Mercruiser 5.0 MPI 2013. Crank but no start.

[Hiecke]

Hello everyone:
I have a gremlin in my engine. Its a Mercruiser 5.0 MPI Alpha. Crank but don’t want to start.
I have changed coil, cmp and ckp sensors, distribution cap, fuel pump, fuel regulator, starter, and a whole of parts, but don’t start.
I tried to start for 5-6 seconds each time and almost start. Only almost.
No fault codes.
Full gas deposit. MOB activated.
Full batteries. Empty patience...

Help please.

 

[alldodge]

Have you scanned for codes or is it from smartcraft display?
Have a serial number?
You say MOB activated, meaning its not active as in open, right?

Said its a gremlin, does this mean it does every once in a while or its broke and it does not work at all?

 

[Hiecke]

Have you scanned for codes or is it from smartcraft display?
Have a serial number?
You say MOB activated, meaning its not active as in open, right?

Said its a gremlin, does this mean it does every once in a while or its broke and it does not work at all?

Both: i have vesselview Mobile and a scanner.
Serial number:2a183053.
MOB circuit is closed.
The gremlim kill the engine. I said that i have a gremlin in my boat because it had a lot of problems and i don’t have any Merc service.

 

[Fun Times]

To try and get a better idea here, 'The engine tries to start with maybe some sort of backfire sound involved as well too Maybe?

It might be time to check the internal engine components with a compression test and cylinder leak-down test.

EDIT: Did you replace the fuel regulator on top of the engine or down below by the oil pan port side?

 

[Hiecke]

Both: i have vesselview Mobile and a scanner.
Serial number:2a183053.
MOB circuit is closed.
The gremlim kill the engine. I said that i have a gremlin in my boat because it had a lot of problems and i don’t have any Merc service.

I forgot that if i try for 8-10 seconds, try to start but erratic.

 

[alldodge]

ok, the key is turned ON and the fuel pump runs for a couple seconds
The fuel pressure is at 43 psi at the rail

When the motor is cranking do you get at least 300 rpm?
If not check for 12V at the coil with ignition ON

 

[Hiecke]

To try and get a better idea here, 'The engine tries to start with maybe some sort of backfire sound involved as well too Maybe?

It might be time to check the internal engine components with a compression test and cylinder leak-down test.

EDIT: Did you replace the fuel regulator on top of the engine or down below by the oil pan port side?

Yes, sounds like a backfire.
I replaced both regulators.
I don’t think that could be a low compression problem. Only a few data ago (before a heavy rain) run over 38 knots.

 

[Fun Times]

I forgot that if i try for 8-10 seconds, try to start but erratic.

Maybe a video of the engine trying to start may help some too.

Maybe try using a timing light at each spark plug wire and coil wire to see if you have continuous in sequence spark.

 

[Hiecke]

ok, the key is turned ON and the fuel pump runs for a couple seconds
The fuel pressure is at 43 psi at the rail

When the motor is cranking do you get at least 300 rpm?
If not check for 12V at the coil with ignition ON

Scanner gives 40 psi fuel pressure.
I get more than 3000 Rpm crancking.

 

[Hiecke]

Maybe a video of the engine trying to start may help some too.

Maybe try using a timing light at each spark plug wire and coil wire to see if you have continuous in sequence spark

I don’t have timing light.
Tomorrow i’ll check 12v coil and try to check sparks.

 

[alldodge]

Disconnect the gray from the back of the Tach. You want to see 300 rpm when cranking but there is no way you will see 3000

It ran fine before the rain so a bad connection is where I'm leaning

 

[Fun Times]

Bear in mind a low engine compression situation could cause an almost no start condition with backfire type effects.

Maybe the spark plugs are wet and/or there is water in the fuel system after the rain.

Distributor assembly is/was dry inside? Any signs of water on the ignition coil?/General area? or at the ignition key switch itself?

 

[Hiecke]

Disconnect the gray from the back of the Tach. You want to see 300 rpm when cranking but there is no way you will see 3000

It ran fine before the rain so a bad connection is where I'm leaning

Sorry, its only 300, no 3000.

 

[Hiecke]

Bear in mind a low engine compression situation could cause an almost no start condition with backfire type effects.

Maybe the spark plugs are wet and/or there is water in the fuel system after the rain.

Distributor assembly is/was dry inside? Any signs of water on the ignition coil?/General area? or at the ignition key switch itself?

The boat ran perfect before the rain. A few days later don’t start. We cleaned the distribuidor (had some water) and started again. The next day works fine. A day later didnt start. Later changed distribuidor cap, rotor and cmp sensor, but don’t start.

 

[Fun Times]

Have you tried opening up the throttle say 1/4 to 100% while cranking to see if it's a lack of air.

 

[Hiecke]

Have you tried opening up the throttle say 1/4 to 100% while cranking to see if it's a lack of air.

Yes, i did without any change.

scanning the ecm, i have found something. The trim signal is always in 5v, and i think that the wires are cutted. Could affect to the ckp, cmp, tps o ecm signals?

 

[Fun Times]

Scanning the ecm, i have found something. The trim signal is always in 5v, and i think that the wires are cutted. Could affect to the ckp, cmp, tps o ecm signals?

The trim shouldn't with what I believe your ECM to be...That mentioned there are some that have claimed a failed trim system in the up position did keep engines from starting on newer engine models of your serial ranges.

Does any of your normal trim gauges still work up at the helm? Whether it be an analog? or digital? read out?

In a higher number of these cases, 'in order for the scan tool to read certain component elements, it takes the component to be psychically connected which was usually not the case in most cases and without being there help confirm, I suspect your engine may not have some of them connected form new and you may not be getting the accurate information you are reading on the scan tool.

For instance the fuel pressure reading you're reading at 40psi...That 40 number is also considered a factory default setting and not uncommon to see that psi number range especially should you not be seeing any other fluctuations of the fuel psi system....Also a 5v reading to the transom assembly sensor components is sometimes considered a default setting should nothing be connected wire harness wise especially without any other fluctuations happening...Plus if they were connected and failed, you ought to be getting other warning signals from horns, bell icons at a digital gauge and the scan tool too in your case here.

But this brought up, Bear in mind for conversation purposes, being a 2013 model, any one of these components may be/have been connected at new as they started to add more things starting around your engine year making hard to judge from here.

The reason I bring up the fuel psi system vs what you see on the tool is because looking over your engine serial number item components, I'm not seeing a fuel pressure sensor being offered to your engine model which had it been there, it ought to of been mounted at the fuel rail which would of been in here, Intake Manifold and Fuel Rail...

...Just so you know for sure I'd recommend you connect a fuel pressure gauge where you see item number 18 & 19 vs trusting the scan tool at this point...Also if your trim gauges moves, then see info above...

Of the following to choices, What design ECM (Item #3) do you happen to have?
[URL='https://www.perfprotech.com/mercury-marine-parts-catalog/electrical-components-mechanical/assembly/15044/40?umodel=3946']
Electrical Components, Mechanical

[URL='https://www.perfprotech.com/mercury-marine-parts-catalog/electrical-components-digital/assembly/15044/45?umodel=3946']
Electrical Components, Digital
[/URL]

I suspect you have the first one above lowering the chances of items mentioned being physically connected but again, not impossible either.

Also you replaced item number 6?, Merc OEM or aftermarket? Its for sure plugged all the way in?.. Even new ones have been know to fail super quick.

https://www.perfprotech.com/mercury...tion-components/assembly/15044/50?umodel=3946

[/URL]

 

[Hiecke]

The trim shouldn't with what I believe your ECM to be...That mentioned there are some that have claimed a failed trim system in the up position did keep engines from starting on newer engine models of your serial ranges.

Does any of your normal trim gauges still work up at the helm? Whether it be an analog? or digital? read out?

In a higher number of these cases, 'in order for the scan tool to read certain component elements, it takes the component to be psychically connected which was usually not the case in most cases and without being there help confirm, I suspect your engine may not have some of them connected form new and you may not be getting the accurate information you are reading on the scan tool.

For instance the fuel pressure reading you're reading at 40psi...That 40 number is also considered a factory default setting and not uncommon to see that psi number range especially should you not be seeing any other fluctuations of the fuel psi system....Also a 5v reading to the transom assembly sensor components is sometimes considered a default setting should nothing be connected wire harness wise especially without any other fluctuations happening...Plus if they were connected and failed, you ought to be getting other warning signals from horns, bell icons at a digital gauge and the scan tool too in your case here.

But this brought up, Bear in mind for conversation purposes, being a 2013 model, any one of these components may be/have been connected at new as they started to add more things starting around your engine year making hard to judge from here.

The reason I bring up the fuel psi system vs what you see on the tool is because looking over your engine serial number item components, I'm not seeing a fuel pressure sensor being offered to your engine model which had it been there, it ought to of been mounted at the fuel rail which would of been in here, Intake Manifold and Fuel Rail...

...Just so you know for sure I'd recommend you connect a fuel pressure gauge where you see item number 18 & 19 vs trusting the scan tool at this point...Also if your trim gauges moves, then see info above...

Of the following to choices, What design ECM (Item #3) do you happen to have?
[URL='https://www.perfprotech.com/mercury-marine-parts-catalog/electrical-components-mechanical/assembly/15044/40?umodel=3946']
Electrical Components, Mechanical

[URL='https://www.perfprotech.com/mercury-marine-parts-catalog/electrical-components-digital/assembly/15044/45?umodel=3946']
Electrical Components, Digital
[/URL]

I suspect you have the first one above lowering the chances of items mentioned being physically connected but again, not impossible either.

Also you replaced item number 6?, Merc OEM or aftermarket? Its for sure plugged all the way in?.. Even new ones have been know to fail super quick.

https://www.perfprotech.com/mercury...tion-components/assembly/15044/50?umodel=3946

[/URL]

Many thanks for your help. Im going to try understand with my poor english.

1. My gauges are analogic. Faria Kronos. They work as usually do. Actually, trim gauge never worked fine. All gauges work except trim level.
I also have vesselview Mobile and also works.
2. This afternoon will check fuel pressure with a gauge.
3. Fuel raíl don’t have any fuel pressure digital sensor.
4. I have the first ECM, with only 2 connectors.
6. i changed part number 6 (camshaft position sensor) for an aftermarket one.

i forgot that i did a spray test directly on the air intake and improve the start.

The first test that im going to do os the fuel pressure.

Many thanks again.

 

[Hiecke]

View attachment 63570572833__46ACD523-53FC-4A18-923B-A04CD5468E41.MOV

The trim shouldn't with what I believe your ECM to be...That mentioned there are some that have claimed a failed trim system in the up position did keep engines from starting on newer engine models of your serial ranges.

Does any of your normal trim gauges still work up at the helm? Whether it be an analog? or digital? read out?

In a higher number of these cases, 'in order for the scan tool to read certain component elements, it takes the component to be psychically connected which was usually not the case in most cases and without being there help confirm, I suspect your engine may not have some of them connected form new and you may not be getting the accurate information you are reading on the scan tool.

For instance the fuel pressure reading you're reading at 40psi...That 40 number is also considered a factory default setting and not uncommon to see that psi number range especially should you not be seeing any other fluctuations of the fuel psi system....Also a 5v reading to the transom assembly sensor components is sometimes considered a default setting should nothing be connected wire harness wise especially without any other fluctuations happening...Plus if they were connected and failed, you ought to be getting other warning signals from horns, bell icons at a digital gauge and the scan tool too in your case here.

But this brought up, Bear in mind for conversation purposes, being a 2013 model, any one of these components may be/have been connected at new as they started to add more things starting around your engine year making hard to judge from here.

The reason I bring up the fuel psi system vs what you see on the tool is because looking over your engine serial number item components, I'm not seeing a fuel pressure sensor being offered to your engine model which had it been there, it ought to of been mounted at the fuel rail which would of been in here, Intake Manifold and Fuel Rail...

...Just so you know for sure I'd recommend you connect a fuel pressure gauge where you see item number 18 & 19 vs trusting the scan tool at this point...Also if your trim gauges moves, then see info above...

Of the following to choices, What design ECM (Item #3) do you happen to have?
[URL='https://www.perfprotech.com/mercury-marine-parts-catalog/electrical-components-mechanical/assembly/15044/40?umodel=3946']
Electrical Components, Mechanical

[URL='https://www.perfprotech.com/mercury-marine-parts-catalog/electrical-components-digital/assembly/15044/45?umodel=3946']
Electrical Components, Digital
[/URL]

I suspect you have the first one above lowering the chances of items mentioned being physically connected but again, not impossible either.

Also you replaced item number 6?, Merc OEM or aftermarket? Its for sure plugged all the way in?.. Even new ones have been know to fail super quick.

https://www.perfprotech.com/mercury...tion-components/assembly/15044/50?umodel=3946

[/URL]

I have tested fuel pressure and gives me 40 psi when pump starts and low very quickly to 30 psi. Is it normal ?

 

[alldodge]

No, that's not good, it should stay there and very slowly drop if at all

It might be leaking back thru the pump, regulator or an injector

To test, need to block off the fuel line going to the fuel rail and attach gauge. Turn key ON and see if gauge stays up then its an injector or fuel line

To test return, block off return line going back to the filter and gauge on fuel rail. Turn key ON and pressure should build and hold. If it still does not, then the pump is leak internally