5.0 mpi shuts off while cruising! (((Update))) Still in need of help with fuel pressure specs and what to try next. Thank you!

[RichRab]

5.0 mpi shuts off while cruising! (((Update))) Still in need of help with fuel pressure specs and what to try next. Thank you!

2002 5.0 mpi alpha 1 gen 2. Been having trouble with rough idle so I thought I would take boat for a ride with some fresh gas. Cruising along around 2000 rpm and the boat shuts off. No alarms, beeps or other obvious problems. Boat restarts immediately. I am going to clean battery cables and maybe try one battery at at a time. Any ideas? Thank you. RR

 

[drewactual]

Ignition switch. Checks connects, clean, reinstall..

 

[Fun Times]

Also try checking the main wiring harness on the engine. It should be a black cannon plug. Try wiggling it with the engine on to see if the engine shuts off on you.

 

[RichRab]

Is the main harness the plug at the rear of motor on the starboard side that I think is called a 7 wire plug? I had a problem last year where the boat would not start and after a guy worked on it the oil pressure gauge would not work and he left that loose. Thank you . RR

 

[RichRab]

I was having trouble with stalling and rough idle as I stated in another post. Boat would not run on Sunday morning and I put some injector cleaner in previously. Went out later and all of a sudden the boat ran perfect. Maybe as I suspected there was a dirty injector. Will run it some more this weekend and it was suggested that I use CRC fuel stabilizer year round. Thank you. RR

 

[RichRab]

Take boat out one day and it runs perfect. Next time it running rich up to 1200 rpm. Shuts off while moving. Stumped. Probably stalled 10 times heading home. Took for a ride next day and still ran rough but did not stall. Thank you. Rich

 

[RichRab]

Fuel pressure spec?

Mercruiser 5.0. Mpi alpha 1 gen 2. Problem with rough idle. Is 38 psi fuel pressure in specs? Thanks. RR

 

[alldodge]

Mercruiser 5.0. Mpi alpha 1 gen 2. Problem with rough idle. Is 38 psi fuel pressure in specs? Thanks. RR

30 psi at 1800 rpm for servise manual 24 1998-2001
43 psi at 1800 rpm for service manual 31 2001-up
38psi at idle could be about right

Serial numbers and years help

 

[RichRab]

2002. Serial number not with me now. I put the year in twice but it would not post then forgot to do it again. Thanks. Would a problem with rough idle and sometimes shutting off store a code? I have been dealing with this problem all year and spelled it all out in another post under "5.0 mpi shuts off while cruising". Also when boat was shutting off I switched batt switch from 1 to 2 and both and it did not make a difference. . Thank you. RR.

 

[Fun Times]

Is the main harness the plug at the rear of motor on the starboard side that I think is called a 7 wire plug? I had a problem last year where the boat would not start and after a guy worked on it the oil pressure gauge would not work and he left that loose. Thank you . RR

Yes the wire harness plug should be at the rear of the engine while normally on the starboard side. It's usually called the 10 pin connector. You'll want to double check it just to make sure there is no bad connections.

Take boat out one day and it runs perfect. Next time it running rich up to 1200 rpm. Shuts off while moving. Stumped. Probably stalled 10 times heading home. Took for a ride next day and still ran rough but did not stall. Thank you. Rich

Since the engine seems to be running rich, you should pull all 8 spark plugs and check or replace them. When was the last tune up done? Cap, rotor, plugs, fuel filter/s?

We really could use your serial number because your engine model year is at a turning point for merc where your fuel pressure could be either 30 or 43 psi with the vacuum hose removed at idle. Plus you need to know what the PSI is when it's having it's problem.

I believe your fuel psi is to high at 38, I think you have a 30 psi regulator but we need your serial number to know for sure.

I went ahead and merged your two topics together so it's easier for us all to keep track of your engine running problems.

Let us know, good luck.

 

[RichRab]

Thank you for the tips. Complete tune up at start of season. New filter at end of last season and again at the start of this season ( April) when boat was running bad and I drained it into a glass jar and gas looked good. I will get the serial number. Thank you. Rich R.

 

[RichRab]

Serial no. 358103

 

[alldodge]

Serial no. 358103

Your missing 2 digits in front of the number. The first will be a number usually 0 or 1, the second is a letter. I tried 1A and it comes out a 496, and 0W is not found

 

[RichRab]

0m358103. Thank you, RR

 

[alldodge]

0m358103. Thank you, RR

Your serial number indicates your fuel pressure should be 43 psi at 1800 rpm (best to know PSI at all RPM) and we would use service manual 31. http://www.mercruiserparts.com/Show...=7585&bnbr=50&bdesc=Fuel+Pump+And+Fuel+Cooler

Check to see if your vacuum line is connected to your fuel pressure regulator or not behind the cover of your cool fuel box. Your cool fuel is on the port side behind the engine mount. Follow the vacuum line up to the intake manifold and verify it is connected. If vacuum line is connected correctly, take a vacuum gauge and put it on the end at the regulator and see if you get any vacuum (should get 15-21 in at idle.

On the electrical side, have you removed the cannon plug on the back of the engine yet? If not remove it and check the pins. Clean pins needed and put some dielectric grease one the pins and push it back together then do a wiggle test while engine is running.

Your engine serial number falls under this Mercruiser service bulletin, so you will want to try all the testing inside the bulletin especially since you have an alpha drive. http://www.google.com/url?sa=t&rct=...ioDABQ&usg=AFQjCNHUdvqBYKGkyHF9hZalwTRD-p2YZw

Your serial number also indicates you should have a low pressure fuel pump and fuel filter inline between the fuel tank and water separator fuel filter that could have a clogged filter screen or low fuel pressure. You may have to inspect this as well. http://www.mercruiserparts.com/Show...el+Filter+And+Boost+Pump(S/N+0M336102+And+Up)

http://www.crowleymarine.com/search_results.html?string=0m358103

http://www.mercruiserparts.com/selectDocs.asp?doc_nbr=884712

 

[RichRab]

Will ck this weekend, thank you. RR

 

[RichRab]

I put a fuel pressure gauge on and took boat for a couple of rides. Saturday after driving for about an hour the boat shut off and would not start. Fuel pressure around 40. Coil sparking but not out of cap. I installed an extra cap and it started right up. Ran it hard for about 10 min and no wake for 20 minutes with no problem. Stumped how a cap would just stop working. RR.

 

[RichRab]

I have had other boat problems so this has not been a priority but it seems like about every 50 minutes or so the boat shuts off. Turn key and it fires right up. With nicer weather I will investigate further. Thank you. RR

 

[alldodge]

Stumped how a cap would just stop working. RR.

You have a crab style cap (most call it a crap cap), it will die and look fine, even look brand new and still be bad. They go bad often and without warning.

I have had other boat problems so this has not been a priority but it seems like about every 50 minutes or so the boat shuts off. Turn key and it fires right up. With nicer weather I will investigate further. Thank you. RR

As for the dying after 50 minutes, check to see if you gas cap and vent line is not plugged. Mud dobbers like to build a nest in them and you could be drawing a vacuum. When it stops open the gas cap and listen for air to be sucked in

 

[RichRab]

Will try that next weekend. Thank you. RR