boat stalls when given gas

[mward82]

So I bought a Mariah shabah 97. The guy said he rebuilt the carberator and put in a new fuel pump. I have a inboard/outboard mercruiser 4.3lx//v6. It starts up great, runs on 5-8mph really well. The radio (not accessory) is working great. All until I try to give it some gas to get on plane. It then starts to go, engine revs, i pick up speed and then it works and can't get there. Sounds like the engine is revving and trying to pick up but it doesn't and the boat stalls out or I put it back in neutral really fast. Then yesterday it was doing that and the radio turned off, no power, and now wont turn on at all. Got a tune up and everythings sounds great but when it gets on the water i can't throttle it and get it going. Fuel pump problem? Carb? Any help would be appreciated!

 

[Bondo]

Ayuh,..... Welcome Aboard,........ My 1st guess is a carb problem,......

Does the accelerator pump dump shots of gas down the carb's throat,..??

2bbl. or 4bbl. carb,..??

 

[mward82]

I think it's four and I can't tell because I dont know that much about it BUT sometimes it smells like gas immediately after.

 

[Bondo]

I can't tell because I dont know that much about it

Ayuh,...... Ya gotta pull the flame arrester, 'n linkage, then actuate the throttle, 'n Look,.....

 

[pacofortacos]

I actually had something similar happen on my 96 Cobalt - it turned out to be a faulty oil pressure switch. It just couldn't pass full voltage and current to the fuel pump.

I found it 2 ways - first clue - the fuel pump was cool, when normally they tend to run a bit warm.
Next jumped the oil pressure switch to try it quickly and the boat ran fine and the fuel pump started to run a bit warm like they do, changed the switch and has been good ever since.

 

[pacofortacos]

Also if you have a water fuel separator, maybe it needs changed.
Could even be bad gas.

 

[mward82]

Yeah I'm nervous to buy a whole new carb audit knowing for sure that's what it is I'm not mechanically inclined so I'll need to get someone to look at it. I did once and he thought it was fixed but evidently not! I wish u I could do these things in my own! Thanks for the tips.

 

[mward82]

Could I run the wires from the fuel pump right to the battery and try that? Is that what you're saying?

 

[mward82]

Ayuh,...... Ya gotta pull the flame arrester, 'n linkage, then actuate the throttle, 'n Look,.....

That sounds way too complicated and dangerous for a novice to try! i actually know what you are talking about a little just not sure I could do it by myself.

 

[pacofortacos]

It's usually easier to bypass the oil pressure switch vs. running 2 wires to the pump. You really don't want sparks in a boat so don't try it unless you know what your doing - at the very least disconnect the battery when making connections.

My electric pump (stock) will get warm even idling on muffs.

After it has been running for 5-10 minutes is the fuel pump warm or fairly cool?

 

[mward82]

It's usually easier to bypass the oil pressure switch vs. running 2 wires to the pump. You really don't want sparks in a boat so don't try it unless you know what your doing - at the very least disconnect the battery when making connections.

My electric pump (stock) will get warm even idling on muffs.

After it has been running for 5-10 minutes is the fuel pump warm or fairly cool?

I'll have to run it and see, i didn't try to feel for the temp of the unit yet. Are you saying basically take the red and black wire that come from the fuel pump and run them directly to the battery? They wont reach currently so I would have to get longer wires.

 

[nola mike]

That sounds way too complicated and dangerous for a novice to try! i actually know what you are talking about a little just not sure I could do it by myself.

You can certainly do it yourself.
If you're not comfortable doing it then it's probably time to take it to a mechanic...

 

[pacofortacos]

I was saying to jump out the oil pressure switch, just pull the plug(s) off and jump the two wires together.
But first I would sit and idle for several minutes and see if the pump gets warm or stays cool.

My oil pressure cutout switch would pass some voltage and current, but not enough to run the pump at full flow. So the boat would idle fine but die out quickly when giving it throttle.

My 96 oil cutout switch has 2 blade terminals - all I did was jump them together with a paper clip BUT if you try that, the paper clip will have 12 volts on it with the key on and short out if it hits metal. If you try jumping it wrap it with a rag or something to make sure it doesn't touch ground and burn your wiring or boat down.

I don't know how mechanical you are

 

[mward82]

So i ran it this weekend on the water and looked at it. Took the flame arrestor off and watched the carb. When its going 10mph it's fine, when i push the throttle more and try to pick up speed it's not getting enough fule from the carb. One of the pistons doesn't look to be firing so then it dies because it's not getting enough gas.

 

[nola mike]

So i ran it this weekend on the water and looked at it. Took the flame arrestor off and watched the carb. When its going 10mph it's fine, when i push the throttle more and try to pick up speed it's not getting enough fule from the carb. One of the pistons doesn't look to be firing so then it dies because it's not getting enough gas.

How do you know a piston isn't firing? How do you know it's not enough fuel? There are a dozen things that are more likely to be causing problems than a partially working switch. And a better way to test that is just check the voltage at the pump. And a better start to all of this is to check your fuel pressure before the carb. And check compression. And when you say "didn't turn on at all", after everything else turned off, that certainly sounds electrical...

 

[mward82]

And when you say "didn't turn on at all", after everything else turned off, that certainly sounds electrical...

That was the radio and it was a fuse. I fixed that and it's running great now.