1998 120 force idleing poorly with spark

[greiner.enoch]

hey just wondering if anyone can help me. If not im selling this boat.

purchased this boat about a couple of months ago. i have done a lot of work to it. Fires right up but shakes when idling and the main problem is when i throttle up it feels like one piston hits the plug like every two or four seconds and sounds like a knock just at that time :facepalm:. I'm getting spark to all new plugs (and new wires) and i did the Seafoam method to the engine. i also did the piston check ( where you push the piston with a wood dowel pin) and doesn't seem to be anything loose. one thing i do notice is that the second cylinder is dry and almost seems like there is no combustion going on in there....maybe timing?? i dont know how to check that, sounds difficult. And i was really looking forward to taking it out next Wednesday :grumpy:. i may just sell it and get a better one. thanks for anyone who can help.

 

[Frank Acampora]

Re: 1998 120 force idleing poorly with spark

There are a number of causes for a poor idle. Timing and fuel mixture are two.

If your engine is "knocking" DO NOT run it until the problem is fixed. Timing too advanced and/or a lean mixture will cause knocking and ultimately will damage the engine.

SO: If #2 cylinder looks dry, it is a good indication that it is running lean. You need to check the brass idle mixture screw and see if it is somewhere near 1 turn out. You also need to check the carb itself to see that there are no deposits inside causing a lean condition. The carb should be removed, disassembles, and cleaned.

Finally, check timing to see if it is at 28 or 30 degrees advanced at wide open throttle.

 

[greiner.enoch]

Re: 1998 120 force idleing poorly with spark

hey thanks for the reply frank! so one turn out means, screw all the way in and then unscrew one complete revolution? im very afraid to take the carbs off just because ive heard they are so touchy. but ill just have to get the courage. do i check with a regular automotive timing gun?

 

[hbryant123]

Re: 1998 120 force idleing poorly with spark

My chrysler was making a loud thud that sounded almost like a knock, it turned out that it was jumping out of gear, so i adjusted the rod under the bottom carb that goes into the lower end and it solved it.

 

[greiner.enoch]

Re: 1998 120 force idleing poorly with spark

no this happens in neutral

 

[Jiggz]

Re: 1998 120 force idleing poorly with spark

If problem persists after following Frank's advice, you might want to check compression on #2 cylinder. If it's good and you said you have sparks, then you can almost isolate the problem to air-fuel supply alone which also includes the reeds.

 

[jerryjerry05]

Re: 1998 120 force idleing poorly with spark

Check comp on all cylinders. Post the results. It could be just a bad head gasket.
Check the fuel pump diaphram too.

 

[cuenta]

Re: 1998 120 force idleing poorly with spark

with force engine
is too complicated to adjust the idle
it according to manufacturer
According to the manufacturer idle is 750 rpm en neutral
but leave it at about 900 or 1000 and you will have a better performance in idle
not fight trying to adjust to 750rpm

knocking noise..
I had this problem was that I was running very lean
when I made the mixture the firts I put the oil and then gasoline
the mixture was lean
now I made the mixture in a gasoline container
and shake well before of put in the boat tank
never more noise

 

[greiner.enoch]

Re: 1998 120 force idleing poorly with spark

Ok, I'm going to check the compression on Monday. Head gaskets are easy, right? what are reeds? where are they? when you number the cylinders, does the first cylinder start at the top? the screw on top of the carbs with the spring in it, is that the idle mix screw? one more thing do i need to buy a gasket kit or anything when i clean the carbs?

 

[jerryjerry05]

Re: 1998 120 force idleing poorly with spark

The screw with the spring. It's for the air/fuel mix. 1 turn out and LEAVE IT.
The idle is adusted with the towershaft on the stbd.side.
Idle above 800 can cause damage to the gears and clutch dog.
The head gasket is easy??? If you run into no problems. The bolts sieze and can twist off.
They are only put on with 20ft lbs. So if you run into any TIGHT bolts, STOP and ask and I'll tell you how I get them free.
Reeds are behind the carbs. They allow air/fuel into the cylinder.They stop it from comming back through the carb as it runs,then you MIGHT???? have trouble with the reeds.
Try taking the carbs apart before you order ny parts. You might not need anything but bowl gaskets
If you remove the bowl gaskets,keep them wet or they will shrink and not go back in. If you can leave them in? Do it.
I use soap and water. Then blow dry with air. Any spray cleaner can leave residue and make things sticky.

 

[Jiggz]

Re: 1998 120 force idleing poorly with spark

For now posting your compression numbers is the key for your next move on that engine.

 

[greiner.enoch]

Re: 1998 120 force idleing poorly with spark

 

[greiner.enoch]

Re: 1998 120 force idleing poorly with spark

these numbers seem a little high to me.

 

[Jiggz]

Re: 1998 120 force idleing poorly with spark

Compression is good. So you need to start troubleshooting with the fuel delivery system starting with the carbs settings. Also try listening with the engine while the cover is off and on muffs and also when with the covers on and in the water. If there is a big difference, let us know. As for the readings being too high, different compression meters gives different readings.

 

[jerryjerry05]

Re: 1998 120 force idleing poorly with spark

Those #s are fair.
Do it again with a different guage.
Auto Zone loans them.
They should all be within 5-10# of each other.
Post all 4 if possible.
I see #1-140 possible blown head gasket between 1/2??
#2=140
#3 160
#4 ??
With the right guage?? It should be around 150#
How are the plugs burning?
Any water or rust?
Plugs real clean? No carbon?

My 3 cyl.started missing,It had good comp on all 3 145#=150#
Bottom cylinder,had a tiny bit of water. Pulled the head and the salt had built up on an edge and eventually burned a spot. Luckily it was a spot on the gasket not on the steel sleeve.

 

[greiner.enoch]

Re: 1998 120 force idleing poorly with spark

Those #s are fair.
Do it again with a different guage.
Auto Zone loans them.
They should all be within 5-10# of each other.
Post all 4 if possible.
I see #1-140 possible blown head gasket between 1/2??
#2=140
#3 160
#4 ??
With the right guage?? It should be around 150#
How are the plugs burning?
Any water or rust?
Plugs real clean? No carbon?

My 3 cyl.started missing,It had good comp on all 3 145#=150#
Bottom cylinder,had a tiny bit of water. Pulled the head and the salt had built up on an edge and eventually burned a spot. Luckily it was a spot on the gasket not on the steel sleeve.

Well everyone was right. I cleaned the carbs and and reset the mixture which was off. That is hopefully what was causing it to sneeze. I pulled the head off and the head gasket had a hole in between the number one and two cylinders. I'm putting it back together tomorrow. Wish me luck.

 

[Jiggz]

Re: 1998 120 force idleing poorly with spark

Just make sure you torque them properly in sequence. Usually, you start from the middle and go outward in spiraling direction.

 

[jerryjerry05]

Re: 1998 120 force idleing poorly with spark

Right!!! Yea. 20# of tourqe on the bolts.
Use a thread chaser to clean out the threads and clean the bolts.
I use a bit of grease on the bolts when I reassemble.
I'm sure others will suggest something else.
Another wrench I know used a mix of antisieze and marine grease.
Not sure how it worked??

 

[cuenta]

Re: 1998 120 force idleing poorly with spark

jerry
the idle at 750 rpm is en neutral or in gear in the water
because in the driveway I can't down of 1000 rpm in neutral

thank.

 

[jerryjerry05]

Re: 1998 120 force idleing poorly with spark

750=800 in gear,motor warm.
On the hose it could be as much as 1200.
The first post in the Force section. FrankA posted a link called Linc and sinc.
http://forums.iboats.com/force-chry...iming-75-150-chrysler-early-force-431021.html
This will tell you how to set up your carbs and set up the linkage.
Post your questions in a different thread. This one is for greiners post on his outboard.