Engine runs for about 30 sec then kills?

[haslambra]

We installed a new 4.3l v6, with a 4 barrel carp. merc engine in our boat, took it out last weekend for the first time, it started fine; then we let it idol to warm up. Then it killed. To start we had to push the throttle forward then start it. That led us to believe it was the fule pump. It would Start right back up then we took off. Almost every 30 sec it would shut off. We took the fuel pump off and turned the key and it was pumping fuel out. We tried adjusting the jets but that didnt seem to work either. We have a new fuel pump we are going to put in since the old one is from the previous engine. But could it be something else? Any sugestion would help.

Thanks in andvance...

 

[watermellonI]

Re: Engine runs for about 30 sec then kills?

Hey Haslambra
Have you replaced any filters?

 

[bjcsc]

Re: Engine runs for about 30 sec then kills?

For safety reasons, fuel pumps get power from their relays from two sources: 1) The cranking circuit and 2 ) The alternator. This prevents the fuel pump from running when the engine is not running. If the power path from the alternator is disrupted, the fuel pump will only work while you crank the engine, fill up the bowl, and the engine will run until the bowl is empty - about 30 seconds. Pushing the throttle all the way forward may have given the engine access to the secondary bowl. May or may not be your problem, but it's worth investigating...

 

[Don S]

Re: Engine runs for about 30 sec then kills?

What bjcsc says is correct, if you have a Volvo, if you have a Mercruiser, it's set up with an oil pressure switch.
Which do you have? Model number, SN, and year would be helpful

 

[haslambra]

Re: Engine runs for about 30 sec then kills?

Its new, bought last year Mercruiser 4.3L v6. (Our oil pressure gage, and RPM gage was not reading anything so we think we may have a wire that is not connected Properly.) Hope this helps.

 

[Don S]

Re: Engine runs for about 30 sec then kills?

The oil pressure switch, and the oil pressure gauge sender have nothing to do with each other, and means nothing. Of course if the engine runs for 30 seconds and doesn't have oil pressure, then YEA, that's a major problem.
But since you have a tach, an Oil pressure gauge, and who knows what else, not working, it might be time to get the ole DVM out of the tool box and find out where you are loosing power.

 

[180shabah]

Re: Engine runs for about 30 sec then kills?

^^^^Agreed^^^^

I wouldn't have that thing in the water untill I knew it could run for more than 30sec. And I would absolutely have my gauges working before I risked destroying my brand new engine.

 

[ulster1]

Re: Engine runs for about 30 sec then kills?

I had the same problem last year??
It was the gasket under the carb it was leaking air I tightened the four mounting bolts no more problem.

 

[haslambra]

Re: Engine runs for about 30 sec then kills?

UPDATE: We put in a new oil switch and took boat out yesterday. Boat ran a little bit longer then would shut down, again. Did this for the first 20 min or so. After going at a slow speed it kept running, after that the whole day it ran fine, never killed. On returning home something must have happened because when you go to throttle up it would pick up speed until a certain point and and throttle back down not picking up any speed. Any suggestions?

 

[180shabah]

Re: Engine runs for about 30 sec then kills?

What condition is the entire fuel system in?

Trash in the tank? trash in the carb? Vent line blockage(possibly water picked up and settled in a low spot in the line)?

 

[Coors]

Re: Engine runs for about 30 sec then kills?

Don's
http://forums.iboats.com/showthread.php?t=167561

 

[Bondo]

Re: Engine runs for about 30 sec then kills?

Ayuh,....

Any chance you might have Looked at the Fuel Filters thru all of this,..??

 

[haslambra]

Re: Engine runs for about 30 sec then kills?

Whats they best way to check gas guage, RPM,s, Speedometer, Oil Pressure. We know that we have oil pressure but still cant get the guages to work. We have tried checking power, and ground to guage and they seem good, but gauges dont register. Can guages stick? Or are they just bad? can we take 12v battery and wire to one side of guage and ground out other side on guages to see if it registers?

We will replace the fuel filter...

 

[Coors]

Re: Engine runs for about 30 sec then kills?

I think more than a fuel filter needs replaced.
Start at the senders, and trace the wires. Clean all contact points, slices, terminals. Or use a meter.

 

[buggiedad_67]

Re: Engine runs for about 30 sec then kills?

did you check your dash fuse's i can see one not working from death but you shouldnt loose all, were they working before you changed engine, if they were you may have hooked some wires up wrong.

 

[haslambra]

Re: Engine runs for about 30 sec then kills?

We have checked all the fuses, We do have a few gauges working but still have 3-4 not working. We have also taken the meter to them and show that there is "power" to them. I'm just wondering if its just the gauges. From my recollection we didn't check them before we replaced the engine.