Engine turns over turns over then cuts off

Ok so I have a 1998 Regal with a 4.3L Mercuiser Alpha I. I'm not sure if I have a TB ignition or not but it's not a points. (not real sure what the difference between TB and standard). Anyway, I have replaced the plugs, plug wires, starter, batteries, and fuel filter. I have cleaned the distributor cap contacts and rotor, carb. with spray, and battery connectors.

When I go to start the fuel sender kicks on, gas jets into carb. (with throttle) and the engine cranks and turns over...then it immediately cuts off. When I go to start it again it will not start with just a turn of the key, I have to pump more gas into the carb. and the same thing happens...turns over and immediately cuts off again. She just won't stay running. I've looked around on the forums and can't seem to find a fix for my specific problem. A little help please. Thank you.

Re: Engine turns over turns over then cuts off

get new cap and remove all liquid from inside of cap it does not help.
do you have 12v at the coil?
get a spark tester and remove lead from centre of distributer,leave attached to coil
turn engine over.is there spark?
if not disconnect green/white cable to sensor and rapidly earth it 3/4 times per second still with spark tester attached
if it sparks then;
sounds like the sensor is finished.

Re: Engine turns over turns over then cuts off

I have spark because the engine turns over. It just doesn't stay running...right?

Re: Engine turns over turns over then cuts off

This might be a long shot, but my control box has a 'run/off' toggle switch.

If it's in the off position, then the engine cranks over but shuts down as soon as you let go of the key. It had me thinking the first time I left it in 'off'.

If it's in 'Run' then I would check that circuit for electrical issue.

GL

Re: Engine turns over turns over then cuts off

pvmtsux said:

I have spark because the engine turns over. It just doesn't stay running...right?

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Turns over means that the engine spins. It doesn't mean that you have spark or gas or compression. If it momentarily starts or "catches", that's different. Not knowing what your ignition system is is going to make it difficult to diagnose. If it seems to catch when the key is in the start position but stops when you release it, that means that you're getting power to the coil from the slave solenoid during cranking, but not otherwise. At least on the older engines. Anyway, sounds like the first step is to figure out what your ignition system is-someone will help you if you post your s/n.

Re: Engine turns over turns over then cuts off

I'll grab and post my ignition SN today. Just to be clear...my engine starts and runs for about 3-5 seconds (until the gas in the carb burns up) then putters out.

Re: Engine turns over turns over then cuts off

Sounds like its time to quit guessing, roll up your sleeves and get into to fundamental engine 101 troubleshooting....
Start on page 1C-7:
http://boatinfo.no/lib/mercruiser/manuals/mercruiser25.html#/72

Good luck!

Re: Engine turns over turns over then cuts off

If you have a electric fuel pump jump the two prong oil pressure switch which is just above the oil filter

Re: Engine turns over turns over then cuts off

ENSIGN said:

If you have a electric fuel pump jump the two prong oil pressure switch which is just above the oil filter

Click to expand...

I did this earlier in the season because the oil pressure switch wasn't working.



I think it may be the distributor ignition sensor. I'm picking up a new one today and hopefully that does the trick.

Re: Engine turns over turns over then cuts off

I went through the troubleshooting steps (thank you ktbarrentine) and ended up replacing the distributor ignition sensor...no change. She still will not stay running. Any other input while I check the compression?

Re: Engine turns over turns over then cuts off

Check voltage at the coil with the key on. Could be you are getting coil voltage in the start position but not run position.

Re: Engine turns over turns over then cuts off

pvmtsux said:

I'll grab and post my ignition SN today. Just to be clear...my engine starts and runs for about 3-5 seconds (until the gas in the carb burns up) then putters out.

Click to expand...

I'm curious why everyone is concentrating on the ignition system when he says it runs until the fuel in the carb is gone. This sounds to me way more like a carb/fuel delvery problem than an ignition problem.
whenever I have a small, 2 cycle engine do this, ie - burns the fuel poured into the carb and then dies, I pull the carb and clean/rebuild it. Why would the same issues on a boat be any different?

Re: Engine turns over turns over then cuts off

Everyone?

Re: Engine turns over turns over then cuts off

Compression is good across the board. I have 11.79V at the coil in the run position.

When this first started, my initial thought was a fuel delivery and/or carb problem. I just didn't want to go straight to the carb and start ripping it down. I don't think this is an electrical issue or an ignition problem because I have tested or replaced almost all ignition components.

Re: Engine turns over turns over then cuts off

Had a buddy last week his boat did the same thing ended up being a loose wire on the key switch maybe look it over but his done the exact same thing

Re: Engine turns over turns over then cuts off

I'll never understand what people have against spark testers, or basic diagnostics. Buy one, they are cheap, much cheaper than your guessing has been already. Start the engine, what is going away? If it is spark then go from there, if you have spark as the engine stalls, and continue to have sprak on restart or crank no start, then its gotta be a fuel isue right? Does it start every time you turn the key and then shut off or does it just crank after it stalls? OK, lets talk fuel.... I am not farmiliar with this exact boat, but I am guessing its carbeurated "When I go to start the fuel sender kicks on, gas jets into carb. (with throttle)" I am taking this to mean that when you advance the throttle the accelerator pump is working as it should. Are you getting any gas into the float bowl? I would guess yes beacuase usually the accelerator pump sits in or near the bowl, thats where it gets gas from to pump. Do you have a fuel pressure gauge / tester? does this system have a few second prime and then a constant run electric fuel pump? Maybe the pump is not running in the on position but is priming the system. Identify what key ingredient of combustion you are losing and then figure out why.