumps. If those are bubbles to be concerned about.
The amount of air I see in the video does not seem excessive. An occasional air bubble here and there is normal. What I am looking for is a steady stream of bubbles. What concerns me is the temperature of the #2 cylinder. There may be an issue there. Has the intake system been inspected for possible dusting?
The temp never stayed that temp for very long, I was trying to catch them all on the miss. The miss happens for a very short amount of time. Cylinder one I could check sometimes and it would be around 150, the rear two were always hotter. I has new filters in it. What do you mean exactly by “dusting”? I haven’t tore it apart at all other than changing filters
So I check it again with my IR GUN, now cylinder 1 is 106, 2 is 334, 3 is 343, 4 is 297. Not sure what is going on with this turd. The miss is literally every 20 seconds for about 5 seconds long. Could there be a sensor going bad? Or the ecm? I’m now sure why the temp would change to a different cylinder?
This to me sounds like some kind of air ingestion. It could also be from a faulty pump/injector. I have seen both to be the cause of air ingestion, hard starts, intermittent issues. Even though we have replaced many pumps and injectors on these units for this issue, I am just reluctant to say for sure it is them without being there and performing some additional steps, one of which involves diagnostic software, a compression check and an inspection of the pushrods (check for any bent ones). Has ether ever been used? That would prompt me to check cam timing since ether can cause the cam gear to slip (why I check the pushrods). It is not likely an ECU issue. Dirt ingestion through the intake. Removing the intake hose from the side of the rocker cover and inspecting for the presence of dirt. I also remove the air cleaners and look at the inside of the curve of the hose to see if there is visible dirt that will show up when you run your finger through it. Check your messages.
I greatly appreciate your help, I’ll check for the dirt in the intake. I read over the files you sent, I can tell you 100% the system does not keep 4psi for over 15 minutes when shut off. I can do a compression check and possibly get dish software as well, I’m replying back to your message
Never mind on the reply, I did ask the local dealer for all of that info and to print it off, but no one there knew how. They also told me cranking should be 7psi…. Crazy how much miss information you can get from a dealer. I really appreciate all of the help. I’m going to start from the top and do exactly as the files say. And I have used either to bust it off when it don’t start right up.
So I got engine to 30psi fuel pressure, pinched off supply to the water separated and return to tank, pressure drops to 0psi within 5 minutes. Read temp on each cylinder like the info you sent me, I averaged the readings since it wanted multiple readings per cylinder. 1 is 170, 2 is 345, 3 is 434,4 is 366. I checked for dusting, did not find anything in the intake boot or filter boot, but I stuck my finger in the intake of engine and got some oily grease looking crap. Picture attached. I’m assuming this isn’t normal There is no abnormal crank case pressure. I’m to the point I need to do a compression check and start pulling injectors/pumps as far as I can tell.
It is not uncommon to have a bunch of goop like that in the intake runners, just not that heavy. #1 cylinder temp is a concern. If the lines were pinched in a way that fuel cannot return to tank in either direction, and the return check was replaced, but it drops to 0 in 5 minutes, I would definitely be looking at the injection system. Was the fuel transfer pump in that circuit when pinched?
The transfer pump was isolated from the test. It was just testing the injectors/pump and the fuel supply fitting in the block it you want to get technical
If fuel pressure is staying at 20 psi while cranking and 31 psi running, I'd be leaning away from a fuel supply issue. An intermittent no-start with no codes can definitely be caused by a failing crank or cam sensor, especially if the ECM occasionally loses the signal while cranking. Next time it won't start, check if the ECM is showing engine RPM during crank. If RPM drops out or reads zero, that's a big clue. I'd also inspect the sensor wiring and connectors closely before replacing parts.
The screen on the skid steer won’t show rpm while cranking and not starting, or when it fires right up. It only shows rpm once it’s running. Assuming I’ll need a scan tool to do that. I’m not thinking it’s a supply issue anymore, leaning more towards injector/pump. I’ve looked over the wiring, I’ve even changed the cam and crank sensors out of a buddies machine just to try it.
So I done a compression test, 325, 395, 400, and 400, as cylinders 1234.
#1 is outside of the 10% margin, making it low. However, if it got washed down with fuel, it might be lower due to that. Concerning what @stephenrobinson98741 said, yes, hard starting can be attributed to low cranking speeds, which affect the cam sensor mostly. Because the crank sensor has so many teeth to read, it provides a better signal at low cranking speeds. The cam sensor, with fewer teeth to see (weaker signal), will tend to drop out when the cranking speed is too low, making starting difficult because the ECU now has to figure out where #1 cylinder is at (compression stroke or exhaust stroke). Usually, when cranking speed is low, it will throw random cam sensor DTC's. For reference, minimum cranking speed for that engine is 250 rpm.
So I done another compression test, squirted a little oil in cylinder one and tested again, got to 400psi, so made me believe I had a washed cylinder. I removed engine from skid and got the head ripped off, the cylinder one piston was pretty clean, very little carbon like 3,4, and 5. Assuming due to all the raw fuel it was not burning. Cylinder and piston look fine. Can’t see anything obvious on the injector either. Going to get injectors tested this week. Should I run a ball hone in # one with new rings and piston? Any recommendations?
Well, I didn't expect the engine to be pulled just yet. At a minimum, a thorough inspection of the pump O-rings along with the pop testing of injectors. If the injectors pop OK, and the O-rings look good, then the pumps should be replaced as well. If you do one cylinder, why not hone and re-ring all 4? I don't think you will need to replace any pistons, unless it is scored or there is excessive piston to bore clearance. If you buy a piston, it comes with rings and a wrist pin (as a kit). A word of caution. Make sure the valve lifters are collapsed when you reassemble the valve train or you WILL bend pushrods at start up.
I would check for taper in all cylinders but especially in #1.