1985 90HP Johnson will turn over but won't start.

[david_hawj]

So I bought an old 1982 Cobia Sunskiff w/ a 1985 90HP Johnson a couple of weeks ago. I was told by the old owner that the boat ran but was old...and was assured most of the parts were new.(New Electric Starter/Electric Fuel Pump/New Water Pump System/New Steering Cables) I took her out for a ride the next day and she performed poorly but the motor functioned as it should.

-First Day Out on the Navarre Soundside-
The motor started off the bat but it wouldn't accelerate fast when I pushed the throttle up for more speed...it would try and then just stay stagnant at a low speed, maybe 15-20 mph. I tested the boat out for an hour or so and took her back home. Wasn't happy w/ what the former owner told me. ( I know...I feel like I got, got.)

I spent the last week buying parts and etc...the other day I saw that the fuel pump may have started leaking fuel (its dark green because I mix oil into the gasoline (OLD OWNER TOOK OUT THE VRO SYSTEM I BELIEVE/FUEL INJECTION SYSTEM). It leaked into the bilge area.

Yesterday I tried starting her up w/ the muffs on and let her run for a minute...when I went to put the throttle up she died right after 10 seconds or so.


Today I switched out all the spark plugs and found a couple of bad ones but went ahead and switched out all four. The motor still will turn over like it is about to start but nothing. My question before I take it to the mechanic is, am I missing out on something easy or am I pretty much going to have to fork out hundreds if at least to get this motor back running.

BELOW ARE PHOTOS of my motor and its parts.
THX FOR THE HELP!

SrA David Her
United States Air Force
Electrical Systems Journeymen

 

[emdsapmgr]

Re: 1985 90HP Johnson will turn over but won't start.

Probably want to check for spark first. You can perform a simple test with a friend. Use an inductive timing light and put it's lead on one of the spark plug wires. Have the friend crank the engine. The flashes from the timing light will show misfires, no fires, and weak firing. Compare the timing light results between all 4 wires and that will tell you about the spark. Usually the replacement fuel pump for the original VRO pump is a mechanical pump mounted on the side of the engine, not an electric pump. You may want to install (revert back) to one of those pumps from an 83 model. The electric pumps can be of concern in certain situations. If you think the carbs are not getting fuel, have the friend constantly prime the fuel hose bulb while you crank the engine and choke it. The constant priming will force extra fuel into the carb bowls. If it runs normally while the bulb is constantly primed, you could have a weak fuel pump. Esp, check for fuel leaks on all the fuel hoses/connections under the cowling. If fuel can leak out, air can leak in, causing poor running issues. I see the prior owner installed a gas/water separator filter in the fuel line. That engine was not designed to run with one of those filters. It may run ok with it, but until you get it running normally, I'd bypass it.

 

[david_hawj]

Re: 1985 90HP Johnson will turn over but won't start.

Probably want to check for spark first. You can perform a simple test with a friend. Use an inductive timing light and put it's lead on one of the spark plug wires. Have the friend crank the engine. The flashes from the timing light will show misfires, no fires, and weak firing. Compare the timing light results between all 4 wires and that will tell you about the spark. Usually the replacement fuel pump for the original VRO pump is a mechanical pump mounted on the side of the engine, not an electric pump. You may want to install (revert back) to one of those pumps from an 83 model. The electric pumps can be of concern in certain situations. If you think the carbs are not getting fuel, have the friend constantly prime the fuel hose bulb while you crank the engine and choke it. The constant priming will force extra fuel into the carb bowls. If it runs normally while the bulb is constantly primed, you could have a weak fuel pump. Esp, check for fuel leaks on all the fuel hoses/connections under the cowling. If fuel can leak out, air can leak in, causing poor running issues. I see the prior owner installed a gas/water separator filter in the fuel line. That engine was not designed to run with one of those filters. It may run ok with it, but until you get it running normally, I'd bypass it.

You are the master of your craft...I do appreciate the knowledge! I'll be getting to this as soon as I can. Much appreciated!

-Dave

 

[Will Bark]

Re: 1985 90HP Johnson will turn over but won't start.

Also, check that fuel/water separator; if it's like mine then it's plumbed wrong. Look at the arrows and see it if one of the hoses shouldn't go on the other side. I have Attwoods and Moellers and both have an in and an out on them. Good luck