Ignition adjustment 150 HPJohnson V6,1990

[sludgemonkey]

My rebuild 150 Johnson is causing me great frustration.<br />Here is the story:<br />- 90psi compression on all cylinders (+/- 4)<br />- spark on all plugs<br />- New Powerpack<br />- Spark plugs appear brownish and dry on one side, and brownish but slightly wet on the other side.<br />- No change in rpm when spraying WD40 into the intake.<br />- No change in rpm when pulling one spark cable (anyone).<br />- Runs OK on idle.(sometimes misfires)<br />- Loose power and stall aout around 3000rpm in Forward.<br />I suspect incorrect ignition (linkage) adjustment being the problem.<br />Question 1. If WOT timing is too high will that cause stall at WOT.<br />Questiion 2.If carburator valve start opening prior to 7° BTDC, will that cause stalling<br />If WOT timing is set too high, wil 3% 2stroke oil<br />allow it to run smoother compared to 2%?<br />Question 3. I tried the method of Cranking with no plugs installed to set WOT timing, but i could not get it below 30° even with the adjustment screw fully screwed in.

 

[fireman57]

Re: Ignition adjustment 150 HPJohnson V6,1990

Welcome to iboats from across the pond. I wouldn't worry about my timing just yet. Do a link and sync to make sure that your butterflies are opening when they should. Procedure is in your manual but you might find one close to yours by using the red search button at the top of the page.

 

[Joe Reeves]

Re: Ignition adjustment 150 HPJohnson V6,1990

That model has the Fast Start feature. You cannot set the timing at cranking speed unless that feature is somehow elimated.<br /><br />WD40 has a somewhat cutting base. Not a good idea to spray it into the interior of the engine.<br /><br />The timing full spark advance being set too high will result in pre-ignition which will cause piston damage.<br /><br />Having the cam roller set incorrectly, allowing the throttle butterlfies to open too soon will cause the engine to hesitate/die out as throttle is applied. Improperly cleaned carburetors will also have the same results.<br /><br />If you indeed have the proper spark on all cylinders as you state, and there is no rpm change when pulling a spark plug lead, that indicates a fuel problem. However........<br /><br />Many (running) V6 engines do not show a response to the untrained ear when removing just one spark plug lead. The cure is to remove one spark plug lead and leave it off, then remove another plug lead. That will (should) result in a deffinite rpm drop. By alternating the removed plug leads, one can prove which cylinder is firing (or not).<br /><br />Example: Remove #1 plug lead (no change), remove #3 (rpm drops). Obviously #3 is firing. Replace plug leads.<br /><br />#1 on, remove #3 (no change), then remove #5 (rpm drops). Obviously #5 is firing. Replace plug leads.<br /><br />#5 off (no change), remove #1 (rpm drops), proves #1 is firing. etc etc.

 

[sludgemonkey]

Re: Ignition adjustment 150 HPJohnson V6,1990

Thanks Joe.<br />Is there a "easy way to semi correctly set the WOT timing"? Boat is on water, but I do not feel like hangin' in the back there at WOT (if i get it up to that speed). I will round up a couple of friends, and have a go this afternoon.