5.7 is hard to start when hot?

[imported_DANA1]

my mercruiser 5.7 is hard to start when engine has been run hard after pulling the kids on tube then shutting down to rest for a while. thought it was carb so we rebuilt it but that didnt fix it. it almost sounds like timing is off when you crank it but if you give it some gas it will run. could this be the accelerater pump adjustment is wrong? thanks

 

[paulie0735]

Re: 5.7 is hard to start when hot?

carb or efi? what year? is this problem new or has it always done this?

 

[Scaaty]

Re: 5.7 is hard to start when hot?

Running hot, and your boiling the gas out the carb. Let it cool down before shutting down.

 

[paulie0735]

Re: 5.7 is hard to start when hot?

oops, yep carb! i suggest you re-check the float level (same as i re-checked your post) This issue is fairly common and with a carb engine its usually the fuel percolating through the lines and flooding into the engine. Short term it can cause flooding, longer term the fuel will evaporate in the manifold and the engine and fuel system will than be dry and will require a long crank to refuel the system but eventually it will fire up and run normally. Fit a new needle and seat in the carb and carefully re-check the float level. You can also try wrapping the fuel lines in a heat proof tape to insulate the lines from the radiating heat from the engine that accrues when you shut it down after a long hard run. The coil can also cause this if it gets to hot, if its mounted directly to the engine than try relocating it to a spot so its not having the engines heat soaking straight into it. The temp under an engine cover can reach 300plus!

 

[Don S]

Re: 5.7 is hard to start when hot?

When was the last time it had a full tuneup. Spark plugs, cap, rotor, etc.
Best carb in the world won't start and engine with weak spark while cranking.
Put a timing light on it and verify the timing.
When you shut it down, does it diesel? ? ?

 

[imported_DANA1]

Re: 5.7 is hard to start when hot?

tuned up in aug 06 after purchase but still working out kinks. thanks for all the great ideas i'll work thrue them and get it fixed

 

[Haut Medoc]

Re: 5.7 is hard to start when hot?

You didn't answer Don S question about Dieseling....

 

[imported_DANA1]

Re: 5.7 is hard to start when hot?

sorry no deiseling and the boat only gave me trouble when on water after good and warmed up, never in drive way . how do i test coil? or as a precation should i just replace and relocate it.

 

[DHPMARINE]

Re: 5.7 is hard to start when hot?

Could be lots of things.Start by operating at lower speeds before shutting down.This gets things back to operating temp,and hot soaking is lessened.You might even try a different brand of gas (different additives).

DHP

 

[jtomanelli]

Re: 5.7 is hard to start when hot?

Had similar problem last year, found my base timing to be too far advanced... I think it should be 8 deg at 1000 RPM. Can anyone confirm?

 

[Don S]

Re: 5.7 is hard to start when hot?

jtom, best to start your own thread with a question like that. You also need to include Make, Model, SN, and any other info about which engine you have if you want accurate info.

 

[jtomanelli]

Re: 5.7 is hard to start when hot?

Good point Don... Just pointing him in the general direction of looking at timing. My limitted experience is that it seems to affect engine when trying to start hot if the timing is too far advanced.