Johnson 150 GT-what next!?

[Rondojigs]

I have a 1985 Johnson VRO 150 GT ( mod: J150STLCOH / ser: J6132020). For the last couple of weeks the motor has been bogging down at various stages of acceleration and often struggles to get up on plane. The idle is weak and even stalls at times. I have run Power tune through it, added Seafoam to the fuel, changed the plugs and wires (after the before mentioned treatment), checked fuel lines, bulb and filters, used higher octane fuel and finally broke down the carbs and cleaned the jets. Compression is ok. Power pack is ok. Oil pump is ok. What do you think about trying hotter plugs (NGK 2522)? Does the carb / timing need adjustment? NOTE: The motor is on a 1985 Ranger V 370 and is the original motor that came on the boat. Although the rig is 20+ yrs old, it has been well maintained and never stored for more than 30 days without being run.

[Sportwin]

A big "NO" to the NGK plugs. Hook an inductive timing light to the plug wires, one at a time and verify that each cylinder has spark. The timing light will flash each time the ignition fires that cylinder. Try this while idling and accelerating. If that checks out, remove the air silencer cover and use an oil squirt can filled with fuel/oil mix to add fuel to each cylinder (one at a time). If the cylinder is receiving enough fuel, you will get a negative response. If the cylinder is NOT receiving enough fuel, you will get a positive response each time you squirt fuel in the carb throat. You should also make sure the timer base is rotating when the throttle is advanced.

[Rondojigs]

Five plugs getting fire, one was only wet. Compression check was good. Changed plugs and coils around and through "process of illimination", determined it was a bad coil. Replaced the coil and now I am back in business. Oh, and I replaced the valve connecting the two fuel tanks as it was letting air into the fuel line.

[RUSTY63]

Glad to hear you got it fixed and Welcome to the BBC.

[DoferGofer]

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Rondojigs &raquo;</TD></TR><TR><TD CLASS="quote">Oh, and I replaced the valve connecting the two fuel tanks as it was letting air into the fuel line. </TD></TR></TABLE>
One thing for sure, these engines will not tolerate leaky fuel lines. Ask me how I know??
Glad to see a fellow X-flow boater back in da running and running strong!