PDA

View Full Version : Engine trouble.



wackwack
10-31-2010, 06:12 PM
I have a '96 18 classic with the mercruiser 350 mag, current on maintenance. I went to take it out the other day and encountered the following troubles. 1. It did not want to start. 2. once it did, it sounded "sick" and choked up. Runs at idle, but still doesn't sound 100%, surges and chokes from 1000-1500 rpm. planes fine. surges again at higher rpm, but when I throw it on the pins, it runs smoothly and i'm getting the usual top speed of 63-65 mph, so the engine is not lacking power. A friend of mine said that it could be moisture in the water separator, or a fuel pump problem. Anyone encounter this before? Any thoughts?

DonziJon
10-31-2010, 06:30 PM
Risers/Elbows. Pull all the spark plugs and look for a puddle of water around the white porcelain electrode. Start on the port side...most likely sign will be found on the aft port side plug. When you unscrew the plug..be gentile..you don't want to loose any of the evidence.

If you find puddles on a couple of the plugs..you need a new riser on that side. A pretty easy fix. DJ

fogducker III
10-31-2010, 07:08 PM
Fuel delivery issue is my guess....but what the F*** do I know......:lookaroun:

The only reason I say that is because I had similar symptoms on a 350 a few years ago, it was a combination of fuel delivery issues, bad inline filter and fuel pump on the way out.....:frown:

mrfixxall
10-31-2010, 07:21 PM
I have a '96 18 classic with the mercruiser 350 mag, current on maintenance. I went to take it out the other day and encountered the following troubles. 1. It did not want to start. 2. once it did, it sounded "sick" and choked up. Runs at idle, but still doesn't sound 100%, surges and chokes from 1000-1500 rpm. planes fine. surges again at higher rpm, but when I throw it on the pins, it runs smoothly and i'm getting the usual top speed of 63-65 mph, so the engine is not lacking power. A friend of mine said that it could be moisture in the water separator, or a fuel pump problem. Anyone encounter this before? Any thoughts?


350 mag what? carb or efi.... if its a carb check the choke and see if its closed after it warms up,,choke coil may be bad..

poorboy
11-02-2010, 10:49 AM
I agree on the fuel delivery problem but it would not be much of a problem to take a plug out and check for water to eliminate that as a problem. If no water is evident, then I would run the motor and check the choke as Mr Fixxall said if its a carbed motor. Then carbed or injected, dump the fuel separater filter into a clean jar and let it sit for awhile after screwing the filter back on so the gasket does not swell up. Check the jar by looking at the bottom since water is heavier than gas and will settle to the bottom. If you find water, you have found your problem. If no water, time to check the fuel pump pressure or in a carbed motor, the carb itself, may have a bad needle valve or bad float. That would explain why it runs like it is loading up (rich) at idle and low speeds and then does ok at higher speeds. The motor cannot use the extra fuel (leaking needle valve or bad float) at low speeds but can at higher speeds. Hope this helps.