Engine spudder

[CTboater420]

I am hoping someone on here can help me out. I have a 1994 bayliner with a 3.0 mercruiser . The engine has been givin me a hard time lately. The problem begain with the motor spuddering out at about 3000rpms , so I check the gas and I had water in the tank so I added a feul/water seperator and added so waterzorb to the remaining gas and also put the 93 oct gas filled the tank . I also replaced the feul filter in the carb. After that the boat ran great for about a month we use the boat 4-5 times a week . Then It started again 2 weeks ago. This time I replaced the ignition coil this morning and I took it out and after about 20 min running at 3500 rpm started to spudder again . This doesnt always happen at the same rpm's but It happens between 3000 and 4300. Sometimes it will happen at say 3300 rpms . So that is why I thought it was the coil . The boat will not die or sthall , it just cuts out to about 2500 rpms and i have to back off the gas . runs fine under 3000 and at idle . Temp is good (new thermo) ,oil pressure is good . No strage sounds comming from anywhere. The oil is fine no water ,no water in the block either. So I am kinda thinking it may be the fuel pump but not sure. I do have to replace the manifold but i was holding off till the winter no leaks just a few years old. So can anyone give me a place to look ? Thanks for the help. Sorry for the rambling on .

 

[tommays]

Re: Engine spudder

i would check the water sepator remove the filter and carefully pour it into a glass if its clean great but i think you will find more water <br /><br />i am guesing your from conn and that you have the 10% gasohol blend like we have on long island it takes on water much easer than 100% gas<br /><br />when your sure thers no water you can look at other thinks like how old your cap rotar points ect<br /><br />tommays

 

[CTboater420]

Re: Engine spudder

Tommays <br /> I dont think this system has any points , as far as the cap and rotar they were replaced in the winter could they have gone bad ? Do you think it is smart to put water-zorb in the tank with every full up . I have only put it in once that first time when I installed the sepator . I have also have been using 93 oct I didnt think that had the 10% blended gas. I will check the filter tommorrow. So you think the fuel pump is out of the question . I have no gas in the yellow/clear hose so I thhink the diaphram is good .

 

[larson186]

Re: Engine spudder

CT Does your engine have an electronic or points and condenser ignition system? If it is electronic there will be several connectors going to and from the coil and distributor you may have one or both of the following parts failing when the engine is at high rpm 1. ignition coil or 2. the ignition module. These components will get hot and allow absolutely no current to flow to the spark plugs. If it has points and a condenser there is usually no other wire or connectors other than spark plug wires from your distributor and may have a vacuum line attached to it some where for timing advance or you can simply remove the cap and rotor to see the points inside. If you have a shop manual, check the specs on point gaps and timing advance. Also tommays has a really good point with the fuel, gas/alcohol mixtures suck and attract large amounts of water especially when the humidity is high.

 

[larson186]

Re: Engine spudder

Also if you haven't invested in one yet, buy a shop manual for your engine/outdrive! This will save you huge amounts of $$$ in the long run, especially if you are good with tools. I know this being in Maine where boats are everywhere and the shops are backed-up with work. Clymer or Selac manuals are the best and can be purchased for $25-$40 depending on the application it will be used on.

 

[CTboater420]

Re: Engine spudder

gibs I have the shop book and it is great . Also today I put a new coil in and took it out for a run and did the same thing at about 3700 rpm . The cap and rotar where replaced by the prev owner when he winterized it there are no points . I picked up the boat in Dec. I never thought about the ignition module maybe I have to try that . I am leaning more toward what tommays said with the feul . I installed a seperator about 2 months ago when the problem first happened . I also added so water-zorb in with a 1/2 tank of 87 oct and 1/2 93 oct and have being using 93 since, but I havnt added anymore waterzorb since that first time. So hopfully the problem is that easy . I also havnt checked the seperator since that first time. The other thing I thought it could be is the feul pump not to sure though there is no gas in the yellowish/clear hose that runs to the carb so I think it is still good .

 

[larson186]

Re: Engine spudder

CT, Sounds like the ignition module but don't rule out fuel problems. Does the base of the distrubtor feel excessively hot when this occurs? If so it may be overheating and quitting on you. The fuel pump would cause a problem right from engine start, and give you problems when you accellerate. One way to check a fuel pump output is by attaching a tube to the output side of the pump and crank the engine with the ignition coil wire removed to prevent a fire and see if there is a forcefull amount of fuel coming out. Alot of fuel pumps are changed out because of ignition problems. Double check your fuel/water seperators strange things can happen here too.

 

[CTboater420]

Re: Engine spudder

I will have to check how hot it is tommorrow when I take it out . I have never touched it ,didnt think to do that . The engine starts great first chrank everytime. Thanks for the help I will check out what you brought up tommorrow . Now I have to spend the next 8 hours at work . I forgot to say before after I changed to the feul filter and added the seperator and water zorb the boat run great for about a month of 4-5 times a week . But the boat is great on feul so didnt use much and two weeks agao when this happened again I filled the tank for the first time in a month so I am almost betting there is more water in the gas.

 

[tommays]

Re: Engine spudder

i dont think its good to add anything to the fuel it makes it harder for the water sepator to work if you blend the water with chemicals it really is not water anymore its some kind of mix that may pass through the seperator<br /><br />i just use stablizer at the end of every season<br /><br /><br />tommays

 

[CTboater420]

Re: Engine spudder

Anyone else have any other idea what could be happening