Mercruiser 5.7 won't start

[imported_LakeLover]

Labor Day weekend I took my Larson 240 out for a day on the lake. I had to use a battery booster to start it, but it fired up fine and ran well to our destination. PArked for a few hours until time to go and it started fine without the booster. Stopped after 20 minutes to pick up some passengers, shut the engine down and it would not start again. It cranked fine, but would never start. Tried for 10 minutes, both with throttle pumped and with throttle at idle position in case I had flooded it. Ended up reattaching the booster cause all the attempts at starting had run the battery down, but still no luck. Ended up getting towed. Tried to start again several times while being towed but no luck at all. Did not even sound like it wanted to start but cranked just fine. Any ideas as to what might be going on?

 

[calwldlif]

Re: Mercruiser 5.7 won't start

No/too much fuel. (did ya sniff?)
Spark/ no spark (did ya check?)
After its home and cool does it start?

 

[flashback]

Re: Mercruiser 5.7 won't start

LL, tune it up and then let's see what happens I had a fresh engine that acted like that for 5 or 10 hrs. but ran good from then on.... guess it was just built a little tight. but after that it has been running well...Ya need to check it out...do some tests and get back with us.....d

 

[imported_LakeLover]

Re: Mercruiser 5.7 won't start

Thanks guys. I will check to see if there is fuel getting to the carb. I could smell fuel when trying to start, which is why I let it sit in case I had flooded it. It was tuned up in March and has not run more than 15 hrs since then, but if it won't start this weekend I will have to take it in. I was unable to start it cold cause the battery had run down by the time we got towed back to our dock.

 

[imported_LakeLover]

Re: Mercruiser 5.7 won't start

Went out to the lake this weekend and the engine started at first crank!!! Ran well so I stopped it for a while and it started again no problems. Could this have been a vapor lock in the fuel lines? Cost me a stiff $230.00 to get it towed so if there is any way to fix this myself should it occur again, I would appreciate hearing about it.

 

[Bondo]

Re: Mercruiser 5.7 won't start

If you Don't do any Diagnosis WHEN it Won't Start,.......

There's No Way to know What wasn't Happening.............

It takes,........ Fuel,.. Fire,..+ Compression,... At the Right Time to make a motor Run..............

Without a Diagnosis,........
Who Knows Which 1 was Missing...........

Btw,...... Vapor Lock is a Rare occurrence,......
Often Blamed when Not the Problem........

 

[searay3]

Re: Mercruiser 5.7 won't start

Next time you think it's flooded, hold the throttle wide open (not idle) and crank till it fires. The idea is to get max air flow to try and clear out the cylinders without adding more fuel. Just be sure and be ready to pull back on the throttle once it fires......

 

[tystick]

Re: Mercruiser 5.7 won't start

No/too much fuel. (did ya sniff?)
Spark/ no spark (did ya check?)
After its home and cool does it start?

i have to say i got a chuckle out of that one

 

[tunahuntr1]

Re: Mercruiser 5.7 won't start

Hi Lake, Just a word and a question,I had a similar problem awhile back.I have a new 5.7 with a thunderbolt ignition,it ran great and all of a sudden it died.Could not start it again so I fired up the kicker and got it home where it promptly started right up like nothing happened.
Well to make a long story short,again I went out to sea and it ran well for a couple of hours and it died again.I knew I was getting fuel so I checked for spark and found none. I did a wiggle test on all of my connections at the distributor and woe and behold I found a corroded pin at the distibutor .It promptly started up at sea and I made the repair when I got home after fishing.Check your electrical system for corrosion,it will give you intermittent problems like that. Let us know how you made out.8)

 

[pete963]

Re: Mercruiser 5.7 won't start

Its a possiblity that your fuel pump may be starting to go .if you didnt pump it thats another thing i would look at besides your electrical system but you need to start at the basic you know you had fuel so if it happens again start there and work from it