Need the big guns a no run problem

[puddle jumper]

I was just out helping a freand on his boat.He has a 1999 4.3 mercuiser.
The problem started as a no power problem but idled fine but had a hard start.Now it wont start or even try to fire.The engine has spark and fuel,
the fuel filter was changed and no water or dirt found.The cap and ignition rottor looked good.Im thinking that either the timing has skipped or the ecm
is giving out a false signel.
Any ideas would be a big help
thank you muchly

 

[Don S]

Re: Need the big guns a no run problem

Besides being a 4.3L, is it carbed or EFI, TBI or MPI?

 

[puddle jumper]

Re: Need the big guns a no run problem

Hi Don
its carbed with a two barrell.

 

[Don S]

Re: Need the big guns a no run problem

Well, you don't have an ECM, and I doubt you skipped the timing.
Have you checked the fuel pump pressure? Does the acclerator pump in the carb squirt gas out when you pump the throttle?
If not, and your fuel pump isn't working, you might put about 2 or 3 tablespoon full of gas down the carb and see if it will fire.

 

[puddle jumper]

Re: Need the big guns a no run problem

Yes the carb does spray fuel,the fuel pump runs,the oil psi safety switch works.The distributor has a hall effect pick up in it and there is an ignition box
on the left water manifold hooked up to the distributor.One thing i did notice
that the engine was not burning all of the fuel when i pulled the spark plugs.

 

[Don S]

Re: Need the big guns a no run problem

When you tested for spark, did you have a bright BLUE spark that jumped at least 1/2"

 

[Don S]

Re: Need the big guns a no run problem

If the spark was ok, next step would be a Compression Test

 

[puddle jumper]

Re: Need the big guns a no run problem

The spark was not as good as i would have liked it but it was blue and i only tested it at about an 1/4 inch. The other funny thing was i could not get spark at the coil wire but had spark at the plug wires. I know impossible.
I did check the coil wire for continuity and it was good.There is a good 12volts at the coil and a good voltage pulse on the negitive side of the coil.

 

[Don S]

Re: Need the big guns a no run problem

When was the last time it had a full tuneup? Plugs, cap, rotor, timing check, carb adjust etc.

 

[puddle jumper]

Re: Need the big guns a no run problem

I think he said it was done in the spring before he came up from down south.
The plugs and ignition rottor looked new but the cap was not changed.In side the cap there did not look to be any carbon tracking and to be in good shape.
The coil is very rusty on the out side shell but does not look to be leeking.

 

[puddle jumper]

Re: Need the big guns a no run problem

yes i also think a compression test is in order and i also checked for fuel in the oil

 

[puddle jumper]

Re: Need the big guns a no run problem

Don thanks for your time he is going to take it back to the place that did the service work.