Case CX36B randomly shuts down... injection pump issue???

[Ronsii]

Hi everyone at HEF... I have a little problem and need some help

So we have a case cx36B 2007 bought it new has about 5800 hours on it... it has been maintained fairly good and been a good little machine. I apologize in advance for not having the pump details or engine for that matter...(sorry pumpguy) It was pretty hot at the site today so my brain was just about fried when quitting time arrived but I will get numbers as soon as I can. I do know it has a yanmar engine in it I think the 3TNV88... I know it uses this shutdown solenoid ->


About a month ago it just died while using it, just like you shut the key off... fuel gauge read just below a quarter so just assumed it had something to do with that... filled er up and started up ran great! now in the last two days it has died about 20 odd times sometimes it'll start right back up sometimes it will die a second time or you wait a few minutes and she's fine again???

So thinking this might be electrical I started tracking things down and only questionable thing in there is the kill solenoid, put in a new one seemed to work fine... thinking it was fixed went to load it up this morning and it died a few times Found that it will run without the kill solenoid installed so today when it died the second time and would not restart I pulled the solenoid off the engine then tried to start... wouldn't start... so I poked my finger in where the solenoid goes a few times gave the spring plate a little exercise and than it started!

I am really hoping someone (especially pumpguy) has some ideas on any other troubleshooting to try or if this sounds like the IP is going out... or something completely different....


One other thing is it seems to die mainly when at idle, it doesn't seem to make a difference when trying to start if you have throttle up or at idle and every time it dies it quits instantly just like the key was turned off, also it has been fairly hot here lately... oh haven't checked fuel pump pressure but hear it working and if the solenoid is pulled and you turn the key off it will run for at least 5-10 seconds without fuel pump running.

 

[thepumpguysc]

1st check the fuel pressure.. & leave the solenoid out for the tests.. no sense in chasing an electrical problem in the process..
Loosen the fuel tank cap BEFORE checking ANYTHING..
The REALLY BAD THING about THAT SYSTEM is, it wont tolerate ANY water..
Change the filters & report back..

 

[Ronsii]

Will do, Thanks TPG.

 

[Ronsii]

Ok finally got some time to do a few things with the mini...got a new filter and changed it, finally rounded up a fuel test setup, checked pressure after the electric fuel pump where it feeds the filter - 0 PSI, gots plenty of flow if you pull the hose off and turn on the key... at least it looked like 0 might be a small amount just doesn't seem to have any resistance going through the filter and IP. If you pull the hose off and block it the electric pump can make about 3 PSI... I guess I need to find a lower gauge this one is 0-100 so not real fine for small measurements. I did finally get pump numbers off the IP.

Ps. started it at least 20 times over the last couple days and it hasn't died again....




here is the fuel pump, didn't see any numbers on it but may be on the underside...

 

[thepumpguysc]

I think you may have somewhat solved/ found your problem??
By changing the solenoid & freeing the rack w/ your finger.. more than likely there is water intrusion/rust in the pump..
The 0 psi on the feed pump bothers me tho.. I'm wondering if the overflow valve on the injection pump is stuck open?? THAT would allow the fuel into & out of the pump with out restriction.. free flow w/ no resistance..
The overflow is located above the name plate.. 7/8-22mm big plug.. it consists of, the plug, a spring & a piston.. remove the plug, the spring & using a [strong]magnet.. see if you can pull out & push in the piston..
THAT is the only thing YOU can do to the pump.. the rest is quiet complicated..
That's where I would start.. & recheck the pressure.. Good luck & let us know how it went.. TPG

 

[Ronsii]

Thanks for the info pumpguy I really appreciate it, IP's are just something I have never really dealt with... I will check the overflow valve like you suggest might take a few days to get to it as we are just swamped right now. It is certainly a headscratcher... one minute it is running and starting fine then out of nowhere it just up and dies??? we'll see how it goes got a semi-emergency job up north Monday, will give it a good workout.

The only time I can remember a decent amount of water in the fuel strainer/sump was about 2008-2009.. we were on a big job and using the GC's fuel truck, one morning I checking the oil and noticed the strainer bowl was 3/4's full of clear fluid on the bottom!!! drained it... then proceeded to find out where the water came from, turns out the fuel trucks tank filler was just a 3" nipple with a cap on it and the nipple was loosely threaded into the flat top of the tank with no sealant.

 

[Ronsii]

Been busy on other jobs lately but got a chance to change the fuel pump 2 weeks ago and also pulled the overflow piston and spring on the IP... came out easily everything looked ok...signs of lengthwise scoring(very light)on piston but no dirt/rust/gunk.

Electric fuel pump change: once I got this changed I rigged a low pressure/vacuum gauge with a tee into the fuel line just after the pump/ before the spin-on filter, turned on the key showed 2.25PSI, let it circulate fuel for a minute, cranked the engine and it started right up fuel pressure went to vacuum about 7hg moving the throttle up/down will change the reading about +/- 2hg. So I am guessing the IP has a fuel pump in it also??? and it pulls fuel faster than the electric pump can keep up???

With the new pump installed I got a chance to run the machine last thursday for most of the day, started it in the morning and it died within 3 seconds... crank it for 15 secs. and it starts up and runs great... about a half fuel tank later it dies when I'm digging (70% throttle) then a while later it dies a couple more times... same routine crank it 15 seconds and it starts back up, so I'm thinking it might have something to do with fuel level so I top the fuel off and get it running again. All is good for about 10 minutes then it dies again while I'm swinging a bucket of dirt around at near full throttle, I was swinging to the right so the instant it died I saw a good puff of light smoke come out of the exhaust when it quit??? also it did this about 5-6 times in around 30 minutes before we called it a day.

 

[Ronsii]

Well, pretty sure I finally got it sorted

It finally started stalling so often the boss said fix it! So right in the middle of a jobsite I started ripping things apart... about a half hour into pulling sheet metal off and anything else I could remove to open things up a bit I decided to start it, once it was running I saw something not seen before!!! the water separator bowl was 1/3 filled with air!!!!! but once the engine would die the pump would keep running and the air would be gone in a few seconds, so any time I'd check things after it died all looked normal. After chasing ghosts for the last couple months I just couldn't believe it was something as simple as air getting in causing random shutdowns, anyways I tracked it down to the actual water separator housing being the culprit and for now just routed the fuel lines around it and it's been running like a top for the last two days I gotta say this thing does not operate like anything diesel I have worked on before when air get in the fuel system, it's all or nothing... no sputtering rough running-some injectors working some not.... it just runs good or stops!

A big thank you!!!! to Pumpguy for giving me guidance and helping out, and don't worry I will get the water separator back in the system as soon as possible

 

[thepumpguysc]

Your welcome.. & good job..
The thing about MOST diagnostic jobs is> they're a 2 man operation.. weather is just an operator turning a key for ya or another mechanic for a set of eyes.. might wanna put a bug in the boss's ear about, the time we spent on that job..?? we coulda had it fixed on day 2 if I had some help..??
That pump is an ODD DUCK.. nobody makes a pump like that anymore.. it was abandoned in the 70's.. but Yanmar brought it back for some reason & complicated the sh*t outta it..
The H2O separator is your friend!!!! get it replaced VERY QUICKLY.. Happy digging..