1990 Johnson v6 200 gt

[ntdm]

motor dies when put in gear, runs fine on hose but in water it dies, any suggestions
seems to be running out of gas, have a electric fuel pump filter stays full?

 

[Joe Reeves]

Re: 1990 Johnson v6 200 gt

Assuming that the engine has run normally in the past (idling, shifting, etc), and nothing has been distrubed, the cause is normally a lack of rpm/power.

First thing to do is to check the compression and spark..... Compression = 100+ psi and even on all cylinders? S/Plugs removed, check spark = Jumps a 7/16" gap with a strong blue lightning like flame... a real SNAP?

If the two above areas check out okay, suspect a fouled carburetor which would cause a cylinder to run lean.

 

[ntdm]

Re: 1990 Johnson v6 200 gt

has new rings 95 compression, runs great out of water put in gear hit the hot foot she goes dead, been told it may be in the timing,
it acts like it runs out of fuel but installed new elct pump filter stays full, im puzzled

 

[metriccrescentwrench]

Re: 1990 Johnson v6 200 gt

..... Compression = 100+ psi and even on all cylinders?

I hate to disagree with Joe, but these V6 loopers always have lower compression than that. I've always heard that 80 - 90 is good.

Also, if you plan on doing your own work be sure to get a factory service manual.

 

[Joe Reeves]

Re: 1990 Johnson v6 200 gt

In agreement with "metric" pertaining to compression. The 100+ psi I quoted was just an average and of course varies somewhat.

The V6 looper engine, when in good condition, usually show compression to be about 95 psi on the starboard bank and 90 psi on the port bank. The 5 psi difference due to engine design.

You didn't check the spark? Best to do that as I mentioned rather than guess at it.

An engine dying out when throttle is applied, assuming that fuel supply delivery, compression and spark is as it should be, is due (usually) to clogged high speed jets or having the throttle butterflies opening too soon (among other causes).

The throttle butterflies should just start to open when the scribe mark on the cam is dead center with the carburetor cam roller.

 

[metriccrescentwrench]

Re: 1990 Johnson v6 200 gt

The throttle butterflies should just start to open when the scribe mark on the cam is dead center with the carburetor cam roller.

That's the sort of information you need to have a factory service manual for. One of the things you need to check is "link-and-sync". I'm not gonna' try describing the procedure in detail because I don't have my manual here at work with me and I'd butcher it without quoting from the manual. But a few basic points - you have to make sure that all the butterflies are closed at idle. You also need to understand that for the first little bit of throttle travel all that's happening is that the timing is advancing with no butterfly movement. Idle timing is supposed to be (I'm working from memory here so someone correct it if I'm wrong) 6 degrees AFTER top dead center, but many knowledgeable people say to set it to whatever it takes to get proper idle speed in the water.

And yes, other than timing being off a lean condition is often to blame for the symptoms you describe. I used to race 2-stroke go-carts and got pretty good at adjusting carbs, I could tell by it's behavior from a standing start if it needed more fuel (and having just one carb to deal with is a lot easier than 6 !)

Also do as suggested and test the spark, a simple variable gap spark tester is under $10 at most any auto parts store.

 

[ntdm]

Re: 1990 Johnson v6 200 gt

The timiming seems to be the popular choose I am reading the manual now to make adjustments. Thanks

 

[daselbee]

Re: 1990 Johnson v6 200 gt

I hate to disagree with Joe, but these V6 loopers always have lower compression than that. I've always heard that 80 - 90 is good.

Also, if you plan on doing your own work be sure to get a factory service manual.

URRFFF...I like em at 110 or so... My 225 has 120 on all six right now.
To me, 80-90 is almost rebuild time.

2 cents.