5.7L 350 Mercruiser Stalls when warm??

[harveycrew]

O.K. This question is geared to all the mercruiser "experts" but those of you seeking to buy a good used boat may want to check in from time-to-time in case of sale. <br />Now, I have a 1995 Genesis Cuddy Cabin with the 5.7L 350 Mercruiser installed. It has 93.5 hrs. The boat sat up for about two years. When we are cruising around, after awhile, it starts to bog, backfire, and if you try to trim it out I have noticed the guages start to twitch. It has good fuel, fresh oil and no water in the engine. Could it need a set of new wires, plugs and distributor? I read all the related post here and am drawing the conclusion that this may be it. Please advise. I meant to add also that it has the Thunderbolt V ignition. What needs to happen here? Fix or Sale???? Who has the best price for the repair parts for my cost/benefit comparison shopping? Thanks in advance to all viewers.

 

[Trent]

Re: 5.7L 350 Mercruiser Stalls when warm??

Do a compression check. They should be within 15 percent of each other. If thats ok. While running at idle. Check for spark at each sparkplug. When removing the wires one at a time the engine should loose a little RPM.<br /><br />It really sounds to me that you need to pull the carb apart and clean. Backfire/bogging is normally from a dirty carb. You can buy some Berryman's B12 in the pour can at Wal Mart and dump it into the fuel tank. It works really well.

 

[harveycrew]

Re: 5.7L 350 Mercruiser Stalls when warm??

Thanks Trent. What do you suggest first? Should I clean the carb by hand or use the "miracle in the bottle?" How do I perform the compression check? Should this be done by a mech? What do you think about the Mercruiser manual- yeah or neah?

 

[harveycrew]

Re: 5.7L 350 Mercruiser Stalls when warm??

something I failed to mention, the boat runs well until it warms up. Acceleration is good. Response is good. But once it's warm, it sputters, missess and backfires. After a brief cooling off period, it is back in the fight. What gives. I'm going to begin work on the carbs this week.

 

[snapperbait]

Re: 5.7L 350 Mercruiser Stalls when warm??

Here's a good source for Mercruser parts.. <br /><br />www.ebasicpower.com

 

[Trent]

Re: 5.7L 350 Mercruiser Stalls when warm??

The little things we forget to say... Somtimes they make all the difference in the world. Take the flame arrestor off the carb when its doing this. Make sure the choke plate is all the way open. You can adjust the plate by loosening the screws and adjust the plate. <br /><br />Really need to know which carb you have. 1995 had three different carbs.<br /><br />Use the B12, It will clean your fuel system. <br />I preferr the Mercrusier manuals. They cost more, But you get more information. The complete manuals are about 150.00 if you get all of them.

 

[vinney]

Re: 5.7L 350 Mercruiser Stalls when warm??

You need to check the voltage at the coil the purple wire positive side. Next feel the coil and see if it's hot it should be cool. Look to see if it's leaking. It's sounds like it's the coil breaking down. If you had a kv meter you could prove it. Vinney

 

[harveycrew]

Re: 5.7L 350 Mercruiser Stalls when warm??

thankyou all. I will either replace or clean the areas you provided advice about.

 

[Bondo]

Re: 5.7L 350 Mercruiser Stalls when warm??

Sounds like you have several issues going on.... you're due(93.5hrs) for a tune-up, plugs, cap, rotor... Check,+ adjust; timing, compression, plug wire resistance, carb, etc.....<br />i also agree that the bog, backfire sounds to be Fuel related..... Somewhere between the fuel tank,+ the carb.......<br />you also have a problem with an unwanted link between the trim wiring,+ the primary ignition...hence the gauge flutter....<br />as to your fix, or sell........ i see a nice running little boat for a day's work,+ maybe $100. in parts,+ beer.......