5.7 vortec motor starts ,then bogs and dies

[newtoboat101]

1996 5.7 vortec ,alpha 1 gen 1 with edelbrock 4 barrel, delco distributor,,carter electric fuel pump with orca cooling half system ,motor starts fine, revs fine ,but seconds later when water comes out of exhaust ,motor changes boggs for a while 5-20 seconds then dies ,starts right back up , fuel pressures fine ,even when it starts bogging i can get gas down the bowls ,i took off and replaced both exhaust flappers and gaskets ,also flushed y pipe ,seems good,but same result, when boat is running and water exits ,its a good flow but still boggs and dies any ideas appreciated , what to check next

 

[newtoboat101]

also get a sound never noticed before ,when engine shuts down ,i hear girgling for stb side exhaust hose from thermostat housing never noticed that sound before

 

[newtoboat101]

i took out the 7th plug and cranked motor for maybe 5 seconds ,no water coming out ,repeated plug 8 and no water coming out ,as for recheck fuel filters, spin on, and any inline or on carb filters. ,i tried my boat gas tank thru seperator,then tried kicker gas tank,portable, no luck,also took throttle cable off ,so i can give it gas maually ,it shows gas but still dies, note, when i try to keep it running manually it still boggs never comes back to running just dies

 

[newtoboat101]

question how much fuel should a edelbrock 1409 marine carb have in its fuel bowls after motor dies, i get three wot strokes and its empty,could be my electric fuel pump is shutting off ,have fuel pressure test , also i noticed my tach is fine till it starts to bog and then it pins ,and then goes to zero back to pin repeatly think it maybe more electrical ,almost like tach goes into rev limit mode gonna unhook tack and check

 

[newtoboat101]

disconnected tach ,still no luck,could a bad thermostat cause a bogg to die? went and unhooked thermostat housing to exhaust hose ,at exhaust ,stuck hose in a bucket started motor til it died as usual,water flowed out ,but what was strainge isafter motor shut off the hose sucked all the water back up into my thermostat or down other exhaust hose ,is that normal, only?

 

[Scott Danforth]

my guess is the idle circuits are plugged

 

[dubs283]

Thermostat has nothing to do with fuel/ignition system and wouldn't cause the engine to bog out and die. That would only happen under severe overheat and at that point you'd have much bigger problems

If you're getting three good blasts from the accelerator pump after the motor dies it sounds like there should be enough fuel in the bowls to keep the engine running

Try dribbling some good fresh fuel directly down the primaries with the engine running, if it stays running with the dribble but dies when you stop the carb idle circuits are most likely the issue and its time for a carb rebuild

 

[newtoboat101]

Thermostat has nothing to do with fuel/ignition system and wouldn't cause the engine to bog out and die. That would only happen under severe overheat and at that point you'd have much bigger problems

If you're getting three good blasts from the accelerator pump after the motor dies it sounds like there should be enough fuel in the bowls to keep the engine running

Try dribbling some good fresh fuel directly down the primaries with the engine running, if it stays running with the dribble but dies when you stop the carb idle circuits are most likely the issue and its time for a carb rebu

thanx , i tried to dribble fuel ,but no success, i do want to check the metering rods , i multimetered the carter electric fuel pump and have question ,should the multimeter go up to 10.925 volts when starting, ,then go to 0.00 when motor starts ,or should it hold at 10.925 while motor is running my guess is the idle circuits are plugged. will look at this ,but not sure its carb related . When i start engine it will run fine for 10 seconds ,but then theres a ,what feels like a load on engine , at the same time the water starts exiting the boat then runs for maybe 15 seconds and then shuts off ,super rough ,no power

 

[Scott Danforth]

thanx , i tried to dribble fuel ,but no success, i do want to check the metering rods , i multimetered the carter electric fuel pump and have question ,should the multimeter go up to 10.925 volts when starting, ,then go to 0.00 when motor starts ,or should it hold at 10.925 while motor is running my guess is the idle circuits are plugged. will look at this ,but not sure its carb related . When i start engine it will run fine for 10 seconds ,but then theres a ,what feels like a load on engine , at the same time the water starts exiting the boat then runs for maybe 15 seconds and then shuts off ,super rough ,no power

look at the wiring.

when cranking, your fuel pump gets it power from the starter R terminal.
when running your fuel pump gets its power from the oil pressure switch

 

[Bondo]

thanx , i tried to dribble fuel ,but no success, i do want to check the metering rods , i multimetered the carter electric fuel pump and have question ,should the multimeter go up to 10.925 volts when starting, ,then go to 0.00 when motor starts ,or should it hold at 10.925 while motor is running my guess is the idle circuits are plugged. will look at this ,but not sure its carb related . When i start engine it will run fine for 10 seconds ,but then theres a ,what feels like a load on engine , at the same time the water starts exiting the boat then runs for maybe 15 seconds and then shuts off ,super rough ,no power

Ayuh,..... You have a wiring problem,..... You should see battery voltage when cranking on the starter, 'n 'bout 13.6 when the motor is running,....

 

[newtoboat101]

could it be 3 prong oil pressure switch not working or break in wiring, if electric fuel pump gets initial charge from starter ,then swicthes to 3 prong would charge from fuel pump still be present at the fuel pump posts

 

[newtoboat101]

i have attempted many things ,with no luck , this morning i went out and changed the 3 prong ,still no luck ,,but then i put shifter in forward and tried to start ,as its supposed to do nothing when i turn key , then put back in neutral and started engine ,tried to get my shift interupt to work ,NOTHING ,now this connects to my 3 prong oil pressure sensor ,could this be my issue would that ,basically ,retard my motor, after 10-15 seconds after starting

 

[newtoboat101]

i have newer style shift bracket ,just a
note

 

[newtoboat101]

checked battery voltage ,good. checked electric fuel pump by starting and putting hand on pump ,feels like its working ,do not feel its gas related ,but electrical issue ,thats when i checked interupt switch ,and its not working at all any help appreciated especially with regards to my interupt switch not working ,and could it be making motor bogg

 

[newtoboat101]

need to clarify ,its the shift cutoff switch thats not working i call it interupt switch

 

[Lou C]

When my OMC Cobra interrupt switch started sticking it did exactly that.
Other things to check…is the auto choke getting pulled open slightly by the pull off or vacuum break? Does it close fully for a cold start? Does it open fully?
Another long shot I recall reading about was that on some Edelbrock carbs if the float isn’t set up right they can rub against the side of the fuel bowl & cause problems….

 

[newtoboat101]

thanx Lou choke seems to work fine,closes for cold start, i will inspect the fuel bowl ,issue but when i get home tonight gonna focus on shift cutoff switch area and wiring for it, thanx again

 

[Bondo]

checked battery voltage ,good. checked electric fuel pump by starting and putting hand on pump ,feels like its working ,do not feel its gas related ,but electrical issue ,thats when i checked interupt switch ,and its not working at all any help appreciated especially with regards to my interupt switch not working ,and could it be making motor bogg

Ayuh,..... How did you check the interrupt switch,..??
How is it wired up,..??

Yer boat appears to be a mismash of whatever somebody had layin' around,....
With an Alpha 1, gen.1, the interrupter should kill the ignition dead when manually actuating it,....

 

[newtoboat101]

bondo i started motor and moved bracket that has plunger by hand ,nothing , i just discovered this at 6 am this morning ,had to stop to go to work , its the old saying ,WTF it worked before