1993 Stingray 609 zpx Mercruiser Backfiring and stalled

[mconner]

1993 Stingray 609 zxp Backfiring and stalled
Hi Just purchased a 1993 Stingray that had been sitting for 2 years. So I bought a new battery, drained the gas and took it to a local marine mechanic.

The motor is a Mercruiser 4.3 Liter LX alpha One with under 100 hours. Owner said it was new when he got the boat just over 2 years ago.

The mechanic did the following:


Compression test - passed
Replaced spark plugs
"Made needed adjustment to make motor run" - this is in his invoice
Replaced seal and rams on lower unit
Replaced alternator

So yesterday I took it to the dock, ran it in the water for 20 minutes then went for a ride. After about 45 minutes of pudding around a no wake zone I opened it up in open water. The engine started backfiring when I reached around 3k RPMs. I would slow it down and it would stop.

Then, i putted around a bit more and the engine stopped and we were stuck. Got towed back and put the boat away.

Any thoughts on how I can troubleshoot and fix this myself? I just dumped 1k bucks for what he did and it still doesn't run right.

Thanks in advance!

 

[bspeth]

Re: 1993 Stingray 609 zpx Mercruiser Backfiring and stalled

Ask him if he checked the timing,and then check the timing and make sure it is advancing to verify that.

 

[Bondo]

Re: 1993 Stingray 609 zpx Mercruiser Backfiring and stalled

1993 Stingray 609 zxp Backfiring and stalled
Hi Just purchased a 1993 Stingray that had been sitting for 2 years. So I bought a new battery, drained the gas and took it to a local marine mechanic.

The motor is a Mercruiser 4.3 Liter LX alpha One with under 100 hours. Owner said it was new when he got the boat just over 2 years ago.

The mechanic did the following:


Compression test - passed
Replaced spark plugs
"Made needed adjustment to make motor run" - this is in his invoice
Replaced seal and rams on lower unit
Replaced alternator

So yesterday I took it to the dock, ran it in the water for 20 minutes then went for a ride. After about 45 minutes of pudding around a no wake zone I opened it up in open water. The engine started backfiring when I reached around 3k RPMs. I would slow it down and it would stop.

Then, i putted around a bit more and the engine stopped and we were stuck. Got towed back and put the boat away.

Any thoughts on how I can troubleshoot and fix this myself? I just dumped 1k bucks for what he did and it still doesn't run right.

Thanks in advance!

Ayuh,.... Welcome Aboard,..... Sounds like crud in the fuel,....

pull the filter, 'n inspect it's contents,....

 

[mconner]

Re: 1993 Stingray 609 zpx Mercruiser Backfiring and stalled

Mechanic just called and told me he sees no water in the seperator and thinks it might be in the lifters? Said $1500 to do this.

Said he didn't check the timing because it is controlled by the computer.

Ugh.

Thoughts?

 

[Bondo]

Re: 1993 Stingray 609 zpx Mercruiser Backfiring and stalled

Mechanic just called and told me he sees no water in the seperator and thinks it might be in the lifters? Said $1500 to do this.

Said he didn't check the timing because it is controlled by the computer.

Ugh.

Thoughts?

Ayuh,.... Find a Different Mechanic,....

A quick diagnostic tune up, woulda told him Where to look, insteada just Guessin',....

 

[wrench 3]

Re: 1993 Stingray 609 zpx Mercruiser Backfiring and stalled

I'm with Bondo on the mechanic, and that fuel is most likely your problem. Remove the flame arrester and open the choke, look down the carburator throat and have someone pump the throttle. If the fuel beads up and doesn't run off as a sheet, it's water and not gas. If nothing comes out then you need to find out why it's not getting to the carb. Also make sure that you have a good spark to the plugs.

 

[harleyman1975]

Re: 1993 Stingray 609 zpx Mercruiser Backfiring and stalled

I am thinking carb problem (i.e. plugged high speed jets or low float level or weak fuel pump) and am questioning the scruples of your mechanic.

 

[dingdongs]

Re: 1993 Stingray 609 zpx Mercruiser Backfiring and stalled

a new fuel filter required as it does not sound as if this has been changed and remove carb and clean bowl thoroughly,You can purchase a carb rebuild set as this sounds like the cause when load is required the fueling is letting you down,if you can view the leads in complete darkness you may see arching and it may be worth getting another set especially if they are of the original year of boat manufacture.An impellor should be high on your list of things to do and all these can be replaced fairly simply if you have diy skills.

 

[mconner]

Re: 1993 Stingray 609 zpx Mercruiser Backfiring and stalled

Pulled the plugs and water came out. Flushed it and put transmission fluid in carb and cranked it so it would lube everything while I figure out why water is in block. Any thoughts?

 

[Bondo]

Re: 1993 Stingray 609 zpx Mercruiser Backfiring and stalled

Pulled the plugs and water came out. Flushed it and put transmission fluid in carb and cranked it so it would lube everything while I figure out why water is in block. Any thoughts?

Ayuh,.... Has this motor got the 1 piece, bat-wing exhaust manifolds,..??

If so, Trash 'em, 'n find a conversion kit to the center-riser style,....

 

[mconner]

Re: 1993 Stingray 609 zpx Mercruiser Backfiring and stalled

It does. So you don't think the block is cracked?

 

[mconner]

Re: 1993 Stingray 609 zpx Mercruiser Backfiring and stalled

Also can you be more specific? Someone told me I might be screwed and need a new engine....

 

[Bondo]

Re: 1993 Stingray 609 zpx Mercruiser Backfiring and stalled

It does. So you don't think the block is cracked?

Ayuh,... We gotta start Somewhere,.....

Did ya have water in the oil when ya ran it,..??

Cracked blocks, rarely put water into the cylinders,... cracked heads, Maybe....

Those manifolds have a reputation,... they're Junk,....
Core shiftin' durin' castin' process, ruined the design,...

How many holes blew Water,..?? All 6,..??
Both sides,..??

Where are you,..?? does it get cold there,..??

 

[mconner]

Re: 1993 Stingray 609 zpx Mercruiser Backfiring and stalled

All 6 had water come out. No water in oil. In south Florida.

 

[wrench 3]

Re: 1993 Stingray 609 zpx Mercruiser Backfiring and stalled

All 6 had water come out. No water in oil. In south Florida.

It's almost impossible to get water into all six cylinders from a mechanical failure. All six cylinders with cracks or blown head gaskets is very very unlikely. To get water in from the exhaust manifolds, the engine has to be stopped and all of the exhaust valves are never open at the same time. The intake manifold is split into two halves. Each half feeds one cylinder on one side and two on the other. The only place they join up is directly under the carburator, and the amount of water left in the top of the engine when it's shut off is insufficient to fill one half of the manifold and run over into the other.
It just doesn't make sense. I'd get the engine running if possible and then recheck for water.