Merc 3.7l 165 died after fueling up

Pcubiotti88

Recruit
Joined
Jun 26, 2019
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2
Ok so first I’d like to express how priceless this wealth of information is on this forum.
I have an 87’ merc 165 3.7l 4 cyl. that I converted to electronic ignition midway though last boating season (July 2018). The boat ran great for a few weeks, one of the weeks seeing daily use, as I was on vacation in the st. Lawrence river with the boat. The boat then sat for about a week, ran it for about an hour, stopped to fuel up, left the dock and as I was getting up on plane the boat cut right off and died. Would not start at all. It was late so I did not have time to trouble shoot at the time. Long story short I pulled and winterized and decided I would get it going this spring.
Well this spring, after determining I wasn’t getting any spark, I changed the plugs, wires, cap, rotor and cleaned all terminals and wires on the coil. It fired right up. Also I cleaned fuel filter before carb inlet and on fuel pump. And I am in fact getting gas in the carb when I pump the throttle. (Carb is good....I think) I rebuilt it winter of 18 and ran it for months before converting the ignition. Now it seems to idle fine when not under load. Haven’t water tested yet. I’m worried it will do the same thing and leave me stranded so I’m brainstorming what went wrong last summer, as I don’t believe bad plugs or wires would have cut the engine right out like that. I was
Externally resisted coil was new when I bought the pertronix ignitor 1 last summer. I notice while idling that the purple resistor wire from the choke is getting quite warm. Is it normal for this wire to heat up? What sort of thing could have cause the engine to abruptly cut right out?

I understand this topic has been discussed before, I’ve read for hours on this very topic and still haven’t came up with any answers I feel comfortable with. Any help is greatly appreciated.
 

wellcraft-classic210

Master Chief Petty Officer
Joined
Sep 22, 2010
Messages
839
1 idea -- Clogged fuel filter ???? If debris in tank got stirred up

2nd idea -- If you think its electrical -- check the condition of all wire insulation and contacts
 

nola mike

Vice Admiral
Joined
Apr 22, 2009
Messages
5,720
Yes, normal for purple wire to get hot. Seeing fuel when you pump the throttle only tells you that the accelerator pump is working. Scott Danforth he says it's idling and starting fine now. While idling wiggle some wires around, see if it cuts out. Intermittent short can cause those symptoms.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
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Jul 23, 2011
Messages
51,383
every pertronix unit I ever used failed where the wires attach to the unit.

it would start and idle and quit as soon as the wires moved a bit from vibration or the mechanical or vacuum advance turned the breaker plate.

if it idles fine, however dies when you rev it, look there.
 

Pcubiotti88

Recruit
Joined
Jun 26, 2019
Messages
2
Well if the purple resistance wire is supposed to get hot, then that puts a lot of my concern to bed. I just never noticed it before I guess. Maybe I fixed whatever problem I had last season when I cleaned the connections and did the maintenance (plugs, wires, cap and rotor). I don’t believe it had anything to do with the electronic ignition as it ran great for a free weeks of hard use.
 
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