Ford 4500 runaway

[FordFortyFiveHundred]

Hi folks,
My 1971 Ford 4500 would not shut off at the end of the day. I went to shut off the engine, and it kept running, pretty rough. Usually it will idle down to 500 rpm, then I pull the fuel cutoff. It stayed at about 800 rpm, and did not respond to the cutoff. I got of the tractor and verified the cutoff was pulled to the rear of the tractor, to no effect. At this point it was running pretty rough, with lots of black smoke. It this increased rpm on its own, to about 1400 rpm. I cut off the fuel at the tank, and used the hydraulics to put a load on the engine. It then finally died.

I am afraid to start it again, without know if it can runaway. Is this possible? I am thinking this is an IP issue, as it seems to effect 1-2 cylinders, the exhaust is black not blue, and killing the fuel disabled the engine.

I thought this may have happened yesterday, but is shut down before I got off the tractor to check. I then restarted it, and it ran fine.

Any thoughts? Something easy to check, or just send out the IP for rebuild? The injectors are new when I installed the new head.

Thanks,
Skip

 

[Billrog]

I'm not sure of your problem Skip but if you ever get a runaway you'll know it. The motor will be screaming.

 

[mitch504]

is your cold-start system disabled?

 

[FordFortyFiveHundred]

Great question, I'll check. That would definitely make sense. I may have left the fuel valve open, as we had a couple of cold mornings.

 

[Delmer]

check the oil, and if it's low be prepared to shut off the air before you restart it.

 

[hookedondiesel]

Good point from delmer, a runaway will run off it's own oil, best way to stop it is killing it's air supply. Does sound like somethings up with the injection pump.

 

[Delmer]

And forgot, if the oil is high, fix the diesel leak before you start it too.

 

[thepumpguysc]

FOR SURE check the oil level.. if its hi.. way hi.. don't even try to start it.
IF its ok, pull the top cover on the injection pump.. I'm assuming its a DPA pump??

 

[FordFortyFiveHundred]

Hi folks, thanks for the feedback. It turned out the "glow plug" was stuck open, dumping fuel into the intake. The oil was about a quart high, and fuel of fuel. One of the cylinder filled with fuel, and hydrolocked too, so I pulled the injectors and cranked it over. I changed the glow plug, filter, and oil, and all seems well now. Thank you all for the help.

 

[thepumpguysc]

For future reference.. its called a> THERMO-START..
I've never heard of one causing a runaway but anything is possible.. They are KNOWN to be a weak spot in the system.. fail all the time.. MOST folks just disconnect the fuel line & bend it over.. personally I hate that..
A NEW th-start only costs about 25.00
Glad you got it sorted out..

 

[mitch504]

For future reference.. its called a> THERMO-START..
I've never heard of one causing a runaway but anything is possible.. They are KNOWN to be a weak spot in the system.. fail all the time.. MOST folks just disconnect the fuel line & bend it over.. personally I hate that..
A NEW th-start only costs about 25.00
Glad you got it sorted out..

That's why I thought of the Thermostart first, not a runaway, but a "run-on".

The Thermo-start isn't a glow plug, it sprays diesel into the intake and ignites it, (I think, I'm one of those guys PG hates, I just disable them, never even knew what they cost. Of course, I do live in coastal SC...), so it just running on at 800-1400 rpm sounded like unignited fuel getting in.

 

[thepumpguysc]

LOL.. The only thing I "HATE" is my J O B.. LOL