3.0 Mercruiser LX (MCM 3.0 Litre/LX 181 CID) Starting Issues on a 1994 MAXUM

[Rush21125150]

3.0L Mercruiser XL

It wont start, it has spark, it will turn over, and when I put gas in the carb it turns on, and will stay on till it runs out of fuel. I thought initially it was the fuel pump, i removed it and it wasn't seized and it seemed to be creating suction. I put it back together and now im back to troubleshooting. I have a little under a half tank of fuel, by the way.

Any suggestions for me?

Thanks a bunch!

 

[alldodge]

Howdy
What is the serial number of the motor or at least the year?
Also think this is an LX instead of a XL

Have you changed the fuel filter?
If not remove it and pour contents into a clear container to check for debris and water.

Next disconnect the fuel line after the pump and place it in a container to see if when the motor cranks there is fuel coming out of the line.

If fuel comes out, pull the inlet fitting going into the carb and see if the filter is clogged up

Let us know what you find

 

[Rush21125150]

A guy told me that the oil pressure sensor could be bad, if thats the case then it would allow the fuel to be pumped into the carb?

 

[alldodge]

Hello ................... !!!!!!!!!!!!!!!!!!!!!!!
What YEAR is your motor??????

IF you have an LX 3.0 then it should be between 1990 and 1997
IF this is the case then you have a mechanical fuel pump and NOT an electric one


IF (again the big IF) you would like some help, PLEASE answer our questions

Thank you

 

[Rush21125150]

I know i have a mechanical fuel pump, its a 1994 MAXUM. I used a hand pump and pushed fuel through the mechanical pump and the filter was dirty, i didnt see any water going through, I havent yet cleaned the carb, i only spray some starter fluid in it, I have to buy carb cleaner and clean out the carb a little. When i pumped fuel through the fuel pump, it came out with no issues, it cleared on the bad fuel.

 

[Rush21125150]

Howdy
What is the serial number of the motor or at least the year?
Also think this is an LX instead of a XL

Have you changed the fuel filter?
If not remove it and pour contents into a clear container to check for debris and water.

Next disconnect the fuel line after the pump and place it in a container to see if when the motor cranks there is fuel coming out of the line.

If fuel comes out, pull the inlet fitting going into the carb and see if the filter is clogged up

Let us know what you find

I dont have the S/N as of now, I can get it and find out.

 

[Rush21125150]

Hello ................... !!!!!!!!!!!!!!!!!!!!!!!
What YEAR is your motor??????

IF you have an LX 3.0 then it should be between 1990 and 1997
IF this is the case then you have a mechanical fuel pump and NOT an electric one


IF (again the big IF) you would like some help, PLEASE answer our questions

Thank you

Sorry I didnt reply to your post sooner.

 

[alldodge]

OK, remove the fuel line at the carb and the larger nut item 6. Remove the nut and there is a filter behind it. It will either be a stone, paper of plastic screen.



You can no longer get the stone type and IMO the others are better anyway. Also note how the spring is installed depending on which filter it is.

There is also an anti-siphon valve at the tank. It is a barbed fitting and the rubber fuel line is attached to it. There is a spring and ball inside and can get clogged and stuck

 

[Rush21125150]

Hello everyone, my engine wont start. Im really unsure where to go from here.

Here is a list of things i've verified/done:
- Has 1/2 tank of fuel
- Has spark, cleaned plugs, no spark issues.
- Battery is about 2 weeks old, i got it brand new from the store.
- Engine turns over, starter and solenoid are good
- I cleaned the anti syphon valve, (it was gunked up)
- I removed the fuel line going into the carb, when i turn over the engine, fuel was coming out of the fuel line.
- The filter on the carb wasnt dirty, but i still cleaned the area and ensured there weren't any obstructions.
- When i turned it over i looked in the carb and it was dry.

Is there any sort of relay or something else telling the carb to not allow fuel to go into it? I was told that its possible that it could be an "Oil Pressure Sending Unit", but i didnt exactly have a way to verify it.
Or could the carb be really clogged?

my engine serial number is 0F354433

Any help would be great, thank you.
-Ryan-

 

[racerone]

OK----So what is the history on this machine.------How long have you owned it ?---Did this problem show up suddenly ?

 

[Rush21125150]

OK----So what is the history on this machine.------How long have you owned it ?---Did this problem show up suddenly ?

I have owned for about a year, it sat in my buddys riveway for about 4 or 5 months, the engine bay way covered and when iwent to start it a few weeks ago, it wouldnt start. I then repled the battery and cleaned the things i listed above.

 

[Grub54891]

You have fuel to the carb, so that part should be fine up to there. Looks like the float is stuck, try tapping the carb LIGHTLY with a small hammer. It may knock the float, needle loose. More than likely you need to disassemble and clean/rebuild the carb.

 

[Rush21125150]

You have fuel to the carb, so that part should be fine up to there. Looks like the float is stuck, try tapping the carb LIGHTLY with a small hammer. It may knock the float, needle loose. More than likely you need to disassemble and clean/rebuild the carb.

Okay, thank you for that, is there anything telling the fuel to close the float? or is this mechanical?

 

[Grub54891]

The fuel fills the bowl, and the float raises up, shuts off the fuel with the needle valve. that needle valve can get stuck sometimes. Look up "how a carburetor works" and you should find some info. you tube also should help. If you have never worked on a carb, find a shop or good friend that actually knows how to do the job. It don't take much to screw up a good carb in the wrong hands. In the right hands, they aren't to hard to repair.

 

[Scott Danforth]

there is no magic mechanic in a can. pull your carb apart and clean it.

 

[Chris1956]

When you buy a rebuild kit, make sure it s a marine grade carb rebuild kit, as marine carbs are a bit different (and safer) than auto carbs.