Engine cuts out above 3200 revs HELP!!!!

[wooly]

I have a 1991 stingray with a 4.3lx mercruiser thats giving me problems, it starts fine runs up to 3200 revs without missing a beat, when I go for the last of the throttle the engine cuts out like someone has unplugged the electricity, the rev counter drops to zero and thats it, it will restart after a few seconds. I have cleaned, replaced and renewed the fuel system from the tank pick up through to the needle valves and jets in the carb, so pretty sure it's not fuel related. I have tried different leads same problem, replaced the coil 4 times, that seems to cure it for a short time but then same problems start again, last coil lasted about 10 mins, the manual says about the ignition resistance wire, it says that it should read 1.8-2.0 ohms, mine is only reading 0.2 ohms so I am going to try replacing this next.
Has anyone got any ideas that might help me sort this problem and let me enjoy the rest of the summer on the boat instead of trying to fix it.
THANKS.

 

[grewvin]

Re: Engine cuts out above 3200 revs HELP!!!!

what type of distributor you have? Points? if so check the sideways play in the shaft. If there is any play it will knock off the dwell at high rpm and will shut down until rev's get slow then engine will kick in again just like someone has thrown a switch, I've just gone through the same thing. If you have eletronic ign. ignor this post.

 

[[OBC]Patch]

Re: Engine cuts out above 3200 revs HELP!!!!

Could be misadjusted points too. Start simple. Is this a new dist cap for this year? Mine wouldn't run hard until I got a new one.

 

[wooly]

Re: Engine cuts out above 3200 revs HELP!!!!

Yes it is electronic ignition and the dizzy cap was renewed last year and has had very little use since.
Could it be anything to do with the ingnition amplifier???

 

[Fishaholic247]

Re: Engine cuts out above 3200 revs HELP!!!!

I have a '87 4.3 that kept burning up coils. The shop I had the motor put in at found out from Mercury that the coil wire he replaced on it bought from Mercury didn't support the amount of fire the Thunderbolt ignition was delivering from the coil to the distributor. I'm not sure if it is the same set up you have but check for a carbon trail in the coil wire where it connects to the coil. If the carbon trail is there replace the coil wire with a Accel coil wire and a new Merc. coil and you should be good.

 

[6meter]

Re: Engine cuts out above 3200 revs HELP!!!!

Sounds like its time for number 5 coil. Mine did last the season but failed first thing in the next spring. Make sure you're buying the correct coil for the application. Auto parts stores are usually dumb about looking up boat parts.

 

[Skybreeze]

Re: Engine cuts out above 3200 revs HELP!!!!

I have just posted my findings today (volvo penta 431a surge problems) on what sounds like the same problem I had except mine didn't cut out completely. It just dropped off one cylinder but has the potential to drop all. I thought like you was a fuel problem. At 3000rpm the boat would start surging. Put a timing light on each cylinder one at a time and took it up to the point that it started surging. One cylinder dropped out above 3000rpm. It turned out to be a badly worn rotor. It was fine at idle but when it got up to speed (above 3000) the arc was unable to jump the gap inside the dizy on one of the cylinders so dropped it out. This could be what is happening to you except it could be dropping out more than one causing yours to die all together.

 

[wooly]

Re: Engine cuts out above 3200 revs HELP!!!!

Thanks for the suggestions. I will be giving them a try this weekend and will post hopefully good news on the results next week.
I have also got the ignition resistance wire to try.
Cheers.

 

[John_S]

Re: Engine cuts out above 3200 revs HELP!!!!

Thanks for the suggestions. I will be giving them a try this weekend and will post hopefully good news on the results next week.
I have also got the ignition resistance wire to try.
Cheers.

Your stock ignition should be Thunderbolt 4 which is not points and should not have a resistance wire. What manual are you looking at?

 

[wooly]

Re: Engine cuts out above 3200 revs HELP!!!!

Only have an older manual, runs up to 1990 , my boat is 1991 so I hoped it may be correct. By your comment I assume that you think that there is no resistance wire?
I received the new resistance wire today and I think you are right as it is nothing like the wire I have ohms tested. Trouble is now I am really stuffed on what the problem is, I am going to test the alternator to see what voltage it's pushing out as someone I spoke to today said that the rev counter does not take its power from the coil it's from the alternator, and as the rev counter drops to zero as the engine cuts out maybe this is the cause.
If anyone has any more ideas I would appreciate any input that you could give.

 

[wooly]

Re: Engine cuts out above 3200 revs HELP!!!!

Checked alternator at the weekend and that is OK, the resistance wire was no good as suggested not even relevant to my boat. Trying another new coil going for a Bosch, will have to see if this holds up any better.
Please keep posting your suggestions as need all the help I can get at the moment.

 

[wooly]

Re: Engine cuts out above 3200 revs HELP!!!!

Put a new bosch coil on and tried the boat this weekend, it went great no cutting out at all, maybe the comments of "some boats just eat coils" is right. Anyway I'm going to stick to the bosch coils over genuine merc ones.
Thanks to all of you who posted your comments. Cheers.

 

[sethjon]

Re: Engine cuts out above 3200 revs HELP!!!!

Dumb is an understatement.