Technical Assistants

[ldabe]

Ok,

I mentioned on another thread that my PT 422 Robin (#@@#&*^) was dying on me in mid-flight.

I would be going along, everything ok, and bam! The engine would just shut off!

Well, I found that the negative cable from the battery connected to the bottom of the engine was not tight. The bolt was very loose. I tightened it up, and walla, it started, and had no problems...............................until
mowing today.

Back to the same thing. I jiggled the negative cable (not easy to get to with the placement of the muffler, and everything hot) and it started up again.

Then died after about 5 minutes. Then same process, ran for approx. 15 minutes, died again.

No jiggling helps at this point.

I am going to let it cool off, undo the negative cable, clean it, put it back on to see if that will solve the problem.

In the mean time, has anyone else experienced a problem like this?

Does anyone have any other suggestions, or trouble shooting ideas?

I did use a digital meter to check, battery...A-ok.

I also went from the neg. connection at the eng. side and to some small (12-14 gauge) positive wires, and get 12.86 volts.

Wish I was better at trouble shooting, but not knowing what half of the parts are, and which wires are what, and what they do, well............I guess you could say that is the other half of the problem.

All feel free to jump in ;~)

 

[BobRip]

Just some thoughts on things I have seen:

Bad battery cable: Looked good, but prevents starting. Check to see if pulling the cable off the termial with the engine running gives you the same symptons. This may not be your problem. Replicate the problem.

Bad fuse holder: There were loose connections in the fuse holder that comes off of the starter. Do the lights still work when the engine dies? You should be able to trace back to the failure. If the lights go out, leave them on and the key on and start wiggling wires, connections, fuse holders, etc. Have somebody watch the lgihts as you wiggle. The component that makes the lights go on and off is probably bad.
I hope this helps. Keep feeding us data.

 

[Wayne County Hose]

I have a 5 hp generator with the Robin engine. I used to have the same thing happen. I finally found the low oil sensor as the culprit. I disconnected it and it hasn't died since. Used to be the same thing you describe. Engine would be running, 30 minutes maybe, and shut off. What the? Go over, check the on/off switch, it's on, gas is good, pull the cord, and fire right up. Might run for 2 hours next time, then just shut off. Hope this helps, I know it's not as large an engine, but maybe the same sensor?

The negative cable should have nothing to do with the engine dying. You should be able to disconnect the cable with the engine running and the engine shouldn't die.

 

[BobRip]

I have a 5 hp generator with the Robin engine. I used to have the same thing happen. I finally found the low oil sensor as the culprit. I disconnected it and it hasn't died since. Used to be the same thing you describe. Engine would be running, 30 minutes maybe, and shut off. What the? Go over, check the on/off switch, it's on, gas is good, pull the cord, and fire right up. Might run for 2 hours next time, then just shut off. Hope this helps, I know it's not as large an engine, but maybe the same sensor?

The negative cable should have nothing to do with the engine dying. You should be able to disconnect the cable with the engine running and the engine shouldn't die.

On my PT the oil pressure switch is not connected. I suspect it's that way on all of them. They connect them on generators because they operate unattended for many hours at a time.

You are probably right about disconnecting the negative cable. Give it a try Idabe.

 

[Wayne County Hose]

I have done a ton of electronic troubleshooting on equipment, and I can tell you that intermittent problems like yours are the absolute worst. It used to drive me nuts. "If this blasted thing would just die, I could fix it." By the time you start troubleshooting, it runs again. Enough to make a preacher swear.

I like Bob's idea. This does sound like it could be a bad connection.

Well, if it died completely, you are in luck. Now, it can be fixed. Do you have an electrical schematic that you can post? I can tell you what to check and where.

 

[BobRip]

I have done a ton of electronic troubleshooting on equipment, and I can tell you that intermittent problems like yours are the absolute worst. It used to drive me nuts. "If this blasted thing would just die, I could fix it." By the time you start troubleshooting, it runs again. Enough to make a preacher swear.

I like Bob's idea. This does sound like it could be a bad connection.

Well, if it died completely, you are in luck. Now, it can be fixed. Do you have an electrical schematic that you can post? I can tell you what to check and where.

Me too on tons of troubleshooting. You could also hook up a beeper and listen to is as you wiggle things. Parallel the beeper with the lights or the fuel solenoid.

 

[woodlandfarms]

Electrical is bad, but for me ground electrical issues are the worst. Make sure where the cable is connecting that it is clean and dry and free of paint First, more than likely you have been arking there so no there is carbon buildup. Second, everything gets painted before wiring so generally the ground points have paint on them

I am going to be running a big grounding strap from my engine to my front and back chasis. Just to make sure that I never have grounding issues...

 

[ldabe]

BobRip,
I have been unable to start it since it last died, but I will try removing the neg. cable when I ever do get it started.
The lights did not work this last time when the eng. died. But before this last time, the oil cooling fan would come on sometimes. This last time it died, I went to lift the hood and before I did the fan came on, so I tried to start (like other times) but no start, and now the fan doesn't come on either.

WCH,
I don't know if I have a sensor. I will try and find out. But your description of what was happening to your Gen. is a lot like what I was experiancing with the PT. (Btw, I am a preacher, and the old familar words did come to mind, but so far, thank God, have not come out of the mouth.)
I will try to dig out the schematic and post it.

Woodlandfarms,
I cleaned the neg. cable pretty good, but still nothing. What kind of "strap" are you going to be using (size, material)?

Thanks for all the suggestions, and please, keep them coming.

 

[cqaigy2]

If i understand right, sounds like nothing electrical is working. Try bye-passing the the switch by running from the battery directly. See if you can get the starter to spin that kind of stuff. When you turn the switch on do you hear a click from the the fuel shut-off solenoid?

 

[John47]

I have done a ton of electronic troubleshooting on equipment, and I can tell you that intermittent problems like yours are the absolute worst. It used to drive me nuts. "If this blasted thing would just die, I could fix it." By the time you start troubleshooting, it runs again. Enough to make a preacher swear.

I like Bob's idea. This does sound like it could be a bad connection.

Well, if it died completely, you are in luck. Now, it can be fixed. Do you have an electrical schematic that you can post? I can tell you what to check and where.

When I was working for a living I was a maintenance electrician, like you say, intermittent faults make one look like an idiot.
No idea what he's operating, but I had one like that on my ride on mower, turned out to be the seat safety switch "making" for some obscure reason, so just pulled the connector and no more problems.

 

[woodlandfarms]

I was referring to grounding straps. They can be found in any automotive store. Silver mesh wire with battery type lugs at the ends...

But now things have become interesting. It is possible that the intermittent contact has blown a fuse.

So start at the beginning... Get yourself a volt meter (cheapo from anywhere) or even one of those probes that lights up can work.

Check to make sure your battery has juice. Follow those leads to the first stop. On my tractor it is the starter solenoid... If you have juice there then turn on the key... Also, as we are thinking ground is the culprit, use the battery terminal ground and then if you get a positive response try the engine as a ground, or the chasis. Your whole tractor is a ground or negative part of the batter, only the covered wires are positive... (this is a real simple way to look at it BTW)

Really, electrical and hydraulics kinda are the same. It all starts at one point and finishes at another. Follow the flow.

PT has a rep for mediocre wiring. Thankfully it is dirt simple so you do not need an EE degree to repair, but still frustrating.

 

[SpringHollow]

I ran a grounding strap from the front to the back when my alternator was putting out 16.5 V. (Did not help with that problem).

I was concerned it might increase ground loops but i do not think there is anything that is that sensitive in the PT.

Ken

 

[ldabe]

Ok,
I found the problem (I think).

A wire from the wiring harness (then going to the eng.?, left side) had a bad connection at the 5 point connector.

I pulled it apart cleaned it up and made sure the connection was tight.

Started right up. Did about 45-60 minutes of mowing with no incident.

Btw, I did the jiggle the individual wire trick with the ignition and light switch on. When I moved that wire (black with a white stripe) the light came on.

Thanks for all the help. (Now onto my zero turn that broke a trans belt the same day the PT stopped!)

 

[BobRip]

Congradulations. The help here is wonderful. Let us know if you have any further problems.