1425 with 18 hrs on it blowing fuses.

[hogi]

I was using the brush cutter on some dry weeds yesterday and noticed early on that the fan was not coming on, I mowed long enough for the PT to get up to normal operating temp and stopped to check it out. I lowered the engine to an idle and just as I pulled back the engine cover the engine stopped. I located the fan fuse and it was blown. I replaced it and tried to start the PT, turned the key and nothing. I checked to see if the headlights would come on and they didn't. I found the 30 amp main in-line fuse and it had blown. At this point I tried best I could to inspect the wiring in the back tub to try and find a short or loose connection. I disconnected some blade connectors and reconnected them , nothing obviously wrong that I could see. I replaced the main fuse again and it started right up. I stopped and started several times with no problems. Any idea as to how the blown fuses are related? Do I probably have a short somewhere? I think the main blew when I pulled back the engine cover for some reason- I don't believe the timing was a coincidence.

 

[BobRip]

I was using the brush cutter on some dry weeds yesterday and noticed early on that the fan was not coming on, I mowed long enough for the PT to get up to normal operating temp and stopped to check it out. I lowered the engine to an idle and just as I pulled back the engine cover the engine stopped. I located the fan fuse and it was blown. I replaced it and tried to start the PT, turned the key and nothing. I checked to see if the headlights would come on and they didn't. I found the 30 amp main in-line fuse and it had blown. At this point I tried best I could to inspect the wiring in the back tub to try and find a short or loose connection. I disconnected some blade connectors and reconnected them , nothing obviously wrong that I could see. I replaced the main fuse again and it started right up. I stopped and started several times with no problems. Any idea as to how the blown fuses are related? Do i probably have a short somewhere? I think the main blew when I pulled back the engine cover for some reason- I don't believe the timing was a coincidence.

You probably have an intermittent short. I would get a 12 volt light bulb and connect it across where the fuse is. This way the light will light when the short occurs. Then start wiggling wires, connectors, etc. The light will get real bright when the short occurs.

 

[ponytug]

BobRip makes a great suggestion to use a test light. I would suggest that you look carefully at all of the crimped cable ends. I suspect that you had a loose strand, which fried since the short took out both the fan fuse and the 30A fuse as well, which means that the surge was fast, and large. In my experience, if you blow a 30A fuse, you should be able to see the remains somewhere. I often find that for unprotected wires, it is useful to run the wire through your fingers, feeling for nicks or cuts, and to do the same for surfaces that the wire runs over. Most of the single wires on the PT are encased in tubing, so those are very likely good; I would focus on the connectors, the fan wiring, just off of the fan.

I would also double check the electrical connector to the engine block, on the back left side of the engine to make sure that it is well seated.

Good luck. Intermittant shorts are the toughest to find. I had one on a horse trailer that the prior owner spent ~$1000 having a trailer expert 'fix', only to have it recurr. Since it ittermently shorted the brakes and brake lights, I was interested in fixing it. It turned out that the cable crossed a hidden weld, with no grommet, and a sharp edge on the weld had worn through the cable bundle. Hit a bump, short. Hit a bump, good. I only found it when I went to rewire the whole trailer, because I couldn't consistently find it.

I was using the brush cutter on some dry weeds yesterday and noticed early on that the fan was not coming on, I mowed long enough for the PT to get up to normal operating temp and stopped to check it out. I lowered the engine to an idle and just as I pulled back the engine cover the engine stopped. I located the fan fuse and it was blown. I replaced it and tried to start the PT, turned the key and nothing. I checked to see if the headlights would come on and they didn't. I found the 30 amp main in-line fuse and it had blown. At this point I tried best I could to inspect the wiring in the back tub to try and find a short or loose connection. I disconnected some blade connectors and reconnected them , nothing obviously wrong that I could see. I replaced the main fuse again and it started right up. I stopped and started several times with no problems. Any idea as to how the blown fuses are related? Do I probably have a short somewhere? I think the main blew when I pulled back the engine cover for some reason- I don't believe the timing was a coincidence.

 

[Charlie_Iliff]

horse trailer that the prior owner spent ~$1000 having a trailer expert 'fix', only to have it recur.

I agree that there is likely an intermittent short, although there's another possibility. Some years back there were reports of a stick in the fan stopping it. That's a short, no back emf and only winding resistance, but I doubt would blow the big fuse.

Re horse trailer, 20 years ago, my wife and two little pony club girls started having the same brake/brakelight symptoms - on off on off, in the dark 120 miles from home in Western PA. A crossroads gas station guy found the wire pinched between the floor and frame underneath and fixed it for $10. I hope he retired rich.

 

[BobRip]

BobRip makes a great suggestion to use a test light. I would suggest that you look carefully at all of the crimped cable ends. I suspect that you had a loose strand, which fried since the short took out both the fan fuse and the 30A fuse as well, which means that the surge was fast, and large. In my experience, if you blow a 30A fuse, you should be able to see the remains somewhere.


Good point about double fuse blowing. It of course is probably in your fan circuit.

For the light bulb I suggest a head light, or something that pulls at least a couple of amps. The more the better up to about 10. A car head light pulls about 5 amps. With this technique I have found several shorts over the years which would have been impossible to find using other techniques.