My C-175 isn't running right!

[Dnalsae 2]

I have a 1983 C-175 twin automatic with the series 1 KT17. One day it was running beautifully for about 4 hours, I shut it down and let it cool to refuel. when I went to restart it, it had what i thought was a misfire. I parked it for a couple weeks and the same thing happened when I started it. It coughs and sputters and is really underpowered right away. Choke doesn't help, but it seems to run smoothly at idle. so far I have put new head gaskets, points/ condenser, ignition switch, coil/ plug wires, all intake gaskets and rebuilt the carburetor. Nothing seems to help and I am at a loss. This tractor is my snow plowing machine and I would really like to get it fixed and would rather not repower it.

 

Is there something I'm missing? Any help is appreciated. Thanks.

[haydendavid380 759]

About the the only thing you didn't mention is a valve issue.

[Dnalsae 2]

That was my next thought. Anything I should look for besides a normal valve job?

 

[pfrederi 18,667]

Did you just set the points by feeler gauge gap or did you use static timing or a timing light??  Valves on KTs are not adjustable.  Too loose replacement to tight you can grind a tiny bit off the end.  Do not get carried away.  i have a KT 17 with a nice valve tick now after I "adjusted" it

[Dnalsae 2]

I just used a feeler gauge to set the points.

[oliver2-44 10,711]

Sure sounds like timing or fuel.  Pull the fuel line off at the carb and check that your getting a good supply of fuel to the carb. with a poor fuel supply it would have enough fuel to idle but be starving for fuel a few seconds after you raise the throttle. If the fuel pump needs cleaning/rebuilding you can get a kit from Then and Now Automotive.  On timing this would be rare, but the points plungers do wear if this is a high hour engine.   

[Dnalsae 2]

I was using a gravity tank to test after all my repairs. The mechanical fuel pump was switched with a vacuum pulse pump before I got it. So I don't think fuel delivery is an issue. The engine has about 1500 hours and doesn't appear to have ever been rebuilt.

[pacer 3,177]

You said it is a series 1 and you are probably aware of their reputation for 'coming apart'! When you had the heads off did you ck to see if both pistons were moving as supposed too? They will run on one cylinder, poorly, but WILL run. When its idling pull one plug wire off, see if it runs, then do the other ......

[Dnalsae 2]

Both pistons seemed to move correctly and all 4 valves moved correctly also. There was a small amount of oil in the bore so I'm sure it could use rings but there wasn't much movement in the pistons themselves.

 

Maybe I should just plan on doing a full rebuild?

[gwest_ca-(File Mod) 11,474]

Long shot but is the condenser well grounded?

Try putting the old one back on. They will 1/2 fail and really affect the timing.

 

Garry

[Dnalsae 2]

It's worth a shot at this point.

 

[pfrederi 18,667]

I would check the timing with a timing light or set it statically

[wfrpalm 218]

If it ran good until you refueled chances are pretty good it is fuel related.

[953 nut 59,925]

21 hours ago, Dnalsae said:

I shut it down and let it cool to refuel. when I went to restart it, it had what i thought was a misfire. I parked it for a couple weeks and the same thing happened when I started it. It coughs and sputters and is really underpowered right away.

 

13 hours ago, wfrpalm said:

ran good until you refueled chances are pretty good it is fuel related.

           When a problem crops up you need to consider what was the last thing done to the tractor before the problem started. It could be as simple as a bit of crud from the fuel can or the nearly 40 year old fuel tank was dislodged and has worked its way into the fuel filter, fuel pump or  carburetor. I would suggest giving the carburetor a good long soaking and cleaning (again), replacing the fuel hose and fuel filter to see if they caused the problem.

[Jeff-C175 7,206]

2 hours ago, 953 nut said:

a bit of crud

 

Or water...

 

There is a very fine mesh filter at the fuel tank shutoff valve (unless it's been replaced with one that doesn't have the filter).  You can see the filter from the filler hole (with a near empty tank).  Take a look with a bright NON SPARKING flashlight.

 

I recently had my tank out and was amazed that the machine was still running with all the crud sitting around that mesh screen.

 

[71_Bronco 1,072]

I'm no small engine expert, so take my advice with a grain of salt.

 

I'd guess fuel line / tank. The fact that it ran okay on the gravity tank (which I'm assuming is not the tank in the tractor), and then running bad in the tractor, makes the tank / lines the only variable. Your pump may be working fine, but if the strainer is super clogged, it wont matter as the gas wont get through.

[racerjohnbf 130]

2 hours ago, Jeff-C175 said:

 

Or water...

 

 

This was my thought too. I would start with known fresh fuel.

 

With the ethanol in fuel these days I've seen even sealed fuel jugs get water in them. 

[953 nut 59,925]

7 hours ago, racerjohnbf said:

With the ethanol in fuel these days I've seen even sealed fuel jugs get water in them.

Don't ever use that engine killing junk!          https://www.buyrealgas.com/

[racerjohnbf 130]

14 minutes ago, 953 nut said:

Don't ever use that engine killing junk!        

Oh don't worry, no ethanol gas goes into any of my small equipment at home. I'm fortunate to drive right by a gas station with real gas on the way home every day. 

 

Unfortunately I don't have that option at work so I still get to deal with it there. 

 

As a side note under the right conditions I've even had water get into a sealed gas can in my garage, even with real gas.  We had a really warm day in the middle of winter and I had the bright idea to open the doors of my insulated garage to warm it up in there some. Within minutes everything was covered in condensation and when mowing season came around I found out the hard way I had water in my fuel. Lesson learned lol.

[Dnalsae 2]

It runs the same with a gravity tank as it does with the tractor tank under the fender pan. Brand new fuel and new fuel line. I'm starting to lean more towards a valve issue because I think I have addressed most if not all of the fuel/air possibilities.

 

Thanks for all the input guys I really do appreciate it.

[haydendavid380 759]

Have you tried seeing if it will run right with carb spray?

 

Super quick and easy to eliminate or confirm if it's a fuel issue.

[Jeff-C175 7,206]

4 hours ago, Dnalsae said:

starting to lean more towards a valve issue

 

But it's certainly quite a coincidence that it started after you added fuel don't you think?

 

Valve issues generally don't appear suddenly,  the issue develops slowly over time.

 

Edited February 4, 2021 by Jeff-C175

[racerjohnbf 130]

16 hours ago, Jeff-C175 said:

 

But it's certainly quite a coincidence that it started after you added fuel don't you think?

 

 

Can't argue that, but anything is possible.

 

On 2/2/2021 at 10:38 AM, pacer said:

They will run on one cylinder, poorly, but WILL run. When its idling pull one plug wire off, see if it runs, then do the other ......

                                                ^   

                                                ^    

Have you tried pacer's suggestion? If not fuel related it sounds as if it could be running on one cylinder.

 

Also I'm guessing you did, but have to ask. Did you replace the spark plugs when going through the rest of the ignition system?

Edited February 4, 2021 by racerjohnbf

[Roger R 459]

Had a similar issue on a single cylinder unit. After untold "fixes" and expense it turned out to as simple as a fine film of oil seeped into the points enclosure.  Quick shot of Brake Clean, and problem instantly gone.

[Bill D 2,247]

Try running a jumper from the battery positive to the coil positive.  If it runs properly then you have an electrical issue causing voltage loss to your coil.  Clean all grounds and consider running an extra ground from the battery to the engine block.  Bill