Keep having to replace condenser... 3.7 litre mercruiser

[zoldy2]

Hello everyone. Did a few searches for similar problems but no luck. I have 1988 3.7 mercruiser. I believe this is a ford engine. Here is what has happened so far.

Died and would not start. Sat overnight and started the next day but ran rough. Replaced Coil. Ran okay for about 15 minutes.

Switched focus to fuel. Change fuel pump and check all lines and filters

Still the same. Despite the fact that they were only 6 weeks old I replaced points and condenser. Problems went away.

Went for a boat ride which was about 1 hour long. Ran good. Approached dock and it died. Ended up placed condenser again. Boat seemed to run fine again.

Another 1 hour boat ride and started running rough again. Yet another condenser and runs good.

It seems something is blowing the condenser I assume?

Any thoughts ideas or suggestions are appreciated ... thanks

 

[wrestling coach]

Re: Keep having to replace condenser... 3.7 litre mercruiser

How did you set the dwell? Did you use a dwell meter? How many degrees of dwell do you read? Check for a bare or chaffed wire in or around the distributor. Is the grommet where your wires enter the base of the distributor OK. Pinched or kinked wire somewhere? Grounds, grounds, grounds check them all, clean and tight? Condenser tight and in good contact with base plate? The condenser is there, at least in part,to keep the points from burning and pitting.

Dennis

 

[stonyloam]

Re: Keep having to replace condenser... 3.7 litre mercruiser

I suspect that you have a poor connection somewhere, or as the coach suggests, the dwell is not set properly.

 

[Don S]

Re: Keep having to replace condenser... 3.7 litre mercruiser

Do you have the Prestolite distributor or Delco distributor? Are you using the right condenser?
I would also check the wire from the coil to the points and make sure it isn't defective, broken, chafed or touching something it shouldn't be. Is the condenser actually screwed down tight?

One other question, what is the voltage on the battery at 2000 rpm? Check with a volt meter at the battery, not the gauge on the dash.

Are the battery cables clean and tight.?

 

[Capt Ken]

Re: Keep having to replace condenser... 3.7 litre mercruiser

Are you using an internal or external resisted coil? If external, check the voltage going into the coil. You should have no more than 9 volts. Mercruiser uses resistance wire rather than a resister and sometimes it gives problems.

 

[zoldy2]

Re: Keep having to replace condenser... 3.7 litre mercruiser

Thank you all for your prompt responses. I will check all of these things and go from there. Thanks again ....

Are you using an internal or external resisted coil? If external, check the voltage going into the coil. You should have no more than 9 volts. Mercruiser uses resistance wire rather than a resister and sometimes it gives problems.

 

[zlman1970]

Re: Keep having to replace condenser... 3.7 litre mercruiser

Lets us know what you find.

 

[1977 SILVERLINE]

Re: Keep having to replace condenser... 3.7 litre mercruiser

3.7 is not a ford engine. I would suspect the shift interupter or the lower shift cable is grounding your coil, thus loosing spark. I have converted mine to electronic ignition and had no problems, which eliminates the need for a condensor.

 

[fmalott]

Re: Keep having to replace condenser... 3.7 litre mercruiser

3.7 is not a ford engine. I would suspect the shift interupter or the lower shift cable is grounding your coil, thus loosing spark. I have converted mine to electronic ignition and had no problems, which eliminates the need for a condensor.

the motor it self is a merc but the head is from a ford 460

 

[Fishin Magician]

Re: Keep having to replace condenser... 3.7 litre mercruiser

the motor it self is a merc but the head is from a ford 460

check HV wires for resistance...ohms.....ie. change your spark plug wires on ur car....corrosion can't be seen under rubber coating
just a guess
FM

 

[generator12]

Re: Keep having to replace condenser... 3.7 litre mercruiser

Replaced Coil....I replaced points and condenser....Ended up placed condenser again....Yet another condenser and runs good....

Zoldy, each time you worked in the area of the coil/distributor you had the engine running properly for a while. Once for the coil, once for points and condenser, and twice for the condenser alone. I suggest that just moving the wires/components around temporarily corrected your problems. Not the specific condenser replacement. (Condensers - i.e. capacitors - fail from only four causes: manufacturing defect, overvoltage, overcurrent, or age.)

As the previous posters have indicated, you have a problem with wiring somewhere around that coil/distributor area.

 

[zoldy2]

Re: Keep having to replace condenser... 3.7 litre mercruiser

We found that the voltage at the coil is 12.3 when running. It should be 9 from what I am told. This particular coil does not have an built in resister so there should be an inline resister. I have decided rather than replacing it to convert to electronic ignition. I did not want to do this until I found the issue in case it was something that was going to start blowing ignition modules. However I think it will be good as I don't need to step down the voltage anymore. I have a kit on order.

Thanks to all who replied. Great advise!!!