72' Chrysler Outboard 120 Hesitation/Bog/WOT Unstable

[boostup]

We have a 1972 Chrysler 120 we can get it to start perfect.. Brand new plugs and checked the distributor points and the wires seem to be ok... we cant get the timing right from what my associate says to me the carbs seem to be adjusted right but, when we go to accelerate it runs up, gets on plane and at full WOT it will after 4 or 5 seconds it begins to shutter, bog, and stall out we'll have to back off of the WOT and go to about 30 - 40% power and it will run for forever on that but, still sounds like it's misfiring or something, no idea what's going on.. we've read up on everything we can on a dozen forums about this and we have power to the coil, power from the coil, stater seem to be putting out 13.5 volts and the battery is fully charged, and the fuel is a semi-high octane gas, getting plenty of gas if we hold our hands over the carb to see if it sucks the gas through it does, and it'll flood the motor out FAST if we do that but, we both are fairly knowledgeable about motors and this one is stumping us... we've read the issues about the carb not being "tuned" and there was like 9 - 10 steps and we're going to try that now... OFF TO THE RIVER... by the way, this TEST is done in the water under load WOT...

 

[boostup]

Re: 72' Chrysler Outboard 120 Hesitation/Bog/WOT Unstable

Ok so FAIL NO MATTER WHAT WE DO, pump the primer ball, or neething we still cant get it right HELPPPP

 

[jerryjerry05]

Re: 72' Chrysler Outboard 120 Hesitation/Bog/WOT Unstable

Ethanol.Fuel pump diaphram.Weak hoses.J

 

[Frank Acampora]

Re: 72' Chrysler Outboard 120 Hesitation/Bog/WOT Unstable

Its not getting enough fuel. You need to check the complete fuel line from tank to carbs for partial clogs or restrictions. If it has a quick connect, the male fitting often clogs behind the check ball.

On general principles, change the fuel pump diaphragm.

Remove the carbs and clean them, then set the float level AND the float drop. With the carb upright, the float should drop almost to the brass high speed jet at the bottom of the carb. If the float drop is not enough, the engine will starve for fuel at full throttle. To set the float level, with the carb inverted the float should be parallel to the casting.

Once it runs consistantly at full throttle, then decide if it is missing or not.

Don't use high octane gas. The engine does not need it and you are wasting money.

Search and read my post on synchronizing carbs and timing.

 

[boostup]

Re: 72' Chrysler Outboard 120 Hesitation/Bog/WOT Unstable

K another question whats the single screws on the tips (intake) of the carbs?? 1 on each?? N how do i set them??

 

[Frank Acampora]

Re: 72' Chrysler Outboard 120 Hesitation/Bog/WOT Unstable

Those screws are the low speed mixture adjusting needles. The procedure to adjust them is in my post: Synchronizing carbs and timing.

DO NOT set them too lean (less than 3/4 to 1 turn out from lightly seated) or you will detonate and melt piston(s) at full throttle.

 

[boostup]

Re: 72' Chrysler Outboard 120 Hesitation/Bog/WOT Unstable

Ok adjusting rite now does anyone know what the fuel pump diaphram replacement part is?? We both work at advance auto parts we can get the part i just need to know what to look up

 

[jerryjerry05]

Re: 72' Chrysler Outboard 120 Hesitation/Bog/WOT Unstable

Make sure you need anything before you buy.Post serial #s and model#s
A 72 120 Not sure without the #s J

 

[DeafMonkey]

Re: 72' Chrysler Outboard 120 Hesitation/Bog/WOT Unstable

The model # is 1207HD and the serial # is 1882. Thanks for your time and any information you can give us with part #s.

 

[boostup]

Re: 72' Chrysler Outboard 120 Hesitation/Bog/WOT Unstable

By the way deafmonkey is the other guy workin on the boat haha

We just wanted to say much thanks for all your help in finding the problems we got it running good now does anyone know the process to tune the timing step by step?? Or a link?? Greatly appreciated !!!!

 

[DeafMonkey]

Re: 72' Chrysler Outboard 120 Hesitation/Bog/WOT Unstable

Just wanted to say thanks for your guyses time again. This forum is a freaking cacaphony of information. You guys rule.


So.. yes... the fun stuff. We replaced the gas tank fittings, the fuel pump diaphram with the gasket, and all of the fuel hoses up to the carbs. We purchased two full carb kits and dismantled the carbs. The original housings and parts that weren't replaced were soaked in carb acid for a number of hours. They look freaking brand new now. The floats were set and we followed Franks guide to tunning the carbs and setting the timing as best we could. I have a few questions about that.

There is a timing plate in front of the fly wheel that has a zero on it close ish to the center then it goes to negative 4 and positive 2 I think. The two is on the right and the four is on the left. It seems funny cause the negative seems like it should be advancing the timing... and the positive should be retarding it. Where should the TDC be set at on dry land? That's static right?

We need to go back out and do the low idle air screws again... those seem to need to be perfect.. I set them perfectly to one and a quarter out but now see about backing them off and finding that perfect average... that makes perfect sense to me.

Now... here's what we can achieve as of much earlier today... we go from dead stop and just hammer the throttle she throttles up no problem but when planes out and wants to start running she starts pinging there's a grip of gnomes in there with hammers trying to beat their way out. So we drop the throttle and the decceleration runs smooth but then once at speed there's the pinging again.

So we get the boat back to the dock after like 4 hours of tinkering and pull the dist cap... we're thinking that we're losing an entire piston in the ignition somewhere... it's eight points under the cap and two of them look like the rotor buton was chewing them up. We've seen this before but sometimes we can get her to run better than others.... so much tinkering. Then we spin the rotor and watch it turn the button. It's got freaking wobble in it and upon closer inspection we find that there's a chip out of the button that's been worn down just enough to make you think it's good at a quick glance. can this be the source of the "pinging hammer gnomes?" ie possible dropping piston at random? and if so... how can we find the replacement parts?

Once again you guys rule and your help is always appreciated. Thank you for your time.

 

[DeafMonkey]

Re: 72' Chrysler Outboard 120 Hesitation/Bog/WOT Unstable

Oh yeah... one more question just out of curiosity. How does this freaking engine get air to it when the motor top is on.. All I can find are a few slits in the rear of it... it just blows my mind that there seems to be no intake...

Thanx.

 

[jerryjerry05]

Re: 72' Chrysler Outboard 120 Hesitation/Bog/WOT Unstable

As far as the parts go.Try valleysales@charter.net Valley989) 366-8178
He has tons of old parts.
The air comes in from the top slits and under the carbs is an opening.
Go to boats.net and look for this: Mercury Chrysler Outboard Parts 120 (1977) 1209BG MOTOR LEG Diagram #68 That allows the air in.J

 

[boostup]

Re: 72' Chrysler Outboard 120 Hesitation/Bog/WOT Unstable

he's talking about the motor seems to be sealed with no "vents" to get air.. i'm also working on the boat with him.. but, the ignition is more important.. please help !!!

 

[boostup]

Re: 72' Chrysler Outboard 120 Hesitation/Bog/WOT Unstable

ok saw what he meant.. didnt know that... thanks