Force 120 Hard Start

[jpwilly]

The Force 120 1994 on my Bayliner ran good heck I'd even say great underway. We got 40mph GPS at WOT with a 17" pitch 3 blade aluminum prop. It pulled the boat onto plane strong with me and a buddy both of us over 200lbs and full fuel plus cooler and fishing gear. No problems no bogging very happy! BUT it started hard every time we went to move spots. I adjusted the idle speed up 1/8th to 1/4 turn on the lake to keep it from stalling in gear. After this it still wanted to start hard and initially idle on the edge of shutting off. It usually would fire then sputter and die. I had to use the neutral warm up to give it some gas (but no choke or it would flood) rev it up and then I could back it down to idle and it shifted into gear without sputtering off.

I haven't changed the plugs but they seem to be working well.
Full tank of fresh gas and oil mix with quicksilver treatment.
I haven't checked the timing with a timing light. My tach doesn't work and checking this on the lake would be a challenge.

Any ideas?

 

[SkiDad]

Re: Force 120 Hard Start

I'm not sure if this is a new boat to you or not. Which screw did you use to adjust the idle ? - at the bottom of the tower or at the top ? the top one is timing and the bottom is idle. I apologize if you already know this. Sounds like your idle is still not high enough ? if you are adjusting the correct screw for idle you might want to check the air screws on both carbs to make sure they are set correctly and then reset your idle speed. I have mine about 800 in gear for it to not stall.

once in a while I have to start my boat with the gear shifter in warm up mode and the bring it back to neutral.

 

[pnwboat]

Re: Force 120 Hard Start

Might want to wait until you run through the tank of Quicksilver treatment before you do anything.

 

[Jiggz]

Re: Force 120 Hard Start

I would at least verify the carb's air-fuel mixture screws are set 1 turn out from lightly seated, idle rpm in neutral around 800~900 RPM and with idle rpm in gear around 700~800. Note, you need to make sure the engine is not misfiring otherwise you will need to check compression on each cylinder.

 

[Frank Acampora]

Re: Force 120 Hard Start

hard starting and too low an idle speed causing stalling in gear are the first signs of fouled plugs--even if they look good. before you do anything else, change or clean the plugs.

Side note: because of the nature and design of the ignition system, fouled plugs will run great at speed, yet give problems at or near idle.. My mantra: Anytime you have starting or idling problems with a Force engine, before you do anything else, change the plugs.

 

[jpwilly]

Re: Force 120 Hard Start

@mitzysman it is a new to me boat but I did use the correct screw on the bottom to turn up the idle. Good call though.

@pnwboat I mixed the quicksilver ethanol treatment 1oz per 10gal per instructions but not sure if this bottle contains the magic my motor needs or not?

@Jiggz my tach isn't working so setting idle was done so that the motor doesn't stall when idle in fwd or rev. I mentioned I had synced and timed the carbs per the sticky they are approx 1 1/8 turn out from lightly seated. How would I know it's misfiring? didn't sound like it just didn't want to run for a few seconds then it would finally kick in after I revved it up with the warm up throttle.

@Frank I checked the plugs. There isn't any carbon or oil fouling on the plugs. They were a little wet after idling in the driveway I assume a 2 cycle is suppose to be? I don't know when they were changed last and not sure what the correct plug is either any help in getting the correct ones would be appreciated. I wouldn't mind swappin in some new ones and keeping the existing ones as spares.

 

[pnwboat]

Re: Force 120 Hard Start

1oz per 10 gallons doesn't seem very much. Who knows.

Do you squeeze the primer bulb before you start? You should only have to do this when you start it for the first time. See if it makes any difference later in the day when you try to fire it up. If it seems to help, you might want to check the fuel pump diaphragm. The rubber diaphragm should be soft and flexible. It gets hard and not as flexible as they get old. It should be replaced ever few years.

Spark plugs should be surface gap type. NGK BUHW (non-resistor) or NGK BUZHW (resistor). Champion L76V. I seem to have better luck with the NGK's. Had some issues with a set of Champions that were made overseas.

 

[Jiggz]

Re: Force 120 Hard Start

Hard starting is usually experienced only with cold engines but even then with proper starting procedure the engine should start within 2~4 times of starting. With a warm engine, it should be no more than 1~2 sec of starting and should start first time. If you haven't done so you might want to verify timing to make sure it is within specs. Next is to install a clear fuel filter between the fuel pump discharge and the carb input. This is really a cheap mod costing less than $5 but very useful for troubleshooting. After moving from one fishing spot to another and the engine is hard to start you might want to check this fuel filter to see if it is at least 1/2 full. If not it is an indication there is a leak somewhere or the fuel pump could not be delivering enough fuel during idle but will do so at high rpm.

 

[jpwilly]

Re: Force 120 Hard Start

@pnwboat Yes I did squeeze the primer bulb at the dock to firm it up and checked it once on the lake it was firm. The plugs in it are Champion L76V and this engine appears to have the blue CDI boxes not the newer style ones does that make a difference when selecting new plugs?

@Jiggz it was around 50 degrees at the dock in the early morning and I put the motor in the water, squeezed the primer bulb till firm, set the neutral warm up throttle all the way forward then I cranked the engine with the push to choke till it sputtered and let up on the key. It seemed to take 3 or 4 tries till it ran and then died another 5 or 6 tries then it ran roughly while it warmed up. When I thought it was good I dropped into idle and it died seemed to be idling too slow. I turned up the idle at the dock. Then some more cranking with warm up throttle and it fired again. This time is stayed running when I shifted into fwd and turned away from the dock we ran out to a spot to fish and as we were idling in fwd it died so I adjusted the idle speed to keep it from engine from stalling.

But it still wanted to start hard 2-3 starts before it would run right or I'd set the neutral warm up throttle and rev for a few seconds before putting it back in idle. Maybe I'm loosing just enough fuel pressure between starts and need to check the diaphragm? I checked the TDC on #1 and timing mark was right at 0 degrees so timing seems good.

 

[pnwboat]

Re: Force 120 Hard Start

Just out of curiosity, could you post a picture of your ignition system?

These motors do not like cold that's for sure. I would expect them to be little more temperamental when cold but yours seems to be a bit more than normal. Might try what Frank suggests and try a new set of plugs.

One other thing, it's pretty easy to flood the motor when starting. Sounds like you are using the correct starting procedure by putting the throttle in neutral warm up position. Make sure the throttle is pushed far enough forward. You should only have to choke it for 3 or 4 seconds max while cranking on the first attempt. If it doesn't start, crank the motor a few more times without choking to make sure you've cleared out excess fuel before using the choke again.

If you don't know when the last time the fuel pump diaphragm was replaced, now is probably a good time to do it.

 

[Jiggz]

Re: Force 120 Hard Start

"I checked the TDC on #1 and timing mark was right at 0 degrees so timing seems good."

I'm not sure how you did this but technically the only time you can have zero degree is if the idle screw is backed off meaning it is not pushing against the engine block to advance the throttles for idle setting. If you actually backed off the idle screw for the purpose of checking timing, then this is correct. But if you did not adjust the idle screw this is an indication the idle screw is not set properly. With properly set idle setting, the timing should be advance around 3~7 degrees on #1 plug. If you can attached a pic of the eccentric screw and cam at idle setting, we should be able to tell if the idle setting is at least set.

Another recommendation is to switch to NGK plugs BUHW. I used to have the UL18V and even tried the L76V with very little concerns. But after reading about the BUHW (lower voltage requirement), I switched to BUHW and starting and running seems to be a lot smoother.

As previously mentioned the $5 clear fuel mod is a very big help when troubleshooting fuel related problems or simply isolating suspected cause of problems. In your case, if the fuel filter stays at least more than half full everytime, you can almost always assume the problem is not fuel related.

 

[jpwilly]

Re: Force 120 Hard Start

I checked TDC by using a screwdriver in the #1 to see where it stopped and started back down then looked at the timing mark. It was basically right at 0. I didn't touch the timing or idle screw. I'm assuming 3-7 degrees would be when it's running?

 

[Jiggz]

Re: Force 120 Hard Start

The TDC with #1 plug is only the first step in checking timing. Using a timing light (inductive same as those used in automobiles) you should be able to verify the timing using the so called static timing procedure. There is actually a video in one of the stickies that demonstrate this procedure. Anyways, if the engine do achieve 40 MPH when running I can presume the timing is most likely accurate. But then if you have a timing light available, it doesn't hurt to validate it.

 

[MickLovin]

Re: Force 120 Hard Start

Sounds to me like the idle isn't correct or you have a carb problem ( too rich? ) my Chysler doesn't use any throttle at neutral warm up, I choke it it starts within several cranks of the motor and starts when warm first time. I would refer to Frank's carbie sync and timing tutorial at the front of the forum page.
I always check my plugs to see what is happening with my motor they are a good indication if it is running rich/lean or some other problem.

 

[jpwilly]

Re: Force 120 Hard Start

@micklovin - yea carbs could be rich but I sync'd and timed the carbs per the sticky. I have already done it does it need done again?

 

[MickLovin]

Re: Force 120 Hard Start

What are your carbs set at at the moment, Frank always says never go less than 7/8 of a turn. You mention it doesn't bog down, so I presume you did a water test after adjusting your carbies by going from idle to full throttle? Also you mention that your timing was done with no adjustment to the idle screw, if you were able to obtain 0 with the idle screw in the same position as when you run it, MAYBE! you have your idle screw adjusted too low therefore not advanced enough. Did you after doing your carb sync, adjust your idle in forward to 700 - 800? If you don't have a tacho, get one. By the way, I started having a similar problem as yours, it would take more cranks and wouldn't idle quite right, my idle adjustment screw wasn't tightened properly. Check everything and then check it again can't hurt. Tighten everything, then tighten again when finished, don't over-tighten.

 

[Qualls]

Re: Force 120 Hard Start

sounds like you need to fine-tune the tie bar thats connected to both carbs. Set the carb screws 1 turn out. Loosen the set screw on the bar. Get someone to help you start it while you set the bar. When you get the rpms you want tighten the set screw.

 

[jpwilly]

Re: Force 120 Hard Start

sounds like you need to fine-tune the tie bar thats connected to both carbs. Set the carb screws 1 turn out. Loosen the set screw on the bar. Get someone to help you start it while you set the bar. When you get the rpms you want tighten the set screw.

Never heard of that method and not sure it's correct...anyone care to verify this? As I have already mentioned i performed the carb sync and time outlined in the sticky.

@MickLovin as I mentioned before my screws are set at 1 1/8 turns out after sync and timing of carbs I set the idle screw to get outboard to idle in both fwd and rev without stalling. I don't have a working tach (yet) and am planning to remedy that. The engine didn't bog when I went from idle to WOT and ran strong. I can tell the startup and initial idle isn't right and want to fix that issue. I have new plugs on the way.

 

[Jiggz]

Re: Force 120 Hard Start

If you have done the synch and link you should be good to go. There are three things the synch and link does, it verifies the throttles are fully closed (with idle screw fully backed out) when the control lever is in neutral; it validates the throttles are fully open in horizontal (in reference to the carb's body) with the control lever in full forward position and the static timing is set at 28 degrees BTDC; and finally the air-fuel mixture screw is properly set (usually 1 turn out from lightly seated). I still recommend the $5 mod for the clear fuel filter to eliminate fuel as the cause of the hard starting problem.

 

[jpwilly]

Re: Force 120 Hard Start

@Jiggz Thanks for the info. I have a question about what your wrote. You said

There are three things the synch and link does, it verifies the throttles are fully closed (with idle screw fully backed out)

I didn't see it anywhere in the sticky or in Franks video any mention of backing out the idle screw when doing the Syn and Link but you specifically mention it. If this is a vital step why isn't it in the sticky that everyone gets pointed to?? Are there missing steps from the instructions on this page: http://forums.iboats.com/force-chry...iming-75-150-chrysler-early-force-431021.html