Stalled and would not start

[clasavi]

Hello

I have a 1998 mercuries 350 EFI MPI
Engine Serial OL067176
Sterndrive OL153367

2 weeks ago I went for a cruise on the boat and she ran very rough. I opened a ticket for the mechanic to look at it since they set the timer last.m I thought it was a timing issuing perhaps it wasn't set right by them

A week later, They called and said the boat ran fine during the test drive, nothing wrong with it.

Today, I go to the marina and she starts just fine, I take out and she runs just great (top speed for 2-3 minutes) till I slowed down and turned around to head back to the marina. That's when she started acting up and wouldn't go. Eventually she stalled and I had to call seatow.

Upon arriving at the marina, I tried to crank her and she started right up.

in short, She starts right up, runs hard till you stop or slow down and then she stalls. I thought I only had that problem at home!
Any suggestions?

 

[Don S]

Re: Stalled and would not start

Pull the water separating fuel filter, pour the contents into a clear container and see if there is any water in it. It will settle to the bottom.
Install a new filter if clean. DO NOT reuse a filter.

 

[clasavi]

Re: Stalled and would not start

I Removed the fuel/water separator and found no water and I also added a can of fuel/water treatment to the gas tank. I went for a ride, she ran fine and strong.

 

[clasavi]

Re: Stalled and would not start

She is not ok. I went back out and ran her hard this time. She stalled again. I had the mechanic test for spark and he said there wasn't so He suggest i change the module ( can't remember the name) by the distributor cap. I did and it still would not crank.

Could it be the fuel pump? I hear the pump come on but perhaps not building a strong enough pressure. What should the pressure be? The mechanic also tested the psi for the fuel and the reading was less than 30 psi.

1998 mercuries 350 EFI MPI
Engine Serial OL067176
Sterndrive OL153367

 

[Don S]

Re: Stalled and would not start

I had the mechanic test for spark and he said there wasn't so He suggest i change the module ( can't remember the name) by the distributor cap. I did and it still would not crank.

Did he test anything or just want to throw some parts at it? Sounds like he want to throw parts at it.

Could it be the fuel pump? I hear the pump come on but perhaps not building a strong enough pressure. What should the pressure be? The mechanic also tested the psi for the fuel and the reading was less than 30 psi.

If you don't have spark, why worry about fuel. You can check the fuel pressure with gauges when the pump comes on for 2 seconds when you turn the key on. But the ECM is not going to turn the pumps on until it confirms you have spark (actually just a reference signal from the distributor).

 

[clasavi]

Re: Stalled and would not start

It's cheaper if I change the parts than if they do it and keep charging till they get it right. I assume, I need to change the coil and the distributor cap. Any other suggestion?

 

[Bondo]

Re: Stalled and would not start

It's cheaper if I change the parts than if they do it and keep charging till they get it right. I assume, I need to change the coil and the distributor cap. Any other suggestion?

Ayuh,.... Cap, 'n rotor maybe,... I truly doubt there's anything wrong with the coil....

as Don's sayin',... Testin',.... Diagnosis is Way cheaper in the long, 'n short run.....

A fuel pressure gauge probably ain't as much as yer Marina's hour of time...

 

[clasavi]

Re: Stalled and would not start

I found the problem, it's the pink wire that goes into the black connector which then connect to the coil. Where can I buy the connector?

 

[Robert D]

Re: Stalled and would not start

I found a similar issue on a '91 Thunderbolt IV ignition, just the ignition wire to the coil. A couple inches from the end of it, underneath the wire wrap.....a section of the wire insulation was split, almost looking like it melted. Wire itself was still intact, but same symptoms you had. Very intermittent. Tested the coil, measures out perfect on the bench.....but signs of it getting quite hot near the top of it. Figured it cooked the wire. Went ahead and replaced the coil. Never seen a coil get hot enough to have melted 'gooey stuff' running down the back side. (Internal oil possibly?) Unit is mounted well away from exhaust. Local marine supply shop with mechanics around said most of the issues they see with the Thunderbolt ignitions are either corroded connections, or coil related, and usually involve the wiring within 4 inches of the coil. Seems to be a weak spot in the system. The ignition modules and pick up's inside the distributors themselves usually either work, or they don't work at all. None of the intermittent stuff goes on.

 

[Don S]

Re: Stalled and would not start

That is the short harness with an inductor in that wire. Merc PN is 84-817376T01