I'm out of ideas...

Hello Forum,

I have a 1994 Evinrude two-cycle doing something I just can't figure out. I'll do my best to explain it:

My engine starts and idles okay, with the occasional spit and some exhaust smoke. It runs great in out-of-the-water. It will hit top RPMs; however, when I put it in-the-water and engage the forward gear, it starts off great for about 2 seconds, then it bogs down around 2500 RPMs and won't pass 3000 RPMs. Sometimes, it will try to increase RPM's but then the engine bogs right back down. I can put it back in Netural, rev the engine backup, but again, as soon as I put it back in gear, it won't perform under a load. It does perform great out-of-the-water. So far, I've replaced the in-line Fuel Fitler and all Fuel lines. I've also drained the Water-Separating Fuel-Filter. The plugs are fairly new and compression is 120psi in all four cylinders. While in gear, I've tried hand pumping the fuel primer, to see if it was possibly the fuel pump. This engine was running fine one month ago. I've spayed the engine down with corrosion guard and used Sea-Foam in the gas tank. I'm at a loss, any ideas would be appreciated.

TIA,

Versipelis

Is it overheating? Maybe going into SLOW and not letting it go faster. Disconnect the heat sensor wires and see what happens. They may be bad.

All motors will wind up in neutral as there is no work to do.----That exercise proves nothing at all.----Do you have spark on all 4 leads ?---------Plug wires on the correct cylinders ?-----Do a test run with the cover off too.

Will Bark said:

Is it overheating? Maybe going into SLOW and not letting it go faster. Disconnect the heat sensor wires and see what happens. They may be bad.

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No overheating alarms have sounded and I also used a temp gun. I did test the overheating alarm one month ago. Do you know if the SLOW would engage in reverse? I have no troubles with a load in reverse. I'll check those sensors tonight.

It was running fine three weeks ago and I've made no changes to the ignition system. I will test the spark tonight as well.

I tested the heat sensors and they work. Can you think of any another possibility?

Versipelis said:

It was running fine three weeks ago and I've made no changes to the ignition system. I will test the spark tonight as well.

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OK, it was running fine 3 weeks ago, that's a start. You say it is a 4 cylinder 1994, is that like a 115hp? I have a 1991 115hp and it has an electrical fuel primer that is key activated. If you have that feature, push the primer when you put the boat in gear and it starts to bog down. If you can get the boat to speed up better by pushing the primer, you have a carburetor problem, your high speed jets are clogged. I once got home just using the primer to keep the engine going.

Let me know how it comes out.

Klink said:

OK, it was running fine 3 weeks ago, that's a start. You say it is a 4 cylinder 1994, is that like a 115hp? I have a 1991 115hp and it has an electrical fuel primer that is key activated. If you have that feature, push the primer when you put the boat in gear and it starts to bog down. If you can get the boat to speed up better by pushing the primer, you have a carburetor problem, your high speed jets are clogged. I once got home just using the primer to keep the engine going.

Let me know how it comes out.

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It's a 1993 Evin V-4 Ocean Pro 120. I have a priming bulb with and key activated choke. Friday, I tried choking it while in gear and it would not increase RPM's. I've tried pumping the priming bulb, while in forward gear, and that didn't help either. I talked to a local mech. who suggested that it might also be clog High Speed Jets. The motor acts like it wants to get us on plane, but then fails and bogs down. It continues to run around 2500 rpms with slight audible surges in rpms. You can also audibly hear the engine bog around 1/2 throttle or roughly 3000 rpms. I can back-off of the throttle and I can hear it run a lot smoother. You think it might be the High Speed Jets?

I would agree with clogged jets. The choke trick can work but you just use a tap. tap, tap the motor picks up then falls off again. tap tap and it repeats is definitely a carb problem. Not familiar with your motor but the 70 and 140 I own the carbs are pretty easy to clean and depending on the boat you may be able to just pull the plugs in the carb and blow 25 psi air though the jets to clean them out.

My two cents is that this may be a spark issue and not fuel. If your motor has the power packs found on the older v4's i would suggest using the CDi test methods as this sounds a lot like a blown diode on one of the packs, which can cause intermittent/incorrect spark timing.

If you don't have the powerpacks i would do a complete diagnostic test if the ignition and spark advance system.

I say electrical because when you back off on the throttle you mention the motor runs a little smoother, pointing to enough fuel and not enough spark or spark advance.

Do you think the Spark Advance System would fail only under a load? The problem only occurs when the engine is in the water, under a load. Performance out of the water is fine. If I can find the time, I'm going to work on it this week. I'll let you guys know what I find. Thanks for the help.

If you see what Racerone said. Any motor runs well out of the water. So that tells you very little. They rev on the muffs with minimal spark and fuel and then will idle and rev pretty well on three cylinders out of water.

in water is a whole different issue as you then add back pressure and a load to the motor and three cylinders no longer cuts it.

do a full ignition diagnostic, I am sure you will find the problem.

spark testing is the first test. Coils, packs, "triggers", staters, optical pickups are next
lots of good info for all this on this site

also remember that you may be chasing more than one issue. So don't stop the diagnostic simply because you find one thing. I did that and spent months because you fix one thing that doesn't fix the problem. It's not unusual that one had area in the ignition system causes failures to other parts as well.

This happened to me on my 1994 OceanPro 175. It was the shift interrupter switch. Located on the starboard side of the engine where the throttle linkage is. It connects at the top of the powerhead under the plastic cover. Disconnect it and see what happens.