1988 johnson 90hp shuts down wit throttle

hopefully someone can offer some starting points on this engine. I was given a boat with a Johnson 90 HP j90ticca. The engine was winterized and not run for years. I have rebuilt the carbs, fuel pump, new plugs, checked the alignment marks and linkages. I have adjusted the floats on the carbs when I rebuilt them. As far as I can tell there are no jet adjustments on the carbs. The engine idles fine but once you increase the throttle the engine immediately dies. even if the engine stays running there is not enough power to get on plane. I ran this boat years ago and it ran fine.

Any thoughts on what I should check. It feels as though there is no fuel when the butterflys open up. what does this sound like?

I thought I had replied to this, but I guess it didn't post.
If you read through other threads here you will see that the experts will want you to test compression on each cylinder, and to make sure you have a strong spark that will jump a 7/16" air gap with a bright blue spark.

IF you have good compression numbers and good spark on EACH cylinder then you will look at fuel delivery.
Could be bad bulb, bad line, bad pick-up in tank. You can test that by using a different small tank and line. If that seems good, you need to pull the carbs and run a piece of single strand copper wire through the high speed jets as solvent won't get them clear.

While you have them off, check your carb bowls. The plastic ones can warp, which allows air into the fuel system. Lay them down on a piece of glass to see if they are straight. If not lay fine grit sandpaper down on the glass and rub the bowls in a figure 8 pattern until they are flat. Or buy replacement metal carb bowls.

I have a 1990 90 hp. I was experiencing similar symptoms. In my case it was the warped carb bowls.
Good luck!

I also meant to mention that these motors will sound fine at idle on 2 or 3 cylinders when on muffs. Ask me how I know..

I want to convert this to a premix. Does anyone know what the cross reference part number would be for a regular pump?

There is a spot on the intake manifold to install a 1983 V-4 pump.----It mounts with a gasket directly over the pulse port that now has a plug in it.----Or look it up for an 88 HP model marketed for many years.----Simple job to do.----The 88 HP model was marketed in 1988 model year.

would this work? https://www.amazon.com/438559-Karba...son+fuel+pump&qid=1563396001&s=gateway&sr=8-3

shows both engines as compatible. I'm not going to go crazy on this boat being it is a second one that is only used for short hops to the beach for kiteboarding.

The pump that mounts directly to the manifold would only have 2 nipples.----Fuel in and fuel out.------It mounts directly over the pulse port as I clearly stated.------But do what you like here.

Most common causes of engine's dying out when throttle is applied:

1 - Timer base under flywheel is sticking: Cure... Inspect visually and correct as needed. Grease brass bushing only, use only oil on the nylon ring.

2 - Throttle butterflies opening too soon in relation to idle timing. Cure... Back throttle roller away from the cam. Make sure "all" throttle butterflies open & close at the same time via their linkage. Adjust and set roller so that the butterflies just start to open when the scribe mark of the cam is dead center with the roller. (NOTE that the idle timing must be accurate here to begin with).

3 - The high speed jets are somewhat clogged, fouled, gummed (most common cause). Cure... Remove and clean "all" of the high speed jets with a piece of single strand steel wire, then reinstall securely. Clean in place if need be, then flush the carburetors before reinstalling the drain screw plugs.

Let us know what you find.

so I made some cable adjustments, greased the shifter being I added new gears in the box. I now have it to where the boat goes up on plane. It will then bog down after . little while then sometimes take off again. If it does stall it will restart and get on plane. It seems pretty sluggish on the take off though. At least now I can time it on the water. Ill have to figure out how to make that adjustment if needed. What pulls the timing arm Back? I noticed that it does not fully pull backwards and there is no back tension on that timing arm. I tried to adjust the cable but i don't have much more I can use to make the cable pull back more. Is there a spring?

Maybe the inner cable on the throttle cable is broken.

Re: 1988 johnson 90hp shuts down wit throttle UPDATE

So I replaced the pump and now the engine is running very good. Still has a sputter at Idle but on plane runs well. Coming in the other day it was rough and after a few waves it started to lose power. Almost like the floats were bouncing and closing the fuel supply. Sort of like they were sticking. I've adjusted he floats a few times and think I have them on target. Is it possible they are sticking? If I hit the primer button the engine takes off and runs but I need to keep doing it. what does everyone think? floats or possibly the fuel pick up in the tank?

I'm new at this, but I've been reading a lot of the posts on this forum for the last month or two. Often I see the high speed jet being clogged as the problem as joereeves mentioned along with riopga. Be very careful not to scratch the jet while cleaning it with the wire. Make sure it's dull.