1975 85 hp Evinrude idle/running issues with videos

[Besegen]

I finally got the motor running on muffs and tinkered with the thottle setting for idle. I ran it the first time for about ten to fifteen minutes. Right off the bat it surged and sputtered around a little then settled in and ran smooth for about ten to fifteen minutes. Then it suddenly started surging, jerking, sputtering for a minute or so then died. I went ahead and tinkered with the throttle adjust a little more and fired it up again. I started it probably 8 or 10 times and let it run til it did this and died. Some times it happened after a few minutes, other times it ran fine for the ten or fifteen minutes then went back to its shaky ways and died. Posting some videos of it running fine and not so much. I don't have a tach working right now either so besides advice on the surging issue, advice on the idle speed here while on muffs would be appreciated too. Thanks guys.

Video one is it running for a bit early on, probably the second or third time I had it running.

 

[Besegen]

Re: 1975 85 hp Evinrude idle/running issues with videos

This is a later attempt after some throttle adjustments where its running smoother

 

[Besegen]

Re: 1975 85 hp Evinrude idle/running issues with videos

And finally this is after it ran about ten minutes after that second video with the rough surging problem

 

[Besegen]

Re: 1975 85 hp Evinrude idle/running issues with videos

I thought I should also mention that I had about ten gallons of gas in the tank. The other day at the advice of someone who thought maybe I had water in the gas I added about half a bottle of heet. Later I got to thinking I was wanting to run seafoam through and wished I hadn't done the heet. A guy at the parts place told me it would be fine to dump a bottle of seafoam in there too and be just fine so I did. I don't know if this would have anything to do with it or not but figured I'd better provide all the information for you guys evaluating.

 

[emdsapmgr]

Re: 1975 85 hp Evinrude idle/running issues with videos

At the end of the first video, it sounded like it was running out of fuel. At least one cyl quit firing and another started missing. When this happens, start priming the fuel hose bulb. This will force extra fuel around the fuel pump. If it seems to run just fine as long as you constantly prime the fuel hose bulb, you've got a fuel delivery problem. Maybe a weak fuel pump or an air leak. Idle rpm's on the muffs on the trailer is unimportant. What's important is how it idles when the boat is floating normally in the lake and it's in forward gear. (should be 650-700 rpms.)

 

[Besegen]

Re: 1975 85 hp Evinrude idle/running issues with videos

Hello, emdsapmgr, thank you for the response. I actually did try a couple of times to pump the ball when it was doing that because I'd seen that suggested in some other posts when motors were bogging down like that. It didn't help at all. I thought maybe my fuel pump was going bad and failing intermittently or something. Does it rule that out if pumping the ball won't help?

Unfortunately I don't know what the RPM's are because my tach isn't working. Having read a few posts and troubleshooting I believe I have a bad rectifier causing it. The needle is always at or slightly above 1100 rpm. I plan to get one ordered this week but would like to know if I need to order anything else along with it for this sputtering problem before I do. Glad to know that RPM range is intended for the boat in forward gear though. I didn't catch that part in the manual. Thank you.

I may just go ahead and order a new fuel pump too. Its affordable enough to be worth doing anyway. No telling how old this one is. Could a fuel filter be the issue too? Is there one somewhere besides in the tank? I was having trouble getting it to prime up prior to this and just replaced the ball and all the fuel lines this weekend. I also dealt with the filter in the tank at that time.

And I don't mean to sound newbie, but I am one, do you mean an air leak in the fuel line or in the air delivery? If you mean air delivery is there a way to check for where it might be or any "usual suspects"? I've been fooling with the fuel system long enough now to have it fairly figured out but I'm still oblivious about the air delivery. Thanks again.

 

[EvstaG]

Re: 1975 85 hp Evinrude idle/running issues with videos

These older motors don't have a fuel filter, only really a mesh screen where the fuel line enters the pump. Many people advise putting a fuel filter on, and in my opinion especially if you have older tanks, where there may be particulates that could get into the fuel system. When emdsapmgr is talking air leaks, he means leaks with the carb gaskets/o-rings. Air leaks could be causing a lean fuel situation or other carburetor mishaps. You can check for vacuum leaks by spraying oil or a dish soap+water solution around the carb gaskets and observing, however you won't be able to tell entirely if you have an air leak with this method. If your carburetor gaskets are paper (some after-market suppliers used paper gaskets, they are prone to leaking) it may be worthwhile to invest in carb kits with the proper (neoprene or something like that I believe) gaskets anyways.

 

[emdsapmgr]

Re: 1975 85 hp Evinrude idle/running issues with videos

Possible you have another issue. The engine may be losing spark on one or more plugs once it warms up to normal operating temps. Not unusual for weak ignition components to act up when heated up. You can test for yourself: warm the engine up. Once it starts to miss, put an inductive timing light on each plugwire. The flashes from the gun will show the quality of spark on each plugwire. Also: Your stator has 2 coils which provide charging to the battery and a signal to the tach. These "charging" issues are not related to the voltage generated by other coils which make power for firing the ignition system on the engine. Two separate systems.

 

[classiccat]

Re: 1975 85 hp Evinrude idle/running issues with videos

I'm bringing an '75 70Hp back to life and was facing some ignition issues (weak spark)...due to some LU work, I never ran it long enough to see how it behaved when it warmed up. It did idle at the PO's residence.

The rectifier was indeed shot and simply removing it helped alot with the spark (part of the CDI troubleshooting sequence). As emdsapmgr said, they're separate systems electrically (confirmed w/ the FSM) however I'm wondering if there's electromagnetic coupling . CDI folks obviously know something that I don't. I also replaced the powerpack and now the spark easily jumps 1/2" gap with a nice pop.

net: test your rectifier with an ohmmeter, and if its bad, you have to replace it anyway. Test the condition of your ignition with the timing light & I'd throw in a spark tester as well.

good luck! sweet engine!!!

 

[Besegen]

Re: 1975 85 hp Evinrude idle/running issues with videos

Thanks all of you. I will try to get my hands on an inductive timing light tonight and do the spark tests and rectifier resistance test. Trying to get it running decent for a camping/fishing trip on my vacation in 3 weeks. Probably will replace all the above by summers end but time and money are ticking on the trip so want to get this issue narrowed down.

Im highly suspicious anyway the rectifier is bad and its cheap so no big deal there. If the running problem is other than a spark issue though after the tests...does pumping the ball not helping smooth the engine out at all definitively eliminate the pump and point me to the carbs? Or is there another test I can do with the pump to be more sure? Also wonder...boat has an old metal tank...wonder if debris is is getting through the tank screen and causing it. Possible? Maybe I should clean the tank out real good and install an inline filter as one of you suggested.

 

[emdsapmgr]

Re: 1975 85 hp Evinrude idle/running issues with videos

Yes, if you constantly prime the fuel hose bulb and the engine does not run better, it may not be a fuel delivery issue. If you are concerned about debris from the tank, why not check/clean the fuel filter. It's under the round cover where the fuel inlet attaches to the fuel pump. Just unscrew the screw and flip it over. A little off track here, but that engine's original factory fuel hoses are not ethanol compliant. Ethanol will break down those hoses and bits of hose debris can migrate into the carbs-even the fuel jets, causing running issues.

 

[Besegen]

Re: 1975 85 hp Evinrude idle/running issues with videos

Will do. I don't use fuel with ethanol or detergents. 100% gasoline thanks to, I think, some farm machinery requirements since the two places here that sell it that way are both farm businesses. I know the previous owner did the same, but no telling about the original owner before him. I changed all the hoses from the tank to the motor and all but the smaller hose (think there was only one) at the carb last weekend. I'll get that one changed. I'll also check that filter. I figured there had to be one besides the screen in the tank somewhere, and I know where that is now that you say it, but I guess I was looking for something different like an inline or something. Didn't get the spark testing done today like I'd hoped, had to leave town for dad's birthday. Hopefully tomorrow. Sure would like to at least get it narrowed to spark or fuel for sure.

 

[emdsapmgr]

Re: 1975 85 hp Evinrude idle/running issues with videos

The factory uses three special hoses for fuel delivery, the two identical hoses from the tees to the carbs, and the one from the pump to the tee. All are heat-formed by the factory to make hard bends and still deliver fuel. If you replace these with bulk hose, it can kink (and possibly restrict fuel flow) when bent into tight turns. They are sold under special part numbers: 319740 (quantity 2 pcs,) and 319739 (qty 1 pc)

 

[Besegen]

Re: 1975 85 hp Evinrude idle/running issues with videos

They are not new in the video but the two larger ones are changed, not bulk hose. I changed them this last weekend after videos. I'd been having problems priming the ball up and a guy I work with was fixated on water in the fuel. He gave me the Heet I put in. That didn't work and he showed back up later with a new ball and hose and the two larger carb hoses. Said he bought them last year fighting a similar problem when at the boat shop 90 miles from us (closest one to us). He said Heet fixed his problem though so he never used them. Said he had the smaller hose too but couldn't find it...still looking. The hose on ball he had was far shorter than mine and too short for my setup. It was also 3/8" and all my fittings are 5/16" so I went to the auto store and got bulk to replace it. Hope that is ok, if not let me know. What may not be good is the ball is 3/8" still and I just mashed it on the 5/16" hose anyway. Intend to get the right ball and swap back out but did at the time what I had to do so we could get the thing started and see what else I needed to do.

 

[Besegen]

Re: 1975 85 hp Evinrude idle/running issues with videos

I got this boat specifically so I could get out on the water and striper fish during a week camping trip I started taking 3 years ago every first weekend of June. I've only had a small plastic john boat with trolling motor too small for that lake.

I bought this 16' deck boat for $1200. The guy had just fully restored the hull...everything from transom to deck to brand new vinyl cushions. Boat is a gem. I felt like I stole it. I'm realizing though...other than a new water pump last year he was easy on the motor and kept up very basic maintenance but did not much else with the motor so most all the parts are old and tired. I don't at all mind and even enjoy putting the work and money in it to get it right. Haven't had something to work on like this since I sold my Dodge Charger to my nephew years ago. I only have x amount money each month to put to it at a time though and right now the goal is get it best I can for the trip in three weeks. Be nice to have it all summer but if need be once I get through this trip I have no problem tearing it all down and just getting it perfect for next year.

Just stinks cause we have a small no wake lake here and no boat supplies. Nearest boat repair and parts is 90 miles. Nearest place I can run WOT for test and adjusts is 120 miles.

We took it there once after I got it and it ran great til the old control cables fell apart at end of day. It seems after that trip though all the old warn parts are showing themselves now

 

[emdsapmgr]

Re: 1975 85 hp Evinrude idle/running issues with videos

Double check the position of the hose bulb. When they get older, sometimes they get finicky. They like to be oriented so that the arrow points upward. If they run downhill, sometimes the ball valves in the bulb don't work correctly. Once the engine gets running, it may not be a problem.

 

[Besegen]

Re: 1975 85 hp Evinrude idle/running issues with videos

I do believe that was a problem. Never thought about it that way but I noticed it did pump up when I held the line certain ways and not others. I figured it was squeezing a crack in the line shut but never could find one. This is a better explanation. Thanks.

 

[Besegen]

Re: 1975 85 hp Evinrude idle/running issues with videos

Just to update...after much ado gathering the proper equipment to test everything and several delays I found the power pack was putting out low voltage. Finally got it in yesterday. Replaced it and took it out tonight and the boat ran great. I suspect there may have been a bad fuel issue too. Last weekend, with the bad pack still on, I put a fresh tank of fuel on and it ran fine two straight days despite the pack. The new pack definitely finished it off though and still made a difference. It runs much smoother and surprisingly quieter. I'm not sure why it made it so much quieter but it did. I only have a "no wake" lake available locally though so I haven't had it up to WOT, but at low speed its running great. Next weekend I'll be headed out where I can let her rip.

I do notice now, however, there is a metallic "clack" or "tap" sound every full turn of the flywheel. Is that normal? I never had the flywheel off or anything but never noticed it before. Either its a fairly new sound or I'm hearing it now because the motor not so loud. If its not normal I'll shoot some video on it and see if it can be heard and make a new thread about it. I don't hear it on these vids. Thanks again guys. Thanks emdsapmgr for pointing me in the right direction with the spark issue. You were right on.

 

[emdsapmgr]

Re: 1975 85 hp Evinrude idle/running issues with videos

When these engines get a lot of hours on them, the pistons loosen up in the cyls. As the engine runs, you will hear "piston slap." That may be what you are hearing. While it may be somewhat disconcerting, it is normal and not an indication of imminent failure. Run it.