Hard starting Jinma 224 with 90 hrs

[greg_g]

1. Battery's fair to good, full charge state is typically 13.2v
2. Very good. That's excellent testament to the Ford switch upgrade
3. Increase is likely due to glow plugs heating up during measurement.
4. Either there's something wrong with your measurement technique - or you've got three bad glow plugs. Those three measurements total 6.8 ohms, through which you'd be pulling less than 2 amps. On this test, I'd expect good plugs to give resistance values between 1.5 and 2.0 amps.
5. normal

Modifying the measured circuit to include glow plugs adds resistance to ground. Ohms Law: Voltage = amperage times resistance.

//greg//

 

[RonMar]

How come there is such a difference in the voltage depending on if the lead is attached to the bus bar or not. Is this a concern


Next is checking the injectors.

When the lead is connected to the bussbar, current is flowing thru the glowplugs to ground. When you draw electrical current thru a resistance, a certain ammount of voltage is dropped by that resistance. With no current flow, you saw 12.7V on the lead wire because no current was flowing and you were seeing full battery voltage at the lead wire. The voltage drop you saw when connected is from the wiring resistance from battery to bussbar. IF we knew how much current you were drawing, you could determine how much resistance the circuit has.

The voltage came up as the plugs warmed which is normal. As the plugs warm, their resistance increases and they draw less current from the battery. Less circuit current = less voltage drop thru the wiring and an increase in voltage at the bussbar. I have never measured the volt drop at the bussbar on my 284. I will take that same measurement on mine and battery readings so you have something to compare to and post again in a bit.

EDIT: I went out and took some measurements on mine this evening. I had 12.59VDC on the battery(right at 32F outside). With the meter neg lead still on the neg battery terminal, I connected the positive lead to the glowplug bussbar. Upon energizing the keyswitch to activate the plugs, I showed 7.6VDC initially on the buss which rose steadly over a 20 second pre-heat to around 8.8VDC. Then the tractor started right up.

Your volt readings with glow plugs engaged sounds OK, but Greg is right about the resistance readings, I think you may be off by a decimal on your ohm readings. If the amp gauge is anywhere accurate, the plugs on mine pull 30+ amps initially and taper off near 20A after about 20 seconds of pre-heat. Now battery drop under this load notwithstanding, 12.6V divided by a 30 amp current draw should = an overall circuit resistance(wire, switch and plugs) of 0.42 ohms. At 20A, that figure would be nearer 0.68ohms which is very near the combined resistance of three 2 ohm resistive glowplugs in parallel. How much current do your glowplugs pull on the amp gauge initially and after 20 seconds?

 

[greg_g]

On this test, I'd expect good plugs to give resistance values between 1.5 and 2.0 amps.

Typographical error: should have read On this test, I'd expect good plugs to give resistance values between 1.5 and 2.0 ohms (each)

//greg//

 

[Soundguy]

I'll add that if messing witht he injectors.. watch out for pressurized diesel.. only use tools ont he hard lines.. keep fingers away while the fuel is under pressure..

soundguy

 

[RonMar]

I'll add that if messing witht he injectors.. watch out for pressurized diesel.. only use tools ont he hard lines.. keep fingers away while the fuel is under pressure..

soundguy

Yep, injection injuries are nasty, and of course wear eye protection.

 

[TractorGuy1]

I will recheck the measurements as I probably goofed up. I will post the results when I get out again.
The in dash meter shows a 30 amp draw when heating the glow plugs and the needle slowly rises to about 20 or 15 amp draw.

 

[RonMar]

That 30A tapering up to 15-20 after 20 or so seconds also sounds about right. Another thing to consider might also be engine crank speed. Poor electrical connections on those large gauge wires running from battery to ground and battery to starter could be limiting the current reaching your starter and causing a slower crankover. This might effect your startup. Do you use the compression release when starting?

 

[DwayneB]

I will recheck the measurements as I probably goofed up. I will post the results when I get out again.
The in dash meter shows a 30 amp draw when heating the glow plugs and the needle slowly rises to about 20 or 15 amp draw.

Sounds about right. When is the fuse blowing, whilst cranking the engine? If the starter is dragging it will be extremely hard to start.

Try boosting it with jumper cables or one of the start assist chargers. If it spins good and starts good with a jump odds are it's not the starter. The chinese batteries aren't much for cranking power.

Another thing that can hurt cold starts is the valves too tight. Almost everyone that owns a chinese tractor checks the valve clearance almost immediately. One rough check for tight valves. Will it rev into the PTO band when the engine is hot or only when it's cold?

Does it start ok in 70 degree weather? What is the outside temp when it becomes hard to start? If it lives outside.


I'm no expert just putting some stuff out there to see what fits. If the tractor runs good when its warm and you can tell a difference when the hard lines are cracked odds are it's not an injection problem. BTW have you changed the injection pump oil and checked the level?

 

[Dave_Lilly]

One of the most common reasons for an iffy starter that has been bench checked is a bad battery cable connection. Be sure both battery cables have a good connection on both ends. Over time corrosion can build up under these cable connections and cause a bunch of problems. This could also be associated with your blown fuse problem. Crud on the cable ends will let a volt meter show that you have 12 volts but when you fire up the glo-plugs the current draw can result in overheating causing the fuse to blow.

 

[TSMART]

Though I am sure others know more, let me share....

On my 224, the starting culprit was the negative cable where it attatches to the frame. I scraped off the paint, roughed it up, and it started right away with no repeat problems.

Also, while looking for the above solution, I removed my starter switch. While inserting it back in, two leads touched some metal behind the dash and I blew the 30 amp fuse. Perhaps you should check ignition switch or the area behind the dash to see if anything metal is coming in contact with the leads.

So far, every problem with my 224 that I thought was going to be complex turned out to be something simple. Knock on wood.

From all I have read, I am certainly glad I equipped mine with the Koyker loader which really works like a cadillac.