Mercruiser 5.0 EFI engine problem
 

Hi all,

The other day I got 100 yards from the jetty after the engine started fine, only for it to die and not restart. It has run fine since I have had it (about 5 months). After about 15 minutes the engine did start briefly but failed the moment I went into gear and then refused to restart. After being towed back I started to investigate the issue. The battery is fine. The fuel pump primes when you switch it to ignition 1 and there is fuel in it. The engine turns over fine when you attempt to start but there is no spark or even fuel in the injectors. I have since replaced the coil and the king lead as they looked knackered but I am now thinking it has more to do with a problem with the engine cut off which is preventing a) any spark from the coil and b) any fuel from the injectors. Has anyone ever heard of anything like this?

Many thanks for any advice offered.

Kind regards,

Re: Mercruiser 5.0 EFI engine problem
 

This happened to mine it would start fine then when it got warm it would stop or if you turned it of wouldent start it endedup being a faulty coil .

Re: Mercruiser 5.0 EFI engine problem
 

Just a thought from you have said so far, I would check your safety switch it should cut off fuel and spark to the engine if it is accidentally being activated.

Re: Mercruiser 5.0 EFI engine problem
 

Hi guys, thanks for your responses. The issue has now been resolved and I thought I would let you know what it was. It was the optical sensor unit within the distributor. The rotor arm looked like it had been vibrating the sensor unit and a tiny microchip had fallen off the sensor unit causing it to fail and not report to the ECU the rotor position. The ECU in turn then would not send a message to the injectors to fire. The new sensor unit cost about £150. Looks like Mercruiser had noticed this flaw as the new unit had the electronics embedded in a resin. Anyway all good now, just waiting on some good weather in the UK. Kind regards,

Re: Mercruiser 5.0 EFI engine problem
 

I would have never guessed.... ;)