Case 1737 only firing on 2 cylinders

[rrwayside]

Trying to troubleshoot my skid steer. I have replaced plugs, cap, rotor and still missing on 3 and 4. Did not replace wires but good spark at the plugs. Seems to have good compression with my finger in the hole. Any input greatly appreciated.

 

[flyerdan]

Was the miss there before you changed wires? Just wondering if two might have gotten switched. If two are firing enough to make it run, that means the timing is right, and a fuel issue is quite unlikely. Since they have spark, a real compression test with a gauge is in order.
If you have some spare spark leads laying around, or you can temporarily swap the ones you know are good and see if the miss follows the wire.
Often times a plug, wire or other ignition component will deliver a good looking spark in open air, but under compression is isn't strong enough to fire off, makes it a little more difficult to troubleshoot.

 

[rrwayside]

Was the miss there before you changed wires? Just wondering if two might have gotten switched. If two are firing enough to make it run, that means the timing is right, and a fuel issue is quite unlikely. Since they have spark, a real compression test with a gauge is in order.
If you have some spare spark leads laying around, or you can temporarily swap the ones you know are good and see if the miss follows the wire.
Often times a plug, wire or other ignition component will deliver a good looking spark in open air, but under compression is isn't strong enough to fire off, makes it a little more difficult to troubleshoot.

It was skipping and that’s why I did the tune up.Quite sure the firing order is correct but I will double check and also do what you recommended with the wires and go from there . I need to make a fitting for my tester as I don’t have the proper thread size.Thanks.

 

[rrwayside]

It was skipping and that’s why I did the tune up.Quite sure the firing order is correct but I will double check and also do what you recommended with the wires and go from there . I need to make a fitting for my tester as I don’t have the proper thread size.Thanks.

Switched the two good wires with the two bad ones, made no difference at all. Still running on the same two cylinders. Took compression test on bad cylinders, both over 100. Good cylinder about 120.pretty sure it’s not internal. ?????

 

[rrwayside]

Switched the two good wires with the two bad ones, made no difference at all. Still running on the same two cylinders. Took compression test on bad cylinders, both over 100. Good cylinder about 120.pretty sure it’s not internal. ?????

Also took the two plugs that weren’t firing and switched with the two good plugs and still the same two cylinders are firing, so I’ve eliminated bad plugs and wires. I also advance the wires both directions on the cap and wouldn’t even fire. Not sure what to try next.

 

[foton]

Also took the two plugs that weren’t firing and switched with the two good plugs and still the same two cylinders are firing, so I’ve eliminated bad plugs and wires. I also advance the wires both directions on the cap and wouldn’t even fire. Not sure what to try next.

some how it has to be spark, if you have a timing light do each cylinder at the plugs, look at the brightness of the pulsing light and see if those non firing cylinders are dimmer, also on a machine like a skid steer I would if it has points and cond. replace the resistor wires with copper core wires and solder the end connections.

 

[flyerdan]

some how it has to be spark, if you have a timing light do each cylinder at the plugs, look at the brightness of the pulsing light and see if those non firing cylinders are dimmer, also on a machine like a skid steer I would if it has points and cond. replace the resistor wires with copper core wires and solder the end connections.

Since all 4 plugs and all 4 wires will fire the two cylinders that run, I'd tend to rule out electrical.
It seems like it is more of a fuel issue, since they are the two back cylinders, I'd be wondering if something is obstructing the manifold. Another thing to check is the valve train; if there are a couple bent pushrods that won't allow the intakes to open, you'll get good compression but nothing to fire.
When you pull the plugs on the non firing cylinders, are they wet with fuel?

 

[rrwayside]

Since all 4 plugs and all 4 wires will fire the two cylinders that run, I'd tend to rule out electrical.
It seems like it is more of a fuel issue, since they are the two back cylinders, I'd be wondering if something is obstructing the manifold. Another thing to check is the valve train; if there are a couple bent pushrods that won't allow the intakes to open, you'll get good compression but nothing to fire.
When you pull the plugs on the non firing cylinders, are they wet with fuel?

Thank you for your responses. It’s been driving me nuts. I’ve been through the carb 2 or 3 times and the other cylinders were running good so I ruled out fuel. After talking to a friend today that also mentioned if the plugs were wet it got me thinking. They werent really wet. There was no way the intake could be plugged as the only access for a mouse would be through the carb.when I got home I took a closer look at the intake and noticed part of the gasket was missing. Have it tore down and waiting on parts.I should have found it sooner, but I was looking in the wrong direction. Thanks again, I hope it helps out someone else.

 

[foton]

Thank you for your responses. It’s been driving me nuts. I’ve been through the carb 2 or 3 times and the other cylinders were running good so I ruled out fuel. After talking to a friend today that also mentioned if the plugs were wet it got me thinking. They werent really wet. There was no way the intake could be plugged as the only access for a mouse would be through the carb.when I got home I took a closer look at the intake and noticed part of the gasket was missing. Have it tore down and waiting on parts.I should have found it sooner, but I was looking in the wrong direction. Thanks again, I hope it helps out someone else.

It will be interesting , I would think a vacuum leak would effect all the cylinders, lets us know.

 

[rrwayside]

It will be interesting , I would think a vacuum leak would effect all the cylinders, lets us know.

The intake manifold has two separate intakes. One feeds cylinders 1 and 2,the other feeds 3 and 4.The gasket that was missing was to 3-4. I do believe it did affect all cylinders as it seemed like it had a hard time picking up gas when it first started, which makes sense to me as it was sucking air.Waiting on parts, I’ll keep you updated.