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Help! My Engine Won’t Start!

When a marine engine whether it’s an inboard or outboard won’t start there is a procedure for testing to find the problem. These test procedures will work with most gas powered engines. A few tools needed for testing the marine engine includes hand tools that would include hand wrenches, screwdrivers, and a socket set with misc. extensions. There is also a need for some special tools a test light or a volt/ohm meter, a compression gauge, a remote start, and a spark tester. A rule of thumb for testing engines is that you need compression, spark, and fuel to run, and should be tested in that sequence.

Compression is rather easy test to be made, the spark plugs need to be removed and the plug wires grounded. The easy way to ground the plugs is to install the plugs into the wires after removing from engine and set aside away from working area so as to be grounded at engine. For an inboard type engine the coil wire may be shorted to block to keep the spark at bay. Now the compression tester can be installed in one cylinder and the engine spun over by key or by the remote start attached to the starter solenoid. Warning, be careful of moving parts such as belts, flywheel, or prop. Do not allow engine to start, remove all spark plugs before testing. Compression for most engines will be around 115-125 pounds. There are some low compression outboard engines that run in the 80 pound area. The best way to test is to look for consistency between cylinders. It’s normal for compression to very 5-10 pounds between cylinders. Any more than about 10 pounds indicates a problem with piston/cylinder, head gasket, or valves. Test all cylinders and look for inconsistencies. See service manual for repairs. 

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Marine Battery Isolator

The battery isolator is very similiar to the battery switch in that it can charge two batteries and yet isolate the two.The difference being that there is no manual switch to operate using the battery isolator, its all automatic. There is pros and cons to both setups, with the battery isolator you have only one battery for the engine and one auxiliary battery for normally cabin use. Both batteries are charged by the engine and when one battery is discharged it will not drain the other. An isolator is basically a diode, a one way path through a circuit. There are different setups as with the battery switch such as dual engine installations and isolators that will charge more than two batteries. The battery switch can be manually switched between batteries to charge or start off from one or both batteries, where the isolator cannot.

 

 

 

 

 

 

 

 

 

 

 

 

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Choosing the Correct Propeller

Choosing the correct prop for your boat can mean the difference between a well performing motor, and an engine that is low on power which is lugging or over revving. A lugging or over revving engine will eventually fail to engine damage. The prop must be for the proper application, be it an outboard, inboard, or I/O, a noticeable differences being the hub design, hub diameter, and spline.

The most important features of the prop is the diameter and pitch, as this will determine the rpm of the engine. It is very important that the engine operates in the proper rpm range of the engine determined by the manufacturer. For a proper rpm test an actual water test will need to be performed. The engine will need to be run up to full throttle operation and trimmed for optimum performance. The tachometer must be in proper operating condition for making the correct choice of prop. The motor must not be allowed to over rev.  Once the rpm is determined the correct prop choice can be made. If the engine is over revving, a higher pitch prop is required, and if the engine is running at a too low of a rpm a lower pitch prop is needed to bring up the rpm. The more pitch in a prop the more water the prop will move in one revolution of the prop. A 2″ change of pitch will in most cases change the rpm by 300-400 rpm. Engines normally can use two different pitch propellers, say a 19p and a 21p and stay in the operating rpm range. The lower pitch prop would be considered a power prop as it will run at a higher rpm and have much more torque, which is good for heavy loads or sking. The higher pitch prop would be considered the speed prop as you would loose your bottom end (torque) but gain on speed as you would be pushing more water at the same rpm.  A prop for example, 14 1/2 x 19 would have a total diameter of 14 1/2 inches and a 19 pitch. 

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Fuel Lines

With todays fuel it is more important than ever before to be aware of the issues that arise in the marine engines. With todays modern engines the issues from the present are different than the engines from the past. With the computer controlled engines ignition problems are becoming less of a problem compared to fuel.

With the alcohol in todays fuel, water is literally pulled from the air and into the fuel. For a test, an open clear container such as a jar with an inch or two of gas poured into it can be left on a bench for a few hours on a humid day. You will be surprised to see the fuel getting cloudy or on real humid days a seperation of fuel and water. Now think about fuel tanks in boats and the condensation issues that can happen on warm humid days and the cooler area of the bilge where the fuel tank is.

Also there are the problems with plastic fuel tanks, fuel lines, primer bulbs and rubber fuel components that the alchohol likes to destroy. This leads to more expensive fuel systems that have to be EPA compliant. The portable plastic fuel tanks seem to always have venting problems, either not venting at all or every time it rains you get water in your fuel. 

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Electrical Basics

Making a good electrical repair or correctly installing electronics on your boat can make a huge difference in the longevity of the project. The correct tools and proper materials will make for a quick and long lasting repair or install. With a good test light tracking an electrical problem is quite easy whether its in the bilge, under the helm or within the gunnels. When installing a new depth sounder, marine radio, bilge pump, horn, radar, ect with all the right stuff the job will be easy. Tools and materials needed for most repairs and installations include, basic hand tools, a 1/2 inch drill, 3/8 cordless drill, a set of drill bits, assorted hole saws, crimper/wire stripping tool, double stranded wire, assorted connectors, electrical tape, fuses, fuse holders, silicone caulk, test light, soldering gun, solder paste, tie straps, misc. stainless screws, side cutters and shrink tube. Depending on the project one or more of these will be needed. All electrical and electronics require that they be fused or go through a breaker, also the proper gauge wire will be needed. A good battery ground is a must to ensure good current flow and help reduce static noise on the radio equipment. 

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