View Full Version : 1995 Merc 57 Low RPM stall when hot
05-01-2006, 02:50 PM
"Just bought my first boat. Sea Ray 220 w/Merc 5.7 EFI and Bravo I. Starts and runs great cold but once warm stalls at idle or when coming up on plane after being shut off for an hour or so. After stalling its VERY tempermental when trying to re-start. Starts but then almost immediate stall again. Wondering if too much / not enough fuel flow, not good spark or some kind of bad sensor in EFI. Can anyone please help a rookie? Thanx<<<Jim"
Eddie from Oregon
05-01-2006, 04:02 PM
Sounds electronic. Do you have a distributor or a coil pack ignition?
"If it's TBI, it has a distributor. How old are the cap/rotor, plugs and wires? Does it have the right plugs and are they gapped correctly? A friend just bought a boat and it had Autolite plugs, with the rear pair gapped at about .060". May have been the second set ever for this boat and it's a '94 model. Started kinda hard. Put the right plugs in and gapped them to spec (this is on the plastic flame arestor cover) and it kicked right over. Also, make sure the flame arrestor is clean. This is the single most neglected thing I see on boats.
Open the motor cover and see if it starts It may have vapor lock and the pump is on the motor, higher than the tank. Otherwise, you'll need to do the usual diagnostic stuff to find it. Try turning the key to ON for more than 2 seconds, turn it off for more than 5 sec and try it again. If it starts, your pressure is bleeding off after running and needs to re-prime. Do a fuel pressure test and go from there. Also, turn the key to ON and look at the temperature gauge. If it has risen too high, the ECM will see it as an overheat when it's just heat soak. Turn the bilge blower on for a few minutes and try it.
Another thing that's very common is the safety switch not making good contact with the lanyard on. If it pulls out normally, remove the lanyard and pull it out manually. If it starts, replace the switch. If it pushes in, do that manually to see if it'll run.
Another thing you need to check is the boat harness- these separate on Mercruisers occasionally and need to be pushed together again.
You probably have the Delphi ECM and there's a diagnostic connector on the harness. Look for the A and B terminals, then with a scan tool or a paperclip, connect these two terminals and turn the key to ON. Your Malfunction Indicator Lamp (MIL) will show 1 flash then two flashes (12). It will do this three times, then display any codes present before flashing 12 again, three times. Post any additional flash sequences here(14 or 15, 21 or 22, 33 or 34, 44 or 45, etc) ."
05-04-2006, 10:57 PM
Vapor lock seems to be a common suggestion how can it be prevented???
"Turn the key to ON and listen for a click and a buzzing sound lasting about 2 seconds. That's the fuel pump priming the fuel pressure to the throttle body. If you don't hear anything, there are other things that will need checking.
Make sure all grounds on the motor and the battery terminals are clean and tight."
Eddie from Oregon
05-05-2006, 02:38 PM
Mr. Cross. Time to stop dreaming and get to work. You have gotten good places check out. Do your self a favor and follow the advice
05-06-2006, 10:01 AM
Thanks for your input Eddie you've been most helpful.
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