Logo
FULL SITE MENU

2002 5.0 MPI hard start

A

AFGUNNER

New member
Hi Folks,
I hope you can help me out with this 5.0 Merc MPI W/ Alpha 1 . It takes 10-15 turns of the key to start. It acts like the timing is off, It sputters and smokes out the spark arrestor. However, once It starts it runs fine. Every start after that, it cranks right up. I start it in the morning (15 turns) before hitting the water and it cranks up all day (first turn). Had the rotor and cap, IAC, shifts interrupts, knock sensor replaced.

Any help is much appreciated.
 
Well the problem started after the items listed were replaced. New Plugs but the wires are old. The Motor serial number is M358361 if that will help any.
 
Check first that when you replaced the plugs that the wire connector fully seated to the plug when replaced. Also unless you changed the plugs one at a time, make sure you did not misconnect the wires, its easy to get adjacent plug wires crossed, especially on the inner 2 cylinders on each side.
 
Sandkicker, Wires are connected properly. If they weren't wouldn't it idle rough?

Dockside, What makes you think the coil is bad. In my experience they produce spark or they dont, or dont produce enough when they get hot. Would an IAC muffler produce this condition? the IAC muffler is not installed because it keeps getting sucked into the IAC from the trottle body. Dont know why this is happening either. There is a strong sucking coming from the IAC when running.It does calm down once running for a while.

I appreciate your inputs gentleman.
 
OM358361



"It acts like the timing is off, It sputters and smokes out the spark arrestor."

Remove the distributor cap and see if you can turn the rotor on the shaft.

"What makes you think the coil is bad. In my experience they produce spark or they dont, or dont produce enough when they get hot."


This would be true on a TB4 ignition system or any other round coil not on a 555 ecm engine. On your engine the coil and the module are mounted together. The problem started after you changed the cap and rotor. Chances are the coil is cracked and now leaking RF. The only other part of your ignition system that controls spark is the crank sensor.

If Fuel pressure is fine and all else checks out,

Things to look for, Loss of 5volt reference will not allow the engine to start. Start with a DVOM and check the wires at the TPS. Do not shove your test probe into the plug, just touch it on the contact. The TPS has 3 wires one should have 5 volts with the key on. If it does not start unplugging all three wire sensors until it comes back. Water Pressure sensor is a culprit.
 
Last edited:
AFGUNNER
I had the same problem, replaced the IAC and replaced the missing muffler and everything was fine for ~ 8 weeks . now i'm getting the same problem, takes around 15 tries to start motor , once started it will restart all day but leave it for a week and it won't start.
 
The ignition system on a Mercruiser 555 MPI engine is very sensitive. A bad ignition wire, dist cap, Incorrect plugs, rotor or coil will take the engine apart. The Dist cap needs to be changed every year.

The ignition coil has the module on it and is $$$. So for testing purposes only, Head on over to your local Junk yard and get this part to test with. DO NOT DRIVE YOUR BOAT WITH THIS PART YOU WILL DESTROY YOUR ENGINE! Just use it to test the cold start issue.

http://www.ebay.com/itm/1056-NEW-CH...id=100005&rk=1&rkt=6&mehot=pp&sd=391155217824
 
Last edited:
Back
Top