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5.0 OMC Engine stalling while trying to speed up. https://www.smwebhead.com/phpBB3/viewtopic.php?f=13&t=5742	Page 1 of 1

Author:	bradmann86 [ Mon May 31, 2010 7:46 am ]
Post subject:	5.0 OMC Engine stalling while trying to speed up.
<First Post New Member> I have a 1993 Four Winns 195 Sundowner with a 5.0cobra 302V8 with holly carbs. Everything starts up fine and idles fine and actually cruises fine at very low speeds. The problem I'm having is that if i try to go down on the trottle it will run for about 2 min and then stalls out. I just bought this boat and was told everything was mechanically sound bought it during the winter and was not able to test drive. The man who I bought the boat from told me it was from running 91 octane and said I should put 87octane in but i just find that hard to believe that a premium fuel would cause this if anything it would make it a little rich and maybe run your RPM's a little higher but nothing noticable. Please let me know what you think. Thanks -Brad

Author:	bradmann86 [ Mon May 31, 2010 7:52 am ]
Post subject:	Re: 5.0 OMC Engine stalling while trying to speed up.
Forgot to mention that it shift smooth from neutral to drive and reverse Runs great at low speeds.

Author:	Aussie_Horizon_190 [ Mon May 31, 2010 6:15 pm ]
Post subject:	Re: 5.0 OMC Engine stalling while trying to speed up.
Sounds like a lack of fuel to me Brad - check or replace your fuel filters, maybe put a fuel pressure gauge on the carb to see if the fuel pump is managing... If you have a mechanical pump, you may just want to replace it as the diaphrams in them don't last forever and it's not an expensive or difficult job to do.

Author:	bradmann86 [ Mon May 31, 2010 9:28 pm ]
Post subject:	Re: 5.0 OMC Engine stalling while trying to speed up.
Alec, I ran the boat today in my driveway and it seems to run smooth even at higher RPM's I can't seem to recreate the problem I was having at the lake. Although I did notice that the hose that ties in to my Valve covers to create the vacuum to the carbs air filter what it does I'm not exactly sure but I'm assuming that it is to draw off any vapor that might be seeping through. Since the hose was disconnected I was wondering if the motor wasn't flooding out or possibly vapor locked which could be the reason why it would only idle or at low speeds. If that didn't fix the problem then I'm afraid that there is an issue in the lower unit which was just rebuilt 2yrs ago. If the issue only arises with a load behind it then I don't suspect it to be fuel system related. Possibly a cut off switch some where in the shift cable????????? Let me know if I'm on a right track I will get the fuel pump switched out wouldn't hurt anything and it's cheap The fuel filter is brand new as I just got the boat De-winterized Thanks for your help. -Brad

Author:	Aussie_Horizon_190 [ Mon May 31, 2010 10:54 pm ]
Post subject:	Re: 5.0 OMC Engine stalling while trying to speed up.
Brad, the fact it runs fine on muffs confirms my suspicion it is probably starving for fuel. In the driveway you have no load on the engine, but in the water you have plenty of load on the engine and so requires much more fuel to make the power to overcome this load. Your pump is just at that happy medium where it will pump enough fuel with no load, but not enough for full engine load. If it was me, I'd swap the pump first - it's probably the original with the boat! Wouln't worry too much about the PCV hoses from the rocker covers at this stage - worst case is they may make the engine idle rough. All they do is take the oil fumes from inside the engine and suck it down the carb to burn them up. This isn't a problem.

Author:	jvthundercat [ Tue Jun 01, 2010 9:44 pm ]
Post subject:	Re: 5.0 OMC Engine stalling while trying to speed up.
+ 1 Aussie_Horizon_190

Author:	LouC [ Wed Jun 02, 2010 2:04 pm ]
Post subject:	Re: 5.0 OMC Engine stalling while trying to speed up.
If you still have a problem after changing fuel filters and making sure the gas tank vent is OK...then check the anti-siphon valve...the one on my boat was corroded and restricted fuel flow...to the point that the engine would idle and rev in neutral fine...but would not plane out the boat at all...I checked everything I could think of and then took it to my mechanic and he found the problem...ran great after that was fixed... The anti siphon valve is on the gas tank and is a spring loaded valve that prevents gas from siphoning into the bilge if the fuel line leaks..there is a spring loaded ball and the fuel pump can normally overcome the spring pressure and fuel flows...bu if the ball corrodes...then you get fuel starvation...

Author:	Aussie_Horizon_190 [ Wed Jun 02, 2010 8:37 pm ]
Post subject:	Re: 5.0 OMC Engine stalling while trying to speed up.
Oooh... good call Lou. I have come across this once about 30 years ago where the vent line in a car fuel tank got blocked - removed the gas cap and drove it home no problems then. As the boat is 17 years old, this is a real possibility.

Author:	LouC [ Wed Jun 02, 2010 9:01 pm ]
Post subject:	Re: 5.0 OMC Engine stalling while trying to speed up.
My mechanic explained that some boat manufacturers use a cheap valve that corrodes easily and he used a better quality one (salt water region) and it's been fine for 6 years since....

Author:	wkearney99 [ Thu Jun 03, 2010 7:28 am ]
Post subject:	Re: 5.0 OMC Engine stalling while trying to speed up.
I'll toss in my nod to the flow issues. An engine without a load on it might rev higher but it's the load that demands more fuel. Think of pushing pedals on an upside-down bike. You can pump it plenty fast with just your hands, but then try the same thing when going up a steep hill...

Author:	chiefphil [ Tue Jul 28, 2015 9:44 am ]
Post subject:	Re: 5.0 OMC Engine stalling while trying to speed up.
I'm having the same problem. Boat starts up good, then when I accelerate or get a load on the boat stalls. I wait about a minute and starts up fine, runs 2-3 minutes then stalls again. Took it into the shop - Water in fuel... tank drained, fuel filters replaced... ran fine in the yard. brought it back tot he lake. As soon as I put a load on it stalls. Mechanic with me. Fuel is pumping good, spark is good ( thought it was week)... then we noticed that the raw water intake pump was hot, real hot... could there be an auto shutoff if the motor gets too hot ? This is a 1995 190 The gauge says 180... but it is 20 yrs old, so who knows if that is write... temp does come up quick.

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