Hi guys. Hoping to get some advice from the more experienced members here. I have a Cat304CR which I bought about a year ago for working on my property. Not sure of year or hours as the meter has been changed, but it's an older machine. I have used it at least 20 times, maybe more - probably 3 tanks of fuel worth. It has been running well, no problems until now. In the last few days, it has developed a problem. When I first start it, it starts right away and runs well for 3 to 5 mins, then the engine begins to bog down as I use the hydraulics. Not for digging, just operating the boom/stick/bucket cylinders or moving the machine. I need to back right off and be very gentle as if I continue to use them as normal the engine will stall. This happens regardless of throttle position. Prior to this happening, I put in 20L of diesel as it was really low on fuel. I wondered if this was related so I removed the fuel/water separator and blew compressed air through the fuel filter and lines back to the tank to make sure there was no gunk or blockage in the lines. Also removed the banjo bolt and checked it wasn't plugged up. Made no difference, still doing the same thing. Engine doesn't blow smoke - load or no load. Nothing has been tampered with or adjusted so it's a problem that has developed on it's own.
Theres 2 things it can be> fuel pressure or hydro. pressure.. either way u gotta put gauges on it.. By chance does it have a hand primer in the fuel system?? IF YES, get someone to pump the HP while U work the hydros & see if it stalls.. THAT"LL "just about" rule out the fuel system??{maybe}
Thanks, I'm thinking fuel system. I used it for a few mins today to check if it was still doing it and sure enough after 5 or so mins I felt the engine bog down. I went to shut it down and dropped the revs to idle and the engine cut out on its own with no load whatsoever. It's never done that before. always idles OK. The engine is a Mitsubishi S4L, don't think it has a hand primer. Where would I put the gauge?
I would replace that fuel filter. I'm not a fan of blowing compressed air back thru them. You may not be filtering anymore and soon may have more problems.
Had the exact same problem on a 304 or 305 a few years ago. Pulled up the floorboards and removed the fuel sending tank sending unit to get a visual inside the tank. Sure enough, whole bunch of debris in there clogging up the filter. Cleaned out the tank with a pump and filter, never had a problem again.
Also check to make sure your fuel tank vent isn't plugged. I'm guessing it vents thru the fuel cap.
The filter on the engine is one of those filter/water separator types, I took it off and had a good look, appears to be very clean. Took the fuel pump off also and hooked it up to 12v, pumped diesel with it, worked perfectly. Put it all back together and started it up, used it for 5 mins or so, problem seemed fixed... I shut it down and let it sit for a while, then started it up again and this time it took a bit longer to start, then it idled rough. I increased the throttle and it ran really rough, wouldn't stay at full throttle - revs varied up/down. Dropped the revs and it just died. Fired it up again and this time it ran but quite rough and still doing the same thing.
Mine is different, i have the hydraulics under the floorboards. Inside the tank is the fuel gauge sender. The feed and return lines are separate and just run along the side of the tank, then along the bottom. I drained the tank and while there was certainly some gunk there it was minimal.
Not sure where it vents through, it may be the cap as I don't see any other hoses anywhere. I'll have a closer look.
Just leave the fuel cap loose or take it OFF to test a bad vent in the cap..
Makes sense, I'll try it tomorrow. While the tank is empty I'd like to try to clean out the small amount of gunk on the bottom, although I'm not sure what is the best way to do it without pulling the tank out. Anyway, I'll put in some new diesel tomorrow and see how it goes.
TO BETTER DIAGNOSE THE PROBLEM I have to know WHAT injection pump is on your equipment. Is it the small square 4cyl pump held down w/4 bolts or is it the BIG 4cyl Kiki/Zexel pump w/ a governor attached to the back of it.?? IF its the BIG Zexel pump, u SHOULD HAVE a hand primer on the supply pump.. U said u checked the banjo bolt w/ the filter YES.?? The HP is directly above the filter bolt.. unscrew it & pump up & down while its running & work the levers to check for a fuel problem.. 1 other thing it could be on the BIG PUMP is the OVER FLOW VALVE.. a weak or broken spring..
Just google Mitsubishi S4L injection pump.. to SEE the diff. pumps. IT SURE SOUNDS LIKE a clogged banjo bolt filter.?? Are u SURE u checked the right one.?
Serial number would help
hell, anything would help..Lol Have u heard of the suck bucket?? google it.. IT WORKS.!!!
Here's a pic of the engine and a close up of the pump. In the 2nd pic you can see the banjo bolt just under the fuel/water separator. Yes, I took it out, no screen or filter in there, it was clean. As for the suck bucket, I made one and use it occasionally, just never heard it called that before. The tricky part is doing it through a small filler opening but I'll manage, thanks for the suggestion.
Did u clean out the head of the fuel filter ?
KOOL.. THATS the kinda info I LIKE to see.!!! U have the small PFR style pump.. No overflow valve to be concerned with.. All u have is an IN & it HAS TO BE under pressure.. U said the "supply pump" works so we'll let that be.. BUT keep in mind.. just because it runs, doesn't mean its putting out the pressure the injection pump NEEDS.. Theres 1 more thing that pump is known for>> a weak shut off solenoid.. that gizmo in the back, looks like 1/2 a beer can w/ wires & has a big nut on it.. Disconnect those wires & UN-SCREW the "can" 1 FULL TURN OUT & snug the nut back up & plug the wires in.. & see what it does.. Looking at the pic> U have TWO shut offs.?? 1 manual w/a cable & 1 electric.?? WHICH ONE are u using??
NEVER MIND.. my eyes weren't adjusting right.. the cable IS the throttle.. sorry.
Yep, took it off and pulled it apart, it was spotless
Yeah it is. You had me looking at the pic for a min LOL. The solenoid works OK. I can get my son to press the button in the cab and I can feel the solenoid click and the engine stops.
and theres no filter in the inlet bolt.. Was the inlet bolt rusty, by chance.?? cuz that's a good indication of how the rest of the system looks.
We know its working.. but u see it has a WIDE adjustment to it..{lots of threads} I want u to back it out 1 full turn..
I didn't see any obvious signs of rust in the banjo bolt but I wasn't looking for it. I'll remove it again tomorrow and have a closer look.
Happy to back the solenoid out 1 turn but curious what it may tell us?
Back the sol. out, Reason Being.. the solenoid gets "lazy" & wont retract all the way & will reduce the movement of the pump control rack.. so its not at FULL FUEL.. The sol. rod might still be pushing on the pump rack.. SO, if u back it out a full turn or 3 it wont be ON the pump rack.. Get it.??
Yeah, totally get it, thanks for the suggestion. Have a couple of q's on the pic.
IF the solenoid is adjusted properly.. after turning it OUT a turn or 3 & starting the engine for diagnosis purposes.. u wont be able to shut the engine down w/ the key switch.. Just unhook the wires again & turn the sol. IN slowly until the engine dies.. Hook the wires back up & try it SEVERAL TIMES w/ the key switch..
U CAN check the pressure there but that's actually the air bleed screw..& I'd doubt u can find a METRIC fitting to go in the hole.. I think its 6x1mm.. The other screw w/ the tamper proof cap on it is more than likely, the max fuel screw.. .. probably shouldn't mess w/ it till we find & fix the original problem.. Most people take the inlet pressure reading off the filter head..
TPG on the case!
The way "I" do it is>> I have a banjo bolt that I sacrificed to the diesel gods.. drilled & tapped a hole in the hex end & screwed in a fitting that will fit a gauge.. THEN I take the original out, screw mine in & I can read the pressure anywhere in the system that takes that threaded bolt.. BTW> its 14x1.5mm if u wanna go buy 1.. OR.. if its your equipment.. just do what I did & get a blanking plug.. When your done checking it, just plug off the hole..
I wonder if pressurizing the fuel tank would force fuel UP TO the inj. pump?? past the electric pump, seeing he/u doesn't have a HP in the system.. I'm just trying to eliminate the fuel system before moving to the hydro. system.. I "thought" it would be easier..lol I guess it still is.. 0-30 psi gauges are easier to come by than 0-5000 psi..lol
Your looking for around 6-8 psi to be safe.. Like I said earlier> just because your electric pump works, doesn't mean its putting out the correct pressure to feed the inj. pump.. I'v run into this problem 100x.. customer says, BUT I JUST bought an electric pump & its working.!! I screw my gauge in & its putting out 1-3 psi.. SURE its "working".. but not enough pressure to feed the inj. pump.. I go buy a 7 or 10 psi pump & they're back workin again..
I don't have a fuel pressure gauge so not sure what thread it has on it but will buy/borrow one tomorrow and check the pressure. Do I have to modify the banjo bolt like you described to do the reading? I can do what you said but it will take time, so just wondering if there's another way like maybe hooking it up into the return line? I also have a spare brand new fuel pump here that I can hook up temporarily. It's not exactly the same but similar enough that it will fit.
Return line?? I didn't see 1 in your pictures.. besides, u wanna find out what the pressure is going INTO the pump, not OUT of the pump.. U HAVE TO KNOW what the pressure is on your "spare" LIFT/SUPPLY pump before u swap it out.. if its only 1-3 psi it wont do any good.. IF its up around 10.?? go for it.. & YES you'll have to modify the banjo bolt if u buy one. U have to have fuel passing thru it inorder to take a reading..
In the first pic that I posted, you can see the banjo bolt and it has 2 lines going to it. The one on the left is the feed coming from the pump, the line on the right is the return, it goes to the middle of a "T" fitting. The left side of the T is coming from the injectors and the right side is returning back to the tank. If I remove the line going back to the tank and hook the pressure gauge there then I'm testing the pressure side, right?
OK, a quick update. This morning I tested the fuel pressure, it varied slightly but on average was 4 psi. I checked the banjo bolt for debris and rust but it was spotless. Rechecked the filter, also clean. While the tank was empty I vacuumed out the little sludge that was there and blew compressed air through both the feed and return lines to make sure they weren't blocked. Put in a fresh tank of diesel and after a couple of tries it fired up and ran well. Jumped in it and proceeded to use it for a good hour, ran really well, no probs at all. So not 100% sure what the problem was but doing this clean certainly didn't hurt. While I was at it, I changed the oil and filter and I'm sure I have never seen oil as black as this, so it was certainly due for a change. Also decided to do the final drives, the left one was full and the oil was still relatively clean, the right one was a different story - not a lot of oil and it was quite thick with fine metal particles, looked like black metallic paint. Not what you want to see....
Good job..I like to see a little higher fuel pressure but if its working, its working.. Good luck w/ the final drive issue..
Yeah, it's working, so far so good. Thank you for your help and all the suggestions you made. I'm sure it will help others that will have a similar problem.