Wife trying to help frustrated husband! 305 LX Mercruiser 5.0

lkmhowe807 · Jun 12, 2007

Hi, we have a 1995 Bayliner 2050 Capri LS. The engine is a 305 LX Mercruiser 5.0. Here is our problem:

Our boat will run for about an hour up to 2 hours then it just quits. It will not even try to start and there is no fire. After it cools down, usually the next morning it will fire right up. We took it out last night ran it for about an hour and it quits, so we hooked the trolling motor up to get back to dock, we now take this with us until we can figure out the problem, tired of being towed in! After about an hour of using the trolling motor it fired up. It has never done that before, its always the next morning before it will start.

So here is what my husband has replaced: Coil, power module on distributor and the magnetic pick up in distributor. The temp runs 150-160 according the guage, if it is correct.

If anyone has any suggestions, or has experienced this same problem please help us!

IN DESPERATE NEED OF ADVICE!!!

Don S · Jun 12, 2007

Re: Wife trying to help frustrated husband! 305 LX Mercruiser 5.0

Keep your trolling motor handy, time to go for a ride till it quits.
When it stops and you don't have spark, then the first thing to do is see if you have battery voltage at the + terminal on the coil with the key in the run position. If not, check at the ignition switch for power on the purple wire. If nothing there, you have a bad ignition switch. If you have it at the switch but not at the coil, you probably have a corroded terminal "Somewhere" between the switch and the coil.
If you don't have power at the coil, as a get home, make up a jumper with a clip on each end. Hook it to the + terminal on the battery and to the + terminal on the coil. That will get you home.

Don S · Jun 12, 2007

Re: Wife trying to help frustrated husband! 305 LX Mercruiser 5.0

Guess I better give some options if you have power to the coil.
Then I would guess it could be a connection in the harnesses for the igniton module. Possibly a faulty shift interrupt switch if you have an Alpha drive.
On the shift interrupt switch, just disconnect one of the wires to it and see if spark comes back.
A wiggle test should show any other cable connections for the distributor and modules.

lkmhowe807 · Jun 12, 2007

Re: Wife trying to help frustrated husband! 305 LX Mercruiser 5.0

Don,

Thank you for your fast reply! My husband says that it is a mercrusier drive, not alpha. We are going to go back out tonight and check what you recommended though. So if you can think of anything else we could check let me know!

QC · Jun 12, 2007

Re: Wife trying to help frustrated husband! 305 LX Mercruiser 5.0

Its prolly a Mercruiser Alpha . . .

I don't think there are any Bayliner's Capris with Bravos.

Don S · Jun 12, 2007

Re: Wife trying to help frustrated husband! 305 LX Mercruiser 5.0

My husband says that it is a mercrusier drive, not alpha.

Yea, I know that, an Alpha is a Mercruiser. Mercruiser made a couple of different drives for the 5.0L engine, an Alpha I and a Bravo drive. The Alpha being the most common.

lkmhowe807 · Jun 12, 2007

Re: Wife trying to help frustrated husband! 305 LX Mercruiser 5.0

Don S said:
Guess I better give some options if you have power to the coil.
Then I would guess it could be a connection in the harnesses for the igniton module. Possibly a faulty shift interrupt switch if you have an Alpha drive.
On the shift interrupt switch, just disconnect one of the wires to it and see if spark comes back.
A wiggle test should show any other cable connections for the distributor and modules.

Ok my husband has replaced the ignition module, he called it the power module on the distributor, so I think that option is taken care of.....

freddyray21 · Jun 12, 2007

Re: Wife trying to help frustrated husband! 305 LX Mercruiser 5.0

just a suggestion. Is it a marine coil (epoxy filled) not an auto coil (oil filled) if the coil gets too hot it won't fire.

whywhyzed · Jun 12, 2007

Re: Wife trying to help frustrated husband! 305 LX Mercruiser 5.0

Get a flashlight and look for anything floating around in the gas tank. (I say that as if I believe there is any possible way to see- but look down the filler if you can)

I had a D8K (Cat Dozer) once with a tennis ball in the fuel tank.

The semi fuel-logged ball would find the fuel pickup every so often. Once the engine shut down, about an hour later the ball floated off when the suction from the transfer pump broke.

Drove everyone nuts for a while.

lkmhowe807 said:
Ok my husband has replaced the ignition module, he called it the power module on the distributor, so I think that option is taken care of.....

that doesn't fix a lose wire...

dave4151 · Jun 12, 2007

Re: Wife trying to help frustrated husband! 305 LX Mercruiser 5.0

How about vapor lock? Next time its happens undo the gas cap and see if you hear it sucking in air. Sometimes the vent gets clogged.

Nova II 260 · Jun 12, 2007

Re: Wife trying to help frustrated husband! 305 LX Mercruiser 5.0

I am with freddyray21 ... replace your coil. Had an Lincoln do that to me, took forever to figure it out.

Don S · Jun 12, 2007

Re: Wife trying to help frustrated husband! 305 LX Mercruiser 5.0

Why put a coil in it??? He did that once and it didn't cure the problem.
Before throwing more parts (aka MONEY) at it, why not find out what the problem is, then fix the problem.
Fuel problems can be ruled out for the simple fact that in the original post, she stated there is NO SPARK when it won't start. Last I checked, vapor lock and plugged fuel lines do not stop spark.

mcleaves · Jun 12, 2007

Re: Wife trying to help frustrated husband! 305 LX Mercruiser 5.0

my first thought was a hot coil but Don mentions he replaced it already. how about a condition which might be burning up coils? I have had several engines over the years that behaved like this and they were all overheated coils.

But, if he changed it then it's either not the coil, or something is killing the coil. What would those possibilities be?

But regardless, follow Don's troubleshooting instructions FIRST!!!

M

Maclin · Jun 12, 2007

Re: Wife trying to help frustrated husband! 305 LX Mercruiser 5.0

Do those have any kind of ballast resistor or resistor wire to the coil? If so could it have been bypassed or shorted allowing full 12v to the coil?

Don S · Jun 12, 2007

Re: Wife trying to help frustrated husband! 305 LX Mercruiser 5.0

No ballast resistor, no resistor wire. It's either a Thunderbolt IV or V ignition.

The problem is, we don't even know if there is ANY voltage to the coil when the problem occurs.

DaveM · Jun 13, 2007

Re: Wife trying to help frustrated husband! 305 LX Mercruiser 5.0

This scenario is so very familiar to me, and I know how frustrating it can be. I had 3 different component failures over time that exhibited the same symptom of stalling after running for an hour or more. In my case the problem was:
1. Anti-siphon valive (season one)
2. Fuel pump (season two)
3. Coil (season three)

Each time I was able to solve the problem with help from this board. The key was to describe exactly what happened when it stalled. I can't wait for Don to zero in on the root cause for this one.

QC · Jun 13, 2007

Re: Wife trying to help frustrated husband! 305 LX Mercruiser 5.0

lkmhowe807 said:
It will not even try to start and there is no fire.

Well she really didn't say no spark, but after reading DonS's posts and figuring that with a fuel problem it would at least "try", I guessed this was no spark. I guess it would be nice if we could get a confirmation . . .

lkmhowe807 · Jun 13, 2007

Re: Wife trying to help frustrated husband! 305 LX Mercruiser 5.0

Nova II 260 said:
I am with freddyray21 ... replace your coil. Had an Lincoln do that to me, took forever to figure it out.

Hi, just wanted to let you all know that we have replaced the coil, so that option is taken of!

Thanks

lkmhowe807 · Jun 13, 2007

Re: Wife trying to help frustrated husband! 305 LX Mercruiser 5.0

Hi all,

Just wanted to thank you all for your posts and help! And yes we do plan on trying Dons suggestion, we were going to go last night, but it was looking pretty stormy, maybe we can get out there tonight!

Will post as soon as we know something!

Thanks!

lkmhowe807 · Jun 16, 2007

Re: Wife trying to help frustrated husband! 305 LX Mercruiser 5.0

YEAH YEAH YEAH ! With Dons advice we solved the problem. It is the shift interrupt switch! It fires right up when we pull it off, re-connect and it wont!

So Don our question is, do we need to replace it or can with just leave it disconnected?

What is this switch used for because I am curious.

Thank You, thank you for your help!

Wife trying to help frustrated husband! 305 LX Mercruiser 5.0

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