350 Mag MPI wont start ?!

[Andi45]

Hi there iam new here from Germany,

I got some problem, I have a 350 Mag MPI from 2004, that dont want to start. The spark is there and it starts immediately with brake cleaner.
Are there reasons why only the injectors are not pulsed ?
When I touch the injector I cant feel that they are triggered.
Fuses are OK, 12V arrives at the nozzles.

Best regards Andi

 

[alldodge]

Howdy Andi and :welcome:

Is this a new to you boat?
Was it running fine before, and if so what changed?

What is the motor serial number?

If there is fuel at the injectors and the injectors are firing (pulsing) then it would start. Your getting spark as you say because it will fire with brake cleaner.

Start with removing the fuel filter and dump the contents into a clear container. See if there is anything other then clean gas.

Measure fuel pressure at the rail. Once we know what the serial number is we can advise exactly where to look, but most likely it will be on the fuel rail under a cap

 

[Andi45]

Howdy

I bought the boat like this. It sit for 3 years.
It went over a rock and nobody was interested in it, after the insurance paid.

I have already exchanged the starter and both fuel pumps. All 3 were rusted.

The serial number is 0w027709

Fresh gas comes fresh out off canister. But i think the injectors are not triggered, because i cannot hear and feel them when starting.

There is no wiring on the distributor, this is normal? There is no blind plug on it either.
But i can't find a connector in the wiring harness either. I read the engine is also available without a camshaft sensor, is that true?

Thank you for the answer, I hope you can understand what I write, unfortunately my english is not good enough, so I write with a translator.

 

[QBhoy]

Hi there.
this could be a number of things, but if you have had the fuel filter off, sometimes you need to bleed the fuel at the test nipple on the rail a few times.
Other than that, bad fuel would be a place to look.

are you hearing the fuel pump prime and then stop ?

 

[alldodge]

I bought the boat like this. It sit for 3 years.

I have already exchanged the starter and both fuel pumps. All 3 were rusted.

With it being rusted prior, I would suspect that the injectors and or the fuel rail is clogged. Suggest removing the fuel rail and clean, then reinstall. To test pressure remove cap item 19 and connect gauge to Item 18. Pressure should be 30 psi (2 Bar)

https://www.mercruiserparts.com/bam/subassembly/31748/8093/90

Fresh gas comes fresh out off canister. But i think the injectors are not triggered, because i cannot hear and feel them when starting.

Need a NOID light to see if injectors are firing, feeling is not a good test

There is no wiring on the distributor, this is normal? There is no blind plug on it either.
But i can't find a connector in the wiring harness either. I read the engine is also available without a camshaft sensor, is that true?

The motor uses a HVS distributor which yours does not have wires to/from the distributor. It uses a crank shaft position sensor which is located in the timing chain cover item 9

The cam shaft sensor is not used by Merc, but is used by Volvo Penta

https://www.mercruiserparts.com/bam/subassembly/31748/8093/110

Your good and do understand what your saying

 

[Andi45]

Hi,

I pressed the nippel twice, but just short.

I thought the injector bleed themselves if start long enough?

Its my first MPI engine, so far i have only had carbed and tbi engines.

 

[alldodge]

Hi,

I pressed the nippel twice, but just short.

I thought the injector bleed themselves if start long enough?

Its my first MPI engine, so far i have only had carbed and tbi engines.

No, the MPI needs the fuel rail bleed

If you do get it running, strongly suggest having the rail and injectors cleaned, it can help over the long term

 

[Andi45]

No, the MPI needs the fuel rail bleed

If you do get it running, strongly suggest having the rail and injectors cleaned, it can help over the long term

Okay, ill do that tomorrow. I thought gas engines always bleed itself..
The pumps were not rusty. they were just stuck. The fuel lines were all clean

I just ordered a noid light. I'll check it out..
:tea:

 

[kenny nunez]

Just to be sure, remove the main engine cannon plug, then with a small thin screw driver gently spread each pin then coat them with dialectic grease, then re-install . It would be real helpful if you could get your hands on the Mercruiser Rinda scanning tool. Needless to say you do not want to throw parts at it without knowing what to throw.

 

[QBhoy]

Okay, ill do that tomorrow. I thought gas engines always bleed itself..
The pumps were not rusty. they were just stuck. The fuel lines were all clean

I just ordered a noid light. I'll check it out..
:tea:

You defo need to bleed the rail then. It can take a few attempts for sure. Key on, listen to pump prime...whilst holding down the nipple until you get clear and pure fuel with no air. If your fuel is good it should fire. But please note, the mpi is famous for not starting with anything g other than a really good battery, despite appearing to turn over well. Common issue which leads many down along a complicated path...when it was only the battery. Only saying because you may slightly weaken it during this bleeding process.

 

[scoflaw]

That system will self bleed

 

[alldodge]

That system will self bleed

Given enough cranking time maybe, but that will be quite a while

Tell me how please, what am I missing?

 

[kenny nunez]

If the fuel system was the “return style” usually bleeding is not needed. But on the “non return” bleeding is the best way to get the engine started quickly.

 

[scoflaw]

8 injectors will bleed air just as fast as that Schrader valve

 

[QBhoy]

Honestly guys. If the fuel feed has taken a gulp of air...the battery on most boats would run dead before it would self prime and fired. Even changing the fuel filter empty will require a bleed at the rail and a few goes at cranking.

 

[alldodge]

Don't believe ya guys without one heck of a lot of cranking. Liquid produces pressure when moved thru a vane pump, air will compress some but will also not increase much. The return line will send air back to the filter.

This is one of those that will need to be proved, agree to disagree

 

[Andi45]

Unfortunately no good news..the first thing ive done yesterday, i bleeded the rail.
There was definitely a lot of air. However, that didn't change my problem. Still didn't want to start.

Then i removed the rail and tested one injector. It looks like they are totally stuck.

Tomorrow i will try to get them back to life in a ultrasonic bath.
If the doesnt help, I will have to buy new ones.
Thank you so far, i will report if i have any news!

 

[alldodge]

Suggest sending injectors out to be cleaned and tested, and us a place that does marine? Cost is around $20 per injector

Also check fuel pressure at the rail

 

[Scott06]

https://injectorrepair.com/injector-service/

$17 per fir cleaning and flow testing

 

[alldodge]

Need to find out if they flow test to 6000 rpm