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WakeWorld Discussion Board » >> Boats, Accessories & Tow Vehicles Archive » Archive through March 18, 2009 » Help! 5.7l Mercruiser Sputters than looses power « Previous Next »
By Matt (loudsubz) on Saturday, June 28, 2008 - 4:07 pm:    Edit Post Delete Post
I have been running my boat since the middle of may with no issues. Fast forward today, I was towing my brother on the wakeboard, and about half way through the set (10 minutes into it) the motor started to sputter and come in and out of power. I pulled the throttle back to neutral and the RPM's were really low and the engine sounded like it was going to die out, and a few seconds later it just died.

It woulnd't start up right away after, but if I gave it 5 min it started back up again and I could drive for about 30 seconds and it would die again.

Does it sound fuel related or electrical?

I also noticed my fuel and volt gauge went to 0 when all of this was happening and stayed there for about 10 seconds. I have been having an on/off issue with those gauges since the start where they go in and out at random, but I have been unable to diagnose the issue.

By Luciano Grimblat (luchog) on Saturday, June 28, 2008 - 6:56 pm:    Edit Post Delete Post
I guess it would help to know what engine model do you have and if it's fuel injected or Carbureted.
By Matt (loudsubz) on Saturday, June 28, 2008 - 7:16 pm:    Edit Post Delete Post
Its a 1995 Mercruiser 5.7L Carbed.
By Sparky Jay (wake_upppp) on Saturday, June 28, 2008 - 7:46 pm:    Edit Post Delete Post
I'm leaning more towards fuel, but it could be ignition as well with the few symptoms you described. Could be as simple as a plugged fuel filter.
By Chad Davis (garman) on Saturday, June 28, 2008 - 8:27 pm:    Edit Post Delete Post
It sounds like a fuel issue, but since the guages went out at the same time, I'd definitely not rule out electrical problem. I once had corrosion on the main circuit breaker on top engine (5.7l also) that gave me intermittent issues. Had to replace it.. It's the one that looks like a red button... 50amp if I remember correctly. Also had the coil give me problems (Look for oil leaking out of the coil). Other than that, I'd check/wiggle all the wiring connections that you can find. You never know... it may be as simple as that.
By Matt (loudsubz) on Sunday, June 29, 2008 - 7:47 am:    Edit Post Delete Post
Chad, how can you check the main circuit break for issues?
By nacho (denverd1) on Sunday, June 29, 2008 - 9:43 am:    Edit Post Delete Post
I'd start with the fuel filter, like sparky suggested. When was current fuel filter put it? I'd put my $$ on the fuel filter.

Gauges sound like a different issue. typically a loose ground behind the dash when several work intermittently or go out at the same time.

Circuit breaker may have corrosion/rust. You could pull the wires and wire brush them off, and reinstall.

If you have a water separator on your fuel line, i'd check that as well.

By Matt (loudsubz) on Sunday, June 29, 2008 - 9:50 am:    Edit Post Delete Post

I just change the fuel/water seperator but can't find the fuel filter. I followed the lines from the fuel pump into the carb but its all through a hard line. Could the filter be in the carb?

By George Aslinger (mobv) on Sunday, June 29, 2008 - 10:07 am:    Edit Post Delete Post
Some carbs have a small screen or filter in the inlet fitting. Many older boats have only the fuel/water seperator. Most newer boats have an inline filter between the tank and fuel pump.
By Matt (loudsubz) on Sunday, June 29, 2008 - 11:01 am:    Edit Post Delete Post
I took the fuel inlet lines off of the carb and looked in, and didn't see any normal size fuel filters, all I saw was a small screen in the vertical position that was about a 1/4 of the size of the entire opening. I assume that is the only filter in there?
By nacho (denverd1) on Sunday, June 29, 2008 - 11:25 am:    Edit Post Delete Post
it's before the pump. follow the line back toward the tank. sometimes on the port stringer area.
By dave clarke (dclarke) on Sunday, June 29, 2008 - 12:19 pm:    Edit Post Delete Post
By trey mclendon (tdiggity) on Sunday, June 29, 2008 - 3:07 pm:    Edit Post Delete Post
could be the accelerator pump on your carb, if you throttle it and it falls on its face or is hard starting i wouldnt rule out needing the carb rebuilt, or having bad gas
By Matt (loudsubz) on Sunday, June 29, 2008 - 3:21 pm:    Edit Post Delete Post
I looked all over today and no inline fuel filter anywhere, from the tank to the fuel/water seperator. Im guessing there isn't one on mine.
By TeamNeptunes (chas) on Sunday, June 29, 2008 - 5:35 pm:    Edit Post Delete Post
Take a look at your cap and rotor also.
By Matt (loudsubz) on Sunday, June 29, 2008 - 6:32 pm:    Edit Post Delete Post
did the cap and rotor last week, as well as new plugs and new wires.

Just replaced the coil today and it seems to start up better which is a good sign, but will have to test it more to make sure it doesn't die anymore.


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