Mercruiser 260 died and wouldn't start back up...

[ojotaylor]

I had a post on here about a rebuild, the rebuild is complete and I had the boat out this weekend. A little info on the engine...'96 350 block with '84 components, basically a mercruiser 5.7 with a newer block - the old one cracked. Ran great all day except for dying on me three times. The third time it would not start back up. The first two times it died, it took a while to get it started back up and even had to play with the timing a bit, luckily I brought a friend's timing light with me.

So I get it home today, drain the oil, it was black and smelled like gas. Put new oil in it with a small amount of seafoam, and it started right up. I did notice two small water leaks on the port side of the engine at the rubber couplings on the exhaust lines. I also manually played with the throttle up and down and noticed the throttle adjustment screw was WAY off. I throttled the engine up and came down quickly and it killed the engine. So I adjusted the screw and that's good now.

After all that and letting it get to operating temp (around 150 deg) and letting it run at operating temp for 10 min, I turned it off and drained the oil. It looked like brand new oil coming out and didn't smell of gas at all. So was that screw my problem the whole time? I thought the fuel pump may have been bad but I'm wondering if I flooded the engine trying to start it so much. Any thoughts?

 

[alldodge]

I had a post on here about a rebuild, the rebuild is complete and I had the boat out this weekend. A little info on the engine...'96 350 block with '84 components, basically a mercruiser 5.7 with a newer block - the old one cracked. Ran great all day except for dying on me three times. The third time it would not start back up. The first two times it died, it took a while to get it started back up and even had to play with the timing a bit, luckily I brought a friend's timing light with me.

So I get it home today, drain the oil, it was black and smelled like gas. Put new oil in it with a small amount of seafoam, and it started right up. I did notice two small water leaks on the port side of the engine at the rubber couplings on the exhaust lines. I also manually played with the throttle up and down and noticed the throttle adjustment screw was WAY off. I throttled the engine up and came down quickly and it killed the engine. So I adjusted the screw and that's good now.

After all that and letting it get to operating temp (around 150 deg) and letting it run at operating temp for 10 min, I turned it off and drained the oil. It looked like brand new oil coming out and didn't smell of gas at all. So was that screw my problem the whole time?

Don't see that as what caused the issue

I thought the fuel pump may have been bad but I'm wondering if I flooded the engine trying to start it so much. Any thoughts?

More the likely this is what was happening with the fuel in the oil. Only way to know for sure is to keep an eye on it and check to see if your oil stays clean and at the original level. If gas starts going in, the level will increase

Here is your previous thread
http://forums.iboats.com/forum/engi...es/9989282-engine-swap-mercruiser-to-crusader

 

[ojotaylor]

That's what I was thinking. I didn't know if I needed to start a new thread since it was running and I had it out on the water.

 

[alldodge]

New threads are good so long as it is a new issue and yours appears it is. You just mentioned it and was just posting a link if you had trouble finding it

 

[ojotaylor]

I had the boat out again yesterday and today. I never replaced the fuel pump. After doing a little more research on here, I didn't see any fuel in the yellowish green hose connecting the fuel pump to the carb. I monitored the boat closely yesterday and today and this is what I found...It will start and run perfectly initially. I did probably an 8 mile ride today going between 1/4 throttle and wot at different intervals-no problems at all. Timing is set right, I do have a new tach on the way because mine isn't working at all at the moment. I'm at 8 deg btdc at idle. After my 8 mile trek today, I throttled all the way down in the no wake zone by the dock, the motor dies. Now, I could have kept it running had I throttled back up but I wanted it to die so I could see what was going on. I immediately opened the engine compartment and saw gas coming out of the starboard side of the carb. Its not cracked or anything, I just think I'm in dire need of a rebuild...seems like the floats are sticking and flooding the engine. I had to wait about 5 minutes for it to crank back up and had to throttle it up slightly in neutral for it to start. Once it started back up, I had no problems trolling around the no wake zone or staying at idle. Its a Rochester 4 barrel on a Mercruiser 260. I need to rebuild the carb right?

 

[biggjimm]

Sounds like a carb rebuild is in order. Where exactly on the carb was the fuel coming from?

 

[Scott Danforth]

I had a post on here about a rebuild, the rebuild is complete and I had the boat out this weekend. A little info on the engine...'96 350 block with '84 components, basically a mercruiser 5.7 with a newer block - the old one cracked. Ran great all day except for dying on me three times. The third time it would not start back up. The first two times it died, it took a while to get it started back up and even had to play with the timing a bit, luckily I brought a friend's timing light with me.

So I get it home today, drain the oil, it was black and smelled like gas. Put new oil in it with a small amount of seafoam, and it started right up. I did notice two small water leaks on the port side of the engine at the rubber couplings on the exhaust lines. I also manually played with the throttle up and down and noticed the throttle adjustment screw was WAY off. I throttled the engine up and came down quickly and it killed the engine. So I adjusted the screw and that's good now.

After all that and letting it get to operating temp (around 150 deg) and letting it run at operating temp for 10 min, I turned it off and drained the oil. It looked like brand new oil coming out and didn't smell of gas at all. So was that screw my problem the whole time? I thought the fuel pump may have been bad but I'm wondering if I flooded the engine trying to start it so much. Any thoughts?

did you replace the complete short block, or did you put your old internals into a newer block?

 

[ojotaylor]

BiggJimm, it was from one of the pivot points, there's a lever connected to it...I can take a picture of it a post in a little bit.

Scott, I put my old internals into the newer block, had to use a new crank as well. The engine runs fine other than this fuel dumping problem when I decelerate after long period of high throttle.

 

[biggjimm]

Sounds like it's leaking around the throttle shaft maybe. Those usually suck air in my experience but I suppose if it's running rich & upon a sudden deceleration the lack of vacuum would allow fuel to come out around the shaft but I wouldn't think it would be very much?? Id think youd have more trouble with it idling properly If the shaft seals or bushings were wore out?? I'll let the experts weigh in.

 

[ojotaylor]

I went ahead and ordered the rebuild kit. Should have it Thursday. Hopefully this will do it.

 

[Scott Danforth]

BiggJimm, it was from one of the pivot points, there's a lever connected to it...I can take a picture of it a post in a little bit.

Scott, I put my old internals into the newer block, had to use a new crank as well. The engine runs fine other than this fuel dumping problem when I decelerate after long period of high throttle.

did you mic the bores and pistons? did you use new rings? new bearings?

 

[ojotaylor]

did you mic the bores and pistons? did you use new rings? new bearings?

Scott, the engine is good. I've got good compression across all 8 cylinders, no knocking, oil pressure is good etc, etc, etc. The engine itself is sound. I can see Gas being dumped out of the carburater and collecting on the top of the intake manifold after it dies when i throttle completely down. I could keep it running if I wanted by throttling back up.

 

[NHGuy]

Next time you run the engine shoot some carb clean around that pivot. If the rpms change it will need a bushing.
Would surprise me cause marine carbs don't normally get that problem, It happens more often with cars cause folks are constantly changing throtttle position. Which wears the shaft and opening.
I'd buy a new carb, But if you want to fix it you can mic the shaft and drill the opening enough to wrap a thin piece of nylon or delrin sheet stock (from McMaster Carr).

 

[ojotaylor]

I rebuilt the carb last night. The needle for the float valve was pretty ate up. I'll be putting it back on this evening and putting the boat in the water tomorrow. I'll post results sometime Saturday.

 

[ojotaylor]

It ran great yesterday, so that confirms it was the carbs. Now I've got to adjust throttle and shift cables. Got pulled over by the DNR for going to fast in a no wake zone and I wasn't throttled up at all.

 

[alldodge]

It ran great yesterday, so that confirms it was the carbs. Now I've got to adjust throttle and shift cables. Got pulled over by the DNR for going to fast in a no wake zone and I wasn't throttled up at all.

Some can be a real pistol, might have to start doing the in-out of gear to keep speed down. My brother in law got a ticket for going to fast in a no wake years ago, and he was on an air boat. Tried to go as slow as he could but not slow enough, couldn't get him for wake because there was none