How can I make my Tracker 40 HP faster?

[jimmbo]

I had a spark plug problem trick me into a new injector a few years ago. The plug would spark in free air while grounded to the engine case but would not spark in a chamber with 5 psi applied to it. I found it was bad by pulling plug wires one at a time with the engine running and confirmed it with a cleaner/tester set.

That is why a lot of us Ask if the Spark will jump a 3/8" or 7/16" Gap. Air is an Insulator, and the Denser it is, the better of an Insulator it is, and the Voltage required to Jump the Gap increases.

 

[Jeff J]

I get that but not seeing how to get a consistent test while holding a firing spark plug a set distance from a clean ground which is moving while also manipulating the starter controls. Sometimes it is difficult to just check for spark without trying for the 3/8” gap and it would have to jump the little gap before jumping the big gap.

Spark plugs can also be checked with a multimeter for the proper resistance. This is probably the easiest and best way anyway.

 

[airshot]

They make a tool to check how far a spark will jump....cheap at most automotive stores, mine was less than 10 bucks.

 

[Buster53]

I said it earlier, and I speak from experience, if 8 mph is all you are getting, sounds like it is only running on one cylinder

 

[Jeff J]

They make a tool to check how far a spark will jump....cheap at most automotive stores, mine was less than 10 bucks.

Can you post a link please? I can’t find a spark plug tester for $10 anywhere. Spark testers yes but nothing that actually tests a spark plug for a 3/8” spark.

 

[racerone]

Just bought a spark tester ( 4 cylinders at a time ) at a flea market for $10.-----But make your own simple tester.-----Take 2 pieces of wire.----Each about 24" long.-----Glue them onto a piece of carboard with a 3/8" gap between them.----Stick one end into the plug boot.----Other end grounded to the block.-----Observe the spark.

 

[Jeff J]

Just bought a spark tester ( 4 cylinders at a time ) at a flea market for $10.-----But make your own simple tester.-----Take 2 pieces of wire.----Each about 24" long.-----Glue them onto a piece of carboard with a 3/8" gap between them.----Stick one end into the plug boot.----Other end grounded to the block.-----Observe the spark.

How does that test a spark plug? Getting spark from the coil is great. Easy to check but has NOTHING to do with checking the spark plug. I suspect the $10 tool option above is a similar test, although it will confirm a path to ground through the spark plug, I am struggling with how it does anything to confirm quality or consistency of the spark plug.

 

[Bottom Mapping]

Had this same boat, got it from my dad. These things are tanks! I never weighed it, but four guys stranded by a descending tide could barely drag it, with driftwood rollers, on a down-slope beach to float it. Originally had a basic 35 Merc, no pwr tilt/trim. Totally inadequate - but your 8 mph suggests major constraints to the power potential of your Tracker. With 35 hp, mine was not easy to plane, and anything more than 3 people was no bueno. Didn't have gps back then, nor a speedo. But a time hack over a known distance worked out to 22 mph or so @WOT, if I recall correctly. I think placardedUpgraded to a Merc 45 ("Classic Fifty" 4-cyl.) with power trim/tilt. Game changer; easy 30 mph on gps - record 35 mph with just me and a few ounces of gas. Popped on plane with proper trim manipulation. Pack it full of people and still planed. Can't address your engine beyond the good advice already provided. Best of luck figuring it out.

 

[racerone]

The tool is used to TEST MAXIMUM VOLTAGE output from the coils.-----Nothing to do with testing the plugs.----If you have maximum voltage output and plug does not fire , you have a defective plug !!

 

[Jeff J]

Why do I seem to be the only one who thinks checking the spark plug is just as important as testing the coil output? Having MAXIMUM VOLTAGE does zero good if the plug is failing.

Checking the breaker box in the house doesn’t do much if the light bulb is burnt out. It’s just one part of what is required to get light and the least likely to fail.

 

[Buster53]

I said it earlier, and I speak from experience, if 8 mph is all you are getting, sounds like it is only running on one cylinder

Just for the hell of it, humor me on this…
Disconnect one spark plug and try to run the engine and see what happens. Now reconnect and disconnect the second spark plug and see what happens. Let us know The results.

 

[racerone]

It is becoming abundantly clear that simple trouble shooting / thinking is quickly disappearing !

 

[Jeff J]

I agree. Always start with the cheapest and simplest and at one end… not the middle.

 

[Jeff J]

It may or may not help this Tracker but had I thought of it at the time, Buster’s suggestion of pulling plug wires one at a time on a running motor would have saved me over $300. So would have testing the spark plugs with a tester or multimeter. I had never seen a plug fail like that before and checking for a 3/8” spark would have yielded good results without guiding me any closer to the problem than laying the spark plug on the block did. I didn’t circle back to plugs until I went through everything else twice. Including swapping the coils around.

All I am saying is to isolate the problem and start there. Don’t pick a system and jump into a random point in the middle. If you go with the running spark plug check and identify a bad cylinder, move that plug to a known good cylinder and check again. Change that plug if the problem moves or start checking upstream of that cylinder one piece at a time if it doesn’t move. I have owned 6 boats in 30 years and changed a lot of spark plugs. I have yet to change a coil on a boat I own. I replaced one on a rental Volvo a couple of years ago but it may not have needed it. There is an ignition module on the coil assembly and that may have been what was bad. Coil and module came mounted to the bracket so I changed the entire unit.

 

[racerone]

On any " problem " motor the first step is a compression test.----The next step is a maximum spark check.----Used this procedure for over 50 years.

 

[Jeff J]

On any " problem " motor the first step is a compression test.----The next step is a maximum spark check.----Used this procedure for over 50 years.

Please read post #1 of this thread.

 

[racerone]

Many folks have been fooled by testing with a sparkplug laying on the block.----In the cylinder it takes more voltage to jump the plug gap ( 120 PSI compressed air ) than it takes to jump the gap on the plug at atmospheric pressure.----Always test the maximum output of the magneto.

 

[airshot]

It may or may not help this Tracker but had I thought of it at the time, Buster’s suggestion of pulling plug wires one at a time on a running motor would have saved me over $300. So would have testing the spark plugs with a tester or multimeter. I had never seen a plug fail like that before and checking for a 3/8” spark would have yielded good results without guiding me any closer to the problem than laying the spark plug on the block did. I didn’t circle back to plugs until I went through everything else twice. Including swapping the coils around.

All I am saying is to isolate the problem and start there. Don’t pick a system and jump into a random point in the middle. If you go with the running spark plug check and identify a bad cylinder, move that plug to a known good cylinder and check again. Change that plug if the problem moves or start checking upstream of that cylinder one piece at a time if it doesn’t move. I have owned 6 boats in 30 years and changed a lot of spark plugs. I have yet to change a coil on a boat I own. I replaced one on a rental Volvo a couple of years ago but it may not have needed it. There is an ignition module on the coil assembly and that may have been what was bad. Coil and module came mounted to the bracket so I changed the entire unit.

How many years experience do you have working on outboard motors ? You ask for help from a group of folks with many, many years of outboard expertise, yet you want to challenge the recommendations given. We can't see, touch, or tell exactly what your motor is doing. By doing simple tests that would help us draw conclusions, you choose to challenge our recomendations. If you already have the answers, why did you post ?

 

[harringtondav]

I'm pessimistic about getting more power, torque, rpm from a healthy, properly tuned engine, and correctly propped boat without mods, which are fun for a while until the engine dies an early death.
If you have deep enough pockets and are good at research, many O/B and I/O engines are the same block/displacement with different ECMs to push more fuel and HP. Beyond that, a tune up per mfg specs and the right prop are about as good as it gets.

 

[flyingscott]

Sounds like you need the 50 hp carbs.