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1979 MCM470 wonbt rev up

J

jw_in_dixie

Regular Contributor
"Bayliner stays in a floating

"Bayliner stays in a floating boathouse in N AL. During the winter I crank and run it for about 10 mins every couple of weeks. Old gas had Stabil added. In Mar/Apr I added 15 gals of fresh gas + Stabil and took it out for a run. Started fine, idled smoothly and ran up to 2200 rpm readily. Revved up to 3200 but with some hesitation and "blubbering"; at 3200 it runs pretty well but I still hear and feel the blubbering. Trying to get above 3200 - it ain't happening. Worse blubbering and just won't go.
Heretofore it has always run up to 4K+ with no problem. Suspected fuel problem; cleaned the inline and f/p filters, connected a small tank of fresh gas, static tested gas flow - plenty; still won't go >3200. Removed, soaked, blewout, reamed the carb - no diff. Cleaned, set points, new plugs, cleaned and examined the distrib cap, wires (3rd season since new), all appear normal. Still won't go.

Fiddled with motors of all sorts for about 70 years - this one has me stumped. Sure need some help. Tnx. JW in Dixie"
 
JW:

"Revved up to 3200

JW:

"Revved up to 3200 but with some hesitation and "blubbering""

I assume that you mean it is missing like a bad plug or two. Are you getting any timing advance? Are the dist. weights rusted and stuck?

Another thought: The condenser can short out easily and the coil can fall on its face at any RPM but most complaints are like yours. Try the condenser since it is cheap. If it doesn't work you have a spare. Next try the coil.

Consider Pertronics electronic ignition; buyers swear by its performance.
 
guy is right go with or consid

guy is right go with or consider pertronics i did and would surely do it again very impressed. now a couple of things that comes to mind with your problem since it sets in water for the most part its more suseptible to moister than the ordinary dry storage. one is the coil and condencer as guy suggested and two the wires may have some moisture internaly i know it sounds crazy but a freind of mine just ran into that
 
"Doesn't feel like ign mis

"Doesn't feel like ign missing. Usually that feels like a machine gun, more of a stutter. This is different somehow, hard to describe - that's why I called it "blubbering". But first thing I did was install new plugs. No better. I thougth sure it was fuel when the plugs had no effect.

I should have mentioned that I have a CDI on it. Don't think the condensor has much effect in that setup, do you? Got a part # for a cond?

I'll check the advance motion. Thanks, JW."
 
"Steve, the boat sits on an ai

"Steve, the boat sits on an airlift but certainly surrounded by water. That, added to the high humidity here in the South makes it a challenge.
I keep two 60 watt trouble lights in the doghouse
and a 6 watt nite lite next to the distrib. Before adding the lights I had to clean the points if a few weeks passed between outings. If I don't find a cure soon a new set of wires is on the list. Thanks for your help. JW"
 
""I have a CDI on it. Don&

""I have a CDI on it. Don't think the condensor has much effect in that setup..."

It does if the points are firing the CDI. You may need to substitute a coil for the CDI unit to exclude the CDI.

PN: 898253003, CONDENSER"
 
"Guy, the CDI uses the origina

"Guy, the CDI uses the original coil - it just shoots about 240 volts to it instead of 12, as I understand the circuit diagram. The points just trigger an scr or triac, don't remember which, so there is almost no load on the points. Not to say there can't be a problem somewhere. The unit has a switch to change from std to cdi and I can't remember if I have tried switching to std. Tried so many things. I will try that. Thanks. JW"
 
"Just shooting from the hip an

"Just shooting from the hip and giving you a list to check on, but how about the cap and rotor? I know most symptoms of moisture or crack will be missing at any RPM but it's worth a try and cheap. Also did you replace the fuel filter in the carb inlet? Not sure if the 79 has that one but the 82 MercCarb does. Is it possible to have someone run the boat while you check your Accel pump jets to see if you get a good solid squirt.

It either sounds like a Dist advance problem not really stuck but sticky. I don't know if you would get that high of RPMs if it was completely stuck but if it's slow to react you might. Other than that it sounds like a fuel problem. Maybe the float is sticking from old gas varnish. It's hard to get stabilizer in the inner workings of the carb unless you run a tank with it through the carb before winterizing. Good luck and let us know what you find."
 
"Cap and rotor appear fine - c

"Cap and rotor appear fine - cleaned both. No cracks or tracks. Replaced filter in carb and one in the manual fuel pump. I also have an electric f/p with a fiber filter between the tank and the manual pump. Also a squeeze bulb as the check valve deal never works. Fuel flow is not the problem - elec f/p moving plenty in static test. Carb removed, soaked, blownout and scalded with boiling water. Float not stuck, valve working fine. Accel pump working fine. Back together - no change in performance. Ran on a separate tank with a squeeze bulb. No change, even when squeezing bulb to ensure full carb. Advancing the throttle to squirt more gas doesn't improve the performance. That almost says it isn't fuel, doesn't it?

Distrib advance is the only thing I haven't investigated. As I recall, you can gently twist the rotor and it should move freely, right?

Thanks for your help, Puget Sounder. JW in Dixie"
 
If you can pull your points pl

If you can pull your points plate from the dist and have a look. Try moving the weights to see if they move freely. Squirt a bunch of WD40 in there and see if it improves. You should be able to move the rotor a bit and feel it spring back into place but a visual for rust and corrosion can't hurt either.
 
"Hmm now you're getting sp

"Hmm now you're getting specific on me! While I do have a mcm470 I've never had to pull the dist apart. My VP140 had a couple of screws holding it down. It also had mechanical advance weights. And when I pulled the plate off there was lots of rusty colored gunk underneath. Probably from years of lots of WD40 and saltwater but never a good cleaning. I installed a Pertronix kit on that boat and made sure the dist was clean and working good. MAN what a difference all that made.

I would look for you tonight but I am in the middle of installing floors in my house. And wouldn't you know it it's been the best weather we've had a long time. Perfect boating weather but ahhhh, priorities. Maybe Stephen Chaplin can take a quick look for you. It should be relatively easy to remove unless it's a pressfit. Sorry I can't be of more help. Next week I will be up to my elbows getting my boat ready for a trip, I can look then."
 
"Warren,
Any verdict? I like

"Warren,
Any verdict? I like to keep a notebook on board of all problems and possible fixes just in case. I'm curious about yours."
 
Had to take a few days off for

Had to take a few days off for chores around the house. ;( May get back on it Sat. For sure I will keep you guys posted. Thanks. JW
 
"Mystery solved! It is a probl

"Mystery solved! It is a problem in the CDI. Simply switched the selector from CDI to Standard ignition and it runs normally. Sure thought it was fuel. Just goes to show - you never can tell. Thanks for all your suggestions.
JW, happy again in Dixie
lol.gif
"
 
"Glad things worked out.

C

"Glad things worked out.

Curious, what is a CDI system? I'm pretty sure I don't have one, just a pertronix ignitor and coil.

Yes those chores sure get in the way of boating."
 
"Re: Curious, what is a CDI? Y

"Re: Curious, what is a CDI? You have probably already read Guy's link, but let me add: Back in the sixties and seventies, before Detroit adopted the essence of CDI, add-on CDI kits were offered as aftermarket to upgrade standard ignitions. I had one left and when I bought the Bayliner/Mercruiser I added the "system" to the standard ign. What it does is remove the load from the points by gating a SS device which, from a separate 12v connection, changed to AC and boosted to 240 volts thru a transformer, charges a large capacitor which discharges to the coil primary giving one hellofa spark to the plug. Quicker starting, and maybe other benefits, but I really can't tell any diff now that I have switched back to std ign. That's just what I understand, in lay terms. JW in Dixie"
 
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