1975 25hp running problem

[MIKE I1]

Hi all, I'm a newbe here. I have a '75 25hp that is new to me. It runs, I've been through the carb. When it is running, it will ocasionally fire out of time, to the extent that it blows all of the water out of the bucket it is in. It also stops abrubptly if at idle. After that, for a while it may not start, or fire off blowing out the water again. I'm thinking that I have an issue with the pickup. The plug gap is OK, the plugs are clean, coils were installed by the previous owner. Also, when the issue is occuring it has weak looking spark, will only jump a 1/4" or so and is not blue, somewhat orange.

 

[coolguy147]

Re: 1975 25hp running problem

check the normal stuff compression cleaned the carb? good spark.

 

[rjezuit]

Re: 1975 25hp running problem

Sounds like ignition to me. Check that the coils are good, and at the correct gap to the flywheel. Rick

 

[MIKE I1]

Re: 1975 25hp running problem

Stupid question: Which ignition configuration do I have? I have the external mounted coils, not the ones that mount within the flywheel. This is an electric start motor. From the parts list I appear to have points and condensor, is this the case? If so, it would seem that some new points would likely clear up my concern. I guess I assumed that it had the same ignition as my '84 15hp (pickup, amplifier) because it uses the same coils.

 

[jbjennings]

Re: 1975 25hp running problem

Hi all, I'm a newbe here. I have a '75 25hp that is new to me. It runs, I've been through the carb. When it is running, it will ocasionally fire out of time, to the extent that it blows all of the water out of the bucket it is in. It also stops abrubptly if at idle. After that, for a while it may not start, or fire off blowing out the water again. I'm thinking that I have an issue with the pickup. The plug gap is OK, the plugs are clean, coils were installed by the previous owner. Also, when the issue is occuring it has weak looking spark, will only jump a 1/4" or so and is not blue, somewhat orange.

From your quote, I also think you are not getting fire to one cylinder, and every once in a while the dead cylinder will kick in and blow the water out of the barrel. You need to get good hot spark on both cylinders. I'll bet when it is running you can ground one plug wire and it will keep running, but ground the only live cylinder's plug wire and it will stop cold. It should keep running with either cylinder by itself. there's too many things it could be to say which, but I'd switch coils to see if the problem follows the coils. If not, clean and regap the points. If not solved then, swap the condensers. If not solved then, it almost has to be whatever part is left.
Spark plug wires could be the culprit as well, but I'd bet the problem is igniton.
JMO,
JBJ

 

[caddokid]

Re: 1975 25hp running problem

Sounds like ignition to me. Check that the coils are good, and at the correct gap to the flywheel. Rick

I have the same motor and have been having the same type trouble. Will bet that you have a bad ingnition coil. One thing that I would also check is the coil ground. These are sweet motors when they run right but can drive you nuts when they don't. They require coil test equipment that is obsolete or rare at best to spot the trouble with the coils. No wonder my hair is turning white.

Caddo Kid

 

[tashasdaddy]

Re: 1975 25hp running problem

read the TOP SECRET FILE.

 

[caddokid]

Re: 1975 25hp running problem

read the TOP SECRET FILE.

Which part tashasdaddy. I have read thur all of them plus my service manual and am still having problems with mine.Wife say hair is diffenatly turning whiter.

 

[Daviet]

Re: 1975 25hp running problem

You didn't list your model number, but if you have points under the flywheel you need to pull the flywheel and check condition and gap. You should check spark with a spark checker set to 3/8". Spark should be bright blue and have a snap to it.

When you overhauled the carb did you remove both jets, clean and blow out all passages? Did you adjust the low speed jet properly? It almost sounds like you have a lean carb adjustment on the low speed jet.

 

[MIKE I1]

Re: 1975 25hp running problem

Model # is 25EL75B.

When I went through the carb, I removed the bowl, the enrichment adjustment screw, soaked everything in Ford foaming carb cleaner (my favorite for eliminating carbon, fuel varnish and most every other gunk a combustion engine can make)
After soaking, I blew through all of the orifices. I could not remove the low speed jet, but sprayed some brake cleaner through and had 3 full streams of fluid coming out from the engine side of the throttle plate. The main jet was completely clear as well as every other orifice and passage I could identify. The needle, seat and float were in good shape and are working well.

At this point I am working without a manual and this was my first time into one of these carbs. Ordered a manual, hopefully that will clarify things. I just traded some car parts for this engine, it was a formerly waiting to be dissasembled for parts, but is in good shape overall.

 

[Daviet]

Re: 1975 25hp running problem

It sounds like a lean sneeze,how did you set the low speed jet,try opening the the low speed jet 1/2 turn and see if it helps. Did you check spark, point gap and coil condition?

 

[MIKE I1]

Re: 1975 25hp running problem

I closed the low speed jet, opened 1 and 1/2 turns to start with, going richer didn't help. I haven't checked the point gap yet, figure I'll wait for the manual so I have the information on settings while I'm there. Been spending time re-working the transom that will hold the engine for now.

 

[caddokid]

Re: 1975 25hp running problem

I closed the low speed jet, opened 1 and 1/2 turns to start with, going richer didn't help. I haven't checked the point gap yet, figure I'll wait for the manual so I have the information on settings while I'm there. Been spending time re-working the transom that will hold the engine for now.

I bought a spark checker and found that I had a bad coil on that model of motor. Coil was new a few months ago and now it has gone bad. So check and recheck.