'90 Force 90Hp Fuel Issues??

[bbfrs1]

I believe that I am running too rich. When motor is warm it is hard to start and stay running. It will fire right up then die. I raised my idle and it helped a little but it still does it. But just not everytime.

I have no holeshot whatsoever. By myself Im about 30-40 secs to full rpm. which is only about 4900. When I have more than 2 people my top speed is about 15. It also takes about 30-45 secs. to get there. Even fully loaded I should be at full rpm faster than that.

I just replaced my spark plugs, after one afternoon of use, they are black and look fouled. My fuel lines and filter is good now. But it takes 5-6 pumps to prime. That seems a little high.

Finally, my jets are .070 and I am at about 4800ft. I believe I should have
.072 in my top carb. Would that make a big difference.

I know this is alot to chew on, but I have checked everything else, and don't really know where to go from here. I have a seloc manual and it doesn't show how to adjust my rich lean adjustment. I guess I don't even know it that is what it is.

 

[jerbear56]

Re: '90 Force 90Hp Fuel Issues??

Could be that you have the wrong heat range of plugs, or simply put, the wrong spark plugs. that would explain your problems.

Also make sure that your choke isn't staying closed.

As far as jets go, you really can't tell by the number stamped on the jet. They just use the smallest size jet and use a pin vise and bit to bore it out to whatever size they need. The only realistic way to know what size the jet is, is to find the bit that fits the hole. But realistically, at 4800 feet, it's hard to imagine that the jets are too big.

First step would be make sure your choke is working correctly, then to make sure you have the correct plugs. Let us know how it goes, okay?

 

[bbfrs1]

Re: '90 Force 90Hp Fuel Issues??

The plugs I am using now is the champion ul18v. I was using the ngk buhw, but I found out that manufacturer recomends the champion for the 90 model year.

My choke seems to be working properly. When activated the shutter closed, when not activated the shutter goes flat.

I noticed on my throttle linkage, when it is at wot I can push the linkage down about another 1/4 of an inch. But that makes the shutter go beyond flat. I don't know if that is normal or not.

 

[jerbear56]

Re: '90 Force 90Hp Fuel Issues??

Well, it's not the plugs. I've had great results with the ngk buhw. Sounds like the linkage and all is working correctly also.

You definitely need to run a compression check. If you need info on how to do it, let us know.

 

[bbfrs1]

Re: '90 Force 90Hp Fuel Issues??

My compression is 123 in top and 121 in middle and bottom. I did just decarb it and gave me about 4-5 more #.

 

[bbfrs1]

Re: '90 Force 90Hp Fuel Issues??

I took the boat out today and everything is the same. IF it was a truck I
would say it is getting to much fuel or the timing is retarded. I cleaned the plugs before I went out checked after I was done and they were black again. The anode looked chared.

When I primed it for the first time I counted 9 pumps till firm. So either my floats are to high or fuel line is bad... Correct or no. Would having floats to high cause it to run like this?

What would be the best option I have from here?

 

[jerbear56]

Re: '90 Force 90Hp Fuel Issues??

Curious if you just started having this problem, or if you inherited it. The motor is definitely running rich.

Without being able to get my hands on the motor, all I can do is tell you what I would try.

First, static check the timing and torque the head bolts.

Second, run it with some seafoam to clean out the engine, especially the drain reeds.
I'd also try running it with the cowl off. That's the easiest way to tell if it's over jetted or if air is restricted.

You should also get the service manual for the engine to make sure you have carbs, timing, etc. to the correct specs.

 

[bbfrs1]

Re: '90 Force 90Hp Fuel Issues??

I inherited the problem, however I sort of knew what I was getting into. I got the boat for $1500 and knew it had a few problems with the motor. I didn't know it would become a hobby of fixing it.

I had my mechanic check timing and clean carbs when I first got it, and he saidthe timing was good. I don't have I light yet so I can't check it.

I pulled the top carb bowl off measured my float. It is 5/16 to 3/8. My manual says 3/16 to bottom so I need to raise it up a bit and check the rest. That should put them just past parallel to carb body.

Just curios does that sound like a solution to running too rich. Sorry I'm pretty new to outboards. Everytime I think I'm right, I usually end up wrong.

 

[foodfisher]

Re: '90 Force 90Hp Fuel Issues??

Being stuck on rich just doesn't feel right. Have you checked the primer bulb to see if it collapses. Try pumping it during the problem. Do the carbs drool?

 

[bbfrs1]

Re: '90 Force 90Hp Fuel Issues??

I tried pumping the bulb at wot, it didn't change anything. It never does collapse.

I was told to take the tank end off of the fuel line and see if stays firm. And it did. So I believe that it is not my bulb. I don't know if that is true or not, a boat mechanic in my town told me that. Who knows.

 

[jerbear56]

Re: '90 Force 90Hp Fuel Issues??

Well, it's often said that the two happiest days in a mans life are when he buys a boat, and when he sells it............

Just have to be persistant. It's not unusual for the floats to be set where yours are. Puts more pressure on the needle and the carbs don't slobber as bad that way. Realistically, I've never seen it cause the problem you are having.

I still think you should try running it with the cover off. Could be as simple as one of the carbs getting covered by the cowl insulation as it's sucking the air in.
And here's another thought. Is your motor trimmed correctly? And what shape is your transom in? A weak transom will flex and let the motor fight itself as it tries to come up to speed.
But to be honest, I'd also want to see with my own eyes that the timing is correct, you know?

 

[bbfrs1]

Re: '90 Force 90Hp Fuel Issues??

I bought a timing light and trying to check my timing. My flywheel has only 4 marks. 3 together and 1 about 2 inches from other 3. My manual shows numerous marks on the flywheel. Which one should my pointer line match to when checking it.

 

[bbfrs1]

Re: '90 Force 90Hp Fuel Issues??

I checked my timing and it is set at 30 btdc. It is the middle mark on the flywheel.

The transom seems to be in good condition. I checked for cracks and checked the bolts, all seem to be fine.

I dont have power trim, so I use a trim bar. I run it in the 2 middle settings. When I put the motor all the way in the water, it seems to run even worse. So thats why I use those settings.

I ran it with the cowl off, and it didn't change anything. I did this before when I first started trying to fix it.

So I really don't know where to go from here. The tank vent is properly working, the pickup was clean, Ive cleaned the recir. bowl, changed filter, new fuel pump diaphram, new plugs, I have good blue spark. I quess the only thing else is primer bulb. If anyone has any more ideas, please let me know.

 

[jerbear56]

Re: '90 Force 90Hp Fuel Issues??

I don't have the specs for the motor you have, but all my motors have always timed at tdc at idle, and 32 before tdc at wide open throttle.

Did you check the timing at idle, or wot?

 

[bbfrs1]

Re: '90 Force 90Hp Fuel Issues??

I checked the timing cranking the motor at wot. I used one of the previous posts for directions.

 

[foodfisher]

Re: '90 Force 90Hp Fuel Issues??

Gut feeling it's the woman's breasts, uh er, carbs. Sticking float/needle, plugged jets,link and sync

 

[sweezy722]

Re: '90 Force 90Hp Fuel Issues??

When your throttle is wide open carb butterfly should be flat or horizontal on every carb I have worked on in the past. If it is opening too soon or too far you probably are running rich. My experience has been if the needle is not working right you will see fuel coming out the vent of the carb. I am suspicous of your jet in the carb. Jets cost around $5 and almost never get replaced. I have seen jets over time and cleanings open up to where the motor run excessively rich.

You have compression and spark so that only leaves fuel. Get the carb right then you get it in sync and you should go. Make sure it is getting fuel and not too lean. Also it is possible on some models for the fuel pump to rupture a diaphram and dump fuel into a cylinder. How do your spark plugs look. They will talk to you if you listen. There are some good pictures on the internet of what your spark plugs should look like. Maybe you get an idea from all of this that helps. Good luck.

 

[bbfrs1]

Re: '90 Force 90Hp Fuel Issues??

I took the boat out yesterday, and it is the same. After adjusting floats and mixture screws. When I try and start it, it fires, coughs, and dies immediatly, I have to give it throttle or it won't stay running.

When i take off it will take off and then makes a groaning noise like the carbs are loading up, then at about 1/2 throttle it will take off. I still have no response after 3/4 throttle.

After everything I've done I believe the only thing else I can do is rebuild the carbs. And start from scratch on them. What do you guys think?

 

[jerbear56]

Re: '90 Force 90Hp Fuel Issues??

Sounds like the thing to do. I'm inclined to think that someone previous may have gone through the carbs and didn't do it correctly.

If you need the carb specs, holler back.

Also, I don't know if this applies to your force, but the old chrysler three cylinders would have some really strange problems that stemmed from the head gasket. Even though the head gasket would check good with a compression test, plugs would fire a good spark outside the head, but wouldn't fire when installed, on and on. Some of those problems were never explained but were always resolved by replacing the head gasket.

 

[bbfrs1]

Re: '90 Force 90Hp Fuel Issues??

I was wondering what size of main jet I should use. I run everywhere from 4750 to 5100 ft in elevation. Right now i have .070 in all 3 carbs. What do you think would be the correct set up for my elevation?