Still at it, 1989 GT150 1 cylinder not firing !!!!

Update on our progress.
We have checked timing,plugs,cleaned carbs #3 times,checked compression,installed new fuel filter,coil on that cylinder,new reeds in that cylinder and still the same thing, #2 cylinder will not fire.
We gave UP!
Took it to mechanic, ask him to check it out for us and let me know the results, $120.00 later tells us that we have a MAJOR problem in the internal part of the motor, exshaust is getting into the vaccum side of the motor causing the motor to heat more and is evaporating the fuel in that cylinder.
We have to tear it down between the heads and I either have a bad gasket or a cracked block. For $120.00 more he will do that to see what the problem is. Due to these great money times we are having I had to hook it up and come back home with it again. NOT FIXED!
After getting in back we tear it down to see what is wrong, but the only thing we found was a little oil leak on the outside of the motor at the bottom cylinder on the left. No cracks Nothing to say it isnt working right.
Pull left side head and check gasket, looks great.
I HAve NO IDEA what to do now.
Can ANYONE help? Its appreciated believe ME!

Re: Still at it, 1989 GT150 1 cylinder not firing !!!!

What does the #2 spark plug look like when you are trying to start it? Is it wet or bone dry? Pull the spark plug out of the #2 hole and crank it, does a fuel mist some out of the spark plug hole each rpm? Compression on that cyl?

Re: Still at it, 1989 GT150 1 cylinder not firing !!!!

Thank you for looking.
The plug is dry, compression test past with flying colors 93 on that cylinder.
We didnt notice any gas mist when we did that.
All cylinders were in the low 90's on the compression test..
All the other spark plugs are wet

Re: Still at it, 1989 GT150 1 cylinder not firing !!!!

I'd pull that carb apart that feeds that cyl. Could be something blocking an internal passage, keeping fuel from flowing on that half of the carb. You could also swap it with the bottom carb and see if you have the same problem on the bottom cyl same side. That would verify a carb issue

Re: Still at it, 1989 GT150 1 cylinder not firing !!!!

I would try injecting fuel,not starting fluid into the barrell of the carb that feeds the troubled cylinder,if it fires,you have a fuel problem,which i would think is carb related,unfortunatly ,that cylinder not getting fuel could lead to scoring if no fuel/oil is getting there,i find the mechanics theory interesting,and certainly want to hear if its right,is there any sign of rust on the plug

Re: Still at it, 1989 GT150 1 cylinder not firing !!!!

Ok let me see here
We did tear carb down and checked, we also switched the carb and still same problem.
We did spray gas in the carb and the cylinder would fire.
We tore into the motor last night to find nuffin really.
We did find a small blow out on the 6th cylider area where oil was on the outside of the motor, we havent got the gaskets yet to replace them and dont know if that was it or not. Just dont see how that would be the problem, seems to me that would have just been a exhaust leak.

Re: Still at it, 1989 GT150 1 cylinder not firing !!!!

You seem to be doing all the right troubleshooting. Crank the engine: If you hold the palm of you hand over the #2 carb throat, do you get the same suction as over #1 carb throat? Do you get any blow-back out of the #2 carb throat (a possible reed problem?) Did you put a timing light lead on #2 plugwire and did it have good spark when the engine was cranked? The exhaust leak could be a powerhead base gasket. Failure of that gasket causes the black, oily exhaust residue to exit into the lower cowl. Additionally, the exhaust smoke will eventually fill the cowling and can get reingested in the airbox-which can affect engine operation. While a messy problem that should get fixed, it is likely unrelated to your problem on #2.

Re: Still at it, 1989 GT150 1 cylinder not firing !!!!

it fires when you manually inject gas,so it has to be gas,the number 1 fires fine right? so they use same carb,you switched carb,so its not carb,you put new reeds in,not reeds,so your noyt pulling fuel into combustion chamber,is there an issue with the side bypass cover,if not my thought at this point would be seal ring around crank.or someting to deny the suction of fuel,did you tear eng down completly,if so check the rings around crank and the block for anything that would deny the suction process

Re: Still at it, 1989 GT150 1 cylinder not firing !!!!

When tearing it down we did find a spot that the gasket was leaking oil out against the block. But that was it.
I do have a black tar like residue coming out around the bottom of the cowl and exhaust. After running it on the water hose in shop from testing it.
I have got to order the gaskets for it on Monday and I guess build it back and test it from there. We didnt notice anything wrong with rings, and cylinders but we didnt go all the way. Just removed the exchaust covers and one head gasket on the #2 side. Side bypass cover was also removed o #2 cylinder but nuthin found that we can see.
Thanks for all the info so far any help is appreciated and needed very much.
We just a punch of shade tree mechanics tring to fix a problem we dont have the money to pay to be fixed..lol Sure wish I could go fishing thou....

I know your post was from several years ago, but I'm curious to see if you ever got your boat running and the issue resolved. I've been having the same problem with my 89 gt 150 for the past 5 years and I've done everything you did and then some. I've put almost $3,000 in new parts on my motor and it still doesn't run right. I'm basically giving up at this point. Any advise or direction would be very much appreciated. Thank you.

Welcome to IBOATs ... as a newcomer it is better not to revive old 13 year posts... just open a fresh new post and describe your problem.

emdsapmgr said:

Re: Still at it, 1989 GT150 1 cylinder not firing !!!!

You seem to be doing all the right troubleshooting. Crank the engine: If you hold the palm of you hand over the #2 carb throat, do you get the same suction as over #1 carb throat? Do you get any blow-back out of the #2 carb throat (a possible reed problem?) Did you put a timing light lead on #2 plugwire and did it have good spark when the engine was cranked? The exhaust leak could be a powerhead base gasket. Failure of that gasket causes the black, oily exhaust residue to exit into the lower cowl. Additionally, the exhaust smoke will eventually fill the cowling and can get reingested in the airbox-which can affect engine operation. While a messy problem that should get fixed, it is likely unrelated to your problem on #2.

Click to expand...

It's not normal for there to be visible oily exhaust (exactly like you mentioned) in the test tank/lower cowl while running right?

rowerowe101 said:

It's not normal for there to be visible oily exhaust (exactly like you mentioned) in the test tank/lower cowl while running right?

Click to expand...

unburned fuel mix is normal when operating at low engines speeds such as in a test tank.