1992 90hp Johnson - wont start

I've posted a few times concerning this problem and tried various solutions. I put gas in the pistons yesterday and it fired over then quickly died. I put gas in the carbs and it fired over and quickly died (not sure if it fired because of leftover gas in the pistons from the previous test though - should have done the carbs first, dumb). This leads me to believe the problem isn't electrical nor carb - either the fuel pump was put in wrong, one of the hoses is cracked and is losing pressure or there isn't enough pressure coming from the crank to run the pump (this one really scares me).

The original fuel pump the motor came with is oil injection, but I replaced it with a regular mixed gas diaphragm pump (one less thing to break and the injection pump was a little suspect to begin with). The electronics on the injection pump were never hooked up - couldt a Murphy switch still running not let the engine turn over because of a lack of oil? I doubt it, but right now I'm grasping at straws.

As always, Any thoughts would be greatly appreciated.

Bozol

Re: 1992 90hp Johnson - wont start

when you pump the primer bulb, you fill the carb bowls. As long as you don't have a leak, and the bulb itself isn't defective, there's enough fuel in the carbs to run the engine for a few minutes even if the fuel pump didn't exist.

After you try to start it, is the fuel line still pressurized? If you pumped it up and walked away for an hour, would it still be pressurized when you got back?
Have you done a compression test on this motor recently?

Re: 1992 90hp Johnson - wont start

This does sound like a fuel pump problem. Disconnect the output line from the pump and connect a longer line. Put that line in a container then turn the motor over with the starter. You should get some strong squirts of gas from the pump.

Re: 1992 90hp Johnson - wont start

I have disconnected the line and gas comes out when the starter engine is turning over, I don't know if there's enough or not though (wasn't a solid stream but a pulsing trickle).

I am assuming if the compression from the engine was low the engine would still cough a bit (4 cylinders, there not all going to be that low are they? Especially considering the boat was working earlier this summer).

Bozol

Re: 1992 90hp Johnson - wont start

You should definately get more than a "trickle". How old are the lines?? New fuel line is under 2 bucks a foot and worth every penny as regular maintainence. See if that improves your flow. Is the filter on the pump clean? Diaphragm ok? You didnt answer JTexas about your bulb holding pressure, does it?? As far as compression, check it, you cant hypothesize on the outcome if you dont even know it for sure. It only takes a few mintues and is easy to do. The screw in testers can be bought at most auto parts stores for under 20 bucks. Make sure your cylinders are even across the board or within 10 percent.

Re: 1992 90hp Johnson - wont start

You didn't mention whether the fuel primer (choke) system is working or not..

Re: 1992 90hp Johnson - wont start

How can I check if the choke is working. I push the key in, but have no idea if its doing anything.

Re: 1992 90hp Johnson - wont start

The choke isn't going to do much good if you are only getting a trickle out of the fuel pump.

Re: 1992 90hp Johnson - wont start

Hi all,

I fixed the fuel issue by re-installing the fuel pump: either the gasket I had made around the pressure hole wasn't all the way sealed, or the fuel pump was in upside down (in previous posts I was told it didn't matter which way the pump went in). This choke idea makes more and more sense to me - the engine goes like hell once running, just can't start when turning the key but starts when gas is thrown into the carbs.

How do you check the choke? Are they fixeable?

I try to start with the idle throttle wide open and nothing happens.

Any thoughts would be very appreciated,

Bozol

Re: 1992 90hp Johnson - wont start

I think this engine doesn't have a choke but a primer - whats the difference? Are primers easy to adjust and fix?

Cheers,

Bozol

Re: 1992 90hp Johnson - wont start

Loosen the carb chke rod fastener lock screws. Place the manual choke lever in the choke "ON" position. Manually close the other choke valves and tighten the screws. You can also adjust the choke solenoid, just close the choke valves with the manual choke lever. Loosen the clamp screws that are on the solenoid and hold the plunger to the bottom of the solenoid and slide assembly aft to remove the slack in the linkage between the plunger and the choke lever. Move the solenoid (only) aft .016 of an inch and tighten the clamp screws.