1994 4.3LX Mercruiser random stalling in heavy wake??

[mxracer342]

Ok I'm a fairly new boat owner and I'm having a intermittent issue that's got me stumped. I've bought a 1994 Bryant 180 with a 4.3 mercruiser. The boat stays and runs fine. The problem is in heavy waves at just about any speed when it's bouncing boat and down will occasionally cut out like it's not getting fuel. Twice it's done so bad that the engine completely died. The first time it fired right back up the second time it would start die so after the 4th time that happened i let sit a minute then fired up. I was thinking carb issues but ice read several posts that say something about oil pressure sensor causing it. My question would be if it is oil pressure sensor would it not just go bad or could it cause an intermittent problem like this and if not could anyone on here me ideas what to check.I talked to my mechanic but can't afford pay him hundreds dollars to find a problem i possibly could fix myself. Any advise would be greatly appreciated!

 

[sr54x4]

i would check your ground wires and other wiring connections.

 

[alldodge]

Ok I'm a fairly new boat owner and I'm having a intermittent issue that's got me stumped. I've bought a 1994 Bryant 180 with a 4.3 mercruiser. The boat stays and runs fine. The problem is in heavy waves at just about any speed when it's bouncing boat and down will occasionally cut out like it's not getting fuel. Twice it's done so bad that the engine completely died. The first time it fired right back up the second time it would start die so after the 4th time that happened i let sit a minute then fired up. I was thinking carb issues but ice read several posts that say something about oil pressure sensor causing it. My question would be if it is oil pressure sensor would it not just go bad or could it cause an intermittent problem like this and if not could anyone on here me ideas what to check.I talked to my mechanic but can't afford pay him hundreds dollars to find a problem i possibly could fix myself. Any advise would be greatly appreciated!

You mention in heavy wake, but how heavy and does it take quite a bit of bouncing before it dies, or is it a short time if the wake is bad enough?

Stated it would die occasionally and then it would completely die. The thing I'm thinking is if it takes long enough maybe the float in the carb is starting to flood the engine with fuel. If this is the case you should see a very wet carb if the flame arrestor is removed.

I don't see the oil pressure as being an issue, because if it was there should be an alarm horn going off as well.

Where are you boating?

 

[mxracer342]

You mention in heavy wake, but how heavy and does it take quite a bit of bouncing before it dies, or is it a short time if the wake is bad enough? Stated it would die occasionally and then it would completely die. The thing I'm thinking is if it takes long enough maybe the float in the carb is starting to flood the engine with fuel. If this is the case you should see a very wet carb if the flame arrestor is removed. I don't see the oil pressure as being an issue, because if it was there should be an alarm horn going off as well. Where are you boating?

I'm boating at my local lake. The two times it died were both at wot and I was bounced around pretty good. It don't take a lot of time to happen. After idling out of no wake zone on Sunday I took off within thirty seconds I hit some waves from another boat and it did it.not completely dying just like I ran out of fuel for a brief moment. Most the time it don't completely die it's just like I'm starved for fuel a moment. I've taken the spark arrestor off the other day and did notice it looked wet.

 

[midcarolina]

I think AD is asking does the stall happen immediatley upon hitting wake? or does it seem to take 30 or so seconds after crossing wake?

I'm thinking it is a bad electrical connection and the bouncing is jiggling the bad connection.

 

[matth121]

my friends 4.3 has a spotty connection to the fuel pump- seems to work fine but if i move the wires left or right from where they hang- the pump will die until i let them go. only reason i noticed this though was that the oil pressure switch had been bypassed so that as soon as you turn the key on, the fuel pump starts. while trying to figure out why it was even on, i noticed the wires. might check the plug on the fuel pump. i could see hard bouncing being enough to shake that wire a bit.

 

[Volphin]

Check your battery connections and make sure they are clean and tight. Then move on to the grounds on the block. You can tell if it is ignition related by hooking a timing light to a plug wire while a buddy drives the boat. When the engine starts acting up, observe the pulses. (Lower rpm would be best for this test). Was there a delay? Then go to the coil and check the connections and the standard coil tests.

 

[BIGALF1]

My 5.7 efi had the same problem and I found that the fuelscreen in the fuelpick up tube in the tank would get clogged when I had a 1/2 tank of gas or less and the slushing in the wake would stir up the junk on the bottom of the tank and stick on the screen. Check the easy stuff first.

 

[mxracer342]

Mine has happened worth a full tank of fuel so I don't believe it's trash in the tank. The stalling happens immediately when hitting the heavy wake. There is no delay. Where is the fuel pump located? Where can I find a diagram to where all the ground wires are so I can could be checking those as well?

 

[MikDee]

I think AD is asking does the stall happen immediatley upon hitting wake? or does it seem to take 30 or so seconds after crossing wake?

I'm thinking it is a bad electrical connection and the bouncing is jiggling the bad connection.

I agree with midcarolina here, check all your wiring closely.

 

[mxracer342]

Thanks for all the help. I like to fix things myself when I can. I'll take it to my mechanic when I know it's over my head but I don't want to pay 75 dollars Ann hour for him to check connections and simple stuff I can do.

 

[Bowboss]

I've had somewhat of a similar issue with my 1997 reinell 184 4.3 volvo penta GL (almost the same exact engine as a 4.3 merc both supplied by GM). The engine would run fine for the first few 10-20 minutes then would randomly cut it's self off like someone turned the key off. Just a clean cutoff. after rebuilding the carbs I did more research and found a highly potential suspect that was very difficult for me to pinpoint after navigating at least over 20 forum posts from different sites.

The perpetrator? The ignition control module found inside the distributor. I ran it to orieleys and they tested it on a special machine. Failed mostly all of the tests. Turns out it was faulty.

I cannot tell you how many times i've read responses from other posters assuming that it's all because of vapour lock or a clogged fuel filter or a clogged gas tank vent. Turns out the issue was all electronic.

 

[mxracer342]

I've had somewhat of a similar issue with my 1997 reinell 184 4.3 volvo penta GL (almost the same exact engine as a 4.3 merc both supplied by GM). The engine would run fine for the first few 10-20 minutes then would randomly cut it's self off like someone turned the key off. Just a clean cutoff. after rebuilding the carbs I did more research and found a highly potential suspect that was very difficult for me to pinpoint after navigating at least over 20 forum posts from different sites. The perpetrator? The ignition control module found inside the distributor. I ran it to orieleys and they tested it on a special machine. Failed mostly all of the tests. Turns out it was faulty. I cannot tell you how many times i've read responses from other posters assuming that it's all because of vapour lock or a clogged fuel filter or a clogged gas tank vent. Turns out the issue was all electronic.

Ya I hear ya. I thought it was fuel related but I'm leaning more toward a lose wire somewhere or something like what your problem was. Where exactly is the ignition control module? Do you know where the other ground wires are I should check?

 

[Bowboss]

Ya I hear ya. I thought it was fuel related but I'm leaning more toward a lose wire somewhere or something like what your problem was. Where exactly is the ignition control module? Do you know where the other ground wires are I should check?

The ignition control module is located inside the distributor. It is the black plastic item in this pic that has the wires connected to it below the distributor rotor. It's pretty easy to yank and get tested at any autozone or any o'reilly's. I hope this helps.

 

[mxracer342]

The ignition control module is located inside the distributor. It is the black plastic item in this pic that has the wires connected to it below the distributor rotor. It's pretty easy to yank and get tested at any autozone or any o'reilly's. I hope this helps.

Thank you that's super helpful info there. Now to find time to troubleshoot it.

 

[Bowboss]

Thank you that's super helpful info there. Now to find time to troubleshoot it.

Looks like after i changed my ICM. The new one went bad right after i took the boat out on the water today. I ended up getting towed which really pissed me off. Looks like the bastard is getting shorted somewhere. Gotta find out where by tommorow. I'll give you guys an update to this frustrating freak show of a problem. bread crumb trails....

 

[Bowboss]

So i changed the ignition coil and tested it in various rpms for a few minutes afterwords. Looks like the engine isn't shutting off at all from the 15 minute test i conducted. Tomorrow i am taking my boat out tomorrow and see if it does this nonsense after 30 or so minutes.I even went as far as to run a multimeter and get a voltage reading on the 12v feed that goes from the coil to the module and it read 14.5 volts when at idle and when reving to 3k rpm. So i know from that time i tested it that it wasn't a bad voltage regulator. Tomorrow will tell if the coil was really bad or not but my theory is that the ignition coil i replaced would tend to short when the whole engine would warm up due to expansion on the magnets causing an overfeed of voltage to the module. If that isn't the case then there must either be a bad spark plug wire somewhere or voltage backfeeding elsewhere. if it doesn't run well tomorrow and start up with the random cutoff issue. I'm taking the damn thing to a certified mechanic to pinpoint the problem and i will definitely post to everyone what the cause was.

 

[Bowboss]

Update! Afte replacing the ignition coil and taking it out for quite a spin today on the delta river. No random cutoffs appear anymore. It looks like i've fully solved the problem. A defective ignition coil that shorts it's self.

 

[mxracer342]

Looks like after i changed my ICM. The new one went bad right after i took the boat out on the water today. I ended up getting towed which really pissed me off. Looks like the bastard is getting shorted somewhere. Gotta find out where by tommorow. I'll give you guys an update to this frustrating freak show of a problem. bread crumb trails....

Man that sucks. I've checked a few wires and my battery ground but haven't found anything loose yet. Ice ran two bottles of sea foam thru my boat the past two weekends and this past weekend the lake was crowded and really rough and the boat didn't stall any. Before this weekend it had done it at least one time every time I took it out the past month so note I'm even more stumped!

 

[Bowboss]

Man that sucks. I've checked a few wires and my battery ground but haven't found anything loose yet. Ice ran two bottles of sea foam thru my boat the past two weekends and this past weekend the lake was crowded and really rough and the boat didn't stall any. Before this weekend it had done it at least one time every time I took it out the past month so note I'm even more stumped!

I found the solution on my boat. The ignition coil was the imposter. It kept shorting and overloading the ICM when the coil warmed up.

Must of been the coils expanding and touching each other due to faulty insulation in the Factory coil. After changing it on the boat never died on me since i took it out this sunday and i punched it pretty hard on plane too for way more than 30 minutes at high rpm. Go down to your local oreily/kragen and grab an ignition coil from them with a lifetime warranty included. Just tell them to match it up with a S10 chevy blazer 4.3 (same exact engine that is in your boat and make sure it's a borg warner coil which is the same exact coil as napas echelin). That should give you your fix. If not then another imposter would be a faulty circuit breaker acting like an inductor (talked to a guy with a mercruiser same exact engine). But for your case. I'd say it's just a bad coil (i'm never buying factory GM parts ever again)

For me it was definitely a bad ignition coil backfeeding into the ICM ultimately frying it.

Oh and lastly if you are mounting a new ICM. Make sure you put lots of thermal paste on it (not dielectric grease) The thermal paste will give the module far better heat transfer and ultimately keep it a bit cooler when operating.