Merc 350 MPI - No Start. 2001
 

I had difficulty starting my starboard engine when hot, so I replaced the Idle Air Control. (as it was easier to start with just a little throttle, I suspected the IAC).

Ever since it's become a no start condition. I even replaced the IAC with the original 20 year old one, with no luck.

The engine ran all season, ran when shut off a week ago, and hasn't been able to be started since. I've tried everything I can think of.

I replaced the fuel filter, it has plenty of fuel. I pulled the gas line going to the fuel rail, and the fuel pump is definitely working.
I put a spark plug tester on and it's getting spark to all 8. the rotor in the distributor is spinning.

I tried starting fluid - no dice. I checked for DTCs. There are no stored codes. Manual says the MAF sensor can cause a no start and to disconnect it - no dice. I even tried disconnecting the IAC and TPS. No dice.

The engine ran at shutdown. Then never again. What am I missing? Fuel, Air, Spark?!

Thanks!

Was spark tester used on all 8 or just the coil wire?

Are you seeing the tach increase to at least 300 rpm while cranking?

What is the fuel pressure at the rail?

I was slightly lazy, I tested 3 of the spark plugs with the tester. the coil wire has enough juice to make my left arm numb! bright blue spark jumped.

Cranking speed seems good/normal. I didn't check on the tach, but the battery is also plugged into a charger/starter, so I don't think it's low on juice.

I didn't check fuel pressure, is there a connector to plug into somewhere? I just removed the line going to the rail, turned the key to run and when the pump ran for 2 sec it dumped a lot of fuel out... I know, stupid, but pump at least pumps fuel.

Could it be the fuel pump? Maybe. But should it not have at least tried to start when I was dumping starting fluid down the throttle? The starting fluid didn't make any difference at all. And that stuff is flammable!

How would I attach the fuel pressure tester? Does the harbor freight one fit?

Did I somehow accidentally rotate the distributor while removing the IAC? How far off would it have to be, for a no-start? Setting the timing is done with an engine running... I can't even get that.

Thanks for your help! I feel like I'm missing something so basic/small. And who the hell uses distributors? My 1990 OMC 460 was smarter than this 2001 Merc...

Unhook the line that goes from the pump to the fuel rail, and hook it into this thing?

https://www.harborfreight.com/Fuel-I...ter-62623.html

manual says it should read 30PSI.

Looked up 2001 (no serial number listed) and you have

EDIT - you did say MPI



check the tach and see if its moving up to 300 rpm or above. Looking at the tach lets you know if its spinning fast enough and more so lets you know the distributor is pulsing. No tach signal no fuel pulse

I needs a serial number

Thanks!

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I will check the tach tonight.

I tried to paste the serial number from excel... whatever that mess above is... sorry.

0M047350

thanks!

MFI-3

Remove cap (item 7) and attached gauge to shrader valve (item 6)

https://www.mercruiserparts.com/bam/...31745/2691/110

To post pics, select the button which looks like mountains

Fuel pressure
 

Its BAM's catalog, I search your SN and it comes up with what I posted, but if I look its the wrong serial number range. I need to make sure to double check. The Mercruiser site comes correct

Pressure would be good to know, but as you said starting fluid changed nothing. I thinking more in the spark area

Good news and awful news.
The good: after swapping the rotor and distributor cap from my other engine I was able to get STRB to start. Although I still suspect bad fuel and think it was more just keep trying to start it. and dumping out fuel.

the awful: I warmed the engine up to change the oil to winterize it, and it came out like a milkshake! Yummy! But also not good. very not good. Lots of water in the oil! Good Times. Break Out Another Thousand.

So, bad intake manifold? cracked block? cracked head? blown head gasket?

The engine also leaks oil, so I've been pondering just getting a 'new base engine' for $3,000 for a GM 350 from Mitchigan Motorz. anyone ever deal with them? No core and they can ship to my house (no loading dock).

I'd also replace anything that's hard to get to or looks bad while I'm in there. Bilge pumps, oil filter lines/fittings/drive coupler/starter/flywheel/etc. anything that's hard to get to or under/behind the engine.

Or should I investigate more into a 20 year old abused block? I have friends and enough know how to do the swap (I think)...
My mobile mechanic wants to take a look before I commit to a new base engine, but I'm not sure the point. the oil came out black last year, not milkshake, so it must have happened over the summer. I winterized it myself last year, and it's in a heated garage. so I don't suspect freeze damage. The engine was almost 1.5 quarts low on oil over the summer. Maybe that killed it :(

Several on iboats have used Michigan motorz with good results. The ones that did have an issue MM step right up and fixed the issue

For me, sounds like the motor needs to be pulled apart and while its apart, I would rebuild. So either rebuild or replace

I have the skills to swap parts to the new engine. I don't have the skills to rebuild one... Thanks!

Well there is only one way to find out. Dive into it and take lots of pictures. Worst case you realize it isnt worth saving and buy a new one.

Compress test:
3 of the 8 cylinders show below 30 PSI. 5/8 are about 140-160.
I am prepping to remove the engine. I've removed the water in, electrical, exhaust, fuel, etc.
Hope to borrow a friends crane to pull this thing out and start tearing down.

I should most likely replace the exhaust manifold and elbows on the 'good' engine as well.

Already planning both on what will be the new engine as well.

I have purchased a 350 MAG MPI crate engine from MM about 4 years ago and I couldn't have been happier with my experience. They made the delivery a breeze to my door (private residence) and as I installed the motor myself they also helped me out to get the paperwork complete for my Mercruiser warranty. I would with out a doubt use them again if I were to be in need of another new engine. Motor is still running strong to this day never had any issues with it.

Good to hear and thank you for the feedback! Mine should arrive this week, and I can start the install the following week.