Logo
FULL SITE MENU

2008 5.0 mpi slowly losing power

M

Mnix2033

New member
Two months ago I acquired a 2008 Caravelle 5.0 mpi mercruiser from a guy that didn't use it much. It only had 34 hours. Beautiful boat. Put in the water and it ran great. About 52 mph at 5000 rpm. On the second tank of gas it started losing rpm at wot. On the third tank it started losing power and struggled to plane out. Now at 54 hrs on the boat it will hardly plane out. It cranks right up but idles with a slight miss. I checked the distributor cap. It had a little crud on the tips. I scraped that off. I drained the fuel tank and filled with 90 octain 100% gas. Added a bottle of Seafoam. Found a small vacuum leak where the pvc connects to the intake. No improvement. My question is with so few hours on unit could the dreaded kool fuel paint flake pump issues be haunting me. Engine serial # 1AO74721 My next move is to replace plugs cap and rotor and try it with fuel pressure gauge attached to the shrader on the rail.
 
Mnix2033 said:
My question is with so few hours on unit could the dreaded kool fuel paint flake pump issues be haunting me. Engine serial # 1AO74721 My next move is to replace plugs cap and rotor and try it with fuel pressure gauge attached to the shrader on the rail.
Click to expand...
Since your engine package is designed to use the Alpha stern drive cool fuel system, No you wouldn't be experiencing the paint issue sometimes found inside the Bravo Gen 3 cool fuel module system.

The things you've mentioned to try testing are a good start to try especially testing fuel pressure and depending on what you find with all those items, you may also need to consider performing an engine cylinder compression test and possibly a leak down test too just in case you're developing an internal issue inside the engine such as tuliped valves or failing head gaskets for examples.
Also try running the boat on an external fuel tank supply too see if things change for the better.

Your fuel pressure should be in the 43ish psi range.
http://www.marineengine.com/parts/mercury_marine_parts/sn/1A074721/4M4102LUS/12840_60
http://www.marineengine.com/parts/mercury_marine_parts/sn/1A074721
 
boat_tech said:
Since your engine package is designed to use the Alpha stern drive cool fuel system, No you wouldn't be experiencing the paint issue sometimes found inside the Bravo Gen 3 cool fuel module system.

The things you've mentioned to try testing are a good start to try especially testing fuel pressure and depending on what you find with all those items, you may also need to consider performing an engine cylinder compression test and possibly a leak down test too just in case you're developing an internal issue inside the engine such as tuliped valves or failing head gaskets for examples.
Also try running the boat on an external fuel tank supply too see if things change for the better.

Your fuel pressure should be in the 43ish psi range.
http://www.marineengine.com/parts/mercury_marine_parts/sn/1A074721/4M4102LUS/12840_60
http://www.marineengine.com/parts/mercury_marine_parts/sn/1A074721
Click to expand...
OK Thanks I will compression check this weekend. The engine never overheated. Is the head gasket and valve issues a common problem with so few hours?
 
Mnix2033 said:
Compression test.. 150 psi on 6, 145 psi on 2. Plugs new cap and rotor on the way.
Click to expand...
Replaced plugs cap and rotor. She is good to go. Running great. In case anyone is interested. Advance auto parts has a cap and rotor. BWD select cap part # C282 rotor D 236. I challenged everyone at the parts store to point out a difference between the factory mercruiser cap and rotor and the BWD cap and rotor. No difference what so ever. I got the plugs, cap,and rotor for $145. Thanks.
 
Back
Top