HELP!!!! Starting Issues

[struss3]

Hi everyone, newbie here. I really hope someone here can help, I'm at my end. Soooo......
Last year I tuliped a valve and head gasket was bad, replaced both. Ever since i have issues either starting, or most annoyingly starting after driving for 15 minutes or longer and then sitting. After cooling down it would start. (I checked cool fuel unit, High pressure fuel pump and regulator and all were cool to the touch, doubt it is vapor lock.) So I replaced: risers and manifolds, alternator, cap and rotor, ignition module sensor inside the distributor, plugs and wires. Timing was set. Fuel pressure was only 33, then would drop to 0 before starting, then go back to 33 when started. I replaced the high pressure fuel pump and regulator, pressure is now 42-43. Still had the issue, so I replaced the battery(750 cold cranking amps), coil (specific for the thunder bolt), tried another cap and rotor (merc oem). Went out saturday, ran like a brand new boat, except it did have the restart issue but only had to sit and cool for an hour instead of 2-3 like it was doing. Sunday, checked plugs just for the heck of it to see how they looked. Monday, wouldnt start. Sounded like a started issue, would click or not even click, then would try to turnover but wouldnt. Put a new starter in last night, still wont start. Almost sounds like the timing is off. Tries turning over then when I release the key it sounds like its trying to start then backfires. It ran perfect Saturday, then wont start Monday!?!? I check compression again just to be sure, one at 140 the other 7 were 160-170. I'm running out of things to replace, patience and MONEY! What else could be wrong? Seems like this is a completely different issue then what I had.

 

[scoflaw]

Any sign of water in the cylinders ? How did the plugs look ?

 

[struss3]

Thanks for the response. No water seen, plugs looked good.

 

[Wanderer 290]

In the opening it is stated a tuliped valve and head gasket were replaced.
Was the caused of the tuliped valve determined?
Was a complete valve job done?

And most importantly, engine type, hours, fresh or salt, etc.

Just a far fetched guess... cam May have jump timing which is indicative of other problems internally.

 

[struss3]

Not sure what caused the valve issue. Only the bad valve and gasket were done. Sorry about the lack of engine info.
2000 Mercruiser 5.7 TBI EFI, 360 hours, was mostly used in salt water but now only fresh. SN # M146519814

Thanks for the response.

 

[struss3]

Just had a merc mechanic tell me he's had key switches go bad to where when it turns over it doesn't give power to the coil but when you let off the turning cycle it does? I guess a new key switch is an inexpensive try.

 

[Wanderer 290]

I would start by pulling all the plugs and valve covers. If the engine spins freely look to cam timing. As the engine turns verify all valve train movement looking for a possible bent push rod etc.
Checking the cam timing will require removal of the timing chain cover.
Scope the cylinders with a scope that can be rented from AutoZone prior to spinning the engine looking for water in the cylinders.
Finally, a complete valve job should have been performed since a tuliped valve is typically associated with excessive heat that also warps the head.

 

[struss3]

Thanks for the info Wanderer290, I will get someone to help me with that one. Hopefully this weekend. Just odd that it ran great Saturday, tried starting it Monday and nothing.

 

[Wanderer 290]

Just had a merc mechanic tell me he's had key switches go bad to where when it turns over it doesn't give power to the coil but when you let off the turning cycle it does? I guess a new key switch is an inexpensive try.

Use a bump starter to verify ignition operation?

 

[scoflaw]

That's the motor that has an electric carb with 2 throttle bodies that sit up high ? Do they leak when you shut down.
Don't think the fuel pressure should be that high, thought that was a 3 bar setup ?

Could be vapor lock, the heat develops at the top of the engine not down by the pump. Is the engine temp hotter than it should be ? That can do it.

Did you lock the distributor before you timed it? Your compression is high like you might have water in it

 

[struss3]

Thanks scoflaw, yes that's the carb. I don't notice any leaking when shut down. The merc manual states the fuel pressure should be between 38-42. Engine temp runs at 150, 160 at 4000 RPM's which is what it should be. Distributor was locked down. I will check for water again this weekend. Thanks for your imput. I am no mechanic so any and all suggestions are greatly appreciated.

 

[struss3]

Well just checked and have no spark.

Thanks scoflaw, yes that's the carb. I don't notice any leaking when shut down. The merc manual states the fuel pressure should be between 38-42. Engine temp runs at 150, 160 at 4000 RPM's which is what it should be. Distributor was locked down. I will check for water again this weekend. Thanks for your imput. I am no mechanic so any and all suggestions are greatly appreciated.

 

[struss3]

Went through dish’s for thunderbolt, have 0 volts at red/white wire coming out of coill(from the sensor). Manual says it’s a bad ignition control module but I can not find it, is it the same as the ecm? Are they one in the same except icm costs $300 and ecm costs $2000?

 

[Wanderer 290]

The ignition control module is located under the rotor in the distributor and is a very common failure item.
Mercury actually redesigned it because of grounding issues.
$300 is high

 

[struss3]

Thanks wanderer, if I follow the diags for troubleshooting the thunderbolt ignition, if I have 0 volts coming from the red/white wire off of that sensor it says the icm is shot. If no spark off the green/white wire coming off of it then the sensor is bad. I replaced it last year, but I know it could go bad again, but according to the troubleshooting it’s the icm. The sensor your showing me I got for $70

 

[struss3]

But another question, trying to find my serial number. The serial number plate, above my starter says Serial Number 640144, then below that it says SAV Cert. M14 65 1 98 14.
I know neither of these are engine serial numbers as they should start with 0xxxxxx

what are these numbers

 

[struss3]

 

[scoflaw]

0L640144 is your number

 

[struss3]

Awesome, how did you find that

 

[scoflaw]

You can clearly see the L before your number and some tags drop the 0