Hard/no start 5.0L efi

[derekf]

So yesterday I started towing a sundeck that was having a hard time starting. It would turnover and idle for 5 seconds and then die. After 5 mins of towing him, he signaled me that he got it started. I follow him back to the marina to make sure that everythings ok and then head back on the lake.

Now for my trouble...... I beach nose in/up at a island and hang out for a half hour. Get ready to leave when the weather picks up and have the same problem, It has plenty of juice to start and will run for a few seconds, but then would die. I was trying to rev it up right when I got it started, but it wouldn't stay running. I ended up getting it started about 5 mins later.

Any ideas as too possible causes? I just found it strange that I saw it happened to 2 boats in 1 hour.....

 

[Presentation]

Take your drive out of gear via the button at the throttle at the helm. Manually control the throttle. Give it some gas (push throttle forward) then try to start it. If you can get it to start via manually controlling your throttle the most likely issue is a bad IAC idler air control value.

This is a easy do it yourself $100 repair.

Get a new IAC, gasket and muffler filter.

Use this mercury site to get your correct parts. Use the serial number from your engine to get the correct parts.

http://www.mercurypartsexpress.com/us/

 

[SeaRide]

Derek,

The temps on Lake Murray were in the upper 90s yesterday. The lake water was nearly as warm. I suspect the temps on Wylie were similar. I experienced a similar issue (vapor lock) with my 5.7 EFI years ago under similar temps after quicker than normal shut down. Now, I simply idle a bit more around 800-1000 rpm and leave the blower on for a bit longer after shut down. I haven't had an issue since.

 

[derekf]

Derek,

The temps on Lake Murray were in the upper 90s yesterday. The lake water was nearly as warm. I suspect the temps on Wylie were similar. I experienced a similar issue (vapor lock) with my 5.7 EFI years ago under similar temps after quicker than normal shut down. Now, I simply idle a bit more around 800-1000 rpm and leave the blower on for a bit longer after shut down. I haven't had an issue since.

It was a much quicker than normal shutdown, as this was my first attempt to beach on an island and I didn't want to let it run in shallow sandy water.

If its the IAC, will this happen everytime I start up...? How can I confirm if its the IAC thats bad?

Thanks for the input!

 

[derekf]

searide where was your signature picture taken?

 

[Presentation]

....How can I confirm if its the IAC thats bad?....

Take your drive out of gear via the button at the throttle at the helm. Manually control the throttle. Give it some gas (push throttle forward) then try to start it. If you can get it to start via manually controlling your throttle the most likely issue is a bad IAC idler air control value.

 

[derekf]

Take your drive out of gear via the button at the throttle at the helm. Manually control the throttle. Give it some gas (push throttle forward) then try to start it. If you can get it to start via manually controlling your throttle the most likely issue is a bad IAC idler air control value.

Sorry to make you repeat yourself.

I just got back from the marina and Searay service said it was vapor lock. Atleast thats a cheap fix without any lasting damage.:smt038

 

[SeaRide]

Derek,

I had what you could call a partial failure once when the boat was under warranty. When cold, the engine would start and then die immediately first turn of the key. The second time around it started immediately and continued to run. The problem did not occur when warm. My dealer hooked up his scan tool, but found no codes. He replaced the IAC anyway - problem solved. A co-worker of mine has a 290 DA w/twin 5.0 EFIs. His symptoms were more obvious as he had to advance the throttle to start the engine. When he returned to idle, the engine would die. Replacing the IAC solved this problem. LWM could certainly give you an opinion or hook up their scan tool for you and see if any faults come up. Years ago, LWM and SR of Cola., experienced lots of problems as you described during one the first really hot days of summer - fall/winter fuel blends could have been a partial issue. In fact the individual with the 290 DA had boost pumps installed to resolve his vapor lock issues. Personally, I would continue to run the boat and idle a bit with the blower on and after before I spent $$$ trying to diagnose the problem.

By the way, the my sig. pic. was taken two years ago during a vacation to the FL panhandle, just south of the Destin Hwy. 98 bridge - definitely not Lake Murray.

 

[SeaRide]

Guess I need to type a little quicker - glad to see your problem appears to be resolved.

 

[derekf]

By the way, the my sig. pic. was taken two years ago during a vacation to the FL panhandle, just south of the Destin Hwy. 98 bridge - definitely not Lake Murray.

I figured, I need to borrow someones trailer and take a road trip! That looks great:thumbsup:

 

[SeaRide]

Go get a trailer! The waters of Destin and the PCB area are absolutely gorgeous. I hope they stay that way. Adults and kids are assured to have a great time.