Generator blew a hole through Venalift muffler.

[bvcllc]

Hello. I'm new here and new to boating. I purchased a 1988 4207 Carver AFT
cabin. I've been having problems keeping the generator running. It seems to
be running very rich. Can smell and see fuel coming from exhaust.

I have changed the oil cutoff switch. Checked the plugs, float, etc. The
other day I started the gene and it ran extremely rough, bogged down and
then restarted with a bang. It blew a hole in the Venalift muffler. Scared
the hell out of me.

Any suggestions? Thank you.

[Midnightsun]

Really sounds like a stuck float, regardless, definitely a carburetor issue. I would start by removing the carb and having it cleaned ultrasonically. While you're there, replace all gas filters and take a peek at the belt. Welcome to the forum by the way.

[bvcllc]

Thanks. I will. I did hear the belt squeak.

[bud37]

Welcome to the forum.....a couple questions to help the guys.....Has it ever run clean and smooth since you have owned it......do you have the make and model number handy.....how does each plug look...has anyone worked on it yet ?

For some reason it fired off the raw gas in the exhaust...hard to really say what caused that at this point if it is the flat head four with the magneto. There is a generator repair guru on here at times, hopefully he sees this.

Just to add, any time you are attempting to diagnose or tune an engine that you have no history with....the first thing would be to verify that the engine is mechanically sound first.....compression test mandatory, then timing etc. etc.

Good luck with it.....

[km1125]

Why did you change the oil cutoff switch??

I agree that the carb needs to be cleaned thoroughly and possibly rebuilt if it has a bad float or needle and seat..

[ColRon]

Bvcllc, welcome aboard! A backfire is generally caused by three basic issues; wrong fuel mixture (carb issue), improper ignition( timing) or valve problems. A compression test is a definite first thing to check. If it’s good at least you know your rings and valve are good, valve timing could still be off, but they are not leaking.

Make and model would be a definite plus to know. If you have the 7.5 Kohler I have manuals to help you.

[bvcllc]

Thanks for the suggestions and input. I am away from the boat and don't have the log. I'll also get the generator specifics and logs of last tuneup in a day or so. It's a Westerbeke and was not used for three years until this year when I purchased it.

Has run for short periods but mainly rough and then would shut down after a few minutes so I changed the oil cutoff switch based on suggestion from mechanic who stopped by for another reason and who checked the plugs and float while there. I first thought it was condensation in gas tank because I had to change filter. Tanks sat 1/2 full for about 3 1/2 years. I can't risk having a mechanic come aboard during Covid because I'm undergoing health care treatments and cannot be around people. Thanks for all the info.

[tomschauer]

If the tanks sat for 3 1/2 years, I would definitely start there. If the engines are burning that old gas and not coughing and choking, burn it off then refill and replace all of your fuel filters. If you burn it off, don't push the engines hard while doing so.
If they are at all missing or rough, have it all pumped out and disposed of. Pull the genny carb and have it cleaned and rebuilt or replaced. Its most likely all gummed up. Do not run the genny off the fuel in those tanks, or it will foul your carb again.
Run it off a separate fuel can after the carb work is done and the fuel filter(s) are replaced for testing.

[bvcllc]

Hi Guys,
Here's the pertinent info:

Fuel and fuel filters all new.

It's a Westerbeke, Model #WT 11C 716 814, gas, 4 cylinder, RPM 1800 (built 1987-88).
Generator has 752 hours on it.
Prior replacement/repairs:
March 2020, oil cutoff switch replaced, oil and filter changed. Oil had fuel smell to old oil. Replaced impeller. Passing dock mechanic said plugs and float looked good. He did not give full checkup.
In April 2014, starter and fuel pump were replaced @ 740 hours.
In August 2011, compression test @ 405 hours.

This is the best I could ascertain about past repairs/replacements.
Ron

[bud37]

Good stuff, I like those low rpm units......

Since you have a compression baseline from 400hrs, the very first thing I would do is another compression test to compare and check condition now, then go from there. It could be just fuel related as has been mentioned, but at this point there would be no sense spending money to find out it is some serious mechanical issue. I was taught a very long time ago.... ... that the first step in any tune up is a compression test. If all is well then renew what you need to get her up to par.....good luck man...