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Mercruiser 57 Starting Problems

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tommyb

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"}I own a 24' Splendor Cat

"}I own a 24' Splendor Cat with a 5.7l fuel inj. Mercruiser. The boat is difficult to start. When I turn on the ignition the horn sounds and I can hear the fuel injectors working but the engine does not always crank, almost as if it were not in idle or there was a problem with the kill switch. If I cycle back to off then I will eventually flood the engine so I keep turning the key from the spring back position (run) and after 5-10 times it eventually turns the engine over. Is my starter shot or what is it? The last time I seen a repairman for a no start he changed the plugs and condenser for $500 so I am wary to go to the shop at this time if I could trouble shoot myself! Thanks, Tommy"
 
"If you have injection, you do

"If you have injection, you don't have a condenser on the distributor. Have you checked the flame arrestor to see if it's clean? If it's not, it's similar to running with a hand over your mouth, blocking off your air. If the motor doesn't always crank, try wiggling the throttle handle. If it works after doing this, it may need adjusting or a new cable/adjuster. If these are good, you may need to clean the ground connection on the motor or all terminals and connections at the battery. Also, the starter is supposed to be serviced every year and it may be sticking if you hear a click but it doesn't engage.

If you're willing to learn about how this system works and spend some money on tools, you can do a lot of what it takes to find problems. A fuel pressure tester is one of the first things you need it cranks but doesn't fire. If you see good pressure, go to the next step, which is to determine if you have spark. A timing light or spark tester will tell you this, and a spark tester is about $10. The next things you need are adequate compression and voltages, which would need a compression tester and digital multi-meter.

You may be hearing the injectors but you need to find out if the pump is working. Don't be afraid to doubt the safety switch (kill switch)- it's a cheap part and the lanyard frequently goes bad when it's not the toggle kind, like on newer models. You should also get a manual for your motor/drive model and year if you're going to do this yourself or have someone else do it, other than the last servicer.

Mercruiser has their own ways of doing things that make it different from other brands, although the basic systems are the same.

The three things you need for a motor to run are: proper fuel/air mixture, compression and spark (at the right time). Everything else has to do with Mercruiser or GM specific issues."
 
"Jim, thank you very much. I

"Jim, thank you very much. I am embarassed to say that I cannot find a kill switch or lanyard-nor is there a button where the piece on a typical lanyard would slip under. Could it be that my boat does not have one? My problem is that I hear the injectors but the motor will not crank and therefore cannot start. When I cycle the starter a few times eventually it catches and then the engine starts.

Where can I get a manual?

Thanks for the advice, it is greatly appreciated.

Tom"
 
"Jim,

I found a manual on t

"Jim,

I found a manual on the hotlink to the right of this web page. Any other thoughts you have about what trouble I could be having are appreciated.

Thanks, Tom"
 
"You didn't say what year

"You didn't say what year the boat is but as far as I know, Mercruiser didn't come out with injection until the '90s and the injectors don't fire unless the ECM sees RPM input from the distributor, which makes it impossible for you to hear them. If you hear a buzzing sound, you may be hearing the fuel pump but even that needs to be told to operate by the ECM and unless you have adequate oil pressure, the pump won't do anything, either.

All boats made after, I think, the late '70s have a safety switch near the ignition switch or throttle/shift. The Coast Guard mandates that kind of thing and unless the boat was modified by someone else, it has to have one.

I would be looking at the starter, solenoid or ignition switch for your problem."
 
"Tom:
Jim N. is steering yo

"Tom:
Jim N. is steering you in the right direction. What I would do before pulling the starter or anything else is DISCONNECT THE GROUND WIRE AT THE MAIN BATTERY.

Using a digital voltmeter on the 20 VDC scale, I would start testing for voltage loss in the starting circuit to the starter. With the battery fully charged and terminals cleaned, I'd measure the voltage across the battery terminals and WRITE IT DOWN for reference. Next, with the key in the ON or RUN position, I'd measure the voltage at the starter (big red BATTERY wire). The drop in volts should not be more than 0.2 VDC. The main wire is suspect if there is a drop greater than 0.2 VDC.

If the voltage is good at the starter, check the voltage at the starter solenoid--someone must hold the key in the start position. If the battery reads 14.2 VDC (for example), the solenoid voltage should be no less than 13.8 VDC. If it is less, then the main engine solenoid and wire that provides voltage to the starter solenoid is suspect. Check the voltage on both sides of the large terminals and also check the voltage at the small terminals from the ignition switch with the key in the start position. A word of caution here--you are dealing with HIGH AMPERAGE that can WELD a tool to the terminals if not done properly. Good luck. Guy"
 
"This test needs the battery c

"This test needs the battery connected normally.

Since it's not cranking anyway, I would put the meter on the battery cables and check the voltage during crank. If it dips really low, it's a bad starter, solenoid, battery (no reserve due to sulfating or low charge level) or maybe there's no current going to the solenoid at all. If it doesn't drop much, I would suspect a stuck solenoid. The starter will cause the battery voltage to drop considerably. The battery should read about 13.65 VDC at rest with a full charge and 14.4 is the commonly used number while running but that will usually only happen at RPM higher than about 2000.

If the starter hasn't been serviced as recommended, I would remove it and make sure the Bendix isn't frozen from rust. It probably is and can be rebuilt for less than buying a new one but it needs to be built to Coast Guard spec.

Not only can the tool be welded to the terminals, the sparks can fly into your eyes or directly toward the most flammable area of the boat (Murphy's Law).

The first place I would look for voltage is at the coil because it's fairly easy to get to. If there's no voltage, look back toward the ignition switch, which is another source of troubles. Loose terminals can cause all kinds of issues."
 
"You won't flood the engin

"You won't flood the engine because the injectors are not open. What you hear is the fuelpump which cycles for 2sec at turn-key.Have somebody put a testlight at the assist solenoid which sits on top of intakemanifold and see if you get power when cranking .This would be the 16 gauge wire (yellow red ) at solenoid. If you have power move up to top of unit and than to starter solenoid,same color wire.If you get power all the way you might have a bad starter but make sure your ground is good and all other connections tight."
 
"Thank you all for your input,

"Thank you all for your input, I will take a look tonight when I get home and get back to you. For info, the boat is a 2000 model year and I have two batteries with a switch that allows me to choose batt 1, batt 2 or all.

I appreciate your advice and I will make every attempt of doing this without getting electricuted.

Tom"
 
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