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Mercruiser starts then quits...

M

malangon

Member
I have a 2003 Mercruiser 3.0 (recently purchased Bayliner 175).

The engine starts and then quits right away. Even when trying to give it gas, same thing.

I changed the fuel filter and same thing.

As I understand it, the next step would be to test the Fuel pump, but it looks like a mechanical pump which I have read are bullet-proof.

The fuel pressure gauge is $20 from harbor freight, but it looks like a new Sierra pump on Amazon is $100. I'm tempted to just change out the pump and see what happens. It's an hour drive to Harbor freight and I've never used one of these before.

Any other advice?
 
Ayuh,.... With the key in the "On" position,.... Is there Power at the coil's (+) terminal,..??
 
Thanks for the replies everybody, but question about these suggestions: if there was an issue with the safety switch or no power at the coil terminal, wouldn't the engine not start at all? It starts up without a problem, runs for 2 seconds and then dies.

I'm reading manual #26 and it seems like I'm getting ignition (if it's starting) and the issue is no supply of fuel.

Again, not sure though...
 
Also, not sure if this is related, but I know I might have a bad connection at the starter solenoid because I occasionally get nothing when turning the key, but that's intermittent...

Now I'm wondering if it's not the starter solenoid and a crazy intermittent safety switch that's causing the issue.

Can somebody recommend a good source for the troubleshooting steps for this safety switch thing...
 
malangon said:
Also, not sure if this is related, but I know I might have a bad connection at the starter solenoid because I occasionally get nothing when turning the key, but that's intermittent...

Now I'm wondering if it's not the starter solenoid and a crazy intermittent safety switch that's causing the issue.

Can somebody recommend a good source for the troubleshooting steps for this safety switch thing...
Click to expand...

Just look at it and make sure its on "RUN" If its "OFF" the engine will start for a second then die. This happened to me when my grand daughter was helping Papa clean the boat and she shut it off by mistake
 
There's a separate feed for the ignition that is used during cranking...to ensure a good spark with the starter spinning....

Like Bondo asked, is there power on the "+" coil post with the key ON?
 
The switch itself is in the up position, labelled "Run".

To check the coil, am I correct that I take off the lead and hold it close to a ground to get a spark or should I use a voltmeter?
 
malangon said:
The switch itself is in the up position, labelled "Run".

To check the coil, am I correct that I take off the lead and hold it close to a ground to get a spark or should I use a voltmeter?
Click to expand...

Ayuh,.... To see if the primary ignition circuit has Power, ya need a test light or meter to see if there's Power at the coil's (+) terminal,....

If there's no power to the primary side, there'll never be a spark on the 2ndary side,....
 
I checked a lot of websites on how to test this coil and they all looked a little different. Let me describe to you what I did and let me know if I tested this correctly.

I disconnected the wire that runs from one side of the coil to the middle position of the distributor cap. I used a voltmeter set for DC to check voltage on that terminal to a ground on the engine. I got nothing.

FYI: This is with the key in the on position, but without the engine cranking.

I assume the other side is considered primary, but there are two plugs going into that side and I have no idea where to connect. Every picture of an ignition coil online has three terminals. Mine has a bazillion.
 
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Ok, when checking the purple wire to ground on the engine block, I get 12 volts with the key turned on.

So, if I don't get that 12 volts on the other side of the coil, does this mean the coil is bad?
 
No A coil works that way.


You need a 12 volt test light to be able to do quick tests, Go to your local auto parts store and get a test light...........they are only about $10.00

a good digital multi meter (if EFI that has 10 meg ohm resistance built into it). (about $100)


Second. go to key switch. look at the back of it under dash.

there should be three wires........

RED...........battery 12 vdc

Purple.........Ignition ON

Yellow with red stripe..........Crank

There may be a couple of wires piggy backed so don't worry about those.


There is a slave solenoid between the key switch and the starter solenoid. Typically on the left side of motor when looking at it and on the top.

it has red, yellow with red, on two large terminals and black and yellow with red on the two small terminals. The small yellow with red comes from the key switch. the large yellow with red goes to the starter. This is your cranking circuit..........

For a carbed motor (NOT EFI)

When you turn the key switch to the crank position to crank the motor over the ignition power is transferred thru the internal contacts of the key switch.


so when you are cranking the motor over, 12 volts it transferred from the Bat + terminal to the yellow with red stripe terminal and also the purple terminal.

When you release the key to the RUN position the only connection is between Bat + and the purple wire.

This purple wire goes from the ignition key all the way back to the coil +. It is or has a couple of other connections such as the choke on the carb and possibly the fuel pump if electric.

So if you put the key to the run position you have to go back and see if there is 12 vdc at the coil +.


Although we are asking about an ignition issue and testing you may have another issue but you are not explaining it very well.

If the motor starts....will it stay running for any length of time? If it does, does it only stall when giving it gas?

Need some more info here............something is missing..........
 
The motor starts up right away in neutral, sometimes dies right away, sometimes runs for a few seconds, but always dies. Never runs for more than 10 seconds. I have tried giving it gas and same thing. If I a rev it up, it holds for 2-3 seconds and then dies.

It started and ran "ok" the first time I took it out. i did notice a few stalls, stalling when giving gas, stalling when the trim was lowered too far.

I had a gear lube leak and replaced a few seals, water pump, etc. Put it all back together, replaced the lube, no leaks.

I have it in my head that this is related to that work, but I don't know what I could have done to cause this issue. Shift rod or something? Added pressure from turning a new impeller causing strain that an already weak engine was having a problem with?
 
I don't understand something - I'm getting 12volts at the purple wire at the coil. When the key is on, shouldn't I get something at the end that goes to the distributor cap?
 
No that is high voltage......you do mean the center terminal (coil wire)???


When starting a marine engine there is no HIGH IDLE so YOU must control the idle speed,

You must use the neutral start button on the shifter how ever yours is designed and once the motor starts you have to keep it running at 1500 rpms for at least 30 to 60 seconds to allow the choke to open and keep adequate fuel when cold.

If it stalls after that then it could be a shift cable issue and may need adjustment.

If the interrupter switch is being activated when throttling up or after you shift into gear then a shift cable issue is the cause.

Need a bit more troubleshooting info...
 
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This is what my ignition coil looks like. (Taken from Google). When I test the purple wire, I get 12V. The metal terminal you see in the picture gets nothing.

I obviously need to do some more research, because I'm not following something here. That metal terminal gets connected to the middle of the distributor cap. How do the spark plugs get any voltage if that gets nothing?
 
That terminal is a high voltage output of the coil... NO 12 volts there........


That only supplies voltage to the distributor cap when the coil is fired. (30,000 volts AC) in simple terms.

You do not have an ignition issue from what I can understand now.

You have a running issue so either fuel, carb or shift cable issue.

Where are you located?
 
I'm in New Jersey.

I changed the fuel filter, and I was heading down the road of a fuel pump issue, but I have a mechanical fuel pump and read that they're pretty bullet proof. I started with that on this forum and the responses all started down the ignition road. (lanyard safety switch, checking for power at coil, etc.)
 
In order to check the fuel pump you need a fuel pressure gage for a carbed motor ( 0-14 psi gage as a carbed motor fuel pump needs 4-7 psi constant when operating properly) and a way to install it between the fuel pump and the carb.

Assuming you don't have either lets start somewhere else...........




When you start the motor, what happens if you start it and have it run at 1500 rpms?
Will it stay running? Or does it stall out all by itself?

Answer that first and then we can go from there.


If it stalls all by itself shut key off, remove flame arrestor, manually move throttle lever and see if you get two long steady squirts of gas in the carb. If this is a two barrel carb then one squirt per side. Actually same for a 4 barrel carb as only the primary is used.
This can flood engine so be aware. You should be able to get two or three throttle movements and corresponding gas squirts. This is the accelerator circuit and it is normal as I described. If NO gas at all comes out when doing this then you have run out of fuel.


If it does work as described then you may want to check gas for water. Also take note of the choke butterfly is it closed or partially open? you may have to open it slightly to all the way to see the gas squirt.


Lest start there and see what answers you have..........
 
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Ok, finally had a chance to take a look.

When I look down into the carb, I get an initial strong squirt of fuel when pushing on the throttle. Subsequent throttle pushes get me almost no fuel with what sounds like air. I estimate I'm getting two good squirts and then mostly nothing. Is this normal? You mentioned I could flood it, but it doesn't seem like that would be possible the way this thing is working.

With regards to the fuel/water question, I thought the fuel filter separates the water and that was just changed. I don't know where there is any other fuel/water separator.
 
sounds like not enough fuel in the float bowl for sure...could be a bad fuel pump or the supply components to the fuel pump. One easy check is to get an outboard tank (or equivalent) and have it feed fuel to the suction line on the fuel pump. if it runs then you know the issue is in the connecting plumbing going back to the tank....an alternate would be the fuel pressure check as suggested over a week ago..
 
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