Forum Replies Created
-
Posts
-
Luke,
My understanding is that you turn the engine until the fuel just stops “spilling”, not until it starts spilling. I think the idea is that you want to time for when all the fuel has been injected, not when it starts to get injected.
You can run the tractor for several minutes without doing harm. You might want to try it out before putting on the radiator.
When you timed to 16 degrees, did you use a protractor or the mark on the front pulley? Does anyone know if that mark on the front pulley is for pre EPA engines without centrifugal advance as well as those with centrifugal advance? I'm wondering if the timing changed with the EPA engine and if so, did they change the pulley marks.
/Jon
Jim,
This is very interesting. I'm not aware of any adjustments or how they are made. I'm told it is a Bosch injector pump, but don't know where I can find out about any possible adjustments.
Did yours run OK at higher RPM until it was allowed to idle down? I suppose it's possible that a limiter would not kick in and limit until the RPM drops or the fuel delivery rate drops. I would very much like to learn more about this. It is an EPA engine.
/Jon
The injectors are working fine. The engine starts well enough, although it usually needs a little ether unless it has been running recently enough to be warm (It doesn't start as well as it used to, so the timing is probably at least a little off.). It runs, responds to throttle and pulls well until the RPM are allowed to drop.
Your understanding is correct, but I've always started with the hand throttle open. If left idling it takes about 5 minutes before it starts to sound different. It is sublte at first, but within another minute or two it is barely able to run and has no response to throttle position (or very little and delayed). If pulling it will pull well as long as it is not allowed to idle down. If it idles down it starves. I test run it in my driveway, which is uphill. I pull up the hill and wherever I stop and disengage the engine the engine starts to starve. I put it in reverse and the hill allows me to pick up RPM on the engine and it seems like it is pulling normally going downhill, but when I stop at the bottom of the hill it can barely move the tractor in low gear at full throttle.
The engine was running fine, but I had a mishap with a seized injector pump that broke the key in the timing gear. I replaced the injector pump and have tried many, many, many timing positions. The only possibilities I can think of are:
1) The centrifugal advance mechanism was damaged when the pump seized. If this is the problem I will get another timing gear that does not have a centrifugal advance.
2) The new injector pump is defective, but why would it work fine until it idles? Might there be something in the governor that does this? There is an injector shop about 75 miles away, but when I talked to them on the phone they said it is very unlikely that they would be able to test this injection pump. If it is a problem with the pump, it is probably a problem of starving for fuel.
3) The timing is wrong. This seems the most likely problem, but I've changed the timing and the start position of the centrifugal advance so many times and have not seen any clear pattern to help me zero in on the correct timing. This engine was, I believe, the first “EPA” engine with centrifugal advance. I think they changed the timing gear advance from the one I have, but I believe all the timing gears and the one injector pump used with them are interchangeable. I suspect the timing mark on the front pulley was not changed to accommodate the centrifugal advance timing gear, but I would guess that the spill test timing would be the same with or without centrifugal advance. I have bent the injector lines so many times to make major changes that I'm reluctant to bend them much more. If I don't find out some test for the injection pump my next move will probably to get a new timing gear without the centrifugal advance. One big advantage of that will be that I can make timing changes without rotating the injector pump.So, to sumarize, I think I have either
1) a timing problem resulting in too much fuel collecting in the cylinders due to it being injected out of time, requiring over throttle to run normally until it is so “wet”, or flooded, that it can't ignite properly at lower RPM. If this is even possible it seems like it would be experienced commonly by others when engines aren't timed quite right.
or
2) A defective injection pump. If this is the problem it would no doubt be a starvation problem (no smoke?).When I start the engine and leave it at idle, never revving it up, the centrifugal advance does not advance. I can verify this by watching it, but the engine will still starve after about 5 minutes of idling. I can also see it smoothly advance and retard when I rev and slow down the engine. One test I have not done, but can, would be to rev the engine while watching the centrifugal advance then, after running a few minutes at higher RPM, let it slow to an idle while watching the centrifugal advance. Since all other indications are that this is not the problem I'm not expecting any surprises with this test.
The smoke is black, but not heavily so. I still haven't thought of a definitive way to figure out if the engine has gotten flooded with excess fuel at this point or if it is starving for fuel. It does seem more like it is flooded. If I crack an injector line in this state it seems like the amount of diesel squirting out is about the same as it is when running normally, but maybe it doesn't have enough pressure behind it to force it through the injector. Is there some guage I could put on an injector line that would solve this mystery?
There is no obstruction on the return line. When I pump the manual lift pump it pumps freely and I can hear the fuel splashing into the tank. Pumping the manual lift pump has no affect on how the engine is running when it is running normally or when it is acting like it is starving. The engine keeps running normally at working speed, but once it idles down it starves fairly quickly.
Tommy,
Yes, the pump was replaced. The old one sheared the key. Is there any way the pump could work normally, then starve? Is there any governor mechanism that could be malfunctioning?/Jon
Tommy,
I took off the hose and noticed where I can position the valve to get just a trickle of fuel. Ran the test and it still starves. It might be my imagination, but it seemed like it was slightly better. I held the throttle open and after awhile it gradually started to pick up RPM. Once it was revving it was responsive, then I let it idle back down and it was starving badly again.
I am wondering if this could be a timing problem how can I be sure where the correct timing is. My timing gear with centrifugal advance was, I'm guessing, an off the cuff design change that might not have been documented or adjusted for with different timing marks on the front pulley. I have a TDC mark preceeded by two marks closer together. It would not surprise me if these marks were for the engine before the centrifugal advance was used and I'm wondering if they are still in the right place. Does anyone know if the timing is set the same with or without the centrifugal advance? I currently have the spill stop spilling just as it gets to the first before TDC mark, but I have also had it start to spill there, as well as a hundred other places. Any ideas on how to eliminate or confirm if it is a timing related problem? I checked with an injector shop and they told me they almost certainly would not be able to test this injector pump.
/Jon
Tommy,
I just re checked the screen on the intake to the primer pump and it is perfectly clean and diesel pours out the hose when I turn on the valve at the sediment bowl. The screen in the sediment bowl was just changed when I replaced the sediment bowl.
It will keep pulling as long as you want without starving, but will immediately starve when you stop pulling.
/Jon
The idle speed is not too low. It idles well and picks up RPM fine before it has run long enough to starve. There is no heavy blue or black smoke, even when it is starving. I would like to figure out a way to determine if the cylinders are flooded with fuel, but it is not smoking. My test is to run it up the driveway a bit, which is uphill. When I stop and throttle down it immediately starts starving, so I put the tractor in reverse and back down the hill. With the help of gravity it is easy to get it revving again and it responds to the throttle, but back at the bottom it will not even get close to idle in neutral without struggling to run at all (but if I keep the RPM up it is o.k.). Once I let it idle down it starves and opening the throttle makes little difference, pumping the manual lift pump makes no difference. Sometimes I can hold the throttle open and it will very gradually pick up a little speed, but not much.
