Engine starts, idles for 10 seconds then dies

[Swedefj40]

1996 4.3 LX, A1G2 Weber 4bbl Carb (800 hrs)... so the wife and I were at the launch yesterday, ready to head out fishing and started the motor. It ran for maybe a minute then slowly dropped rpm sputtered and died. I left it for maybe 20 seconds then tried it again and same thing. Idled for a minute then died. Third time I tried it and it stayed running for a good 5 minutes so I decided to continue on our trip.

I recently had the fuel line apart at the tank to put In a tee so that I could run my kicker off of the main tank instead of the portable 3 gal tank (added antisyphon valves to each line) so in the back of my mind I'm thinking it was just an air lock problem. Anyway, we left the dock and headed out and it ran great for the 45 minute run to where we were going to fish.

We fished (using the kicker) for about an hour and decided to run to a different spot and the same issue happened. I tried to start it 4 or 5 times and it never would stay running. I changed the fuel/Water filter no change. Swapped in a new electric fuel pump, no change.

I have voltage at the pump when trying to start.

I direct wired the fuel pump to the battery to bypass the safeties (oil pressure, water temp) expecting the pump to prime the carb and shut off but it kept running and that's when I noticed fuel dripping from a venturi into the primary bore.

Sorry for the long post but I just wanted to give as much detail as possible.

I'm going to rebuild the carb next thinking it might be a stuck float but any opinions on my issue would be helpful.





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[flashback]

If this problem came up after installation of tee I would suspect it caused the problem.

 

[tank1949]

1996 4.3 LX, A1G2 Weber 4bbl Carb (800 hrs)... so the wife and I were at the launch yesterday, ready to head out fishing and started the motor. It ran for maybe a minute then slowly dropped rpm sputtered and died. I left it for maybe 20 seconds then tried it again and same thing. Idled for a minute then died. Third time I tried it and it stayed running for a good 5 minutes so I decided to continue on our trip.

I recently had the fuel line apart at the tank to put In a tee so that I could run my kicker off of the main tank instead of the portable 3 gal tank (added antisyphon valves to each line) so in the back of my mind I'm thinking it was just an air lock problem. Anyway, we left the dock and headed out and it ran great for the 45 minute run to where we were going to fish.

We fished (using the kicker) for about an hour and decided to run to a different spot and the same issue happened. I tried to start it 4 or 5 times and it never would stay running. I changed the fuel/Water filter no change. Swapped in a new electric fuel pump, no change.

I have voltage at the pump when trying to start.

I direct wired the fuel pump to the battery to bypass the safeties (oil pressure, water temp) expecting the pump to prime the carb and shut off but it kept running and that's when I noticed fuel dripping from a venturi into the primary bore.

Sorry for the long post but I just wanted to give as much detail as possible.

I'm going to rebuild the carb next thinking it might be a stuck float but any opinions on my issue would be helpful.





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I suspect air getting in or defective plumbing. Block off kicker.

 

[Swedefj40]

I've had the boat out a few times after the tee was installed and no issues then. No signs of fuel leaks on either lines and the kicker ran perfect for the 3 hour trip home too.

 

[bbook83]

Try isolating the problem between the carb and fuel plumbing by disconnecting the fuel hose downstream from the T and connecting to a remote tank, even a half full 5 gallon gas can, if you can do that safely.

 

[flashback]

Maybe some debris got knocked loose when you worked on the fuel line and it lodged In a pre filter or float valve... since you mentioned fuel dripping in the carb My guess is the float valve has dirt in it..

 

[tank1949]

I've had the boat out a few times after the tee was installed and no issues then. No signs of fuel leaks on either lines and the kicker ran perfect for the 3 hour trip home too.

go back and tighten clamps. What has changed????? Look for line crimps. Pump fuel into a bucket and measure flow

 

[Swedefj40]

Maybe some debris got knocked loose when you worked on the fuel line and it lodged In a pre filter or float valve... since you mentioned fuel dripping in the carb My guess is the float valve has dirt in it..

Yeah I'm leaning that way too... I'll pull it off this weekend and do a rebuild kit too.

 

[Bondo]

1996 4.3 LX, A1G2 Weber 4bbl Carb (800 hrs)... so the wife and I were at the launch yesterday, ready to head out fishing and started the motor. It ran for maybe a minute then slowly dropped rpm sputtered and died. I left it for maybe 20 seconds then tried it again and same thing. Idled for a minute then died. Third time I tried it and it stayed running for a good 5 minutes so I decided to continue on our trip.

I recently had the fuel line apart at the tank to put In a tee so that I could run my kicker off of the main tank instead of the portable 3 gal tank (added antisyphon valves to each line) so in the back of my mind I'm thinking it was just an air lock problem. Anyway, we left the dock and headed out and it ran great for the 45 minute run to where we were going to fish.

We fished (using the kicker) for about an hour and decided to run to a different spot and the same issue happened. I tried to start it 4 or 5 times and it never would stay running. I changed the fuel/Water filter no change. Swapped in a new electric fuel pump, no change.

I have voltage at the pump when trying to start.

I direct wired the fuel pump to the battery to bypass the safeties (oil pressure, water temp) expecting the pump to prime the carb and shut off but it kept running and that's when I noticed fuel dripping from a venturi into the primary bore.

Sorry for the long post but I just wanted to give as much detail as possible.

I'm going to rebuild the carb next thinking it might be a stuck float but any opinions on my issue would be helpful.





Attach files

Ayuh,..... My guess is,.... The fuel pump oil pressure switch is dying,....

The fuel pump runs off the starter, while crankin', then the fuel pump is suppose to be powered by the oil pressure safety switch,....

If that switch is failing, while crankin', the float bowl fills, it runs on the gas in the carb, til it's gone,....

 

[flashback]

OP mentioned that fuel was dripping in the carb, so he may have more than one gremlin...

 

[Swedefj40]

Ayuh,..... My guess is,.... The fuel pump oil pressure switch is dying,....

The fuel pump runs off the starter, while crankin', then the fuel pump is suppose to be powered by the oil pressure safety switch,....

If that switch is failing, while crankin', the float bowl fills, it runs on the gas in the carb, til it's gone,....

Yup I agree 100% I'll be checking that too. The more I think about it that's what it sounds like. The fuel leaking into the carb may just be another separate issue. I'll look into both though.

 

[tank1949]

1996 4.3 LX, A1G2 Weber 4bbl Carb (800 hrs)... so the wife and I were at the launch yesterday, ready to head out fishing and started the motor. It ran for maybe a minute then slowly dropped rpm sputtered and died. I left it for maybe 20 seconds then tried it again and same thing. Idled for a minute then died. Third time I tried it and it stayed running for a good 5 minutes so I decided to continue on our trip.

I recently had the fuel line apart at the tank to put In a tee so that I could run my kicker off of the main tank instead of the portable 3 gal tank (added antisyphon valves to each line) so in the back of my mind I'm thinking it was just an air lock problem. Anyway, we left the dock and headed out and it ran great for the 45 minute run to where we were going to fish.

We fished (using the kicker) for about an hour and decided to run to a different spot and the same issue happened. I tried to start it 4 or 5 times and it never would stay running. I changed the fuel/Water filter no change. Swapped in a new electric fuel pump, no change.

I have voltage at the pump when trying to start.

I direct wired the fuel pump to the battery to bypass the safeties (oil pressure, water temp) expecting the pump to prime the carb and shut off but it kept running and that's when I noticed fuel dripping from a venturi into the primary bore.

Sorry for the long post but I just wanted to give as much detail as possible.

I'm going to rebuild the carb next thinking it might be a stuck float but any opinions on my issue would be helpful.





Attach files

Do fuel tank pick up tubes have screens that can clog???? Mine did!

 

[nola mike]

OP mentioned that fuel was dripping in the carb, so he may have more than one gremlin...

Yeah, not sure why the effort wouldn't go towards fixing the flooding carb first

 

[Swedefj40]

Do fuel tank pick up tubes have screens that can clog???? Mine did!

My 15 HP Kicker runs off the same pickup tube and ran fine wide open for 3 hours to get back to the launch so I think it's good.

 

[Swedefj40]

Yeah, not sure why the effort wouldn't go towards fixing the flooding carb first

I'll get to that this weekend

 

[tank1949]

My 15 HP Kicker runs off the same pickup tube and ran fine wide open for 3 hours to get back to the launch so I think it's good.

Kicker sucks less fuel???

 

[Swedefj40]

I'll deal with the oil pressure switch circuit 1st and go from there. Hopefully just a bad connection or faulty switch. Then on to rebuilding the carb.

 

[Swedefj40]

Update:
Hooked up my DMM to the fuel pump and it showed 10 v when starting (as expected) and 14+v after it started. I checked around the O.P.S. and wiggled the connector and no change in voltage. As soon as I touched the Purple/yellow spade terminal that goes to the fuel pump, the voltage dropped out. Turned out to be really loose and a bit corroded. Cleaned up the spade (male) end and replaced the female end and it's now rock solid!

What's frustrating is that I thought about checking these leads but assumed they were good since I replaced the switch a few years ago, and was focused on the fuel side since it was the last thing that I was messing with. KISS.

Now for the carb... I quickly checked the primaries after I fixed the O.P.S. issue and noticed the fuel still dripping out of the venturi while it was running. I let it run for 10 minutes or so while I was cleaning up and checked again and found the dripping stopped. I'll look into that next.