75hp Chrysler

[Hulen]

I do not know the year I think its a 1975-76---<br /><br />Its got a Motorola Electronic Distributor Ignition<br /><br />It Idles fine but in the water and when I shift forward it dies out. it will start back up but<br /><br />dies when I shift forward. Thank you for any help you can give.

 

[eurolarva]

Re: 75hp Chrysler

Try choking it when you shift. If performance improves you have a fuel issue. If so I would start with a rebuild of the fuel pump which is easy and cheap. If that dont improve it the carbs will be next.<br /><br />On the top faces of the carb above the choke plates there is an adjustable screw. Turn these screws out 2 full turns (counter clockwise) Try and start the motor a couple of times then turn them back to where they were. Does this help the idle on the motor? Sometimes these mixture screws get crap trapped on the tips and by turning them open it frees the obstruction.

 

[RRitt]

Re: 75hp Chrysler

does it die out even if you give it some throttle? <br /><br />if it conks out when you shift but keeps running if you give it a little gass (just a tiny little bit faster than idle) then it could just be your idle speed adjustment.

 

[Hulen]

Re: 75hp Chrysler

I had the carbs done when I bought the boat, but had to replace floor and transom. That took about a year <br />to finish. Should I rebuild them again???. I have a Clymer Manual I might have messed up, I Turned the screws clockwise on the carbs untill the end and then counter clockwise 3/4 turns. is there a specific way to set them??

 

[eurolarva]

Re: 75hp Chrysler

I would start at 1 1/4 turns out. Better to be a little rich then lean. First test the fuel system by choking while shifting to see if it improves the condition. Two carbs are harder to set then one. What you want is the motor warmed up and idling as low as you can get it in forward gear. Turn carb setting 1/8 turn increments every 30 seconds counter clock wise till motor starts to stumble. Then go back and turn clockwise 1/8 turn every 30 seconds till motor starts to race. Half way between stumble and race is the correct position. Do this to both units. If you have only done the carbs I would rebuild that fuel pump. It is only about 10 bucks and if it has not been done in 30 years it needs to be done.

 

[Hulen]

Re: 75hp Chrysler

Thank you I'll try that today

 

[Hulen]

Re: 75hp Chrysler

I hooked the water to it and put it in gear and<br />gave it full throttle, started to sputter then I adusted the carbs like you said and it smoothed<br />out. sooooooo I took it to the water put it in<br />crank it up put it in gear and putt putt putt and died I did replace I guess you call it a baffle in the fuel housing. is that what you were<br />talking about the fuel pump? I don't know what to do next.

 

[RRitt]

Re: 75hp Chrysler

Eurolava - that is just about the best and most concise description of mixture setting that I have ever read.

 

[eurolarva]

Re: 75hp Chrysler

Hulen the fuel pump is a figure 8 looking thing that is probably located on the starboard side of the motor. Yours might have a glass sediment bowl.<br /><br />Couple of questions. When you prime the fuel does the bulb get a hard and stay firm? When you test it at home are you using water muffs or are you using a tank full of water?. Did you try choking the motor when it tried to quit on you during shifting? If motor runs good on muffs but dies in the water you could have a compression problem or a cylinder not firing. Remove each of your spark plugs and look at the tips. Are they all dirty or do you have one that is clean? If so that unit with the clean plug is the problem. If all plugs have equal wear I would attack the fuel pump and rebuild it. If still having problems you may have to go after the carbs again. When you did the carbs last year did you rebuild or just clean?

 

[Hulen]

Re: 75hp Chrysler

The bulb gets hard for a sec and does not stay firm<br />if i close the gas vent it will stay hard. The carbs was rebuilt. I used water muffs, but I have used tank of water also. there are no glass sediment bowl<br />that I know of, just a filter with a screen (round)<br />When I replaced the baffle I saw some valves in the housing..... I did check the spark plugs all three were dirty.

 

[eurolarva]

Re: 75hp Chrysler

Sounds like the problem is the fuel pump or the fuel hose and primer bulb. If the diaphram has a hole or is stretched in the fuel pump it will give you the symptoms you described. The rebuild kit is 18-7806. NAPA sells them for about 10 bucks or you can order one here at Iboats click on this LINK<br /><br />This baffle you mentioned. Is this the impeller from the lower unit? or is it some other part?<br /><br />Edited by Eurolarva<br />My guess is you are describing the fuel pump when you mention the baffle. If so it is possible that one or more of fuel valves in the fuel pump are damaged or have bad seals. Mercury sells these parts The fuel valve gasket is 27-F84792 (you need three) and the fuel valves are 21-F177330 and you will need three of these as well. The valves are 5 bucks each and the gaskets are half a buck each (note the valve gaskets that come in the rebuild kit will not fit these valves. The valves are check valves which means fuel will only flow in one direction which is why I am leaning toward it being the problem. Also check all fuel hoses including the disconnect at the tank. The little rubber oring on the disconnects tend to damage easy which will give you too much air and will cause you problems when you throttle up

 

[Hulen]

Re: 75hp Chrysler

I replaced the diaphram, are there more parts to replace in the fuel pump?

 

[Hulen]

Re: 75hp Chrysler

Thank You guys I will try that