5.0 MPI cranks but will not start.....

[JP_R]

Long story short, I was out on the water this past Saturday and 15 minutes into my day, the boat turned off while at 3000 RPMs. Now, it will not turn back on..... I did feel a slight rough idle while leaving the dock. Rough idle went away while accelerating....

Background info....
When the boat turned off, I heard the steady alarm as it was shutting down..... not while running.
When I tried to turn it back on, it did turn on for 1 second and before turning off again and 2 beeps were heard
When trying more times, no audible alarms and no start. Does not even feel like it wants to.
Touched the elbows and while very hot, I could touch them for 5 seconds before feeling getting burned. Also checked the temp on gauge and it was below 175 degrees

* Fuel pump is working and there is pressure in the system
* When cranking, I can now see the tach needle bouncing all over the place... It would not do that before
* Have not been able to take a plug out to check for spark

any ideas on what to check next time I go to the marina to try to diagnose the issue?

Thanks

 

[alldodge]

I'm thinking CPS but would need to scan for codes

The bouncing of the tach would be a key

 

[JP_R]

I'm thinking CPS but would need to scan for codes

The bouncing of the tach would be a key

Yeah a friend said the same. I have the mercury vessel view in order and arriving tomorrow. I’ll check to see what code it gives me.

 

[salty3rd]

First thing I would try is a distributor cap and rotor, Ive had my share of issues with them in my 5.0 mpi’s, including a no start like you described..

 

[JP_R]

First thing I would try is a distributor cap and rotor, Ive had my share of issues with them in my 5.0 mpi’s, including a no start like you described..

Will do. I am trying to find time to go to the Marina this evening a check for corrosion on cap and spark.

 

[JP_R]

Ok so as usual, life happens and I could not find time to go to the marina until yesterday.

that said, a mechanic I had spoken to said “I’ll take a CPS with me and a coil”... with that in mind I went to advance auto parts and bought a chevy c1500 coil to rule that out prior to purchasing the marine version....

when I got to the boat I hooked up the mobile vessel view and it gave me 4 codes... after a quick search, I found out that all 4 are for optional sensors that are not normally installed and that is the computer searching for them and not finding anything.

I hooked up the battery (that I had brought home to fully charge) and replaced the coil...

When I tried starting, I heard the regular BEEP, fuel pump prime and then a faint beep while trying to crank..... I took off the dist cap and there was corrosion, cleaned it with a wire brush and reinstalled.

tried cranking again and this time the engine seem to sound better while cranking but no start or even like it wanted....

finally, decided to creep in the tight space and remove a spark plug.... grounded the plug and no spark while cranking.....

Wondering if it could be the ignition coil module???? no sure how to test it though....

 

[alldodge]

Swap main power relay with fuel pump relay. See if you still hear the pump turn on

 

[JP_R]

Swap main power relay with fuel pump relay. See if you still hear the pump turn on

Thank you... i’ll try that.

 

[Searay205]

Please tell me you didn't bump the ignition cut off device by gear lever. The one with the lanyard.

 

[alldodge]

Please tell me you didn't bump the ignition cut off device by gear lever. The one with the lanyard.

Thought the same thing for a few minutes until I looked at the wiring diagram. 12V from the key is what powers up the ECM which turns ON the fuel pump

 

[JP_R]

Please tell me you didn't bump the ignition cut off device by gear lever. The one with the lanyard.

Quadruple checked...... i did not.

 

[JP_R]

Well... I wanted to thank all of you for the help offered.

Today I was able to go to the marina for a couple of hours and after changing the distributor cap and rotor and the motor still not turning on, I decided to check a three fuses in detail and discovered that one of them instead of popping where usual (at the top) it actually broke where the leg meets the plastic casing.

Since I did not have a spare with me, I actually jumped it with a piece of wire and it turned on!!!

Problem solved and moving forward I am adding small fuses to my boat bag.

 

[QBhoy]

I don’t think that’s your issue. Think you’ve just been lucky. Get that diz cap changed out for sure. Make sure that battery is tip top too.

 

[JP_R]

I don’t think that’s your issue. Think you’ve just been lucky. Get that diz cap changed out for sure. Make sure that battery is tip top too.

Diz cap and rotor were changed.... I kept the old and will still to go back and try each part at a time.

diz cap might be bad but rotor might be OK or vice versa.... need to spend more time trouble shooting but at east for now, it fires up and runs good.

for now, I left the NEW rotor and cap in place.

Bought a set of fuses and keeping them on my boat bag for future just in case.