Merc 3.0 surging

[blacklab75]

I have a 1996 Merc Alpha 1 3.0 that has been giving me problems with surging. The boat starts and runs great at low rpms but, when I accelerate past 2300 rpm's it will begin to surge and eventually stall (10-15 seconds) if I don't reduce throttle.

I have no inline or screw-on fuel filters, just a gas line straight to the pump then the carb. so I can't check/replace a filter. I have sprayed the carb with cleaner and have good fuel flow when I pump the throttle.

What could it be any help would be appreciated?

 

[libellav15]

Re: Merc 3.0 surging

The lack of a filter doesn't really confirm the fuel quality is beyond question.

Is there a water seperator installed anywhere between tank and carb?

If not take a sample of fuel from the tank - put some in a clear jar and let it settle - if there is water in it thats the problem.

might be worth getting a seperator installed anyway

cheers

adam

 

[sltintexas]

Re: Merc 3.0 surging

could also be carb issues. In my manual it lists these are possible causes of engine surging.

4. Engine surges
A. Main metering jets
B. Leaking gaskets
C. Float adjustment
D. Saturated float
E. Power piston or valve
F. Throttle valves

I can speak from experience doing my first carb rebuild that it was not too hard. The final adjustments took some time to figure out but I got through them.

Spraying carb down the throat doesn't clean out much since all the that is past all the internals.

 

[blacklab75]

Re: Merc 3.0 surging

I took a fuel sample and could'nt find any water. I was wondering if it was worth removing the carb and letting it soak or to just go ahead and rebuild.

 

[acuraguy81]

Re: Merc 3.0 surging

I have seen coils do this. what carb is it some are very basic and a rebuild would not do that much. "stalling i would think some thing is failing"

 

[libellav15]

Re: Merc 3.0 surging

true

but simple or not - dirt in a carb passageway will starve the engine and stall it.

they are simple though i agree - certainly simple enought to pop off and clean/rebuild - if only to eliminate

 

[antsmands]

Re: Merc 3.0 surging

I took a fuel sample and could'nt find any water. I was wondering if it was worth removing the carb and letting it soak or to just go ahead and rebuild.

Rebuild the carb. It will solve the problem. Not hard if you put back together like it comes apart. Kit is inexpensive.

 

[blacklab75]

Re: Merc 3.0 surging

Now I'm stumped.

I just rebuilt the carb and installed new plugs...it did'nt work.

Same problem as before, runs fine at idle and neutral, however, stick her in gear and throttle up past 2000rpm and 20 seconds later acts like it's starving for fuel.

What else should I look for?

 

[stevenoyes]

Re: Merc 3.0 surging

Fuel pump maybe getting weak it should have 4 to 5 pounds of pressure. correct me if I'm wrong on those numbers. either that or the float it's set to the proper adjustment.

 

[essveedub]

Re: Merc 3.0 surging

No fuel filters to check? I have 2 filters - one that is on the fuel pump itself - and another inside the carb where the fuel line is attached. Although, my motor is 20 years older...

 

[Blk-n-Blu]

Re: Merc 3.0 surging

Try this link to the "Adults Only" sticky By Don S:
http://forums.iboats.com/showthread.php?t=283269

 

[blacklab75]

Re: Merc 3.0 surging

I think I finally tracked down what the problem was...fuel pump. It's funny I looked at the sight tube numrous times and never saw any fuel in it. However, when I was checking something else the sunlight hit the tube just perfectly and I saw fuel sputtering through.

I disconnected it from the carb and collected a little into a bottle to make sure. Then I reconnected the tube back to the carb and it stopped. I had to run the engine up a couple of more times to get it to start again. It seems to be such and intermittent problem that 's why I missed it.

Any idea's on why it's acting so goofy. Also, can the pump be repaired or is it better to just replace it.