Mercury Boating - Page 4 - Recent Questions, Troubleshooting & Support

i am struggling to find that number please check and let me know if it is correct

this is your engine MERCRUISER 1998 & Newer 350 MAG 44420H7UU 5.0L, 350, 377 MAG MPI STERNDRIVE https://www.perfprotech.com/mercury

sounds like you have gone to far down please let me know where the lower cavitation plate is in relation to the keel (ie hieght difference

try this link http://download.brunswick-marine.com/download/dosearch/@isnew/desc?lang=EN&categories=OUTBOARD$&mod=4

what do you need? the gap or the entire procedure?

i thought all the gauge options including backlighting for each gauge was on the main harness coming from the engine.

there are carburetor jets for midrange running sounds like a carb disassembly and cleaning might be in order.

what you are trying to say is that the engine wont rev up? or it revs up fine with no load but cant rev up when trying to push the boat? maybe its still running on 5 cylinders

I got this free Pdf manual from an online store for free and I don't think Ive visited a mechanic or fixya for help for more than 3-4 times out of the all the times I fixed the chipper in these 4 years

Ahhh Mercury electrical... always a problem. The charging system on a mercury is really simple. You should have 2 yellow wires coming from the under the flywheel and possibly a black one running with them. These are high voltage a/c. They run to the rectifier/regulator which converts the a/c to d/c and sets the voltage to around 14 volts. To test the charging circuit, disconnect the yellow wires from the rectifier/regulator, *CAUTION HIGH VOLTAGE!* hook up a meter, set to read a/c volts to the two yellow wires and crank the engine, be careful not to touch the wire ends while doing this, it could be a shocking experience. You are just looking for any voltage above 12 volt a/c. If you start the engine during this test you could see upward of 100 volts. If this test fails replace the charging coil under the flywheel, it the one with the yellow wires that you just tested. Chances are this test passed with flying colors.So plug it back in and test the rectifier/regulator. Disconnect the red wire(s) and set your meter to read > 12 d/c volts, there may be 2 red wires. Start the engine and test from the red wire(s) to engine ground, you should see >12vdc. 99.9% of the time this test fails. So replace the rectifier/regulator. It is the weakest link. They will fail for something as simple as a loose or corroded battery terminal.

When checking the compression on an outboard motor... you aren't looking for the final number as much as the percentages of variation. There are so many things that can vary the compression numbers, like throttle position, air temperature, and even the tilt of the motor on a four stroke, that the manufacturers don't put the numbers out. What you are looking for is less than 10% variation between all cylinders. So if 3 cylinders are giving you 120 psi and the forth cylinder is giving you 105 psi, that hole has a problem. In the old 2 stroke days what we would find is people were using air cooled 2 stoke oil, which has a much higher burn temperature, and fouling the piston rings with tar.

If the serial number is 3065967, it is a 1971. (Not 80659677??) It appears that the last year produced was 1976 with serial numbers starting with 4314385. 8 and 3 misreading is not uncommon.

Not enough info, but this should help. https://www.perfprotech.com/mercury-marine-parts-catalog/searchserial?search=3335186

Possibly a bad bearing in the tilt motor? Try disconnecting the motor from the tilt mechanism if possible then operate the motor. If it makes noise but less of it, it will be because it is no longer under load. Good luck.

Check the actual model and serial number with Mercury. If newer it’s possibly a four stroke. If it’s an older motor it’s more likely to be a two stroke.

Only things I could find ...

1. S/N beginning with 8075603 , 2.2 Hp was 1984
2. There was a different reference that different countries could have different serial number series which complicates matters.
3. But there was also a reference indicating for outboard motors ... that the nameplate which has the model and serial number ALSO had the year written down ... the last 2 digits of the year in a box in the lower right hand corner

yes. Will work fine

Depends on model and shaft lenth.

Does it spark?

The fat red wire will go to the input side of the solenoid along with the trim power on the same 5/16ths lug. the black is not power it is ground and the starter wire should be yellow with a red tracer, the start wire is connected to one of the two 1/8th inch connections and the ground goes to the other. For future questions include your year and serial number. I could be way off if this is a 1970s model.