Crank no start on 02 5.7 MPI MerCruiser

[daleatskiworldorlando]

Hi all, I'm running out of ideas on a 2002 MerCruiser 5.7 MPI with ECM 555.

It has a crank no start condition and so far I have checked the spark - good jumps 1/2 gap, checked the fuel pressure good at 40 PSI, injectors are firing.

A scan shows no codes and the temp and map are good. I did notice a 0 RPM showing when I crank the engine over and I'm puzzled by this. If I disconnect the crank position sensor I get no spark so it looks like it is working and the ECM is getting the signal but why no RPM on the scan tool when cranking?

The engine will kick from time to time when cranking and I have had a few backfires. It also seems like it is firing out of order as it kicks back sometimes. Sounds just like it has some crossed spark plug wires but they check ok.

Thinking the engine might be flooded I pulled the fuel pump fuse and cranked the engine at WOT and still no go.

Any ideas?

Thanks, Dale

 

[Silvertip]

Re: Crank no start on 02 5.7 MPI MerCruiser

So tell us what you did just before this condition began. You mentioned plug wire routing. Did you change plugs perhaps? If so, are you "positive" the plug wires are on the right plugs. 1-8-4-3-6-5-7-2 is the firing order. Spark, fuel and air are required and everything needs to happen at the right time. Since you claim you have spark, fuel and wires are right, the engine should run. Since it doesn't, one or more of them is wrong or missing.

 

[Don S]

Re: Crank no start on 02 5.7 MPI MerCruiser

Check the voltage on the battery while the engine is cranking, if it drops below 8 volts, it won't start.
If that's ok, then go to the OEM service manual link below, and start on page 2A-8 and work your way to 2A-13.
Bet you find the problem.
http://www-alt.mercurymarine.com/mnetdata/SERVICE/CRUISER/Servmanl/36/cover36.pdf

PS: To clear a flooded engine on an MPI, you open the throttle to WOT and crank it.

 

[JustJason]

Re: Crank no start on 02 5.7 MPI MerCruiser

are you sure it's 8 volts don? Something tells me it's 9.5...... but i'm to lazy to look it up right now

Dale... on the scan tool does the tps appear to be closed and the iac appear to be open during crankin?
and for giggles... pull the engine harness plug and the pcm plug and make sure those connections are clean and dry.

 

[Don S]

Re: Crank no start on 02 5.7 MPI MerCruiser

are you sure it's 8 volts don? Something tells me it's 9.5...... but i'm to lazy to look it up right now

I would worry about anything that got below 9, but the book does say 8

The fact that it doesn't show rpm on the scan tool, is leading me to believe it's not turning fast enough to be starting the engine. And I know for a fact, if it's not spinning fast enough, it WILL NOT START.

 

[newport dave]

Re: Crank no start on 02 5.7 MPI MerCruiser

injectors are firing

How do you know they are firing?

The engine will kick from time to time when cranking and I have had a few backfires. It also seems like it is firing out of order as it kicks back sometimes. Sounds just like it has some crossed spark plug wires but they check ok.

This sounds like it could be moisture/corrosion under the distributor cap. Also kinda sounds like low voltage, like Don said.

 

[JustJason]

Re: Crank no start on 02 5.7 MPI MerCruiser

hmmmm maybe dale should double check the cranking rpm with a shop tach

 

[daleatskiworldorlando]

Re: Crank no start on 02 5.7 MPI MerCruiser

Hi all, thanks for the replies. I plan to check/recheck a few things.

The cranking voltage in on the top of the list to check. I think I will check both the battery and the ECM voltage to see if they are dropping too far.

BTW the engine will not start on starter spray, just back fires or kicks back making me think something is out with the timing. I did check the position of the distributor rotor to cylinder # 1 at TDC and it was ok. Will try to shoot it with a light later today.

I remember running into a condition just like this on the older Merc 5.7 MPI that had the distributor sensor in it. Replacing the sensor would fix it almost every time but this engine does not have the same sensor.

I will also check the link Don sent and see if I can find anything using it.

Will post a follow up on what I find.

Got to run, Dale

 

[daleatskiworldorlando]

Re: Crank no start on 02 5.7 MPI MerCruiser (Solved)

Re: Crank no start on 02 5.7 MPI MerCruiser (Solved)

Hi all, got it running. Looks like it was the battery. Even though it was cranking the engine over fine and the voltage was staying above 10 volts while cranking it would not start. The battery was a deep cycle and not a cranking battery and this is known to cause problems with some EFI engines. I replaced the deep cycle with a 1000 MCA battery and the engine started instantly.

Got to run, Dale