Fuel question

[Tidefan99]

I just bought my first boat about a month ago so I’m green on everything. I bought a 2005 Caravelle 187 with the 4.3 mercruiser engine. I have already noticed that when the boat sets for a few days it takes forever for it to start. Once it starts it runs great, idles at 900rpm. You can go out 6-8 hrs later and it will start right up. But if it sits for a few days it’s like it loses it fuel prime. Any idea what yo check ? Any help is greatly appreciated.

 

[Bondo]

Ayuh,.... Welcome Aboard,....... Carbed,..?? Which carb,..?? Efi,..?? Mpi,..??

 

[Tidefan99]

Ayuh,.... Welcome Aboard,....... Carbed,..?? Which carb,..?? Efi,..?? Mpi,..??

EFI

 

[Tidefan99]

EFI

What is MPI ? Never heard that term before. I am an old school mechanic. My 70 mustang does the same thing if it sits for a long time without starting it up. It takes awhile to get the fuel back up to the carb.

 

[nola mike]

What is MPI ? Never heard that term before. I am an old school mechanic. My 70 mustang does the same thing if it sits for a long time without starting it up. It takes awhile to get the fuel back up to the carb.

Multi port injection...been around since the 80's at least. On the mercs EFI usually refers to a throttle body injection.

 

[Scott06]

What is MPI ? Never heard that term before. I am an old school mechanic. My 70 mustang does the same thing if it sits for a long time without starting it up. It takes awhile to get the fuel back up to the carb.

Multi port injection - individual injectors for each cylinder. EFI in mercruiser speak is throttle body injection two injectors for entire engine

 

[Tidefan99]

Learn something new everyday. Mine definitely looks like a throttle body. Haven’t pulled the breather off of it yet to look. Can you use starting fluid for gas engines on these engines ?

 

[Tidefan99]

Or I should say the flame arrestor off to look at fuel injection.

 

[Scott Danforth]

Throttle body injection will have two injectors in the throttle body

MPI will have 6 injectors in the manifold and the throttle body will not have injectors

You should not need starting fluid

What is the fuel pressure?

Your carbureted 1970 mustang simply suffers from fuel evaporated out of the fuel bowls. Most carbed boats have the same issue

 

[Scott06]

Learn something new everyday. Mine definitely looks like a throttle body. Haven’t pulled the breather off of it yet to look. Can you use starting fluid for gas engines on these engines ?

Or I should say the flame arrestor off to look at fuel injection.

EFI is throttle body with flame arrestor off you should see injectors spraying.

Yes you can use starter fluid just be carefully looking down there with flame arrestor off and trying to start. I was helping a friend get a older motorcycle running, I was keeping it running by dribbling fuel down the carb. It backfired as valve was sticking... I was holding a flaming cup of gas... was quite an attention getter.

 

[cyclops222]

Could be 1 or more injectors slowly leaking out all the pressure / fuel. Takes a while to fully reprime everything sometimes.