Hello all! This is my first post here. Thanks for allowing me to participate. My Bobcat 853 with 4JB1 engine and Zexel VE pump has accumulated 3000 hours and lately has become hard to start. It is unclear if the vane pump might be failing or if I have wear in the pump head or possibly something else. What would be a reasonable action to take? My choices as I see it presently would be to get a new injection pump or try to service what I have. The engine runs reasonably well once started. I did advance the power screw one turn and it does start a little better now although doing this only helps an ailing pump on startup. Hopefully someone has some experience with VE pumps and can steer me along. The injectors are not the problem as they have been tested. I think of how many times the pump has rotated and wonder if it may be a case of general wear on everything or maybe not. Any comments are welome. Thank You
If your talking about the max fuel adjustment screw..(power screw) u turned 1 full turn.. if u turned it IN 1 full turn, your going to melt your engine down..1/4 turn in, will give u 10% more fuel.. and it has no effect on cranking fuel..
What I need to know then is what does affect the cranking fuel delivery? The governor was inspected and seems not to be the problem. The battery is cranking over the engine robustly so it is not slow cranking speed.
Timing effects the starting.. But mainly the tightness of the head and rotor.. if it doesn’t meet cranking spec on the test stand, the head and rotor is replaced.. Are u pulling the throttle back to wide open when you try to start it.?
Why would you start with injection pump. With sidsteers, in general, I start at the screen in tank, then the screen before or in the lift, then injector test, followed by a compression test. I'd never screw with injection pump first. Why did you? Also, in my experience, hard starting, if you want blame the high pressure side of the fuel system, has always been poor spray patterns from the injectors, when the engine is cold. Hard starting hot could be the injection pump.
I was thinking injectors too.. Always start w injectors, after pulling the rubber feed lines off and cleaning all the 90* elbows out and changing filters and draining tank and adding fresh fuel. But he said they tested good.. One would assume they were pop tested.??
I have checked the lines for any air leaks and replaced the tank screen and fuel filter. On start up I generally have the throttle cracked a little over idle. If there is some sort of small screen filter in the line, I have not found it. The pump was overhauled 500 hours ago. With the power screw in a turn, it will start cold after cranking a while and starts well when the motor is up to working temperature. The injectors were tested on the engine while cranking with no output and pop tested on the engine at idle before I advanced the power screw to determine there was no output when cranking. Also, a new injector was tested with the same results. By the process of elimination, it's apparent that the pump is the problem.
No lift/supply pump.?? If there is one, try to “T” into the line to take a pressure reading.. I’ve heard it’s possible somewhere on the filter.??
There is no lift pump, just the vane pump in the VE4. Maybe I can put a gauge on the pump body somewhere, probably in the vicinity if the return line.
Don’t bother.. How about hooking 1 up to it.?? U only need 1 less than 10psi..
Since there is no pump before the injection pump, it would make sense to me that there would be suction along the fuel line.
That’s why I said don’t bother.. to b honest, I’ve never seen one that didn’t have a supply pump .. Are u very familiar with that machine.??
Looking at a parts list for a 4BJ1, they list a supply pump.. It looks to b a mechanical pump bolted to the engine..
I have owned the machine for about 20 years and have accumulated about 1500 hours on the hour meter so am quite familiar with the machine. There is a squeeze bulb and a filter in the line on the way to the pump, that's all there is. As an experiment, I squeezed the hand pump bulb till it was hard and had a second person try to start the engine. It didn't help it start any better.
That won't bleed the air from the injection pump if it has leaked down from sitting. Testing the injectors for output tells you nothing about the injectors, if you don't know how the pump is working. That's not how it works. Injectors are tested off the engine. An injection pump head failing at 3,000 hours would be the result of very bad fuel, and very bad filter maintenance. Try this, crank the engine cold at low idle, is there any visible smoke from the exhaust? Put the throttle to fast, crank it again, is there any visible smoke from the exhaust? If not, then loosen an injector line at the injector and see if that squirts fuel when you crank it. Yes or no? Then do whatever you normally do to start it, once it starts, does it run smooth right away, or sputter a bit and then smooth out? After it runs smooth for thirty seconds, shut it off and start it again, does it start right up, or go through the whole process again?
Well, I had a session with Mr. 4JB1 today and timed the pump once again. The instructions are not very clear to me. They mention two sets of timing marks, one set vertically and the other set at about 90 degrees facing the operator.. Anyway, I followed the **** poor instructions to the best of my ability and it will start but not robustly as one might expect. A good starting diesel VE pump will start with the crackly sound of plenty of fuel but this is still cranking over a bit before it catches. I suspect it is wear on the head due to ULSD fuel but that is only my guess or maybe the timing is still off a little due to the PP instructions in the Bobcat manual. So, anyhow, that's where I'm at as far as progress is concerned. Before I did the retiming, there was not much if any smoke out of the exhaust while cranking either on idle or full throttle. Thank you all for your input and hopefully in time this difficulty will get resolved.
Today I ran the Bobcat a bit and other than getting trying to it started, it ran fine, restarts fine too. My view is that it just isn't getting fuel when one tries to start the engine cold so fishing for answers. Thank you.
I’m still stuck on a bleed back problem.. Try this:: Loosen the INLET LINE A FEW TURNS.. Now have someone turn the key on.. “IF” u installed a supply pump, the fuel should be RIGHT THERE flowing into the inlet.. If it’s not right there, u gotta bleed back issue..
We might be getting somewhere now as I work this out. I don't have a supply pump in line but maybe the squeeze bulb would work. A while back I inserted a reverse flow valve in the fuel inlet and took it out later as it didn't help. Would the BLEED BACK have to be in the fuel line or could it be in the RETURN LINE as well? Some time back I removed the inlet pressure controller part and noticed there was a little bubbling going on in that hole and thought it somewhat puzzling but considered it possibly normal discounting it to flow back through the return line. So it's all progress I guess. Of course progress does not have to move forward and can go backwards as well... Also it is worth mentioning that the engine began to start warm after I retimed the pump so found that interesting.
Ahh the plot thickens.. U took the pressure regulator out.? Interesting.. The bubbles u saw were from the inlet.. no fuel at the inlet.. Another thing is, the pr. reg. has a spring pin on the bottom of it.. That pin holds all the guts in.. IT MUST B THERE.. Some manufacturers use a roll pin and some a cap.. the PIN MUST B FLUSH. & the cap is self explanatory.. & for god sakes, put a supply pump on this thing so we can move on.!!!
Can u post a pic of the pump.?? I need to see if it has an adjustable START SCREW.. or a Cold Start device.. DO NOT GO TURNING SCREWS.!!
I'm sorry for the slow response. Hopefully this photo is good enough to be helpful.
Yea, the pic is good.. unfortunately u don’t have any start screws. U could try turning the pump a smidge..(change the timing) There should be a timing line on the pump mounting flange..& one on the intermediate plate.. Use them as a starting point..& move the pump a dimes width in either direction.. Be sure to tighten the nuts after each movement.!!
Thanks for the idea. We are in the middle of a snow storm so it will be several days until I can experiment a little with the timing. I will post again in a few days with some results.
Have you used the glow plugs before attempting to start? Does it make any difference?
Be sure to give it half to full throttle before cranking.. I think you’ll find a difference..
Yes, I generally use the glow plugs at least a little bit, more when it's cold of course. There is pretty much no smoke on cranking so it is a fuel thing. From my understanding, the governor is supposed to give full fuel on start up, maybe it isn't.
Generally, I use a medium idle but will try more throttle when I get the chance to try it. Thanks
Yes do that.. if the head and rotor has any wear on it, you’ll need the extra throttle travel.. Let’s here MORE about these glow plugs.. have they been tested.?? How did u test them.?? How long do you leave them on for.?? R u waiting on the “idiot lite”?? Have u counted it out.?? 1 Missippi, 2 Missippi.. to 10 Missippi, THEN crank the engine.. Another thing is the elbows going into and out of the filter head .!! THATS a biggie.. Let us know and stay warm..
Yes, I have disconnected the glow plugs and tested each one for continuity using a VOM. As far as time heating the glow plugs, I rely on the temperature of the machine to dictate how long I use them. Generally I will heat them for 15 seconds or so, more if it is exposed to cold weather up to maybe 30 seconds or so. I would think the glow plugs are the 10.5 volt units but I don't know for sure as it is a used machine when I got it. It has about 3000 hours on the hobbs meter now and 1600 something when I bought it. Tell me more about the elbows and filter head. I'm not sure what that is all about. The snow is pretty much over and the next is the northwest wind blast and below zero temps for a day or so.
Dont know on on that BC but some BC have a check valve in the suction screen to prevent drain back to tank
The elbows collect debris and won’t let fuel pass..
Finally I got to adding an electrical fuel pump before the filter. That made no difference at all in starting. I will be adjusting the timing next as a rotary pump is more touchy than the standard cam type pump I would think. Also I will be checking the lines more carefully.
Full throttle didn't make any difference, no smoke...
I did try moving the timing a dime's width in either direction and it didn't make much difference on starting. The engine will start when warmed up if you shut it off and start it again in a minute or so. If you wait 5 minutes, it just cranks and cranks...