422 Robin eng...problems AGAIN.

[ldabe]

Went to fire up the PT and would not start. Just kept cranking over and over. Had to get ready to go somewhere so I left it till the next day.
Fired right up!
But, started sputtering and also had greyish white smoke come out of the muffler.
It wanted to die if I throttled full, then it would do better as I moved throttle back down, almost to idle.
I took the cover and filter off of the carb, and it was spitting fuel (lightly, off and on, not a steady thing) out of the port to the side of the carb as you look directly at it from the top.
It always has seem to run rich, but I think, for some reason it is really rich now. So much so that it is spitting excess.
Before I search the forum for others that have had similar problems, or go to the Robin site, can anyone help with this?
Do I need to try and adjust something? And where would that adjustment be?

Thanks in advance.

 

[Gator6x4]

Do a engine compression check, you could have either a bad or leaking valve.

 

[ldabe]

Do a engine compression check, you could have either a bad or leaking valve.

Is that with 2 breaths to every 15 compressions? ;~)

Just kidding. But I have no idea of how to do that, much less if I even have the tool (if tool needed) to do it.

Not very mechanical.

But thanks for the suggestion.

 

[Gator6x4]

My next suggestion would be to have someone with mechanical skills determine if the problem is internal or with Carburetion. Given the cost of parts today, it can get very expensive quickly if one starts turning screws or making adjustments without knowing what the consequences of their actions or the outcome of adjustments or modifications made is going to be.

 

[Marks481]

Stuck float or sticking intake valve. My vote is stuck float valve, which is much easier to fix then the sticking intake valve.

Engine compression test is easy. You need a compression gauge, which you can buy at any auto parts store for $25 or so. It must have an adaptor that fits 14 mm spark plugs (almost all do). Search Amazon for "JABETC compression tester" will show you one for $30.

You take out a spark plug and thread it in the hole, then turn over the engine with the starter. The compression gauge will put a pointer on the highest pressure it sees. You should see something like 110-120#. Repeat for the other cylinder.

 

[westcliffe01]

And hold the throttle on the carb fully open while cranking to get the cylinder compressiion. Else you are building up a high vacuum in the intake and will get low compression readings even if the compression is good.

Not doing this is a neat trick for getting un - savy consumers to spend money on rebuilds that they don't need.

 

[ldabe]

Thanks guys! I will try and get me one of those testers soon. First, I think I will ask a couple neighbors if they have one to borrow.

Also, Tim, should I check the "float" first, or do the test first?

 

[ldabe]

Was in the barn doing some work, took a break, went over to the PT to see what it would do today.
Throttle - full
Choke - off

Turned the key, had a small pop, and immediately fired right up!
Ran great at full throttle, no choke, for about 45 seconds.
Then, began to sputter. Got worse over next 20 seconds.
Throttled to half-throttle, seem to even out...until about another 20 seconds.
Trottled all the way down, and engine died!

First, a question for "MossRoad" (and others that never seem to have a problem with their eng).
- Do you have a gas cock shut off valve under your gas tank, and do you use it?

Second, now that I think about it.....this seems to be what was going on when I had a piece of junk (object) in the bottom of the gas tank a couple months back! I think I will try to look at that possibility today if I can work in into the schedule.

Thanks again guys for all your knowledge and advice, especially for a "mechanically challenged" fellow like myself ;~)

 

[westcliffe01]

If you can start the engine cold with no choke I suggest it is flooded. In fact, the procedure you describe is exactly what to do with a flooded engine. But once you burn off the accumulated fuel it will go lean and rough and probably quit. You sould try adding some choke and if it smooths out, the first paragraph is confirmed. Once it is warm, open the choke (it should start "hunting" which indicates the misture is too rich).

Could well be that the needle is not sealing on the seat. Could be due to dirt or plain wear and sometimes they just never work out of the box (had this on an outboard after installing a carb rebuild kit). The priming bulb would never get firm and fuel would overflow into the intake.

I have a generator with a robin engine and it starts first pull every time.

 

[toy]

Idabe have you checked the fuel filter?

 

[MossRoad]

First, a question for "MossRoad" (and others that never seem to have a problem with their eng).
- Do you have a gas cock shut off valve under your gas tank, and do you use it?

No, there is no fuel shutoff on my tractor which is a 2001 PT425 with the Kohler engine.

 

[PTOuser]

Idabe I hope I'm way off but this sounds quite a bit like my gas in my crankcase issue. I got quite a bit of whitish smoke and she died. Have you checked your oil level? See http://www.tractorbynet.com/forums/power-trac/149992-2-part-gas-1-part.html. You might take a sniff of the towell you clean the dipstick on too just to be on the safe side.

 

[J_J]

No, there is no fuel shutoff on my tractor which is a 2001 PT425 with the Kohler engine.

David,

Some of the Kohler's I looked at had a solenoid fuel shut-off at the carb, All my vertical Kohler 25 HP engines have this feature.

 

[Gravy]

Most fuel shutoff solenoids on carbs only shut off fuel to the main jet. They have no effect whatsoever on the float valve. They mostly exist to minimize dieseling/run-on after turning off the ignition.

 

[J_J]

Most fuel shutoff solenoids on carbs only shut off fuel to the main jet. They have no effect whatsoever on the float valve. They mostly exist to minimize dieseling/run-on after turning off the ignition.

I agree partly.


Maybe I am wrong here, but my thinking is that a carb with no fuel shutoff in the carb, and float hanging open, will let fuel up through the main jet and settle in the crankcase. With a solenoid in the carb, and closing off the main jet, even if the float was sticking, the fuel might only run out the bowl to the outside. Don't know for sure. I am also thinking this only happens when a tank is located at a level above the carb. One could easily set up a test to verify this.

 

[hogi]

I posted a thread not too long ago about a flooded crankcase. My 2005 PT425 w/Robin engine has a fuel shutoff solenoid on the carb and it does not prevent flooding of the crankcase. I have installed an in-line shut-off to get by, but its hardly an ideal situation. It's easy to forget in the rush to get a project done, and just a pain to have to pop the cover and manually shut off the fuel for any time you want to stop 1/2 hour or more. My PT starts w/out needing to be choked, and runs rich all the time. I definitely think the shut-off is needed and Robin calls for it when the fuel tank is mounted above the carb, as with the PT 425. I think I will have to clean out my float valve to get my engine running right again.

 

[woodlandfarms]

What about this for the Robins users?

http://www.snydersantiqueauto.com/4008

Wire it to the key.....

 

[ldabe]

Mine has always seemed to run rich! It seemed like it when I first bought it (used) and then also after a new carb replaced the old.

Once again, I have to say I am not impressed with Robin engines. This is the first I have ever had, and will be the last unless I just can't get around it.

 

[ldabe]

Anyone know off hand what the gap is suppose to be on the plug for the Robin 422?

Just got two new ones. The old ones (I say old, but they were new at the beginning of summer) were black with "soot". So much, I almost called a Chimney Sweep!


From Robin site: "If the smoke is black in color, it typically indicates that the mixture is too rich. Incorrect mixtures of air and fuel cause the majority of carburetor problems; therefore, it is important to prevent clogged jets, air passages and fuel passages that keep air and fuel from flowing freely. Check the carburetor for dirty or defective parts and clean or replace them if needed. A change in elevation also may cause black smoke, in which case the engine should be modified to handle the difference. If basic troubleshooting maintenance techniques fail to work, have a trained mechanic conduct a leakdown test or compression test to determine the cause for any smoking or power reduction."

http://209.62.29.198/articles.aspx?t=e&id=34

 

[Gravy]

I agree partly.


Maybe I am wrong here, but my thinking is that a carb with no fuel shutoff in the carb, and float hanging open, will let fuel up through the main jet and settle in the crankcase. With a solenoid in the carb, and closing off the main jet, even if the float was sticking, the fuel might only run out the bowl to the outside. Don't know for sure. I am also thinking this only happens when a tank is located at a level above the carb. One could easily set up a test to verify this.

Yes, there are a lot of details of carb design that come into play. Some will overflow to the outside and not flood the engine, while some have a bowl vent that will dump right down the throat. I just wanted to point out that most solenoids do not cut off the fuel supply to the whole carb.