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