Hi Everyone,
I'm new to the board and new to Mercury outboards. Have been working on Johnnyrudes for years but this engine has me scratching my head.
My son purchased this engine on an 18' Starcraft and I've been having problems getting it to run right. I've read up on the 2+2 design and understand how its supposed to work but it has a mind of its own!!
Can't seem to get this engine up to rpm's or speed. A bit of what I've done is: Compression 136-138 on all four, new spark plugs, rebuilt carbs, rebuilt fuel pump, rebuilt accelerator pump, all new fuel lines from tank to engine, new fuel water separator, link & sync and timing and spark gap test of 7/16" plus with a nice bright blue spark on all four. The prop is a 13.75" x 15".
A couple of times on the water it jumped up and ran about 5500 rpm at around 40mph but then falls on its face again. Engine stumbles a bit when going to WOT and won't get over around 4800-5000 rpm at about 28mph on the gps.
It feels like it's starving for gas so I hooked a gauge into the fuel line to check the pump pressure but when running the needle bounces all over the place and when just cranking it reads about 3psi which is too low according to the service manual. Anyone have any more ideas? What am I missing?
Thanks,
Larry
I'm new to the board and new to Mercury outboards. Have been working on Johnnyrudes for years but this engine has me scratching my head.
My son purchased this engine on an 18' Starcraft and I've been having problems getting it to run right. I've read up on the 2+2 design and understand how its supposed to work but it has a mind of its own!!
Can't seem to get this engine up to rpm's or speed. A bit of what I've done is: Compression 136-138 on all four, new spark plugs, rebuilt carbs, rebuilt fuel pump, rebuilt accelerator pump, all new fuel lines from tank to engine, new fuel water separator, link & sync and timing and spark gap test of 7/16" plus with a nice bright blue spark on all four. The prop is a 13.75" x 15".
A couple of times on the water it jumped up and ran about 5500 rpm at around 40mph but then falls on its face again. Engine stumbles a bit when going to WOT and won't get over around 4800-5000 rpm at about 28mph on the gps.
It feels like it's starving for gas so I hooked a gauge into the fuel line to check the pump pressure but when running the needle bounces all over the place and when just cranking it reads about 3psi which is too low according to the service manual. Anyone have any more ideas? What am I missing?
Thanks,
Larry