Hi folks, I have a Jcb 3 CX, 1985. It didn't start the other morning. I thought I might have run it dry but I'm not sur. I have made sure fuel is getting through the filter to pump and I don't believe there is air in the pump. I'm going to order a new lift pump as I'm not happy with the way it feels when I pump it. It Pumps but not great I think?? Any how here's the thing. I took off the single pipes that come from the pump off the injectors and there is no fuel coming out of them when I crank it. But when I open the nuts on top of the injectors where the common line goes across the top it oozes out when I crank. It's smoking so I assume It's nearly going to start. I thought that the line on top was to send excess fuel back to the pump and the single lines were to fuel each cylinder. Can anyone enlighten Me on how the injector system work.? Thanks.
You are correct in your assumptions. If there is no fuel spurting out of the individual injector lines it ain't gonna run.
Yes, there are return lines. As long as you're replacing the pump, you may as well replace the filter(s) and make certain the fuel tank is clean. If that doesn't send good fuel, all that's left after that is the fuel pump.
How can I make sure the fuel tank is clean? Something I noticed is that the lock on the fuel tank lets in water, not sure if much got in as it was stored inside. Anyhow I'll order a filter, this engine only has one fuel filter strangely enough.
When it is almost empty you can peer in. You can drain it by disconnecting the line to the lift pump. My point is now is time to clean the system, and get a new fuel cap if you need to (so you don't have any fuel delivery problems in the future).
The strangest thing is when I crank it with the 4 individual lines disconnected smoke comes out of the exhaust like its gonna start. I expected at one moment when I had shoved a rag wet with petrol into the air intake that it would just take off! Oooh ghost in the machine!!! Anyhow must wait for the pump to arrive in the post..
does it not have the sediment bowl attached to the chassis fuel pump side of the engine
Fuel line comes straight from the tank into the lift pump from there to the filter and there to the injection pump. I've changed the lift pump, I can feel resistance(like it's pushing diesel) when I pump manually, after a couple of pumps there isn't much resistance on the pump lever? Is this normal? I undid the lines at the injectors and cranked but no fuel came out. I would expect to have fuel after a minute of cranking, would I be correct in assuming that? I loosened the little bolts (8 or 10 mill) on the injector pump, one on the square housing on top the other on the cylindrical body on the side, diesel came out, no bubbles. So I assume that there is fuel in the injector pump. How can I make sure the dead mans handle is functioning correctly? It's in the correct position, the spring pulls it all the way.
One last thing, I just plugged the lift pump into place the lever against the cam. Is it the lever supposed to be positioned specifically some other way?
Yes, it's normal for the pump to have resistance as it's pumping, and no resistance once the fuel pressure is built up. That means you have fuel at the correct pressure (there may be air somewhere still, but not in the transfer/primer pump). I haven't seen a lift pump that can be installed wrong. If there was spring tension against the cam lobe, you can crank the engine around a bit, or tighten the pump down against the tension. Did you get a good little squirt out of the bleeders on the injection pump when you prime it? Then it might be time to pull the cover off the top of the pump and check the linkage inside? Also, is that a mechanical shut off? no electric wires on the injection pump?
Yes indeed it did a good squirt. It's a mechanical shut off. Anything I should be aware of before opening the lid on the injector pump? Can I do it insitu or do I need to take the pump out?
I don't know that you want to, or need to disassemble the pump. I would loosen each line at the head and bleed there, tighten from the rear first toward the front. If your fuel, filters and lift pump are clear and good and you still have no fuel delivery, there is then an issue with the pump.
I take it the head is the back of the pump where the high pressure lines are connected. Should I loosen them all and turn the engine over then start tightening one at the back and work around the pump?
Well, I don't know where your pump is located, but in a word, yes. You loosen the lines at the top of the engine (leading from the pump) and then tighten when cranking over...or running. It's a little messy, but purges all air from the system.
I thought you ment the head of the pump. I already loosened them at the injectors but not much coming out there. I loosened them at the rotary side of the pump and nothing there. Looks like I'll have to take the pump off. Strange how it stopped pumping all of a sudden. It was sounding a little like it was fuel starved the last time o used it. It was causing the machine to rock a little over and back. Then the next day it wouldn't start. I noticed the lever on the pump that shuts the engine off was half open. The spring hadn't pulled it back to the starting position. Maybe I damaged the pump trying to start it with that thing half open. Should there be a connection or a spring between that lever and the throttle lever? I saw a diagram on YouTube it seemed to show both working together? Also where the oil cap is above where the pumps drive shaft goes in, a little oil might help in there?
One other thing, the pump isn't sending diesel up the 4 high pressure lines but the engine is smoking a lot when I crank it. Where is it getting it's fuel from? The only other place would be the line that connects across the top of all the injectors, but my assumption was that this takes away any surplus diesel??
Also the engine smokes a lot when cranking even when the 4 lines are disconnected .
That doesn't make any sense to me. What does the "smoke" smell like? I assume you mean a whitish mist/fog coming out of the exhaust? Have you checked the coolant level? Oil level? How does it sound when cranking? any different than before, like maybe one or two cylinders don't have as much compression as the others? There might be a "timing window" on the side of the pump that you can remove to drain the fuel and confirm that the pump is turning inside. You can take the cover off the pump in place, if there's room to get to it. Just take note of which holes the springs go into, and use new seals when you put it back on (for the last time).
Ok the plot thickens! The smoke is made, I believe, by an injector that goes into the air intake. I undid that injector and cranked the engine. It pulsed fuel and didn't smoke as much.. I tightened it up and when I tried manually pumping the lift pump it didn't feel like it was pumping any more. I believe it was pumping to compress the amount of air that was in that pipe. When it had compressed it then thaw lift pump felt like it wasn't pumping any more. So no air, it retains pressure after the engine has cranked. Also that injector is not from the rotary side of the pump like the other 4 that go to the head. It's a return from the top of the fuel filter. There are 4 fuel lines connected with the filter on top. They are numbered 1 to 4. I have run out of batteries and my wife insists I finish working. It might crank on a well charged battery. Will know Tuesday. The engine and fluids are fine, I believe. I haven't tested compression, but it was ticking over like a rats heart before it broke down. I sensed a little fuel starvation or something, probably the dead mans handle slightly engaged.
OOPS, I forgot about those fun little flame throwers. I've run across them, but never seen them work. All of that sounds correct. Does that operate every start, or do you just use it for cold starts? Back to either taking a look inside the pump, or taking the pump somewhere, after you're sure you have no air in the pump.
tubing to intake manifold usually feeds a cold start thermostart valve.. this is activated by turn key to the left, that feeds power to theromstart coil heating up and opening letting fuel flow, then the coil flames the fuel,,,, this could be holding open by power feeding it all the time,,, flooding the engine,, plug the tube or replace thmostart valve,,, priming fuel system should at filters and going step by step thru each fuel item on up to injecter pump,,,, the fuel return to tank has to be able to flow back to tank at all time,,, it wont start if return line is blocked or pinched off,,, don't jump around on air bleeding to injectors STEP BY STEP
Not sure if it is on all the time. There is a round thingy with a wire on it built into the air intake that looks like a thermostat and a wire onto the flame thrower that is good and thick like as if it's for power to heater. The wire was off the thermo so I put it back on but it's been smokin whether wire is on or off the thermo. Maybe it's to shut it off when it warms up rather than turn it on when it's cold if you catch my drift?. There's a switch in the cab that could go to a solinoid somewhere that might be a manual override (I'm guessing now). I was playing with all the lights and electric switches the evening before it broke down. I'm wondering if it might have anything to do with my troubles. I assumed the dead mans handle not having returned to its start position was the cause of my troubles and not a possible electrical problem as it's a fairly basic engine, 1985.
It's actually just after 3am and I have to go to work in the morning. Waking up in the middle of the night to discuss diesel mechanics is not a good sign.
Here's a thing, am I right to assume that when the lift pump feels light (except for the spring) that I have all air out up to the injector pump at least. And when I bleed the pump, I just need to open the little bleeder screws and pump the lift pump, no need to turn engine over except to get the air out of the injector lines?
I'm liking Jim's explanation. That wire heats up the coil and the hot coil opens the valve to dribble the fuel. If that valve was leaking when there was no power, it could let air back into the lines, especially if other parts of the system were 30 years old.
No, if the lift pump feels light, it has built up pressure, but it will do that with the injection pump FULL of air. Just using the bleeders on the pump is good enough for me, Jim suggested step by step. Yes, you can bleed it with the lift pump.
Interesting..
The diesel comes out both bleeder screws and no air I believe in the pump so I can only Assume it is full of diesel. The lift pump is one side of the engine, the injector pump and filter is the other side. I wish both were the same side.....
its pumping fuel thru the thermostart vavle flooding the engine with injectors line loose and showin smoke incidates that got have a strong battery to crank when flooded
Right, I'm hoping that if I drag generator up there, with a battery charger on it connected to the battery whilst cranking it, it should crank it. I would like to try and get the jeep up there to jump it. it's deep mud and up hill. Might give that a try first.
When we need to bleed the old Cats we put a rubber drain pipe cap on the fuel filler at the tank with a valve stem glued into it and put about 5 to 7 lbs of air in it to push the fuel through the whole system. Then you can loosen lines and bleeders and bleed right to the injector with no hassle. Not sure if it works on a Perkins but may be worth a try. Might be a vent on the tank you have to close.
Ok, I'm pretty sure there's no air in the system. I'm taking off the pump. I've taken the three nuts off but it seems to be jammed in position. It can rotate a little but won't come off the engine. Do I need to mark something for timing to make it easier to put back on later? I'm hoping that when I get it off it will be something simple like the shut off lever broken. I'll bathe it in ATF as well overnight.
My guess is you should look for a bolt on cover on the front of the timing cover, centered on the pump shaft. if it's there, remove it, rotate the engine until the factory marks on the gears line up, remove whatever bolts or nuts hold the gear on, remove gear, then the pump will fall off the back. Usually there's a key or a dowel pin so the gear only goes on one way. :my2c
Ok eventually it's on again and the machine is working. Thanks for everyone input. There was air getting in at the little filter on the pump inlet: the thread was gone. So I brought it to a Deisel mechanic had the end cover of the pump changed and it serviced. When I put it all back together I realised one of the studs holding the pump on to the engine was also sheared. I had everything back on pipes and All and it was the last nut I was tightening. Pain in the the behind. Had to take it off again and tap it out to 3/8ths and get another stud. Well I made a stud from a bolt but didn't have an imperiel stud that size so lost another day going to town. Anyhow, it's really easy to bleed if all's clean and the pump is good. I can change a pump in no time now as well. So happy days I'm making my foundation. Thanks again everyone for the input.