4.3L MPI MerCruiser doesn't start when it's hot.

[loav8r]

Hello guys. I've read a similar thread to the problem that I'm having, however, the other thread referred to a carb. engine. My problem is that I have a 4.3L MPI on a 2005 Sea Ray 2000 Sundeck and when the engine has been running over an hour (not running hot, she's running at 156 F) and then shut-off, it doesn't want to start again. It tries to start but sputters, pops (backfire) and idols real rough at an extremely low RPM before eventually dying. I try to restart while adjusting the throttle to help manually control the fuel but that doesn't help. After a few tries and then a cool-off period, it will run again without any problems.
I've ran of couple of experiments: (1) I've left the engine cover open while eating lunch at the marina (believing that cooling it off will help with the restart) - negative results; (2) I thought maybe E10 fuel was the culprit and ran only on non-ethanol fuel - negative results.
I work in Africa for 6 weeks at a time and quite often I put the boat in the water just after returning home (she doesn't run at all when I'm gone). I turn the key and she starts right up within a second, never a problem, but if I run her for an hour and shut-down...we have problems.

Ok, any suggestions would be great.

 

[Bondo]

Re: 4.3L MPI MerCruiser doesn't start when it's hot.

Ayuh,.... I'd start with changin' the fuel filter, 'n inspectin' the contents of the old 1...

Much more than that, ya need a 'puter to look for codes...

 

[loav8r]

Re: 4.3L MPI MerCruiser doesn't start when it's hot.

I'm not too sure about the filter, we had it checked before and it was good. There seems to be an awful lot of talk regarding this issue on the Net; there's even a YouTube video of a boat with the same problem. However, you're right regarding the computer. I was talking to the mech. today regarding my car and we got on the topic of the boat. He suggested bringing it in to put it on the computer but I'd like to help him with information from some of you guys who've had this problem before. I'm suspecting a need for an electrical "boost" pump in the fuel system to give positive pressure but that's just me.

 

[Don S]

Re: 4.3L MPI MerCruiser doesn't start when it's hot.

Sounds like vapor lock. Is it very hot in your engine compartment? Many of the new boats are so well insulated for sound that it keeps all the heat in the engine compartent when the engine is shut off. If there is a lot of sun on it it makes it worse. If boating in very warm water it makes it worse.

For a test, take it on a good run like you normally do, only when you shut it off open the engine hatch so it can cool off and see what happens. Then you will have some idea which direction to go. Work on the engine, or vent the engine compartment.

View attachment 99-7.pdf

 

[loav8r]

Re: 4.3L MPI MerCruiser doesn't start when it's hot.

Hey Don, thanks, but I've already try opening up the hatch and letting it cool (for over an hour during lunch at the marina) and that doesn't help at all. The water temp is typically around the mid to high 80s, coupled with the OAT of 90+, that can't be good either. However, the last time this happened was in March when the temps were lower. Other than moving to the Arctic, I've got to find a solution.

 

[Don S]

Re: 4.3L MPI MerCruiser doesn't start when it's hot.

Sounds like you need to do some fuel pressure tests when it doesn't start. Have you checked spark from the coil when It won't start? Is it bright blue and snap across a 1/2" gap easily?

 

[David Fortunat]

Re: 4.3L MPI MerCruiser doesn't start when it's hot.

Sounds like you need to do some fuel pressure tests when it doesn't start. Have you checked spark from the coil when It won't start? Is it bright blue and snap across a 1/2" gap easily?

Where is the continuing of this thread

 

[ouachitaman]

OEM Mercury MerCruiser Quicksilver V6 V8 Check Valve Assembly Kit 21-862271A1

MerCruiser Exhaust Manifolds, Engine Parts, Outdrives and Outdrive Parts, Watersports and more!

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This will fix your problem

 

[Martyfa]

Hello guys. I've read a similar thread to the problem that I'm having, however, the other thread referred to a carb. engine. My problem is that I have a 4.3L MPI on a 2005 Sea Ray 2000 Sundeck and when the engine has been running over an hour (not running hot, she's running at 156 F) and then shut-off, it doesn't want to start again. It tries to start but sputters, pops (backfire) and idols real rough at an extremely low RPM before eventually dying. I try to restart while adjusting the throttle to help manually control the fuel but that doesn't help. After a few tries and then a cool-off period, it will run again without any problems.
I've ran of couple of experiments: (1) I've left the engine cover open while eating lunch at the marina (believing that cooling it off will help with the restart) - negative results; (2) I thought maybe E10 fuel was the culprit and ran only on non-ethanol fuel - negative results.
I work in Africa for 6 weeks at a time and quite often I put the boat in the water just after returning home (she doesn't run at all when I'm gone). I turn the key and she starts right up within a second, never a problem, but if I run her for an hour and shut-down...we have problems.

Ok, any suggestions would be great.

Loav8r are you still around. Realize this thread is pretty old but if you get this did you ever find the cause or fix for your hard start problem? Thank you Martyfa