Mercruiser 4.3L won't start

[thekidd77]

Well It's been a long story.

A few years ago I went to start the boat and just a click.... got all the schematics off here to troubleshoot, and narrowed it down to the starter. Replaced starter, ran perfect.

Now this year, same click, troubleshoot list again and this time it is the remote starter solenoid, so I order one, leave the boat tied to the dock overnight.

Boat gets hammered by waves, drenched under the hatch and takes out the dock, decide I need to get it out of the water, try to jumper the solenoid, it turns over like crazy but won't start. Walked it to the beach and try to load it there, whole nother gong show but get it out of the water eventually.

Leave it sit at campsite until the solenoid got here. Replace remote solenoid, now cranks over like crazy at the key but doesn't start, watching down the carb as it cranks over the carb is bone dry no sign of fuel. Read it might have got water in the bowl (it did get spalshed lots) and won't let gas through so take the carb off and drain it upside down, lots of gas was in it somewhere for looking bone dry. Turn engine over with the fuel line off the side of the carb and it pumps gas into a little jar so fuel is getting to the carb.

Start second guessing that it isnt fuel so test the coil, and all plug wires coming of the rotor all are firing, verify the fuel pump makes noise when the key is on and for the five second after turning over so the oil switch is working. Also jumkper the oil swithc leads so the pumps runs constantly and still looks bone dry down the carb.

Decide to start manually pumping the throttle lever, this seems to be working and it seems like is firing a bit and about to go, realize if I pump the throttle lever a bunch and then try to start it but at idle it will start and run for a bit, if while idling i try to give it throttle it dies, seems to only run for as long as I manually pump the lever. The more I pump the lever ahead of time the longer it will idle when I start it, but still never longer than maybe 20 or 30 seconds.

So In summary, I think the pump, filter/water separator, pickup line, and antisyphon valve are good as it pumped fuel into the jar. All the electrical for ignition and fuel seem good, I think the throttle pumping seems to get some fuel into it but only for a short run. The fuel is getting into the carb, and even being stored somewhere you cant see, but none is getting from there into the engine.

So is this a stuck float? Plugged needle valve? seized doohickey?

 

[Bondo]

Re: Mercruiser 4.3L won't start

I think the throttle pumping seems to get some fuel into it but only for a short run. The fuel is getting into the carb, and even being stored somewhere you cant see, but none is getting from there into the engine.

So is this a stuck float? Plugged needle valve? seized doohickey?

Ayuh,... Maybe ya oughta try rebuildin' it, instead of just shakin' it upside-down...

Sure sounds like the Carb is the problem...

 

[thekidd77]

Re: Mercruiser 4.3L won't start

I was of the impression carbs gradually got worse and eventually needed rebuilt, this boat has been running great, so was expecting it to be a single thing that happened, like water stuck somewhere, for this carb to go from running perfectly to passing no fuel thru all 4 barrels, has me thinking there is a single failure point somewhere

I read on here the single failure might be a bowl full of water and that you have to take it off and turn it upside down to dump it out, didn't exactly think I was being stupid when I did that

 

[NHGuy]

Re: Mercruiser 4.3L won't start

Well if you have to ask you should get it to a carb guy unless you are a fussy perfectionist do it yourselfer. If you haven't redone a carb before there's a lot to it, but it can be done. Here's a link to a video on rebuilding a Rochester quadrajet for a 5.7. http://forums.iboats.com/showthread.php?t=362542

 

[thekidd77]

Re: Mercruiser 4.3L won't start

Well I do like doing things myself. Read some other posts and seen Bondo starts all his responses with Ayuh...thought you were just picking on me.

I have the weber carb, the one that looks like an edelbrock 1409, my choke is run by a lever off a coil spring in a tin box on the manifold.

Is it true I can get the 1409 rebuild kit and go from there or is there something else I need to get?

 

[Bondo]

Re: Mercruiser 4.3L won't start

Well I do like doing things myself. Read some other posts and seen Bondo starts all his responses with Ayuh...thought you were just picking on me.

I have the weber carb, the one that looks like an edelbrock 1409, my choke is run by a lever off a coil spring in a tin box on the manifold.

Is it true I can get the 1409 rebuild kit and go from there or is there something else I need to get?

Ayuh,.... It's the Same carb,....

Here's the manual...
In it is Anything you'll ever wanta, or need to know 'bout that carb...

 

[thekidd77]

Re: Mercruiser 4.3L won't start

Thanks, I found the manual this afternoon and read thru it. I am doubting the carb needs rebuilt after reading it. Mainly because the carb is an absolute redundant system with two halves ,(given it needs the volume of both to run properly). The odds of both halves failing at the exact same time to have zero fuel delivery is low, there is also different ways it gets fuel based on throttle position and i have zero fuel regardless of throttle position the one central point on each side are the main jets/rods and both would need to be plugged and I was able to pull them out from the top and they are clean.

Does anyone know if the manual pump gets its fuel from the bowl? If it does than I doubt my floats can be stuck either as I would of manually pumped the bowl dry by now, so it must be refilling.

Just not seeing anything within the carb that could be rebuilt that could cause both sides to have zero fuel into the throat at once. How does the carb push/pull fuel through it from the bowl? I assume the vacuum mentioned is a suction from the intake manifold? There isn't any external vacuum lines attached to my carb from what I can see. If the carb gasket is bad (and I'm certain mine is after turning the carb upside down LOL), can that be enough to lose vacuum stopping flow of all fuel? Other than the bit the throttle lever can pump of course

 

[glennj3]

Re: Mercruiser 4.3L won't start

Just wondering have you adjusted the lean/rich needle? I don't know about the 4 barrel but my 2 barrel would crank and run fine until it got hot, then at slow or idle it would cut off or just not take the gas when I tried to go. Got her cranked up and played with the adjustment until my son could give her gas (in neutral of course) and she would take it. Seems I leaned her down till she wanted to fun rough, then turned rich until it ran not as good, then turned back 1/2 between the two, then started moving the throttle while adjusting the needle until she took the gas fine.
Otherwise you could have gotten some trash in a port or jet that is causing your problem. This would require some disassembly, air pressure and maybe a soak in some carb cleaner for several hours.