'89 50hp Force Irratic idle and bad skip until runnig full throttle

[bagged68vw]

New to the site, thanks in advance for any help. I just recently replaced the head gasket and removed the thermostat (due to over heating) rebuilt the carb. ran perfect for one afternoon, then the problem showed up again the next day. I have to throttle the engine up every time to get it to start. Replaced the plugs also. When you pull the throttle down to idle it shakes the pontoon scaring all the fish away. LOL when you put it in gear it skips really bad and when you give it more throttle the skip feels like it is trying to go faster (RPM's feel like they are jumping up) when you get to full throttle it eventually stops skipping but it feels and sounds like it is running on 1/2 of the horsepower. Again thanks for any help given!

 

[pnwboat]

Re: '89 50hp Force Irratic idle and bad skip until runnig full throttle

Make sure that you're getting a good strong spark to both plugs.

 

[MickLovin]

Re: '89 50hp Force Irratic idle and bad skip until runnig full throttle

You mention that you re-did the head gasket due to over-heating and removed the thermostat, may I ask what made you suspect the head gasket and after replacing the head gasket did you replace the thermostat. It sounds like you have a miss on one or more cylinders.
Have you checked your spark plugs for any signs of water on them? Have you checked your spark plugs for spark on each cylinder?

 

[Jiggz]

Re: '89 50hp Force Irratic idle and bad skip until runnig full throttle

Try doing a compression test first.

 

[jerryjerry05]

Re: '89 50hp Force Irratic idle and bad skip until runnig full throttle

Possible the air screw needs adjusting?Set at 1 and 1/8th turn out.
Water in the fuel?
The diaphragm in the pump,check for holes.
Compression/spark test?

 

[bagged68vw]

Re: '89 50hp Force Irratic idle and bad skip until runnig full throttle

Thanks for your previos help. Ok, verified torque on head bolts and they are good,checked compression and it is at 135 psi on both and holding. Pulled the plugs and checked the spark and they looked good to me. Verified the timing to 28 degrees. Checked both plug wires with a timing light at idle and they both were firing and at the same timing of about 4 degrees. Vent on gas cap was stuck fixed that problem also. Took it out for a run and idled like a champ, but when I gave it full throttle it would not idle up to full throttle, it was really struggling. I worked on a buddy of mines boat and it did the same thing and it turned out to be the trigger. Pulled the boat out and pulled the trigger, and the stator, checked the resistance on the trigger and got 51 ohms on both legs, and the stator had ~750 ohms per leg. From my studies these are good. Pulled the coil packs and the CD unit (what ever that is) and cleaned all grounds and found one wire that was pinched skint the insulation back to verify the wire wasnt broken and it wasnt so I repaired the wire. Pulled the carb just to verify that it was clean, it had alittle trash in it so recleaned the carb. Took it out for another run and it ran the same way but it seemed to rev a little more that the last time, but it still wont get to full throttle. Dont know where to go from here. How do you check the coils on these boats and the CD unit? I am thinking that I have a coil that is breaking down under a load or not the right output from the CD unit? Please Help I'm at a loss now!! LOL

 

[oldboat1]

Re: '89 50hp Force Irratic idle and bad skip until runnig full throttle

I can't quite figure out what you mean by "skipping." An increase in rpms could be carb related (rpms increase when the air fuel mix leans out), but could also indicate a prop hub or clutch dog issue. Did the engine overheat, for example, because you sucked up some sand after grounding? Anything to suggest prop or lower unit involvement?

It sounds offhand like you might still have a clogged jet in the carb -- might be getting some contamination from the fuel tank (that debris you found). Check and clean the fuel filter, and check to see that the fuel pump output is good (just pull the line at the carb while cranking).

 

[MickLovin]

Re: '89 50hp Force Irratic idle and bad skip until runnig full throttle

Did you put a filter between the carbies and the pump? I agree with oldboat1, sounds like a clogged jet, have you checked your fuel pump diaphragm at all? Might have a small hole in it which is only affected by higher rpm. worth a look if you have a spare gasket. Also I can't see where you mentioned about adjusting your air mixture screws, do you know what they are currently set at?

 

[bagged68vw]

Re: '89 50hp Force Irratic idle and bad skip until runnig full throttle

Yes I have checked diaphragm in the fuel pump, Yes I have a fuel filter in the line after the bubble. And the carb is very clean, but not too sure about the output from the fuel pump. Will check it today.

 

[MickLovin]

Re: '89 50hp Force Irratic idle and bad skip until runnig full throttle

As you rebuilt your carbies, you still haven't told us what and how you set your carbies air mixture screws. May be running to lean, also when you cleaned and rebuilt them did you blow compressed air through them? Did you set the float correctly, I have set floats up and had to do it again, even though I thought I had set it correctly, when I rechecked them they had dropped. Sounds like you still have a carbie issue to me.

 

[bagged68vw]

Re: '89 50hp Force Irratic idle and bad skip until runnig full throttle

What is the correct height for the Float 13/32?

 

[MickLovin]

Re: '89 50hp Force Irratic idle and bad skip until runnig full throttle

yes that is correct, what is your air mixture screw set at?

 

[bagged68vw]

Re: '89 50hp Force Irratic idle and bad skip until runnig full throttle

1 turn from lightly seated

 

[Jiggz]

Re: '89 50hp Force Irratic idle and bad skip until runnig full throttle

Yes I have checked diaphragm in the fuel pump, Yes I have a fuel filter in the line after the bubble. And the carb is very clean, but not too sure about the output from the fuel pump. Will check it today.

What do you mean after the bubble? You mean the primer bulb? If yes, it is at the wrong location unless your original intention is such. However, the clear fuel filter mod is to be installed between the fuel pump outlet and the carb's inlets. It is more of a troubleshooting tool than a secondary filter.

 

[bagged68vw]

Re: '89 50hp Force Irratic idle and bad skip until runnig full throttle

Ok, heres the update, fuel pump diaphragm looked stretched. So I replaced diaphragm and all gaskets all the way to the block with a fuel pump rebuild kit, also I pulled the carb back off and set the float to where it was level but I did notice that with the carb upright with the float on the bottom the float would hang way below the main jet, adjusted it to where the float was just above the jet and then flipped the carb and set the float height to level but with it level iti did not have alot of travel. I set a pair of calipers to 13/32 bout i am unsure of where to measure it to (from the base; to the lower edge, middle, or top edge of the bowl) with the carb inverted. But with me raising the float up made it run alot better in the barrell just curious about the closing height?

 

[bagged68vw]

Re: '89 50hp Force Irratic idle and bad skip until runnig full throttle

Sorry I found a typo Not the top edge of the bowl but edge of the float.

 

[Jiggz]

Re: '89 50hp Force Irratic idle and bad skip until runnig full throttle

See attached pics how to set carb float. One important thing is to make sure the float lowest drop is even with the pick up tube as shown on Step 10 and should not rest or touch to it. A little higher would not hurt but a little lower will.

 

[bagged68vw]

Re: '89 50hp Force Irratic idle and bad skip until runnig full throttle

Thanks Jiggz, I believe that will probably solve my problem of the surging. When I am going down the lake and I slowly icrease the throttle, any where in the throttle it will suddenly pick up RPMs only once but after it does that it runs like a champ, I have never heard it run that good. Im thinking that it still has to do with the float now that I have a picture og what it is supposed to look like. Thank you for all of your help.

 

[bagged68vw]

Re: '89 50hp Force Irratic idle and bad skip until runnig full throttle

Hey Jiggz does the book you got that pic out of show how to install the spring that goes around the float pin?

 

[MickLovin]

Re: '89 50hp Force Irratic idle and bad skip until runnig full throttle

Have you tried going from idle to WOT real quick (hole shot) to see if it takes off correctly? Possibly float, could also be set to lean or too rich