Mercruiser 3.0 Trouble Starting

[macdonda]

Hi all, I’m new here, if this isn’t appropriate please let me know. I recently purchased my first boat a 91 Bayliner with a 3L mercruiser inboard (OD442923) and alpha one gen one drive. Had it out a few times, will confess the hi test here may contain ethanol. Last weekend engine stopped and would only restart after numerous attempts at restarting with lots of priming then died again. I assumed water in the gas so removed all gas, replaced water separator, fuel pump filter, new spark plugs, put new gas in and again, it cranks fine but won’t bite. I did today jumper the kill switch and immediately it fired up which I thought was finally the issue, I stopped the engine then back to difficult start. With the amount of turning over and trying using gas/spray in carb, I’m thinking it might not be getting proper spark but if that’s the case, why would it all of a sudden run? I don’t mind tinkering/troubleshooting but if anyone has a direction worth trying I’ll appreciate- I really want to get it running enough to winterize. Vid is of the few minutes I had it run tonight.
Points/wires/spark plugs were done 2 years ago.
Thanks!!

 

[markhodges78]

Hi all, I’m new here, if this isn’t appropriate please let me know. I recently purchased my first boat a 91 Bayliner with a 3L mercruiser inboard (OD442923) and alpha one gen one drive. Had it out a few times, will confess the hi test here may contain ethanol. Last weekend engine stopped and would only restart after numerous attempts at restarting with lots of priming then died again. I assumed water in the gas so removed all gas, replaced water separator, fuel pump filter, new spark plugs, put new gas in and again, it cranks fine but won’t bite. I did today jumper the kill switch and immediately it fired up which I thought was finally the issue, I stopped the engine then back to difficult start. With the amount of turning over and trying using gas/spray in carb, I’m thinking it might not be getting proper spark but if that’s the case, why would it all of a sudden run? I don’t mind tinkering/troubleshooting but if anyone has a direction worth trying I’ll appreciate- I really want to get it running enough to winterize. Vid is of the few minutes I had it run tonight.
Points/wires/spark plugs were done 2 years ago.
Thanks!!

For starters you do have water going to engine right?
Next when it doesn't want to start and you push forward on the controller are you getting 2 good streams of fuel spraying into the carburetor?

 

[macdonda]

Hi, yes I have the muffs on with water running, I’ll restart tomorrow, push forward on controller and verity two streams - should they appear well aerated/spray (I’m assuming)? I was spraying starter fluid down, carb & choke cleaner and it wouldn’t bite but will definitely check for two visible streams, thanks for the feedback!

 

[kenny nunez]

If you think there is water in the carburetor you will have to at least remove it, flip it over in a clean bucket to check. If there is none then re mount it. Otherwise it needs to be taken apart and cleaned. You may not need new gaskets if you are lucky.
Or just get a kit from Sierra. # 18-7098-1
Mercury Marine #. 3302-804844002

 

[macdonda]

If you think there is water in the carburetor you will have to at least remove it, flip it over in a clean bucket to check. If there is none then re mount it. Otherwise it needs to be taken apart and cleaned. You may not need new gaskets if you are lucky.
Or just get a kit from Sierra. # 18-7098-1
Mercury Marine #. 3302-804844002

Thanks I’m going to check spray pattern then I’ll pull it off / flip over and check for water

 

[ROY WILLIAMS]

Thanks I’m going to check spray pattern then I’ll pull it off / flip over and check for water

I did the carb top screws .... take it off the carb inspect it . also the float spec position adjusted it .. the throttle cleaner [no carb cleaner ] did the cloth and a very small brush... the gasoline is the alcohol in the carb bowl ... the gasoline is the preventive gasoline marine gasoline additive ..
did the spray throttle cleaner and the spray plastic tube of the CARB orifice ....
also the gasoline tank of that water ...also the gas tank venting outside ?

 

[markhodges78]

Hi, yes I have the muffs on with water running, I’ll restart tomorrow, push forward on controller and verity two streams - should they appear well aerated/spray (I’m assuming)? I was spraying starter fluid down, carb & choke cleaner and it wouldn’t bite but will definitely check for two visible streams, thanks for the feedback!

No it should not be a spray it should be 2 steady strong streams and the boat should not be running as you will have to look down in the carburetor and you don't want your face over it while running in case it back fires unhook the cable and control carburetor by hand also make should you have 12 volts going to the purple wire on your coil while the switch is on

 

[macdonda]

I confirmed tithing coming in from the carb down the throat, but when I disconnect the fuel pump line it pumps into a jar, it’s just not making it down the throat, I pulled the carb out it appears clean, no blockage from what I can see so cleaning it up.
I checked voltages and they looked good.
Any thoughts?
Thanks!

 

[macdonda]

I pulled/cleaned carb, kept same components but cleaned them all, reinstalled and can see lots of gas going down now but still won’t run, I got it to start at high throttle but it ran very slow, open to any suggestions, if it’s likely carb, I’m thinking about buying a cheap Amazon one to try out, if it doesn’t work, keep for parts as needed

 

[Scott Danforth]

I pulled/cleaned carb, kept same components but cleaned them all, reinstalled and can see lots of gas going down now but still won’t run, I got it to start at high throttle but it ran very slow, open to any suggestions, if it’s likely carb, I’m thinking about buying a cheap Amazon one to try out, if it doesn’t work, keep for parts as needed

do NOT buy the cheap chinesium junk carbs from Amazon.

Visit mikes carbs or Cliffs and rebuild yours.

if you didnt chase every passage with a piece of fishing line or fine copper wire, its not clean.

 

[Grub54891]

yeah, I don't buy cheap carbs. I did once. It was a total failure. I rebuild carbs myself so I don't know why I did that. lol Afer rebuilding properly, it ran like a champ. Did you change the filter at the carb itself? The one where the line goes into the carb.

 

[ROY WILLIAMS]

do NOT buy the cheap chinesium junk carbs from Amazon.

Visit mikes carbs or Cliffs and rebuild yours.

if you didnt chase every passage with a piece of fishing line or fine copper wire, its not clean.

yes all those china parts , very mess ...all my maintenance fix the wrong china products ..did the electronic components of those country ...

 

[macdonda]

The fuel pump working well as is the carb, lots of gas flowing. I started looking at the electrical and with the key turned on (and all gauges/lights working) have no voltage across the return purple wire to ignition components (i.e. nothing to the ignition coil, the electric choke, alternator etc.. ), it’ll turn over but no spark. I can confirm 12v across the safety lanyard but downstream nothing, I checked main connection at the back, looks clean and tight, open to any suggestions- thanks!

 

[macdonda]

Another drawing, I don’t have voltage across the purple to ground on anything coming back

 

[ROY WILLIAMS]

Another drawing, I don’t have voltage across the purple to ground on anything coming back

the emergency switch of the ignition components ..
starter the engine ... then the no running . the distributor is no spark ..
did the ignition fuse / emergency switch .. did the corrosion of the lugs/fuses ...

 

[macdonda]

View attachment 389684

the emergency switch of the ignition components ..
starter the engine ... then the no running . the distributor is no spark ..
did the ignition fuse / emergency switch .. did the corrosion of the lugs/fuses ...

No spark at distributor but no voltage to any of the ignition components, I checked the lugs, no corrosion, one of the 7.5A fuses is discoloured hard to see if it’s bad but I’ll replace tomorrow l, from what I can see though there’s no fuses for any of the ignition components (purple wires)

 

[ROY WILLIAMS]

No spark at distributor but no voltage to any of the ignition components, I checked the lugs, no corrosion, one of the 7.5A fuses is discolored hard to see if it’s bad but I’ll replace tomorrow l, from what I can see though there’s no fuses for any of the ignition components (purple wires)

yes the fuses of the corrosion ...I was the 1978 boat .... and the electrical components inspected it ... also the connectors ...
I was the war veteran NAVY electronic tech DESTROYERS/SUBMARINES , and the Boston MBTA trains the electronic / mechanic .....retired 27 yrs ...

 

[nola mike]

So you don't have any power to #5 on the female side of the plug, but do at the gauges? Find the common point of your purple wire under the helm. They daisy chain off the gauges and eventually one goes from the helm to the cannon plug in the stern. Would be strange that you had spark before, rebuilt carb, and now no spark. But of course not impossible.

 

[macdonda]

So you don't have any power to #5 on the female side of the plug, but do at the gauges? Find the common point of your purple wire under the helm. They daisy chain off the gauges and eventually one goes from the helm to the cannon plug in the stern. Would be strange that you had spark before, rebuilt carb, and now no spark. But of course not impossible.

I should have said I assumed spark it did start up eventually before but took many, many tries but agree - to go from some spark to none is odd

 

[cdavy000]

Okay I have had similar issues and it sounds like your timing/ fuel mixture are off. It sounds like your engine is immediately flooding itself on start up because it isn’t combusting the fuel in the cylinders soon enough. Have you changed fuel/air mixture screw or idle speed screw on carb at all?? Next time you are at the boat push the throttle SLOWLY all the way to the wide open throttle position with the throttle in NEUTRAL mode, then crank the engine and see if it starts up better. If so that means something is causes your fuel mixture to be too rich. You can also try just bumping the key to the start position multiple times for one second each in quick repetition to see if that makes it start.