5.7 bogs out and dies - Maxum Boat Owners Club

Liunatic · 03-09-2018, 03:15 PM

JUst purchased a 2700 my 5.7 liter runs fantastic for about 1 hour then sputters and eventually dies, any ideas?

Phillbo · 03-09-2018, 07:19 PM

Need more info on the engine. What year and model? Carburated?

mmwjr · 03-09-2018, 09:03 PM

Welcome aboard

As stated what year and is it carb or MPI?

However based on running good for one hour then dies sounds like a blocked fuel tank vent. Next time it dies open the fuel fill cap, if there a rush of air and the engine now runs the tanks vent is clogged.

Liunatic · 03-11-2018, 01:25 PM

Its a 1997 5.7, carburated, its funny every one says vent hose. I removed it from tank an could blow out no problem, so yesterday im sitting here thinking i was able to blow out no problem but i never tried to blow in from outside down to tank! Took out the anti siphon valve thinking it was hanging up, it did the same thing. Thinking of installing an electric fuel pump, dont really want to. Iwould rather find an fix the problem. The motor is a complete rebuild on a new block with 40/hrs runs fantastically smooth for 50-60 minutes

mrt214 · 03-11-2018, 06:29 PM

Could be the fuel pickup in the tank. Might be gas stirring up the bottom and plugging the line. I would also check fuel filter that is in carb where the line comes in.

Phillbo · 03-11-2018, 06:59 PM

Could be the coil heating up and failing ... But, since it's a fresh rebuild i would assume the coil is new as well.

Liunatic · 03-11-2018, 07:47 PM

Had the pickup line out, it was clean really clean, we changed the fuel filter 3 times havent checked the carb one is it just a screen in the fuel line? If it was any of the filters i wouldnt think it would fun 1 hour fine for 3 days in a row. Starting to think its electric

mmwjr · 03-11-2018, 09:12 PM

Switching to an electric fuel pump will not fix the problem.

It could be the coil heating up or the ignition sensor in the distributor, both are know faults to electrical issues once the engine is warmed up.

jrsick · 03-12-2018, 12:08 PM

What does the inside of your distributor cap look like? I rec calling ignition system manufacturer and ask if that system is appropriate for your application. That sounds likes the problem to me, if... you are certain that there is no gas tank vent problem.
Next time you take out your boat, try opening the gas cap every 15 minutes or so.
If not vent problem or ignition system mismatch, next suspect is loose wire in ignition system.

shrew · 03-12-2018, 01:16 PM

If it were a vent line clog, it would be in the through hull the vent line connects too. The screens are known to corrode, and occasionally be the home for insect nests. You did say you disconnected the vent line from the tank and tested. I assume the vent line was still connected to the through hull at the time?

Jduncan99217 · 04-17-2018, 01:08 PM

Check the torque on the exhaust manifold. After a rebuild they need to be re-torqued after about 2 hours.

Corydaniell · 06-06-2018, 08:02 PM

We had the same thing happen with our 2100 sc. We figured out that it was the manual fuel pump that wasn't working so we installed a fuel squeeze bulb ($18 walmart) in the fuel line that runs from the fuel pump to the engine. We squeeze it 3 times or so before each engine start and haven't had any issues since. Planning on ordering a new fuel pump in the future, but this is working great for now.

mmwjr · 06-07-2018, 12:58 AM

Quote:

Originally Posted by Corydaniell

We had the same thing happen with our 2100 sc. We figured out that it was the manual fuel pump that wasn't working so we installed a fuel squeeze bulb ($18 walmart) in the fuel line that runs from the fuel pump to the engine. We squeeze it 3 times or so before each engine start and haven't had any issues since. Planning on ordering a new fuel pump in the future, but this is working great for now.

This is a terrible idea, the bulb is not designed nor approved for an IO application. On an outboard the fuel pump is on the engine so the bulb is on the suction side and what you did has it on the pressure side.

Fuel evaporates from the carbs bowl, cranking the engine a few seconds is required to fill the bowl back up. Then two pumps of the throttle to set the choke and prime the engine is all that is needed.

shrew · 06-07-2018, 02:53 PM

Quote:

Originally Posted by Corydaniell

We had the same thing happen with our 2100 sc. We figured out that it was the manual fuel pump that wasn't working so we installed a fuel squeeze bulb ($18 walmart) in the fuel line that runs from the fuel pump to the engine. We squeeze it 3 times or so before each engine start and haven't had any issues since. Planning on ordering a new fuel pump in the future, but this is working great for now.

If this is a carburated engine, then the Mercruiser starting sequence is to put the shifter into neutral, then pump the shifter 3 times. Then start the engine and slowly advance the shifter until the engine starts. Once started, drop back to zero throttle.

That should essentially do the same thing as a primer ball. I don't believe that a primer ball is legal below deck. Like a portable fuel tank for an OB isn't allowed below deck either.