UPDATED: Important information concerning engine oil and marine engines with catalytic converters.

When it comes to boats, engines, parts, and parts repair, you need to know  that there are alternatives. Make your decisions wisely, shop around, and Know your rights

The Anti-Siphon Valve
All you ever wanted to know and more.

Knowing if that strange noise an engine makes is normal or not, could mean the difference between a minor repair or a full blown rebuild. Sometimes they may sound almost identical. Here's some tips on finding the culprit. Who knows, you might find it easier than you think.

You turn on your favorite radio station or hook up that new Depth sounder, and they just don't seem to be as good as they were when the salesman demo'ed them for you? One possible cause is Radio frequency Noise. With Depth Sounders, sometimes, the only way to know for sure is to be systematic and test for it. You know you don't have to hear it for it to be there.

And how about getting a better hole shot from your rig, just by drilling a few small holes in just the right spots.....  How much is it worth to you? It's worth a try...  you can always fill the holes back in....

Do you have that used boat that seems to be propped out correctly and yet, something doesn't seem quite right? Maybe, somebody changed the gear ratio in the drive or it just has the wrong gear ratio for your area.  Without too much trouble, checking the gear ratio of the drive is the thing to do if you suspect tampering or can't properly ID the drive ratio. Inspect the gears and use this:

Speaking of holes... Ever wonder what PreIgnition and Detonation might have to do with you? I suppose that first you'd have to know what it is.

Using approved Marine Grade Hose will prevent you from having a "hole" story yourself.

Looking for a parts supplier for that old motor? And/or like looking up your own parts online?
Try our Supplier Reference page...

Diesel engine reference guide is covered in another section. But, electrical, drive train and operational equipment information, basically,  pertains to all power boats.

Some pages are in "PDF" format and require Adobe Reader.

The basics of analyzing a problem with a MARINE engine is covered in numerous books and manuals. The good thing is if you have the problem, someone's had it before and learned to find it. So, here's the.....

4 CYCLE scoop.

2 CYCLE scoop.

2 Cycle engine "Tune-up in a Can"?


And what about EFI. It's no mystery. It's precise approach to fuel delivery removes the guess work. Either, each component is functioning properly, or most likely the whole system won't work. It also has the ability to tell you what is wrong. (sometimes) Testing just means finding out what it is telling you. Need the wiring diagram?


Also, See MEFI 4 & 5 below and to the left.



Did you ever wonder what are the major influences  that affect your boat and engines performance ? Here's the quickie list concerning engine output and the final result of overall boat performance.






This has nothing to do with boat engines but we enjoy the scenery.
She probably wouldn't be walking on a beach if she found someone with a nice running fish boat..:~]






Engine Spec Sheets & Line Drawings, to the left, are for 2009  and above GM marine product.



  • Onan Control-O-Matic Generators are in an awful lot of boats. They are actually easy to keep running. It was the simplicity of the design that also made it affordable.

Delphi MEFI  System

pdf 4.3L MEFI 4 Service Manual
(3.5 megs, dialup: 8 min. download @56
pdf 5.0L 5.7L MEFI 4 Service Manual
(4.2 megs, 10 min. download @56)
pdf 6.0L MEFI 4 Service Manual
(3.8 megs, 9 min. download @56)
pdf 8.1L MEFI 4 Service Manual
(3.7 megs, 9 min. download @56)
pdf 4.3L 5.7L MEFI 4 Engine Wiring Diagram
(712 kb)
pdf 5.7 MEFI 5 Service Manual
(8 megs, 19 min. download @56)
pdf MEFI 5 ECM Pinout
(142 kb)
pdf MEFI 5 Engine to Boat Wiring Schematic
(8.2 megs, 20 min. download @56)

Service manuals





2007-2013 MEFI 5


Wiring Diagram

Engine Spec Sheets & Line Drawings

pdf GM Specs 2009 3000
(471 kb)
pdf GM Specs 2009 4300
(490 kb)
pdf GM Specs 2009 5000
(534 kb)
pdf GM Specs 2009 5700
(476 kb)
pdf GM Specs 2009 6000 LY6
(490 kb)
pdf 6.0L Front View
(524 kb)
pdf 6.0L Port View
(502 kb)
6.2L LS3
pdf GM Specs 2009 6200 LS3
(595 kb)
6.2L LSA
pdf GM Specs 2009 6200 LSA
(750 kb)


pdf 901M Jet Parts
(5.1 megs, dialup: 12 minutes)

Transmission Spec sheets and line drawings

ZF Marine Drive Systems

All products from this company.

pdf Twin-Disc operators manual

Still Love your OMC/ Johnson/Evinrude 
Then click their logo.

The worst has happened. Your boat sank or the engine back filled with sea water. You have her floating, but what's next....


Have a bunch of questions about your Mercury and/or Mercruiser product? Click above.

The proper care and feeding of an aging outboard motor can assuredly be time well spent. Always follow the owners manual but in addition we offer these tips.

We have some basic support for Chrysler/Force motors.. Surprised?.. there is still a lot of these engines out there.


Have a technical Question
Try our Ask A Tech. form

Looking for a Manual?

Here's a link to where they have assembled a list of downloadable PDF manuals for boats and inboard marine engines/transmissions. 

Yamaha Outboards has online owners manuals. [PDF format]

Volvo owners typically love their Volvos but they actually need repair from time to time.


  Have you read any good sparkplugs, lately? Like a good mystery novel, reading between the lines when your doing a tune-up can prevent a lot of  hassles.  The secret clues to what is going on inside every motor is written    all over those spark plugs.

Made in America

Check out  The Biopsy Page  , where you'll see all the fun and adventure of a boat mechanic.  It contains illustrations and text for some of the interesting moments of the " guy."

Over the last 25 years, or so, we have constantly asked the manufacturers if they tested and or recommended any type of oil additive.  Usually the answer was that additives weren't needed in their engines, just follow the maintenance requirements and you  won't have any trouble.
As the horsepower outputs went higher and higher, each passing year, our concerns of  the oil's ability to hold up to the average user grew with them.
We can't tell you about Prolong or Slick 50, but Johnson's LL-5 has unofficially, become the additive of choice for several of the top  High Performance engine builders. We've been putting it in all the supercharge stuff we service, and they don't seem to break down due to oil failures, but we  wouldn't call our experience the  definitive  test bed for oil additives. Basically, we haven't scientifically tested any of the stuff we use it in, because, we haven't had to tear any of them down, due to oil failure. Maybe, a good thing....


Cam problems?
Johnson LL5 Engine pre-lube, engine oil additive from Sealed Power.

Mercruiser part # 92-801779

Also, see our engine oil and lube FAQ page.

  Who's the loneliest guy in the boat business? It's poor Mr. Carb Filter.  All his friends like, Mr. Water Separator, and Mr. Oil filter seem to get all the attention. He sits lonely and dark in his little home, waiting. And then one day he eats too much and he puts a stop to all the traffic going thru his home.  If this didn't give Mr. Piston an overheating complex, then I guess it wouldn't be such a big deal. So, don't ignore Mr. Carb Filter....
Note: pictured is a Rochester, but almost all brands have one built into the carburetor. Unfortunately, some of the newer ones have a final filter built into the needle and seat, and service requires removing the top half of the carburetor. (Check your service manual.)

Note: Not all carburetor filters incorporate a "check valve" as depicted in the diagram. Screen type filters are cleanable and re-usable, in many cases.

Additional Note: Excessive/consistent re-occurrence of grayish brown dried powder in this filter probably indicates "MTBE" residual build-up being cleaned from the fuel system of the boat. Current ethanol blended fuels are really good at cleaning a fuel system.

Didn't find what you were looking for?
Try our Reference Book Section.

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