3.0 dies after 5 min

[shale1]

I have an old Mako with late model Mercruiser 3.0 I/Os with electronic ignition. Stbd. engine idles fine, will run 3,000 rpm for about 5 min under load then dies - will restart but will only idle. Temps and oil pressure are fine. All fuel filters have been changed. Carb has been rebuilt, fuel pump fills a quart jar with no bubbles in about 15 seconds at idle. Ran engine off a portable tank with same effect. Help - don't know what else to look at.

 

[ron7000]

Re: 3.0 dies after 5 min

sounds like ignition system is crapping out. When running upper rpms after a few minutes, it heats up and dies. When motor is off for a bit, it cools off and works again. Most likely the ignition coil. It could possibly be the ignition module.

 

[Blk-n-Blu]

Re: 3.0 dies after 5 min

shale, Swap the coils and see if the problem moves with the swap.

 

[gtaeza]

Re: 3.0 dies after 5 min

also check your high tension wires. maybe it's<br />leaking.

 

[shale1]

Re: 3.0 dies after 5 min

I was busy over the weekend. I switched coils, ignition modules,fuel pumps, ignition wires, disabled the tach and checked the fuel filters again (to be sure about water) - but same thing seems to happen (did each one at a time). How much silicone grease should be used under the ignition module? Also, could a clogged distributor vent cause these problems? How about too little grease under ignition module?

 

[joecanton]

Re: 3.0 dies after 5 min

I have a1993 Mercruiser with a 3.0L, 135 horse with a EST ignition. The engine shut off at high speed and would not start. <br />I checked it and I have fuel to the carb, no spark at plug, no spark at coil wire to distributor. I was wondering what is the test for the coil and the other electronic control.<br />thanks!<br /><br />joe