Mercruiser 496 crank no start
 

I would like to start out that I'm a new member. I was at a lake this past weekend and I hit a sand bar going around 10 mph and only the lower drive scraped about 6 inches. The prop is fine and the lower is scraped up with some small damage to the edge. When it started to drag i immediately threw it in neutral and turned it off and then trimmed it up. But now it will not start. I bypassed the neutral safety switch and nothing. The motor is a mercruiser 496 with a bravo one x. Any help would be appreciated

When you turn key to crank, do you get power to yellow/red wire going to remote solenoid ? If so, power also at yellow/red on same solenoid to starter ?

Before I crank i have 12.5 on one side of the solenoid. when I crank I'm getting 9.5 volts on the other side. Its cranks fast but I checked for spark and nothing

Safety switch/lanyard pulled?

While cranking im getting 10.8 on the yellow wire on the starter. And I checked the kill switch while I was on the water

I also bypassed the neutral safety switch and nothing

Ok, thanks. You didn't mention it was cranking. Lol. Neutral safety switch effects crank /no crank.

Do uou have soark and fuel psi when cranking ? Does tach go to 400-400 rpm when cranking ?

edit in: i guess i didn’t read the title. Lol. Sorry

No spark and when cranking tack is slightly lower than 1000 and ill have to get a fuel pressure gauge

So I have tested the kill switch, neutral safety switch, red circuit breaker, unplugged every connection and checked the harness, checked voltage on the batteries. I'm trying to see if I can get ahold of a scanner. But I'm out of ideas. I've hit big waves that jarred the boat harder than I hit this sandbar

My 2002 496HO has 3 relays near ECM which all are same part number. Have U tried swaping them?

I have not but when I get off of work I will try. Do you know what they are used for.

GRAb a free loaner fuel psi tester from Autozone on your way home too.

Ok so I tested the fuel pressure and it was 40 psi while cranking and I swapped the relays on the top of the engine and it still won't start. I call a local service center near me to get it scanned but the soonest they can get me in is in two months. Any other suggestions?

Rinda Technologies Inc. Marine and Industrial Engine Diagnostic Tools

good investment

Where are you located?

Albuquerque New Mexico

Okay, so this is where we stand. Fuel psi okay. Tach shows cranking dpeed (should actually be closer to 4-500 rpm) , therefore crank sensor should be okay.
No spark though. So, lets look into this. Sorry for basic question but have to ssk - how did you check ?

I used a inline tester that lights up when there is voltage

I don't know the ins and outs of the 496 ECM but I know there's a crankshaft sensor and a camshaft sensor. Wouldn't surprise me to find out crank sensor measures RPM and cam sensor controls ignition.

On a side note, there are a few different types of both sensors so make sure you get the one for your eng serial number if replacing.

Some good tests/look see’s/info:
https://forums.iboats.com/threads/me...diacom.570913/

Found this posted by Raylar ( 496 guru):
"If you have an active fault code or a problem with a cam sensor fault it can take the motor longer to start and if the cam sensor circut is bad it sometimes won't start at all."

See post # 4 of this thread:
https://www.offshoreonly.com/forums/...-pressure.html

It's still not clear to me if a bad cam position sensor circuit prevents ign or fuel inj or maybe both?? Wouldn't hurt to check the wiring for it. You may be able to find what the proper resistance range is for it online somewhere.

Ok so I borrowed a scanner and these are the active faults I have.
Pitot ckt lo
Fuel level ckt 2 h
Steer ckt h
trim ckt lo

Are there fuses located on the engine. I have checked all fuses on the fuse block on the boat behind the steering wheel
also where is the crank and cam position sensors located

No need to be concerned with them faults... common if not used.

After doing some research I agree but it still won't start. i guess I'm going to swap out the crank and cam position sensors and hope for the best

Need a voltmeter
Need a serial number or at least a year of the motor?

Measure voltage on pin D of the DLC connector, should see 12V with key ON and while cranking
Disconnect one of the injector plugs and measure voltage with key ON
When cranking listen for the fuel injector ticking

Have you put your fingers on the starter selenoid wires,, my friend went thru this,,same engine as yours,,spent $1500. at 2 repair shops,,still would not start,, finally found a boat mechanic that knew what to look for,, a loose wire on selenoid,,fixed in 39 minutes.,,,just sayin don't overlook the easy things first,,,good luck.

The serial number is 1a059707
when I have the key on im getting voltage and with a testing light it pulses when being cranked. And I don't know which connector is the dlc

You should have 12V full time on one side of the injectors with it ON and not running, or running. The ECM supplies a ground to the other side to turn them ON/OFF

First check fuse with a volt meter, then trace it back to the connector

https://cimg8.ibsrv.net/gimg/www.off...b89a247b60.jpg

My tester leads were to big to touch the injectors and I used a tester that has a light built in to test. Do you need the exact voltage

With that tester light I double checked and the injector has voltage key on and the ground does pulses when being cranked

If your not using a NOID light on the injectors then it could be a miss-read

If the injectors are pulsing then its a spark issue. Would need to use a spark gap tester to see what kind of spark your getting. If your not getting spark then its scanner time because there would be a code

I'll have to pick up a noid tester and a spark gap tester. I used a inline spark tester the kind that lights up and there was no spark but I will try the other type. And I did scan the engine and nothing came up with codes that had to do with it not starting. If you look back in the posts you can see what codes pop up. When cranking i can smell a little bit of fuel

Agree, but my understanding is your still using a test light and not a voltmeter.
If incorrect, please advise

No need for a NOID light, I'm just stating facts as NOID verses test light

Your not getting spark, got it
Do you have a "full" 12V at the injectors?
If Yes, then need to have PCM tested
If No, then need to back trace

Well I finally got it to start after checking all the grounds and looking at every wire and connection still nothing. The 90 amp fuse that is on the starter was slightly loose I tighten everything on the starter and that was it. I would like to thank all of you for your time and help.

Jfc

Glad to help.