1988 454's ignigtion problems!
 

some problems, any advice please. the symptoms are. engines start up and purr like kittens. but after about half hour port engine starts to die off. sputtering and rpms dropping untill shes dies completly. starbord runs fine and gets us home everytime. so could this be a faulty coil? or what should i check for?

Re: 1988 454's ignigtion problems!
 

You could swap coils on the motors and ignition boxes to see if it follows before you start spending money.
Mike

Re: 1988 454's ignigtion problems!
 

should also be able to change sensor without disturbing dist. However timing should be at least checked after changing module or sensor. I've seen the hall effect sensors cause this same crap out problem on cars. BBB

Re: 1988 454's ignigtion problems!
 

could a plugged fuel tank vent cause these problems as well?

Re: 1988 454's ignigtion problems!
 

Gremlins......

Re: 1988 454's ignigtion problems!
 

I had similiar couple years ago, would go out and after a while starboard would die out, let sit for a while and would re-start and do again. Turned out to be the harness quick connection. had some corrosion and with heat and movement of boat would lose spark. Try pulling the quick connector apart and inspect inside.
good luck

Re: 1988 454's ignigtion problems!
 

I think that your first thought was best. When coils start to go bad they begin to break down when they warm up with use. Do like goob says and see if the problem follows the coil. A sensor usually quits completly and never comes back. Seen this often with T-Bolt IV's (I assume that is the ignition you are running) and it's always been the coil. --- Jer

Re: 1988 454's ignigtion problems!
 

thanks a lot for all the input. did not have time to work on her today but, should be at it tomorrow. now if the coil does need replacing is there a better type to use or should i stick with the merc stuff?

Re: 1988 454's ignigtion problems!
 

I have been using MSD Blaster II for the past couple years with my T-Bolt IV and the V8-HP (20 deg. adv.) module. Couldn't be happier! --- Jer

Re: 1988 454's ignigtion problems!
 

ok we checked the coils and swaped em for ones that were good. and the problem returns. the engine starts up fine and runs smooth. but after 20 min. she starts to sputter and cut out. what should i look at now! ignigtion control unit or something like that?

Re: 1988 454's ignigtion problems!
 

Check the entire igntion circuit. Some boats have another fuse in the line before the switch (in the dash or dc panel area). Replace it no matter how it looks. Ive seen a fuse go open after it got hot and then close up after it cooled, drove me crazy.

Re: 1988 454's ignigtion problems!
 

Everyone's is on the ignition blame game. Are you for certian it is not fuel related? what kind of carbs do you run? what kind of fuel pressure do you see? give me as many details about your fuel system as you can. I personally don't think your problem is spark related.

Roby

Re: 1988 454's ignigtion problems!
 

the engines are all stock. quadjet merc carbs. not sure on the fuel presure. dont know how to check that. except for the old pull the line and see if it squirts far. we replaced the water seperators, replaced fuel filters, replaced cab and rotor, replaced spark plugs, replaced high tension leads. ?

Re: 1988 454's ignigtion problems!
 

I'm having similiar problems, but I think my issue is fuel related. One idea (that is on my list to check) is the anti-siphon valve to the tank.

Re: 1988 454's ignigtion problems!
 

what does this anti - syphon valve look like? i sure will check as well as any thing else thats needs attention. it seems odd though, but all the power is there when needed and she hits wot, but after twenty min mark she slowly starts to die off! dam those gremlins and their furry little bodies.

Re: 1988 454's ignigtion problems!
 

Oh a quadrajet? Okay try this, Remove the fuel filter that is in the inlet of the carb. There is a little rubber piece on that filter that is supposed to prevent drainback in the event the fuel line should break. (really stupid idea) Pull that rubber piece out and disgard it. See if that works because some of those rubber pieces severely restrict fuel flow and some don't. They are not manufactured to tight tollerances because they used to be sold by the tens of thousands back in the carb days. That is why this problem is hard to troubleshoot. Back when I used Quadrajets I ran into this problem from time to time whenever I changed fuel filters.

Let me know
Roby

Re: 1988 454's ignigtion problems!
 

removed fuel filter and problem returns. tried with filter and with out. fuel pump pumps fuel like crazy. what else to look at? getting stumped, or missing something in the ignigtion system that is faulty! ignition has no points, so what replaces the points? this sytem is new to me , use to the old piont style...

Re: 1988 454's ignigtion problems!
 

the conclusion, faulty coil pick up in the distributor. .....

Re: 1988 454's ignigtion problems!
 

So how did you come to that conclusion? As I said I'm having a similar problem, will be trying a new coil this weekend.

Chuck

Re: 1988 454's ignigtion problems!
 

That is an odd one on me. Usually if it faulty, it don't start.

Roby

Re: 1988 454's ignigtion problems!
 

Chuck he is not refering to the coil. it is the pickup inside the distributor be it magnetic or IR. aparently it was getting too hot would be my guess and breaking down. Be sure to liberaly coat the underside of it with dielectric grease.

Roby

Re: 1988 454's ignigtion problems!
 

Check this out for a troublshooting flowchart.
http://www.marinemechanic.com/site/page251.html

You just need to ground out the trigger wire (green/white) at the distributor and check for spark.
Gary

Re: 1988 454's ignigtion problems!
 

well, i could not stand being stuck at the dock any longer so i had the mechanic come by. they did a tune up. but after the tune up, she would start and die instantly. so he swaped the coil from the other engine, no dice, swaped the ignigtion control modual, no dice, swaped the pick up inside the distributor and start up!
so anyway we changed both of them to be safe.
part number 87-86178Q 4 made by quicksilver. ignigtion sensor assembly. says on the box "ignition sensor for all mercury mercruiser v-6 & v-8 ignitions with nut attaching connectors" anyway just happy to have her back in running order!

Re: 1988 454's ignigtion problems!
 

sorry #87-861780Q 4

Re: 1988 454's ignigtion problems!
 

My problem turned out to be the mechanical fuel pump.