Still won't plane aghhhh.

Wen

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Oct 6, 2011
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12
I posted before that my 1985 70 hp evinrude would not get on plane and it would bog down. I have checked the timer base, cleaned all the contacs on the power pack , new plugs,wires, rebuilt crabs. Before when it was cold it would run like a brand new boat till it warmed up.Yesterday when i went out, it was cold(the motor)and would not plane.Even when the bulb was pumped I had a small surge but no plane.When i advanced the throttle all the way it would die. I am just trying to narrow it down before i spend tons of money replacing the power pack and coils. If the power pack had issues could it cause the motor to mis fire or not get on plane.
Thanks.
Wendell
 

eclark53520

Petty Officer 2nd Class
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Sep 2, 2010
Messages
174
Re: Still won't plane aghhhh.

My 77 70hp had the same problem.

Cleaning all the contacts on the ignition system ESPECIALLY the ground wires helped immensely.


Every once in a while it will do that, and I tap on the power pack with a screw driver handle and she's good all day. That's typically only when it sits for a long time though. I probably need to replace the power pack, but after a tap it works well.
 

F_R

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Re: Still won't plane aghhhh.

It's always the "Black Box". That is the mentality that has prevailed ever since black box ignition was invented. Truth is, with today's ignition systems, it rarely is the power pack. For the most part, they either work or they don't work. They are all solid state with no moving parts and beating on them won't do any good exept vent your frustration.

Check the spark properly. Will it jump a 7/16" open air gap with ease? If it will, the power pack is doing it's thing. Quit fretting about that.

Have you checked the compression? The three cylinder motors have a known problem with water ingestion. Over time, it will destroy the innerds of the powerhead. So, first order of business is to check the general health of the powerhead.

Once you are satisfied with that, look at the plugs after it has run a bit. Look closely for water droplets, especially the center one. If you find any at all, you have a job ahead of you.

OK, so if you have been lucky so far, those carburetors are suspect. You say you cleaned them. Did you pay particular attentin to the high speed jets (orifice plugs)? They are in the very bottom of the float bowl where crud collects. They must be absolutely, positively CLEAN!! Nothing else will do. But DO NOT oversize them by jamming wires and drills and stuff through them.

Hopefully, you have found the problem by now.
 

aerobat

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Re: Still won't plane aghhhh.

When i advanced the throttle all the way it would die.

in this case you for sure have a fuel supply problem. when the engine starts and idles fine the ignition is ok, most probably the compression also. check the carbs again, the engine does not get enough fuel when you open the thrlottle wide.
 

eclark53520

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Re: Still won't plane aghhhh.

in this case you for sure have a fuel supply problem. when the engine starts and idles fine the ignition is ok, most probably the compression also. check the carbs again, the engine does not get enough fuel when you open the thrlottle wide.

It's not a 100% guarantee that's the problem. My outboard gave the exact same symptoms and it was an ignition problem. After rebuilding the carbs myself, and then taking them to a professional I still had the same problem. Cleaning the grounds is what solved the major part of the problem for me.
 

Tim Frank

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Re: Still won't plane aghhhh.

I did a quick check on your other threads about this motor.
Two things stand out...
1) You have just changed over from a VRO to a non VRO fuel pump, and it does not sound like that went "perfectly". What caused you to change that out? Some problem that it did not solve?
2) As far as I can see you are just going at each "system" and R&Ring at random. If you don't approach this in a systematic fashion, your frustration level will go one way, your bank balance will go the other.

At this point I am surprised that nobody has suggested measuring compression and VERIFYING spark performance....oh, well FR did, but it's amazing how it is the guys who know the most that seem to get ignored. :facepalm: Seriously, if you haven't done those two simple checks, they should only take 1/4-1/2 hour at most. and without those results, even putting in new plugs can be a waste of $$.

Next after that, check your manual for the procedure for VERIFYING the fuel pump output......quantitatively....you want a number.
Then if you did not pop the welch plugs on the carbs when you cleaned them, redo them.
Finally, I may be disagreeing with FR, but I always ran a drill though those high speed jets..,..but there is a CORRECT SIZE for every jet, and in my case it was a numbered drill (forget the exact number, but I think my jets were 52D, and the correct drill was #55) that the manual spec'd. I think FR is really saying, don't scratch, bend, fold etc. the inside of those jets as they are fussy and need to be right on size and smooth. That would be my first suspect in what your problem really is. I redid my carbs once...they looked pristine...but there was a "crust" of varnish-like crap inside the jets....they "looked" fine, decent diameter and smooth...but were not!
 

aerobat

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Re: Still won't plane aghhhh.

It's not a 100% guarantee that's the problem.

of course never say never , but when the OP claims he gets a surge when pumping the ball and the engine dies when giving full throttle but starts runs at low power good i would be very surprized if its the ignition and not a bad ( insufficient) fuel supply at high power demands.

even a compression check is not needed in my eyes when the engine starts like a champ. - hard starting, bad idle, stalling at gear shifting- that are the classics for bad compression, bad ignition or fouled plugs .

nevertheless tim frank is right when he suggests a systematic search and not screwing on everything on speculation.
 

F_R

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Re: Still won't plane aghhhh.

The main reason for suggesting a compression check was to detect damage to ONE Cylinder. Sure, they will start and run on the other two, but with no power. Which is likely in this guy's case.

I have no problem with the fuel theory. In fact, notice that is where I went after some preliminary checks.
 

Tim Frank

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Re: Still won't plane aghhhh.

Finally, I may be disagreeing with FR, but I always ran a drill though those high speed jets..,..but there is a CORRECT SIZE for every jet, and in my case it was a numbered drill (forget the exact number, but I think my jets were 52D, and the correct drill was #55) that the manual spec'd. I think FR is really saying, don't scratch, bend, fold etc. the inside of those jets as they are fussy and need to be right on size and smooth. That would be my first suspect in what your problem really is. I redid my carbs once...they looked pristine...but there was a "crust" of varnish-like crap inside the jets....they "looked" fine, decent diameter and smooth...but were not!

When I say "ran a drill through " what I meant is a drill BIT....and NOT chucked in a drill, but held in hand...and use the shank end which should be the exact size of the jet.
Scratching, denting, etc. will render the jet u/s.
 
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Re: Still won't plane aghhhh.

The main reason for suggesting a compression check was to detect damage to ONE Cylinder. Sure, they will start and run on the other two, but with no power.

That's absolutely correct and I've experienced it once when some dummy tugged a plug wire loose putting the cowling on. It idled ok, seemed to accelerate ok at 1/4 throttle, but when I told it to get up and go - nothing.
 

Wen

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Oct 6, 2011
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Re: Still won't plane aghhhh.

First i would like to thank everyone for their contributions and suggestions for my problems.
i would like to ans Tims question about the VRO. It was disconnected when i purchased it from my buddy, his grandfather had removed it. I had this same problem last year and figured since i changed plugs,wires etc it would be solved.....WRONG.
I did find out that the sierra pump i placed on it is part number 18-7353 replacing omc 438555.I found the box this is for a 1990-2000 20-30 hp/ would/could this be the issue.I looked at the plugs the gap was 25 i made it 30 and took some pics. I still have to check the compression which i plan on doing in about 20 min2012-03-21 13.58.19.jpg2012-03-21 13.58.05.jpg2012-03-21 13.57.51.jpg.
No water drops in/on any of the plugs.I did pop the welch plugs. The carbs were rebuilt by myself and my buddies dad who owns and automotive shop,he has rebuilt marine carbs before, so i feel pretty confident in the rebuild.He is also an avid Boater.
 

Tim Frank

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Re: Still won't plane aghhhh.

First i would like to thank everyone for their contributions and suggestions for my problems.
i would like to ans Tims question about the VRO. It was disconnected when i purchased it from my buddy, his grandfather had removed it. I had this same problem last year and figured since i changed plugs,wires etc it would be solved.....WRONG.
I did find out that the sierra pump i placed on it is part number 18-7353 replacing omc 438555.I found the box this is for a 1990-2000 20-30 hp/ would/could this be the issue.I looked at the plugs the gap was 25 i made it 30 and took some pics. I still have to check the compression which i plan on doing in about 20 minView attachment 137562View attachment 137563View attachment 137564.
No water drops in/on any of the plugs.I did pop the welch plugs. The carbs were rebuilt by myself and my buddies dad who owns and automotive shop,he has rebuilt marine carbs before, so i feel pretty confident in the rebuild.He is also an avid Boater.

You are still not telling us why you changed the fuel pump.
I am no expert on VRO removal, but if i were doing that, I would go back to the pre-VRO versions of that motor....look up the fuel pump and try one of those or its present day equivalent.....OMC kept discontinuing those and there may be a long super-cession chain.
My gut feeling is I do not think you have the right fuel pump and of course that could be causing an insufficient fuel delivery.

The part number at present for a 1979 70HP is 0438559. I'd start with that.
But what I'd suggest first is to find some specs for what fuel delivery you need from the fuel pump and verify that you are...or are NOT getting it.
 

Wen

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Oct 6, 2011
Messages
12
Re: Still won't plane aghhhh.

I changed the fuel pump because i had this problem when i purchased the boat originally,so i assumed that it was the VRO pump not working.I looked for an hour last night trying to find out what the volume should be for the fuel pump w/o any luck. I did find that the pre-vro was last in 1983 and that pump number is 18-7252 sierra.
Wendell
 

F_R

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Re: Still won't plane aghhhh.

Fuel pumps are so easy to test. "Tee" in a fuel pump pressure test gauge between the pump and carburetors. If it is maintaing proper pressure it is ok. Spec probably is 1.5 PSI @ 2500-3000 RPM, 2.5 PSI @ 5000 RPM. A gauge will probably cost less than those pumps. OR, the el-cheapo test is simply squeeze the primer bulb when you suspect it isn't pumping enough fuel. If that causes it to take off, the pump isn't supplying enough. No improvement, that is not the problem.
 

Wen

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Oct 6, 2011
Messages
12
Re: Still won't plane aghhhh.

So i checked the compression 150 -160 on all 3 cyl. My buddy who is an avid boater,had a spark tester from Harbor Freight,it showed that the plugs were all working. So after some fiddling around we took the boat for a spin. At first it would not plane but after tightening some fittings and my buddy pumping the bulb it took off, even when he stopped pumping the bulb it was able to get on plane. I turned it off waited and tried again...success stayed on plane and went like a bat out of hell. I would like to thank everyone fro their help with the issue.Now i have a new issue with a manifold gasket which i will start a new post on.
Wendell
 

aerobat

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835
Re: Still won't plane aghhhh.

So i checked the compression 150 -160 on all 3 cyl. My buddy who is an avid boater,had a spark tester from Harbor Freight,it showed that the plugs were all working

please let me quote my own posting here...

but when the OP claims he gets a surge when pumping the ball and the engine dies when giving full throttle but starts runs at low power good i would be very surprized if its the ignition and not a bad ( insufficient) fuel supply at high power demands.

even a compression check is not needed in my eyes when the engine starts like a champ. - hard starting, bad idle, stalling at gear shifting- that are the classics for bad compression, bad ignition or fouled plugs .
 
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