Thread: 89 70hp Johnson

you'll be glad you did...make sure they link and sync it right. pull the cowling off and have someone throttle it up with it not running...make sure ALL three carbs open and close at the same time...some are not a proficient as others with getting them all together....LOTS of little linkages in there. A++++ to all those posts above....run sea foam every third tank and by all means add a marine water separator....will really help! Sea foam will help preserve your gas through the winter and you won't have any carb trouble if you run some ever so often. Be sure too if you run fuel with ethanol in it that you either drain the tank or run ethanol treatment...although that still doesn't keep phase separation from always happening. if you can stay away from it stay very far away!!!

Carbs rebuilt, floats checked and reset and still the same thing, going to replace the reeds.

We had the same problems with an 85 horse. We rebuilt cards and fuel pump, replaced the gas lines, tank and primer bulb, and replaced the plugs. It still ran good one time and then the next it wouldn't start.

We had it to three diff. marinas. Finally at the third they replaced all the electronics and now it runs great. They replaced the coils, rectifier, spark amplifier and something else ( i can't remember the last thing)


We've been running a "cocktail" in the gas mix that I found on a musky site that does wonders for rough running engines.


3 ounces seafoam
3 ounces quickleen sp.
3 ounces marine stabil
to each six gallons of gas

They smoke a lil at first but run excellant after the first tank. We've been running this cocktail in three boats all summer includeing two that have set for at leat five years. My dads boat has never ran or started as good as it does now.

Originally Posted by roger46982

Motor has sat for 10years, ran once a year to keep lubed. Damn thing will idle great on muffs in the driveway but put it in the water and it spit spudders and dies. Only way I can get it to idle 800rpm's and troll is to trim the motor almost all the way up, drop it just a bit and it runs rough and dies. The vro system is plugged and is "running" on pre mix. Any ideas and suggestions greatly appreciated.

If your still running the VRO fuel/oil pump your problem might be there. I have put traditional fuel pumps on what were VROs when removing the system. That VRO pump is still pumping on the oil side of it. I did see that you are running premix but I believe your oil pump is still trying to do its job and its tied to the fuel pump.

Originally Posted by JLeus

If your still running the VRO fuel/oil pump your problem might be there. I have put traditional fuel pumps on what were VROs when removing the system. That VRO pump is still pumping on the oil side of it. I did see that you are running premix but I believe your oil pump is still trying to do its job and its tied to the fuel pump.

The wiring to the VRO is unhooked would it still be trying to pump? I had thought about the fuel pump from the start but doing a search doesn't list much in the way of standard pumps for this motor. Best I could find is a Sierra 18-7353??????

Originally Posted by roger46982

The wiring to the VRO is unhooked would it still be trying to pump? I had thought about the fuel pump from the start but doing a search doesn't list much in the way of standard pumps for this motor. Best I could find is a Sierra 18-7353??????

Man I'm sorry, forgot I posted over here. Your not going to find a traditional pump in the lists for your motor, need to go to one "pre-VRO". If the Sierra part is listed for that size motor it should work. I make mounting bracket and plumbing changes to accomodate the different pump. The wires to the VRO pump are for the warning buzzer, the pump is not electric, it is driven by presure oscilations from the crankcase the same as a more traditional pump.

Originally Posted by JLeus

Man I'm sorry, forgot I posted over here. Your not going to find a traditional pump in the lists for your motor, need to go to one "pre-VRO". If the Sierra part is listed for that size motor it should work. I make mounting bracket and plumbing changes to accomodate the different pump. The wires to the VRO pump are for the warning buzzer, the pump is not electric, it is driven by presure oscilations from the crankcase the same as a more traditional pump.

A ha!!!! That may explain a few other symptoms, thanx for the come back!!!!!