Engine Stalling

[MI Bearcat]

New to forum and wanted to get some opinions before I possibly spend unnecessary money. 1998 5.7L GS carburated engine. Engine stalls often when in idle (even sometimes up to 1500 rpm). Engine doesn't sputter it just cuts off like someone turned the ignition off. Instantly starts back up without any delay. Had mechanic at marina listen to it back in July although at that time he didn't have any time to work on it. He heard it stall and said it must be the ignition. They sent me an estimate to replace the whole ignition system as parts are supposedly no longer available. Couple thousand total for both engines.

I didn't take the boat back and have them do the work as I had a hard time spending that type of money when the mechanic came to that conclusion after only seeing it stall twice. I tried figuring it out myself by talking with others but never solved it. Normally once I was up and running there was no issues except a couple times it did bog down while on plane for a split second. As the season went on, there were also a couple times were it wouldn't start right back up and just kept cranking.

Boat is in heated storage now and mechanic has time to work on it. I told them about it bogging down and not starting up right away later in the season but they still want to replace the ignition system. I would happily pay them to replace the ignition system if I new that would solve the problem. Anyone have any similar experiences or suggestions? I've always put non-ethanol gas in it, treated it before storage and always indoor heated storage.

 

[Bt Doctur]

a 98 carb`d engine should just have electronic ignition. module in the dist and a ign module mounted someplace else..You have a couple of options before spending a chunk of money. Is it fuel or is it electrical? When it does die and you pump the throttle is there fuel going down the throat ?
Is the coil getting abnormally hot? Is the module mounted in a hot area or is the module getting hot?

 

[Scott Danforth]

start with connections in the harness and the key switch

 

[Bondo]

Ayuh,..... Welcome Aboard,.... I'd find another marina,...

One that understands Diagnosis, rather than throwin' a few thousand dollars of parts at it,...
Hopin' they get it right,....

They'd probably suggest replacin' the whole motor, rather than changin' the spark plugs for a skippin' motor,...

It may well be an ignition issue, but every part of the ignition system can be replaced, without replacin' the entire ignition system,,..

 

[Sunken Ship]

After the guesstimate I would be in the market for another opinion. As Scott stated check connectors on the back of the distributors then all of the engine connectors. Wiggle key switch around while running. Check wires going onto the key switch as well-wiggle gently to see if they are loose.

 

[Dave-R]

Sunken Ship gave you great advice. I have had more than a couple boats that the ignition switch wires have been loose. Boats can take a pounding, and loose connections can cause the intermittent problems you describe. Also I have had problems with the kill switch connections being loose also. I would replace a lot of parts before I gave them 2K. I also have had loose connections on the fuel pumps, they are known to fail. Dave-R

 

[QBhoy]

Start with the simple things for sure. Fuel passage right from tank to carb (few filters and potential pit falls here)
Check all electrical earth connections and signs of corrosion on circuits. Use a multi meter on Ohms setting to check continuity if you need to.
Simple still check the battery. This is the source of countless problems in boats, despite the obvious telling you it isn?t.
Perhaps check auto choke isn?t faulted and smothering the engine.
Good luck.

 

[QBhoy]

Presumably this is when in neutral and not in gear. ?
I?d firstly and simply check;
Battery condition and connections
Alternator connections
Ignition at dash
Run a new main earth wire to known ground
Run an earth wire off ignition to known ground.

See how it goes.

 

[MI Bearcat]

Thanks for the suggestions. I did wiggle many wires and also swapped the ignition switches at the helm. I added electrical grease to main harness and replaced spark plugs. It does only happen when in neutral although not just at idle. Fuel filters looked clean, changed fuel pump and AS valve. Mechanics reasoning was if it was losing fuel, it wouldn't instantly start back up as it would take a few cranks to get fuel again although near the end of the season it did have problems starting back up a few times. I climbed back there and checked voltage at coil and it was not losing voltage when it stalled and the coil didn't seem overly hot.
A few times I started it up and let it run for 10 minutes with no stalling. Turned if off, let sit for 10 minutes, start it back up and it would stall 3 or 4 times in a row after a couple minutes.

I'm not sure which parts of the ignition system are no longer available which was his reasoning for replacing the whole system. I do believe he's a good mechanic in a large marina but he is so swamped with work all summer didn't take time to diagnos which was my reasoning for not letting them proceed. My boat is not at his marina so he couldn't come to my slip. As I mentioned boat is in storage now at his marina so I'm not able to try anything.

 

[MI Bearcat]

One other thing I didn't mention which now I'm thinking could be important, when I had the ignition wires swapped at the helm, the problem engine didn't turn off instantly and dieseled for a couple seconds at the dock. It had never done that before. I took it out to an anchoring spot and it must have done it again as it sucked in water and hyrolocked. Didn't ever diesel again after I changed the wires back. I didn't swap the switches at the helm, I ran the wires in the back to the opposite switch and figure they must have gotten too close when I put the panel back on and and were possibly arching?

 

[Scott Danforth]

I'm not sure which parts of the ignition system are no longer available which was his reasoning for replacing the whole system. I do believe he's a good mechanic in a large marina but he is so swamped with work all summer didn't take time to diagnos which was my reasoning for not letting them proceed. My boat is not at his marina so he couldn't come to my slip. As I mentioned boat is in storage now at his marina so I'm not able to try anything.

anyone who suggest replacing the whole system simply is not doing his/her job of diagnosing the problem

and for the record, you could source new Delco Voyager dizzy's and replace them yourself for 1/10th of what your marina would charge.