Robin Subaru Engine Problems With Solutions

[BobRip]

We have had complaints about problems with the Robin Subaru engines.
I would like this to be a thread that someone could use to quickly find a solution to an engine problem. Let's try to keep this to solutions that you are sure of and have personally tested. Here is the example format.

Problem #: 1

Problem: Engine runs on one cylinder, runs rough at all speeds and stalls when idled.

Safety Concerns: The spark on the ignition coil can give you a nasty shock. Handle with care.

Test: Run engine at medium speed. Pull one plug wire and see if engine stops. If it keeps running put that wire back and pull the other plug wire. If it stops there is a problem with the ignition on that side. Test for a spark by putting a screwdrive in the spark plug wire cap. Hold a portion of the screwdriver near a ground, crank the engine. If there is no spark then the ignition coil or wire is bad or the magnets are dirty. If there is a spark then check the spark plug.

Solution: I found a bad ignition coil. It was originally erratic but then failed completely.

[BobRip]

Problem #: 2

Problem: Engine does not start when cold. It cranks normally.

Safety Concerns: Normal care about rotating parts. Wear safety glasses.

Test: Crank engine with choke on. If it does not start remove air cleaner and verify that the choke is closed. Manually try to close choke if needed at carburetor. (The choke is closed with a spring and may erratically stick open). If it starts then this is the problem.

Solution: Try cleaning the choke assembly with carburetor cleaner. If this does not work do this.

Close choke and remove the screws that hold the coke plate to the choke shaft. (Be very careful not to drop the screws in the carb. You might want to put a piece of tape on the choke plate hole) Observe how the choke spring is installed. Remove the choke plate and pull the choke shaft out. Clean the shaft, choke plate, and holes that the shaft when through and reassemble. This problem was erratic and once I manually closed the choke it would be OK for awhile. The next monring it would not close.

[BobRip]

We have had complaints about problems with the Robin Subaru engines.
I would like this to be a thread that someone could use to quickly find a solution to an engine problem. Let's try to keep this to solutions that you are sure of and have personally tested. Here is the example format.

Problem #: 1

Problem: Engine runs on one cylinder, runs rough at all speeds and stalls when idled.

Safety Concerns: The spark on the ignition coil can give you a nasty shock. Handle with care.

Test: Run engine at medium speed. Pull one plug wire and see if engine stops. If it keeps running put that wire back and pull the other plug wire. If it stops there is a problem with the ignition on that side. Test for a spark by putting a screwdrive in the spark plug wire cap. Hold a portion of the screwdriver near a ground, crank the engine. If there is no spark then the ignition coil or wire is bad or the magnets are dirty. If there is a spark then check the spark plug.

Solution: I found a bad ignition coil. It was originally erratic but then failed completely.

I have an error in the above post. The corrected Test: section is below.

Test: Run engine at medium speed. Pull one plug wire and see if engine stops. If it keeps running put that wire back and pull the other plug wire. If it runs there is a problem with the ignition on that side. Test for a spark by putting a screwdriver in the spark plug wire cap. Hold a portion of the screwdriver near a ground, crank the engine. If there is no spark then the ignition coil or wire is bad or the magnets are dirty. If there is a spark then check the spark plug.

[BobRip]

I am hoping others will post issues here. If they think this is valuable. Maybe it's not.

[westcliffe01]

If you pull a plug wire and it makes no difference, THAT is the defective side (it is not firing, hence pulling it makes no difference).

[BobRip]

If you pull a plug wire and it makes no difference, THAT is the defective side (it is not firing, hence pulling it makes no difference).

That's right. Thanks for the clarification.

[JIMMY JAMES]

I have a robin subaru EX27 9 hp engine on a portable backhoe that can run from for the first 1hr to 45 mins and will just stop. I can get it started with one pull and it will run for another 5 mins to 30mins. It usaully doesn't happen for the first 45mins, but once it happens then it will keep happening the rest a of the day Any ideas on the problem.

[woodlandfarms]

Vapor lock or gascap issue

[JIMMY JAMES]

Thanks for the reply. Definitly not gas cap had that problem on a generator once so I am on top of that issue. It still happens when the cap is loose and well vented. Is there any thing I can do for the vapor lock? I thought vapor lock only happen after you stop the engine

[Tim_in_CT]

The mechanical fuel pump is mounted on the cylinder head. Close proximity between it and the muffler can cause it to vapor lock. You can move the fuel pump anywhere you want (it is pulse driven off crankcase vacuum, not using a mechanical linkage).

Also look at how the fuel hose is run. If you put some heat shielding around it (or just user thicker hose), it can partially solve tis problem.

Big assumption here; I am describing the robin 22hp engine, not the 9 hp version.