4.3 LX stalls under load

[BurleyCove]

Srange problem. My port motor runs fine at idle. (starboard too but thats not the point) when I accelreate to get on plane the port motor stalls and then quits. it wont re start until it cools off. seems flooded, I replaced coil, plugs, wires cap,etc. No differenrce.
any other ideas?

Can the carb cause this?

holiday weekend and no boat. this is not fun!

 

[Lazy Daze]

Could probably be a number of things, but, do you use an anti-ethanol additive (or is it in the gas)? When is the last time you changed the fuel/water separator? What year is your boat?

Forgot to mention... Remove the flame arrestors and observe how the choke and throttle plates move under various throttle positions - compare port to starboard.

 

[BurleyCove]

Hi Dennis thanks the reply. I use Sta Bil every time I add gas. I used 93 octane last time i added fuel. Its a 1994. I put new fuel water separators on just a few weeks ago.

I took the carb off and sent it to be re built. Talked to a few mechanic friends and they said it was either the carb or fuel pump. the fuel pump looked new so i went with the carb.

 

[Lazy Daze]

Sounds good. If they've never been done, it's probably a good idea, anyways. Just for kicks, remove the separator and dump it into a clear, glass jar (pickle jar/tomato sauce jar). Let it sit for a day or two and see if you notice any obvious water/gas separation in it.

Make sure you are using the "green/blue" Stabil or the Startron brand (a little less expensive than the Stabil brand... actually stabilizes better, too).

Oh... Did you send both carbs?

 

[BurleyCove]

I'm not smart enough to have remembered to send in both. This is my first cruiser boat and I'm learning the ropes. My runabout is simple compared to this.

will do the glass jar chcek.

 

[annie]

Hi Bill, another thing to check is the oil pressure switch that operates the fuel pump. 4.3's don't have a mechanical pump. If you crank it until you have oil pressure ( without starting ) and then stop cranking you should be able to hear the pump running for a while afterwards. You will need to lift the hatch to hear it.

 

[Lazy Daze]

This is my first cruiser boat and I'm learning the ropes. My runabout is simple compared to this.

No worries - you'll get the hang of it. Try not to think about "everything" on the boat all at once. Take it one system at a time. The engine is basically the same as your bowrider. Then you have a water system, head system, etc - but again, just try to think of them individually.

 

[BurleyCove]

the oil pressure guage looks fine the whole time even when the engine is stalling. Does the oil pressure switch that runs the fuel pump have different sensor than the oil pressure gauge?

Thanks for the reply.

 

[tdappleman]

There is an oil pressure sending unit and an oil pressure switch. If the oil pressure switch senses no or low (I think less than 5 psi) then it will shut down the fuel pump to protect the engine. I'd check the pressure at the fuel pump - should be ~6psi - and make sure it is running when the engine warms up. A bad pump can start producing lower pressure or shut down completely when it gets hot due to increased resistance. I'd check the filter screen at the carb where the hard line from the pump connects up. Also - the Weber carbs need to have the floats adjusted correctly - it's pretty easy to get knocked out of adjustment. The Weber 9600 which is what I originally had on my 96 is basically the same carb as the Edelbrock 1409 Marine which is what I have now. Here's a link to their manual:

http://www.edelbrock.com/automotive_new/mc/carbs_acc/pdf/carb_owners_manual.pdf

 

[BurleyCove]

tGot teh carb back rhis weekend and put it on. Boat runs great! All those new parts matter, but teh carb was the problem all along.


Thansk to everyone for all teh advice.

 

[Lazy Daze]

Good to hear! Now, when you know you won't be using the boat for a week or two, send the other one out.