Mercruiser 5.0 MPI 2013. Crank but no start.

Hiecke

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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
 

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Hiecke

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I have changed almost 2 fuel regulators that i remember. In october oficial service changed fuel pump, regulator and cooler. Its not easy to check because is very narrow. Actually i don’t know where is the fuel pump in the Alpha One gen 2.
 

alldodge

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I have changed almost 2 fuel regulators that i remember. In october oficial service changed fuel pump, regulator and cooler. Its not easy to check because is very narrow. Actually i don’t know where is the fuel pump in the Alpha One gen 2.

Look at the fuel filter housing, there will be 3 lines on it. One from the tank, one going to the fuel pump and one coming back from the fuel pump regulator. Look at the arrows on the filter housing,

If the line coming back from the regulator is removed and blocked off, and the filter head is plugged, turning the pump ON should keep pressure up unless the injectors are leaking

Does sound like its not getting gas, and since you have replaced everything on the list except the injectors, I would suggest removing them. Then send them out for pressure and flow testing

The fuel pump is under the port side motor mount next to the block. Real hard to get to
 

Hiecke

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Look at the fuel filter housing, there will be 3 lines on it. One from the tank, one going to the fuel pump and one coming back from the fuel pump regulator. Look at the arrows on the filter housing,

If the line coming back from the regulator is removed and blocked off, and the filter head is plugged, turning the pump ON should keep pressure up unless the injectors are leaking

Does sound like its not getting gas, and since you have replaced everything on the list except the injectors, I would suggest removing them. Then send them out for pressure and flow testing

The fuel pump is under the port side motor mount next to the block. Real hard to get to
Last year we sent injectors for test and them were perfect and show the same problem.
My wife says that is at least the thirth time that this fail happens. I don’t remember because I try to forget this nightmare...
I have contacted with a mechanical and tomorrow are going to change the lower fuel regulator.
I have checked the vacuum from the intake manifold while crank and shows 0 hg. Is it normal?
 

Hiecke

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Last year we sent injectors for test and them were perfect and show the same problem.
My wife says that is at least the thirth time that this fail happens. I don’t remember because I try to forget this nightmare...
I have contacted with a mechanical and tomorrow are going to change the lower fuel regulator.
I have checked the vacuum from the intake manifold while crank and shows 0 hg. Is it normal?
A new problem. Today I have checked the bilge after two days of rain and the bilge is full of oil. The crackcase is rusted and leaking oil. Do you know the chevy reference ?
 

alldodge

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Unless your getting bad parts, the fall off of fuel pressure is easy to diagnosis. Mentioned the cool fuel module was replaced, and the module contains pump, cooler and regulator. Unless these were used parts, you should not be having this issue.

0Hg would be fine while cranking

You could hot wire the fuel pump by removing the fuel pump relay and then jump contacts 30 and 87 which will keep the pump running

A new problem. Today I have checked the bilge after two days of rain and the bilge is full of oil. The crackcase is rusted and leaking oil. Do you know the chevy reference ?

If your asking about part number for the oil pan its item 9
https://www.mercruiserparts.com/bam/subassembly/31855/15322/130
 

Fun Times

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View attachment 334219

I have tested fuel pressure and gives me 40 psi when pump starts and low very quickly to 30 psi. Is it normal ?
Unfortunately it seems maybe your fuel gauge doesn't seem very accurate because it starts off at 10 or 11 psi then jumps to only 40psi then settles at 32 psi which may or may not indicate you are missing out on a 10ish psi reading. :(

Does/did the gauge start off at 0 psi for any of the earlier/first tests?

Your actual over all psi should be 43....If your gauge is off 10 psi then you might only be getting 33 psi and resting at 23 psi. which if so/yes, that's to low to start the engine.

Where you ever able to start the engine with help from the fuel spray test you did?

Here's a video of someone else testing their Mercruiser for reference points,
He removes the vacuum hose line at one point from the fuel regulator which helps gain 3 - 5 psi while engine is running...That's normal "usually" telling you the regulator is working okay.

One trick you could consider trying would be to get separate fuel tank and a "outboard fuel primer bulb" and create some of your own fuel pressure by hand to see if it help start the engine any, 'Possibly clearing away some debris should there be any and to maybe help clear the debris out first, remove the upper fuel regulator up on the fuel rail and catch the fuel flow to try and not make to much of a mess of things...Turn your batteries off first though should you try this.
s-l400.jpg


Also you'll want to know that the regulator up on the fuel rail isn't used as a fuel regulator to control fuel psi, it used to dampen/lower the fuel pulses for the fuel injectors.

When did you install the 1 on the rail? Before or after the engine won't start?
Plus where did you buy it?

The fuel pulse damper works by allowing the volume of the fuel system to change slightly to absorb the pulses. This is done with a spring loaded flexible diaphragm. There is a diaphragm that changes shape and compensates for a pressure fluctuation.
A fuel pulsation damper is a device used to regulate the oscillation of fuel caused by the injectors opening and closing and smooth this out.
 

Fun Times

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A new problem. Today I have checked the bilge after two days of rain and the bilge is full of oil. The crackcase is rusted and leaking oil. Do you know the chevy reference ?
What does the oil dip stick level read?

Is there now maybe water in the oil?
 

Lou C

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A new problem. Today I have checked the bilge after two days of rain and the bilge is full of oil. The crackcase is rusted and leaking oil. Do you know the chevy reference ?
Sounds like you need a new oil pan, the steel ones sometimes rust out, they need to be sprayed with corrosion preventative sprays to last. Look it up in a mercruiser parts catalog then see if a Chevrolet standard pan is the same. Unfortunately if that is the case the engine must come out to repair. If the boat is a 2013 though I'd be surprised they usually last much longer unless you've had salt water in the bilge for a long time. The one on my engine is original from 1988.
 

Hiecke

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Unfortunately it seems maybe your fuel gauge doesn't seem very accurate because it starts off at 10 or 11 psi then jumps to only 40psi then settles at 32 psi which may or may not indicate you are missing out on a 10ish psi reading. :(

Does/did the gauge start off at 0 psi for any of the earlier/first tests?

Your actual over all psi should be 43....If your gauge is off 10 psi then you might only be getting 33 psi and resting at 23 psi. which if so/yes, that's to low to start the engine.

Where you ever able to start the engine with help from the fuel spray test you did?

Here's a video of someone else testing their Mercruiser for reference points,
He removes the vacuum hose line at one point from the fuel regulator which helps gain 3 - 5 psi while engine is running...That's normal "usually" telling you the regulator is working okay.

One trick you could consider trying would be to get separate fuel tank and a "outboard fuel primer bulb" and create some of your own fuel pressure by hand to see if it help start the engine any, 'Possibly clearing away some debris should there be any and to maybe help clear the debris out first, remove the upper fuel regulator up on the fuel rail and catch the fuel flow to try and not make to much of a mess of things...Turn your batteries off first though should you try this.
s-l400.jpg


Also you'll want to know that the regulator up on the fuel rail isn't used as a fuel regulator to control fuel psi, it used to dampen/lower the fuel pulses for the fuel injectors.

When did you install the 1 on the rail? Before or after the engine won't start?
Plus where did you buy it?
The gauge start at 0 psi and when the fuel pump start, rise to 40 psi, drop to 25-30 the fuel pump stops, and drop very slow. When I started the test, I was looking how fast or low drop the pressure.
 

Hiecke

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The upper regulator was changed 2 years ago. It’s a Bosch part. I changed it due to a fail like this. Actually the engine was stalling but start at least.
The lower regulator was changed in October.
Tomorrow I’ll try with the outboard tank and I want to test the fuel system, but I only find 2 hoses.
 

alldodge

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Lets find out for sure its fuel with an easy test
Remove the flame arrestor off the throttle body (TB)
Take 15 to 25 ML of gas and pour into the TB
Try to start the motor.

If it starts and dies its fuel and were on the right path
 

Hiecke

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Sounds like you need a new oil pan, the steel ones sometimes rust out, they need to be sprayed with corrosion preventative sprays to last. Look it up in a mercruiser parts catalog then see if a Chevrolet standard pan is the same. Unfortunately if that is the case the engine must come out to repair. If the boat is a 2013 though I'd be surprised they usually last much longer unless you've had salt water in the bilge for a long time. The one on my engine is original from 1988.
Engine was made in 2013, but boat was buildt in 2016, when I bought. And yes, the boat is always in the sea and the bilge is always wet.
 

alldodge

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Engine was made in 2013, but boat was buildt in 2016, when I bought. And yes, the boat is always in the sea and the bilge is always wet.

Always wet, if it rains a bunch and your not under cover then ok, but if it has always been wet even when it doesn't rain then there is a leak somewhere
 

Hiecke

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I have news! Tomorrow I have checked the distributor and it has a thread broken and don’t fit with the cap. In an hour I’ll be back to the port to fix it.
 

Hiecke

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Lets find out for sure its fuel with an easy test
Remove the flame arrestor off the throttle body (TB)
Take 15 to 25 ML of gas and pour into the TB
Try to start the motor.

If it starts and dies its fuel and were on the right path
Tested without any change. I think that is one distributors thread broken.
 
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