00" Mercruiser 5.0L Starting Problems

[dukethedog]

I have a 2000 FWC Mercruiser 5.0L Alpha 1. Yesterday I pulled the boat out of the slip had the kids get into the tube. While waiting for the engine to warm up it died. Upon subsequent attempts to start the boat it would fire for say one second and die. Little history on the boat -- is that it has 70 hours on it sat for one year unused. Five hours ago I installed a rebuilt card and had it professionally adjusted. At that time they found the fresh water-circulating pump was leaking and that was replaced. The boat ran like a champ for five hours and then died. I think it’s the fuel pump or the oil pressure switch. <br /><br />Any thoughts form the experts out there on what the problem may be?

 

[Wotknot]

Re: 00" Mercruiser 5.0L Starting Problems

Have you changed the filter in the water separator? If not, I would start there.

 

[dukethedog]

Re: 00" Mercruiser 5.0L Starting Problems

Yes separator, fuel filter and all fluids changed within the past 15 hrs?

 

[Don S]

Re: 00" Mercruiser 5.0L Starting Problems

Merc uses an oil pressure switch to control the electric fuel pump. While cranking, the fuel pump gets power from the starter, once started and oil pressured closes the switch the oil pump runs from ignition power. <br />Check that switch or the wiring to it. It's located just over the oil filter location on the block (Port side of engine, aft. Just above oil pan level.<br /><br />Below is the wiring diagram. 5 is the switch, 6 is the fuel pump.<br />If you disconnect the 2 wires off the switch and hook them together, the fuel pump will run, even if the engine is not running, but the ign. switch is in the on position.<br /><br />

 

[Wotknot]

Re: 00" Mercruiser 5.0L Starting Problems

I'd still look at the separator again and see if you've got anymore water in it. After sitting for a long time, condensation will get into your fuel tank......just a shot in the dark, but I'd start with the cheapest fix first.

 

[dukethedog]

Re: 00" Mercruiser 5.0L Starting Problems

Sounds like a great way to test the FP. How will I know if the FP is running? Will the engine start with the two wires connected? I assume if the engine starts the issue is with the pressure switch and shut the engine down immediately. If it doesn't fire is it a safe stretch it assume the FP is bad?<br /><br />Anxiously waiting your advice!<br /><br />Bruce

 

[dukethedog]

Re: 00" Mercruiser 5.0L Starting Problems

Sounds like a great way to test the FP. How will I know if the FP is running? Will the engine start with the two wires connected? I assume if the engine starts the issue is with the pressure switch and shut the engine down immediately. If it doesn't fire is it a safe stretch it assume the FP is bad?<br /><br />Anxiously waiting your advice!<br /><br />Bruce

 

[Don S]

Re: 00" Mercruiser 5.0L Starting Problems

If you hook the wires together from the pressure switch and turn the igntion switch to on, you will hear the pump running. Then try to start the engine, if it starts and keeps running, then the switch is defective or the connections were bad. If it still runs for a few seconds and dies, then it's something else. <br />Troubleshooting is a process of elimination.