Mercruiser 5.0 mpi No Start

[tpenfield]

Yes, my bad on the EST comment . . .

Is this engine covered under Mercruiser service manual #31 ??? :noidea: It has the newer 'crab' style distributor (right?)

The symptoms seem to indicate that the injectors are not firing until the engine 'thinks' it is running . . . The engine apparently is not in 'start-up' mode :noidea:

Just wondering what sensor input (or lack thereof) would be causing that (crankshaft position indicator ? . . . distributor? . . . something else ? )

 

[18Booth]

Fuel quality is good nothing in the filter as I expected. Have not gotten a chance to test battery voltage at injectors yet (been hauling power and sailboats out most of the week) but as Ted mentioned what sensor could cause this?

 

[dubs283]

.
Heres what I have done so far:

Fuel filter changed
Scanned the engine and no codes popped up
New cap and rotor
41 psi at the fuel rail on top of the engine
Pulled the little filter out of the throttle body and that still didn’t help.

spark plugs?

 

[Searay205]

Why don't you check the crank position sensor. Its on the front of the engine by the harmonic balancer. I am sure there is resistance specification. If you wanted to be real savy you could find the pin out for the PCM and check it from there. That way you wouldn't even have to bend over.

 

[muc]

(been hauling power and sailboats out most of the week)

Do you own this boat?

 

[muc]

Yes, my bad on the EST comment . . .

Is this engine covered under Mercruiser service manual #31 ??? :noidea: It has the newer 'crab' style distributor (right?)

The symptoms seem to indicate that the injectors are not firing until the engine 'thinks' it is running . . . The engine apparently is not in 'start-up' mode :noidea:

Just wondering what sensor input (or lack thereof) would be causing that (crankshaft position indicator ? . . . distributor? . . . something else ? )

Parts of the engine are covered in #31. But this engine has an ECM555 as it’s controller, so those items are covered in #36. Yes as mentioned earlier this engine has an spark switch in lieu of a distributor.

Side note for those people stealing manuals from the internet Manual #36 was updated by MerCruiser Jan 2020. Apparently MerCruiser thought the first 2 versions of #36 were so bad, they produced a new version when they don’t even use this ECM on new engines. So if you’re going to do a illegal download, at least try to get the right one.

There are a few sensors that can cause this. As an example let’s take a look at the TPS. If this sensor has gone bad and is telling the ECM it is at 98% during cranking. This won’t show as a fault because it’s a valid value. But it will be interpreted as commanding the ECM into “clear flood mode” so there won’t be any fuel from the injectors until the engine has reached a predetermined RPM. So using starting fluid to get the engine speed up would cover this up. This is why it’s best to do testing rather then guessing. There are other sensors that are more likely than the TPS. But it’s a much greater possibility that all the sensors are good on this engine.

Another side note, Don’t ever use starting fluid in a boat. It is much to dangerous and could lead to misdiagnosis due to needing a much weaker spark to ignite. Use a small squirt bottle of gas.

 

[18Booth]

We’ve used starting fluid for over 50 years and has never failed us. Using it isn’t guessing, it’s pinpointing whether you have a spark issue or fuel. Pretty cut and dry. A little flame in the throttle body shouldn’t get anyone’s panties in a bunch. If it does, go write manuals

 

[muc]

We’ve used starting fluid for over 50 years and has never failed us. Using it isn’t guessing, it’s pinpointing whether you have a spark issue or fuel. Pretty cut and dry. A little flame in the throttle body shouldn’t get anyone’s panties in a bunch. If it does, go write manuals

HaHa

50 years and your on a DIY site trying to troubleshoot a pretty easy problem?

Might want to tell your customer to take this to an authorized MerCruiser dealer. This engine should be registered into their name and the outstanding safety recall preformed.

Guess you put me in my place.

P.S. How many new screen names have you gone through trying to troubleshoot customer boats. What labor rate are you charging these poor people?

 

[alldodge]

Manual #36 was updated by MerCruiser Jan 2020

Unable to find anything past 2006, happen to have a number?

 

[muc]

Unable to find anything past 2006, happen to have a number?

8M0160555 eng JANUARY 2020

edit, the 2020 version isn’t all that much better than the 2006 version
they added some pages and changed the format some. Biggest difference is they deleted all the info on CDS and replaced it with G3 information. Probably won’t matter all that much to DIY person because they don’t have access to CDS or G3.

The first version was garbage. Don’t remember what year it came out and I threw my copy away.

 

[alldodge]

Thanks, looks like BAM is the only one showing up on a search with it. They list is as $25.62 so pretty cheap

 

[muc]

Mercury Marine has a lot of them in stock.
MSRP is $26.00
Any Mercury dealer can order them.

i feel all these manuals should be free to the owner, but that’s just me.
Probably wouldn't matter anyway because of how many questions I see that are answered in the owners manual. Most manufacturers provide a free copy on their web site. Mercury Marine and Volvo Penta have a easy to use means to view the owners manual and a list of all the other repair manuals available for that engine. It is apparently easier to ask that question on a forum (and maybe get the wrong answer) then it is to READ THE OWNERS manual.

Quite often the manuals are less expensive than the cost of one sensor, that could have been easily tested with the knowledge that’s available in the manual.

But out there is a problem with the factory manuals. They have long been written on the assumption that they are being read by a trained mechanic. I have noticed that in recent years they are getting better. In some of the newer ones they give instructions on how to properly use a volt meter. How many people on this board know that you’re supposed to make your connections to the circuit before you turn the meter on? While this won’t matter on some circuits, it will on others. And if you don’t know something this simple. How will you know why and when it does matter? But this knowledge is only available if you read the entire manual.

Still i see the question “what sensor could cause this?” When the answer is “most of them”. Parts swapping is a poor substitute for troubleshooting.

I can see why so many people want to do their own repairs. They have probably taken their boat to an unqualified repair facility (that has their mechanics googling “what sensor do i replace next”). instead of investing the time and money in training and tools

Note; as I reread this post. It seems like I’m calling out alldodge. I’m not. He is one that I think is “getting it”. It mainly my frustration with people who are looking for the easy way out. Especially people who hold themselves up as marine mechanics but don’t spend the time to actually be one.