1963 40HP Rude, Cutting out

[cajun555]

Just got back from a 4 day outing. Motor ran fine till yesterday. Normally I run 3900 rpm. Wot will run 4600. Anyhow, running along motor cut out to a idle. I was using a new to me tank and figured problems with the vent. Now this tank has the pin that when you hook up line the connector hits pin to vent tank. So I lossened up the tank cap and tried it it again. Back up to 3900, ran about 150 ft then shut down then idled for several seconds then took off again. I let it do this several times then opened it up. Ran great for a couple of miles till I backed off to 3900 then the same thing. I'm thinking its the fuel pump not pumping properly at that mid range. Any ideas will be helpful.<br /><br />Now I've only had this motor for a few months. Did service the L/U and ign. system but it has ran so well that I was going to wait on the carb and fuel pump rebuild. May be its time to rebuild.<br /><br />BTW, I was running on the same fuel the day before with no problems.

 

[Laddies]

Re: 1963 40HP Rude, Cutting out

Did you try to run it with the cap loose, ussally if the pump don't work it doesn't come and go, have you changed the sock filter in the fuel pump

 

[cajun555]

Re: 1963 40HP Rude, Cutting out

Yes I did run with the cap loose. I haven't done any thing to the pump or carb. Its strang that I can pour the meat to it and it won't shut down. Only shuts down at mid range. Now at one point I did squeeze the primer buld and did pump fuel which leads me to believe the pump might have a pin hole in diaphram in it. <br /><br />BTW, it is a new fuel hose aswell and I can pump the system up firm.

 

[Paul Moir]

Re: 1963 40HP Rude, Cutting out

Your '63 has the old style pump with the glass bowl right? If so, did you notice if there was air in there when it shut down? I'm thinking of a leak at one of the fuel line connections, and the mid-range thing is coincedance. <br />If the fuel pump has a pin-hole, you should be able to see a difference on it's cylinder's plug. Normally fuel tends to get drawn in.<br /><br />Also, did you have a chance to try pumping the primer while having trouble at part throttle? If it picks up, that suggests fuel pump or fuel line leak.

 

[cajun555]

Re: 1963 40HP Rude, Cutting out

Let me clarify, It would shut down to a idle then several seconds take back off then 150 foot or so shut down to a idle and the samething and take off. Yes Paul, it does have the glass fuel bowl on the pump, Yes at one point I did pump bulb and it seemed like it had air in it. Paul the thing that is strang is while I was having this problem I could run her up to wot and had no problems at all. I kept it at wot for a couple of miles then backed to half throttle then it started it again. <br /><br />To answer another question, I just replaced the gasget on this tank and it was clean as a whistle and the fuel pickup tube does go all the way to the bottom of tank and the filter is clean on pickup tube.

 

[Paul Moir]

Re: 1963 40HP Rude, Cutting out

Well, I can sure see why you're thinking fuel pump diaphram then. Easy enough to check - pull the 'pressure' line off the pump, and squeeze the primer. If any fuel comes out there's a leak. The rebuild kit is 379777 and comes with the large-plunger-washer fix. There's a couple check valves in there that could cause a problem too if one was stuck part open. But you'd think that would cause idle problems too.<br /><br />Another thing to keep in mind - at part-throttle the ignition system and the cooling system are both working the hardest. Since it doesn't behave like an overheating problem and you say that you recently R&R the ignition system, I don't things down that path are likely.

 

[cajun555]

Re: 1963 40HP Rude, Cutting out

I think I know what your talking about. Pull the line that makes the pump work and pump the bulb on fuel hose. If it leaks then diaphram has a pin hole in it and a rebuild is needed. If it dosen't leak I guess my next recourse is to fill up my other tank and go out to the lake and try it out. If it dosen't do the same thing I'll hook up to the tank the motor was failing on and if it dois it again then I would think I've got a dip tube problem.<br /><br />Thanks for the help and I'll post back later as to what happened at the lake.

 

[readyakira]

Re: 1963 40HP Rude, Cutting out

I am definatly no boat mechanic but was looking thru this thread and wondered.... when it goes to idle does it sputter at all or just drop straight to idle? I assume a 63 motor doesn't have much in the way of sensors to cause this. I'd have to agree with paul on the "working the hardest" part. This is at least true with car motors I know. Thus the reason I asked about if it sputtered. Is it possible a gap got missed on a plug and when mid throttle the plug miss fires and at idle it cleans itself back out?

 

[daveswaves]

Re: 1963 40HP Rude, Cutting out

The other thing that might be specific to 3900 RPM is the attitude or angle of the boat at that speed, it sounds like you are picking up a blob of "gum" in the fuel system. As soon as the motor slows down again and the fuel demand lessens the blob falls away from the fuel pickup and away you go again until it picks it up again. Same thing can happen with incorrect float setting in the carb, you are basically starving for fuel at that rpm. That model should have the fixed high speed jet at the bottom of the carb, facing forward. Remove the plug and drain the carb fuel bowl into a cup, my guess is you will see water or something other than fuel come out. If so your carb needs cleaning.

 

[cajun555]

Re: 1963 40HP Rude, Cutting out

Filled up other tank, back to lake. Seemed anything under 4000 and motor would drop off to a idle then take back off back up where rpm was when running. Anything over 4000 and motor did fine. Just before posting, I did disconnect vacume off fuel pump and I did get fuel out the pump vacume hook up. I assume this is not normal. It wasn't alittle bit of fuel but a whole ***t load.<br /><br />Is this what you were talking about Paul? pulling the vacume line off the pump and pumping bulb to see if fuel would come out the port.

 

[Paul Moir]

Re: 1963 40HP Rude, Cutting out

Yeah, exactly. The line on the side of the pump that runs over to the lower intake bypass cover right? It should be dry, otherwise it's a ruptured diaphragm. <br />Iboats has the aftermarket repair kit 18-7801, but it doesn't come with new check valves or the big diaphragm plunger fix. If you find the little protector on the end of the spring in the check valve chamber is metal and basically the size of the spring, you'll want the dealer kit. They replace it with a much larger plastic one that can't work it's way off and puncture the diaphragm.<br /><br />Odd that it seems to be able to keep up with it at idle. The crankcase drain valve must be keeping up with it or something.<br /><br />PS - Don't forget to laugh all the way to the bank. The rebuild kit is pretty inexpensive. In '64 they changed to the new style pump for which no kit is offered. A new one of those pumps is around $50.

 

[cajun555]

Re: 1963 40HP Rude, Cutting out

Thats what I was talking about. I would go thur no wake zones, up the boat roads, slowing down out of common courtesy to other people fishing, all at idle speeds. Back up to 3900 and motor would die off to an idle then without touching the throttle right back up to 3900. <br /><br />I just pulled pump off and the diaphram is ripped, really just wore plum out. I guess its off to my dealer to get a kit as well as a carb kit, fuel lines. Just as well do it all that way I might get another 40 years out of the old beast.<br /><br /><br />Many thanks to the folks who visit this forum.

 

[Paul Moir]

Re: 1963 40HP Rude, Cutting out

If you get some new fuel line, pick up some new stainless hose clamps too. They're hard to find that small but they're around. <br />I have a strong suspicion about where the guy that designed the stock ones is now.

 

[cajun555]

Re: 1963 40HP Rude, Cutting out

I do refrigeration work as well as work on soda systems. I've got to where I use the stainless "otiker clamps" on just about everything to do with fuel lines. I think I know which clamps your talking about. The spring clamps that you can never get a grip on.

 

[cajun555]

Re: 1963 40HP Rude, Cutting out

Finally got my fuel pump kit on Thur. rebuilt the pump, went out to the lake yesterday. Motor ran like a champ. <br /><br /> Thanks to all