1993 evinrude 70 hp

[StevetheSkate]

Hi, I am new to this forum, I have a small problem (I hope) with my 1993 evinrude 70 hp, the engine runs fine on my Pilot 590, except when shifting from neutral into gear, the revs just seem to die away slowly until it stalls, in neutral the tacho reads 1100 rpm, wot at 5600 the boat achieves 28 knots on a calm sea, it can be a bit tricky when coming in to dock at busy times, i.e. having to slip into neutral and lifting the idle lever while positioning the boat then re-engaging gear and repeating the process several times until safely docked, any ideas or solutions would be greatly recieved, regards Steve.

 

[phillnjack2]

Re: 1993 evinrude 70 hp

Well i would say either dirty carbs or the fuel pipes could be leaking a bit of air .
this would be more noticable at idle than full throttle.

also might be an idea to check compressions, if they are not upto the mark then get a tin
of power tune or similar and squirt it down the plug holes and carbs.
Could be a sticky ring tp bring compression back.

also has anyone altered the throttle cables ? or changed one recently ? changed the throttle box position.
it just might need a bit more idle on the cable.

if it runs good in nuetral then maybe the compression is the problem under a bit of power.

And what prop are you using (size) has this been changed ? is it damaged in any way ?

have you checked the plugs ?

are you buying cheap supermarket fuel ?????????????? this can be very poor quality sometimes and realy does
cause a lot of power problems due to low octane rubbish.


just a few ideas


phill

 

[ob]

Re: 1993 evinrude 70 hp

Sounds like the link and synch adjustment may be your problem.Not sure if your 93' has an adjustible idle mix screw ,but if it does that could also be the culprit. Some of the 70 models had them and some just have fixed idle orifices.

edit: Did a little research on your 93' engine and it looks like it does in fact have an idle/slow speed needle valve that can be adjusted. Try gently seating all three in clockwise direction,counting the exact turns it takes to seat them, and then open each one up starting with 3 turns open and se if it helps you issue. All three of mine on my 96' 70 hp are open to 3 1/2 turns as it operates best there on mine. Otherwise on the lynch and synch I mentioned,there is a throttle linkage roller, that when the control lever is in the neutral position ,that should be adjusted so that the center of the roller is in exact line with the scribed line of the fiber throttle cam and just touching. Just touching, as in not so hard against it that the throttle plates are cracked open,and not too far away either which would cause the carb flaps from opening late when throttle is applied. This adjustment is actually quite critical when throttling up from a stop as it synchs the opening of the carb flaps with the advancement of the ignition timing.

#15 in the below diagram is the low speed adjuster.

http://www.ishopmarine.com/ishop/js...&isStandAlone=&is4CmsShop=&reqln=Unknown&reqe

 

[fishfeatures]

Re: 1993 evinrude 70 hp

what does the tach read when it's knocked into gear? should be about 600 -750 when in gear ,under load..

 

[StevetheSkate]

Re: 1993 evinrude 70 hp

Hey, thanks guys, great ideas and suggestions, I will check all of them out when the - degrees have gone away, as I can't run it up on the muffs just yet, it was fully serviced 50 hours ago by Seamark Nunn (Felixstowe), so hopefully no real dramas ahead! Will update when I have checked out a few suggestions, thanks again, regards Steve.

 

[StevetheSkate]

Re: 1993 evinrude 70 hp engine slowly dies at very low speed

Re: 1993 evinrude 70 hp engine slowly dies at very low speed

Just a quick updatefor the very helpful guys who suggested some ideas, everything in East England is still frozen solid, so I havn't been able to run her up on the muffs, but I have checked out the plugs, the NGK's have only done around 40 hrs and to be honest were not as clean as one would expect, not oily I would hasten to add, I did however check the gap size which I found to be .035, on the NGK site they state that the correct setting should in fact be .030, can any one confirm the correct gap size please, also, I have been asked what size prop I am using, I am currently using a 17 x 15 stainless in vgc, it achieves 28 knots wot at 5600 revs, I origionally had a 17x 15.75 which gave me 33 knots at wot, I kept to the former as at my cruising speed of 4500 revs it achieves much better fuel economy, regards Steve.

 

[phillnjack2]

Re: 1993 evinrude 70 hp engine slowly dies at very low speed

Re: 1993 evinrude 70 hp engine slowly dies at very low speed

The evinrude site does not reccomend ngk spark plugs, and NGK are wrong in your engine.
i have recently had problem with plugs and it was the ngk plugs that were the cause of the problem.

get the correct champion spark plugs before going any further, you can do damage to cdi if the wrong plugs fitted.
The correct plugs for your engine are CHAMPION QL77JC4 .

Many people argue about ngk v champion...blah blah blah etc etc.
but if you contact NGK they will tell you they do NOT actually do a plug that is a direct replacement for the champion QL77JC4..
so its best to stick what omc /brp recommend.

Now as for the propellor and a few speed /rev figures......
you definitely are NOT using a 17 x15 and have never used a 17x 15.75,
A 17 inch diameter cannot fit this engine and neither can a 15 inch diameter.
Max 14 inch diameter but more than likely to be 13 inch diameter x 15 pitch.
with 15 pitch you are not going to be doing anywhere near 33 knotts.

also if a prop of 17x15 was giving 28knotts (32.22 mph) then a 17x15.75 would not give 33 knotts (37.8mph) impossible.

i know what a pilt 590 is, and to get 33 knotts youl be needing a much bigger engine than 70hp.
these boats are cathedral hull dory type boats and weigh in pretty heavy due to the way they are built as fast fishing boats and recreational boats..
25 knotts would be a very good speed for such an outfit. your speedometer is way off.

the pilot 590 uses the exact same hull as the wilson flyer and a few others.
Ive seen these boats first hand being built in the moulds at the home of wilson flyers, nice strong construction, long lasting boats.

phill

 

[StevetheSkate]

but Re: 1993 evinrude 70 hp engine slowly dies at very low speed

but Re: 1993 evinrude 70 hp engine slowly dies at very low speed

Thanks for the information, will look for the Champions after this thread, would you know the correct gap for them by any chance, and yes you are 100% correct I did give the wrong dimensions for my prop, I really shouldn't try and trust my memory at my age, I have just checked my logs and the prop it came with from Seamark Nunn was 13" Dia and a 17" pitch which gave the higher speeds, the prop now on is 13.75 Dia with a 15" pitch, I tried to photograph it but the picture of the size was unreadable, the speeds I gave came from my Standard Horizon plotter (SOG), the same speed readings also came off my SH vhf which I suppose would as it is linked to the plotter.