1998 190 hp merc 4.3L v-6...dying after warm up but restarts quickly

last fall we bought a 25 ft pontoon with the 190 HP Merc Alpha One, 4.3L gm motor. Used myself 4 times before season ended and then winterized. On last outing after the boat warmed up, the boat would frequently die suddenly like I had turned the ignition off. The motor would quickly restart and we limped back in and loaded it up for winter. Took to local boat mechanic with a good reputation to winterize and check the problem. He was unable to reproduce the shutoff. Besides winterize we replaced the starter, rebuilt prop and replaced an exhaust hose to the lower unit.

This weekend first trip out, boat starts well, we ran the boat for 15 + minutes without problem. Then started back out to open water and it started doing the same thing. The boat would quickly die and quickly restart. It did not seem to sputter out. The problem did not seem to materialize if I was just idling.

Almost like we had a tempature shutoff to prevent overheating but my temp guage read normal, nothing extreme or pushing high temp.

I had mentioned to mechanic when winterizing to check the fuel pump. Said he found nothing wrong.

Any feedback / recommendations greatly appreciated

Dwayne

Re: 1998 190 hp merc 4.3L v-6...dying after warm up but restarts quickly

went back out to run in idle in the slip and the problem did reoccur. The problem seem to begin once the engine reached the temp of 170. My spec book says the thermostat should be 160. Don't know if this adds anything to the problem solution. Problems seems by my guess maybe an auto shut off.

Re: 1998 190 hp merc 4.3L v-6...dying after warm up but restarts quickly

Problems seems by my guess maybe an auto shut off.

Click to expand...

Nope,... It ain't got 1....

Bubba told ya where to look...

The purple wires on the motor is the igntion circuit,...
Find the Bad spot...

Re: 1998 190 hp merc 4.3L v-6...dying after warm up but restarts quickly

Thanks...I'll go back out and look again....I did not see his message before I left.

Thanks again

Re: 1998 190 hp merc 4.3L v-6...dying after warm up but restarts quickly

found no noticable problem with wiring. did find problem with spark plug wires with a couple of them cracked and could see sparks. Would bad plug wires cause it quick die off? I assumed bad wires would lead to rough running, which I did not notice. Going to replace plugs, distributor, plug wires, rotor and ignition sensor assembly. Another problem I have is local marine dealers did not have marine plug wires in stock and would be a few days before delivery. Is it ok to replace marine plug wires with auto plug wires? I have bought Bosch Premium Wire set

Re: 1998 190 hp merc 4.3L v-6...dying after warm up but restarts quickly

Is it ok to replace marine plug wires with auto plug wires?

Click to expand...

Ayuh,... Generally speakin',... They'll be to short, 'n probably have the wrong ends on 'em...

Re: 1998 190 hp merc 4.3L v-6...dying after warm up but restarts quickly

certainly had problems trying the auto wires...too short...autozone could not locate a long enough set. Fortunately they gave me 2 long wires to replace the 2 bad wires. put the remaining old ones back on and ordered new set of marine plugs from local dealer but it will be a week for delivery. Thanks for everyone's input

BDY

Re: 1998 190 hp merc 4.3L v-6...dying after warm up but restarts quickly

forgot to disclose the actual problem....iginition sensor...

Re: 1998 190 hp merc 4.3L v-6...dying after warm up but restarts quickly

Welp it was not the iginition sensor....mechanic thought he had it fixed....I took it out yesterday evening....had to limp back into the doc....only difference this time...the engine felt more sluggish dying out and would occassionally backfire. New plugs, new distriburer cap, new iginition sensor, replaced 2 of 6 plug wires (will replace all when in), timing set. Starts up nicely but again after awhile going across water or just sitting still it dies out. the die outs become more frequent each time, meaning it stays running shorter and shorter between dye outs.

Re: 1998 190 hp merc 4.3L v-6...dying after warm up but restarts quickly

is the coil getting hot??

Re: 1998 190 hp merc 4.3L v-6...dying after warm up but restarts quickly

will check with mechanic tomorrow...thanks for the suggestion

Re: 1998 190 hp merc 4.3L v-6...dying after warm up but restarts quickly

....mechanic thought he had it fixed....

will check with mechanic tomorrow...

Click to expand...

Aren't you working on this boat yourself? or just giving your mechanic instructions?

Re: 1998 190 hp merc 4.3L v-6...dying after warm up but restarts quickly

tried to do it myself first...thought it would be a simple fix...trying to educate myself on what it would be