Mercruiser 888 stalls at 3000 rpm

[jabroni]

So I purchased an 1973 Century Raven with a Mercruiser 888 I/O (Ford 302) and ran fine the first few outings. Soon after it started stalling around 30 seconds after getting on plane around 3000 rpms. It was hard to start but eventually stalled again. We creeped back to the dock around 1000rpms, but slowly they started to drop and soon sputter and stall when it got down to 800 rpm. Would not start unless left for 10 mins. Again, and again I followed this till we got back to the dock. The next day, I tried to trouble shoot the problem, but it would not start at all. I thought that it was a fuel problem, but can easily see gas spray into the carb. and also tried my trusty can of starter fluid. I gave the boat a full tune-up, replacing plugs, wires, coil, distributor cap, points, condesor, fuel filter/water seperator, battery and everything else I could think of. Re-tuned the carb., and filled it with fresh fuel. Still, same problem. The carb is a 2 barrel marine carb from holley and looks like it was replaced not too long ago. I dont know what else to check. I tried the many safety kill switches but they all seem to operate correctly. I have heard of this problem before with other boaters on this forum but have yet to really find a solution, others believe it could be a bad tach., timing advance is offset, fuel pump, and breather valve. I am really unfamiliar with these and could use some advice. Please help. Thanks!

 

[dubs283]

Re: Mercruiser 888 stalls at 3000 rpm

do you now have spark?

when you did the tune-up did you set the dwell?

could be a bad tach, diconnect grey wires from coil (-) and see if you have spark

 

[forgeworks]

Re: Mercruiser 888 stalls at 3000 rpm

Jabroni, I have a 1973 Cobalt 888 w/ Ford 302. The symptoms you describe are all too familiar. I replaced the points with a Mallory electronic ignition (twice), new coil (twice) second one WITH a resistor! The fuel pump sprayed fuel so thought it was O.K. Replaced ignition switch, new wire to the coil also. Still would get on plane for 30 seconds then die! I finally just said F#!k it and replaced the mechanical fuel pump with a Holley elec. fuel pump. It is NOT a marine pump so I would not recommend it BUT, after installing it the symptom disappeared! What was happening was 1) not enough pressure from the pump at high RPM so the mechanical fuel pump (very old probably original) was not putting out enough pressure to fill the bowl at high RPM. 2) float needs to be set properly by someone who knows what they are doing. I set the float level several times and ran it hard to eliminate surging (like when going over another boats wake). Good luck, remember to us ONLY marine grade replacement parts, they are designed with safety in mind. I only put the elec.pump in as a temporary measure. Measure the pressure with an inline gauge, its the best test. Good luck, let me know if this helps. Tim