1990 Mercruiser 3.0l has spark, fuel and compression...still no start

[cheesytaters]

I've been reading the forums for a while now, and I'm usually mechanically inclined, but this one has me stumped...

I have a 3.0l mercruiser with the Prestolite dist. When I purchased the boat this spring, I installed new plugs and wires, upgraded ignition to pertronix with flamethrower coil. At one time, I had the engine running, but it stalled in the first 30 minutes at the lake and would not restart. After sitting a few days, it started up again ran a few minutes, then stalled again and would not restart. So, I soaked and rebuilt the carb, put it back together and it won't start. I checked spark at the plugs and seems strong. I compression tested the cylinders and got 130 psi on all cylinders. When I advance the throttle fuel squirts down the throat. I'm leaning towards timing, but the distributor hasn't been moved since it was running...I'm out of ideas. Against my better judgement, I even tried starter fluid and no start. Please help me...

 

[jim arthur]

Re: 1990 Mercruiser 3.0l has spark, fuel and compression...still no start

I am having same issue and am ready to throw in the towel! i am now going through the harness to see if there is any short or blown fuses. Check shift interrupter, mine was out of adjustment

 

[mxcobra]

Re: 1990 Mercruiser 3.0l has spark, fuel and compression...still no start

starting fluid is a good diagnostic tool you did nothing wrong their- alltough others on here will disagree with me.
Ok we know gas is not the problem if the juice dont start it
TIMMING or spark must be the isue
mabie you have a bad ground check and clean all the wire connections...
is the timming belt turning the cam?
check your volts at the coil with the key on.... and cranking should be getting 10 12 volts their
My guess is a bad ground wire when she was running and skaking somthing wigled loose or came apart in the wires just a guess?!.

 

[cheesytaters]

Re: 1990 Mercruiser 3.0l has spark, fuel and compression...still no start

I used a spark tester at each plug and it appears that I have spark coming from the distributor. Would it be a good idea to go back to square one with timing by pulling dist, setting cam to TDC? I'm afraid of doing that and being wrong but I think at this point I have no other options...

 

[cheesytaters]

Re: 1990 Mercruiser 3.0l has spark, fuel and compression...still no start

BTW MX, I checked out your thread when I was replacing my floor. It was very helpful, thanks for posting. I hope your project is coming along well...

 

[airshot]

Re: 1990 Mercruiser 3.0l has spark, fuel and compression...still no start

I had a similiar problem last year and found it to be water in fuel. What I thought was gas squirting was water. Completely drained tank and lines, put in fresh gas and changed water filter and then it ran good as gold.
Airshot

 

[joewithaboat]

Re: 1990 Mercruiser 3.0l has spark, fuel and compression...still no start

Not sure about a 1990, but in my 1996 mercruiser i had trouble with the kill switch once. Gives power to the ignition while cranking, but not running. It will sound like it is going to start but won't.

 

[cheesytaters]

Re: 1990 Mercruiser 3.0l has spark, fuel and compression...still no start

Thanks everyone for your help. Reset the timing today and got it running...just now it won't stay running below 1500 RPM. I suppose I'll take a look at the float level and see if that does it.

 

[mxcobra]

Re: 1990 Mercruiser 3.0l has spark, fuel and compression...still no start

thats cool man atleast someone looked at my disaster...
Glad you got her going.
Good luck with it...