Need Help with Robin Engine

[pairodime]

I'm having a problem with my 425 Robin engine-- she starts and runs for 3 to 15 seconds and then stops. I suspect it is starved for fuel but hate to randomly try solutions.

Here is some background-
-My 425 is the newest model with 50 hours on it.
-I've been having a minor problem with fuel hose. The engine would stall due to too much vapor in the fuel line. Terry had me reroute the fuel line so it wasn't in contact with the hydraulic lines and it seemed to make a difference, but it would still happen to stall after running for a long time.
-I ran the engine 10 hours over the past 2 days with my only problem being the fuel line. You can tell this was the problem because the fuel filter bulb had no fuel, only vapor. Once it cooled for a 15-20 minutes, the bulb would have fuel in it again and she would run fine.

So today, I was planning to do my 50 hour service, when I can't get it to run longer than 15 seconds. There is fuel in the line, filter bulb, all the way to the fuel pump. A review of the Robin service manual shows the carburetor has a float chamber that holds fuel. My suspicion is that my fuel problems have cause this chamber to not be refilled adequately and the PT dies when its contents have been exhausted? After a few minutes the PT will start again and run again' but once stalled will not start until some time has lapsed. Or, could there be some other problem with the carburetor? No matter how I adjust the choke or throttle, I cannot keep the engine running.

Any help would be appreciated. Thanks

 

[Egon]

Have you tried changing the filter?

Egon

 

[reb]

I'm not familiar with that particular engine, but I have had similar problems with carbureted engines where a screen at the carburetor inlet got clogged.

 

[pairodime]

Egon,
I haven't replaced the filter, but it is visible and has only minor deposits in it.

Reb,
There is no screen shown in the service manual, but I do believe there is a partial block somewhere or poor fuel pump performance. This problem is occuring when the tank is half full. On a whim, I topped the tank off and the problem goes away. Seems the the extra 8" of head pressure on the fuel system is able to keep the fuel flowing to the engine.

Anyone else have a suggestion? I think I'd like to call the Robins rep, does someone have the phone number of Jack?

Thanks.

 

[J_J]

You might try and add some extra fuel hose to the output of the fuel pump, and see if the fuel pump is pumping like it should. Disconnect the spark plug wires and crank the engine over several times. If you have good pressure, the fuel pump is good. If not, the diaphragm on the fuel pump could be bad. A diaphragm with a hole in it will let gas seep down to the engine and let you start and run for a little bit . If the carb has a solenoid in the float bowl, it might be sticking.

 

[pajoube]

Is this the first run 425 with the Robing Engine?
PJ

 

[toolz_not_toyz]

This sounds like vapor lock. You need to route the fuel line away from any heat source. That's probably what Terry was trying to get you to do when he asked you to reroute the line.

 

[landscapercarl]

We have had the same problem but usually in the fall and early spring We never got an answer form Robin or Power Trac but after 900 hrs the rings were froze and valves shot had to have engine rebuilt. Power Trac said thats about how long it should last and for 3000 they would put in a new engine that was bigger. They didn't want to sell us what we needed to mount a Kohler in it. They wanted to do the work.
I'am not pleased with this engine nor have we been since day 1 We will replace this engine in the off season with a Kohler since I know they will last. We are sure it's all heat related and are going to mount a fan to get more cool air around the engine.

 

[tracdoc]

Still waiting for Jack from Robin to engage in this thread...

 

[pairodime]

Pajoube, yes it is the first run 425 with the Robin engine

JJ- Thanks for the tip. I did pull the hose and check the fuel pump. I get a very minimal flow so I'm very sure that the problem is the fuel pump. Just need to get it replaced. Until then, as long as I keep the gas tank full enough, there seems to be enough flow to run the engine.

I do believe that it is all about heat management. I've rerouted the fuel line and insulated it where it was immediatley adjacent to hot components.

 

[Tak]

Pairodime,

Been having the same problem with our 422. Always starts when cold and will run for a while until hot. Then will die and will be practically impossible to start unless it sits for 5-10 min. Suspected vapor lock so rerouted fuel line. Still had the problem. Area where fuel line attaches to carburetor gets extremely hot from engine air (not even able to leave my hand there for any extended period). Fan would definitely help blowing over that area.

However, even after insulating the fuel line, engine still cut off while the fuel line was not hot at all.

Solenoid cut off switch had wire looped back on itself and tied to body. Wire insulation was not cut but was discolored where it contacted the solenoid. Appeared to ground itself when insulation heated up thereby shutting off the solenoid (fuel flow). Removed wire from solenoid body and problem seems to have gone away.

Conclusion - inadvertent ground

 

[Schultz]

Wow only 900 hrs. It should last at least twice that, especially since they market this engine as a premium engine. They also started building the engines for Onan, which has a great reputation for long lasting engines.

I'd like to hear Jack's company explaination of engine life or the real mean time to failure number????

 

[MossRoad]

Good troubleshooting. /forums/images/graemlins/wink.gif

 

[landscapercarl]

When the repair shop called Robin to get the parts the reply was we havent had any problems at that end of the engine.
He asked what problems they have been having and they quickly said none. The rest of the motor was fine just the rings and valves he cylinders were within the tolerances.
The repair shop was surprised that the motor didn't last longer. We have had alot of kohler that last years with no problem ususally the machine wears out and the motor still keeps going.

 

[duane]

Carl,

Just curious if you could elaborate on the rings froze and valve shot problem.

Did you experience something breaking, or poor running, or excessive oil consumption

Were the valve seats dislodged, or just beat up.

Did the repair shop indicate if it was a lubrication problem, valve adjustment problem?

The 2422 seems to have less ventilation than the PT422s, so I can see how it would really heat up in the engine bay.

Thanks for any information, just trying to learn up pick up whether we should be doing ant type of accelerated or different prevent maint.

Thanks
Duane

 

[landscapercarl]

The exhaust valve froze open on one cylinder and the rings on both pistons were froze they wouldn't budge. We use synthetic oil and the repair shop said using regular oil they would have froze sooner. We have only one person operae the machine and he opens the engine cover as soon as he gets off the seat so the heat can get away. As I said we have probelms when they reformulate the gas in the fall with boiling the fuel and the machine wont run. we use this machine commercially and when it runs its great but would I get another don;t know right now there are alot more alternatives today. We are taking about a fan and more holes for the heat to escape since there all on the sides and heat rises were going to try some on top.

 

[Schultz]

It's too bad Robin didn't offer to take the engine. I imagine their R&D group could have learned something it and actually figured out if it was heat or oil or a combination of related failure.

 

[JackRobin]

Hello Everyone,

I have been missing from the forum for a while, I've been busy implementing an online warranty processing system, I still will not be visiting the forum as often as I used to, but I'll try to answer at least a few questions.

In reply to the first gentleman that started the thread, seems like you might want to upgrade to the higher output fuel pump. We use higher output fuel pumps in the 25HP motors (EH72). We've included bigger diaphram spring in this pump for better performance. Please let me know if you have your engine up and running again, I think I helped Terry resolving your issue over the phone, I'm just not sure if it was your machine or not.

Regards,

Jack Gawecki
Robin America, Inc.
Technical Support Dept.
800-277-6246

 

[JackRobin]

</font><font color="blue" class="small">( Wow only 900 hrs. It should last at least twice that, especially since they market this engine as a premium engine. They also started building the engines for Onan, which has a great reputation for long lasting engines.

I'd like to hear Jack's company explaination of engine life or the real mean time to failure number???? )</font>

According to the EPA regulations we are requried to stand behind 3000 operating hrs. on the engine, but that doesn't mean that the engine will fail after this time. I was discussing severe wear of parts with a customer in Alabama that had our engine on another hydraulic application tractor. With over 6400 hrs. within a year and a half, he called me demanding warranty on the wear of rings and some other parts, I've declined it, telling him that he's definately is getting his money's worth.

Regards,

Jack Gawecki
Robin America, Inc.
Technical Support Dept.
800-277-6246

 

[MossRoad]

<font color="blue"> 6400 hrs. within a year and a half, </font>

YIKES! /forums/images/graemlins/smile.gif That's 24 hours a day strait for 267 days.

Just out of curiosity, do your warranties go by years and/or hours like automobiles go by years and/or miles?