Engine stumbles and dies after exiting no wake zone. Help and advice please

Hi All. Merry Christmas.

i need your kind assistance again please.

on my last two outings my motor has started to give me grief at low speeds as follows;

When going at WOT the engine runs fine with no missing or stutters. However whenever I come to shore, shut the engine off and then startup and leave shore the problem shows up.

The motor starts on the first try, quickly and will idle all day, i can cruise in gear to exit of the no wake zone, but when I then go to WOT the engine seems to "bog" and die. This seems to happen when the motor is warm or cold.

When this happens I can easily start the motor and it will idle fine, but stalls again when I try to go to half or full throttle. To fix the problem I have to use the warm up lever and rev the motor for a few second in neutral, before quickly slamming it into gear and then sometimes it takes off or I have to repeat a few times before getting under way.

If I'm towing and come to a stop and shut the motor off and then quickly go from start to wot the problem does not present itself and once under way there are no other problems.

I'm using the recommended NGK plugs, as I cannot find champions in my area and the carbs were rebuilt about three months ago. The fuel is new and I am pre mixing 50:1. The thermostats were recently replaced and the water pump etc is all working 100%

the motor is an 81 v4 Johnson j90mlcim

I suspect that the plugs may be fouling at trawling speeds as the engine may be running too cool or that the linkage between the timing and carbs needs adjusting. does anyone have any ideas for me please?

thanks as always.

Quick addition, when I got the boat the engine had NGK B8HS 10 plugs, I did run it with these and replaced with the recommended BR7HS 10, plugs

Champion plugs are garbage stay with NGK. Did you try this, before you go to WOT, PUMP up the primer bulb on the fuel line to make sure carbs are full of gas and if that works check for leaks in fuel line, exp; at mtr; connection o ring. Had same problem on 150 and eliminated said connection, went strait to fuel pump with fuel line. Just a thought, good luck.

You have to make sure this engine is reaching operating temperature on both cylinder heads. If not it will condensate water in the combustion chambers and put the spark out.

Is the idle speed / RPM ( in gear ) set correctly ?-------------If it is then this may be a classic too lean condition.------------Ideally you would test that theory with a set of adjustable low speed jet carburetors.-----So you do not have a set i am assuming.------Carefully use the primer injector red lever to experiment in getting a richer mixture.--------Good luck with this testing.

Thank you for all the responses.

I have a fuel pump kit that I was planning on installing as I haven't done that yet in my maintenance schedule and think that "run out" may be onto something as I see the logic that running a low rpm's the pump may not be putting enough fuel into the carbs for take off... Will also make sure the motor is warmed up before pulling away from jetty and re do the link and sync process given in my seloc manual.

@Racer one, you are correct the carbs are non adjustable on the '81. In my view My idle is a little high, I don't have a tach so I'm not sure how high. When running in the drive I manually hold the throttle and timing levers back to reduce the idle when flushing, in the water the back pressure lowers the idle, but still not low enough for my liking. I have tried disconnecting the remote cables, but the mechanism still won't return all the way (my idle speed screw doesn't meet the block if you know what I mean) I thought the red lever on the primer was "on" in one position and "off" in another? Are you saying If I move the position it will change the richness of the mixture? If so then is it better to have lower idle using this or a higher one? Or is this down to something I can use to solve my hole shot problem?


Sea foam is something I cannot get in my area, I will ask my local boat shop for an alternative and give that a whirl as well.

Thanks again for all advice provided. i will revert as to what solves the problem when I've had chance to water test next week.

Experimenting with the primer is a " no money spent " method to come up with the answer.----Yes I know that the 81 carburetors are a fixed jet item.--------Once you determine it is a lack of fuel / poor fuel condition then you may be able to compensate with bigger jets.----They are available from the factory.

Am I overlooking it? I see nothing pertaining to the initial troubleshooting procedure. Checking compression and spark.

With all of the spark plugs removed, what is the compression psi reading of the individual cylinders? (Stating that the compression is okay just doesn't do it.)

With the s/plugs still removed, the spark should jump a 7/16" gap with a strong blue lightning like flame on all cylinders... a real SNAP! Does it... what do you have?

If the above two areas check out as they should................

Personally, it my opinion that you should use the proper Champion QL77JC4 plugs, gapped at either the original recommended gap setting of .040 or the late 1990's revised setting of .030 . However, I don't feel that this is your problem.

You say that this problem started on your last two outings, giving me the impression that the engine did at one time run properly in this same location. If so................

If the fuel pump diaphragm was broken/leaking thru it, pumping the fuel primer bulb would be flooding at least one cylinder and it is unlikely that the engine would idle properly. However, do the following test to eliminate any fuel pump diaphragm problem possibility.

(Fuel Pump Diaphragm Test)
(Two Hose Type Only)

(J. Reeves)

Note: This pertains only to the regular Two Hose type fuel pumps.

Leave the hoses attached to the fuel pump. Remove only the two screws that attach the fuel pump to the powerhead.

Re-insert those two screws and install a nut to each of them so that the fuel pump is securely clamped together. With the fuel line attached to the engine, pump the primer bulb while observing the pressure/vacuum operating hole on the back side of the fuel pump. Should any fuel leak out that hole, the diaphragm is faulty.

If the diaphragm is faulty, the fuel pump will require rebuilding or replacing. Note that repair kits are not available for all fuel pumps, in which case replacing the pump would be necessary.

Thousands of parts in my remaining stock. Not able to list them all. Let me know what you need and I'll look it up for you. Visit my eBay auction at:

http://shop.ebay.com/Joe_OMC32/m.html?_dmd=1&_ipg=50&_sop=12&_rdc=1

If the fuel pump diaphragm checks out okay, as is the compression and spark, then I would assume that the four (4) high speed jets are still clogged. I normally make sure they're cleaned out good by running a piece of single strand steel wire thru them as solvent just doesn't do a proper job on them.

Also, regardless that you may have excellent spark when doing the spark test on a cold engine, check visually the stator under the flywheel. Should that stator be cracked and/or dripping a sticky looking substance down on the powerhead area... it may function properly when cold BUT when hot, it would result in a voltage drop to the powerpack which in turn would result in weak, erratic, and eventually no spark.

And the obvious check..... Is the vertical throttle arm at the engine sticking? Is the timer base under the flywheel sticking?

Let us know what you find.

Hi All thank your again for your comments and advice.

Compression readings are 110 psi on the left bank and 112 psi on the right bank. Cold spark jumps the 7/16" gap. I have not tried it hot as yet. No black residue under the stator, throttle arm, cams, cables not sticking and working smoothly

Boat ran beautifully a few weeks back and I didn't change anything between it running well and poorly, jets are the correct ones for my altitude.

took boat out today having redone the link and sync process and regapped plugs to 0.30. Held off on fuel pump overhaul and carb kits. Adjusting the primer solenoid kills the motor in all but one position, which is when the lever is parallel to the boat from bow to stern with the end at the rear.

The problem only occurs when starting the motor after launching and when re-starting from cold. When motor is warm it runs all day at WOT and idles very smoothly. When warm we can stop change skiers, kill motor, start up and take off like a stabbed rat without hassle.

when the motor is cold and in the water it will start, but the idle is weak. Using the warm up lever the revs will build but the engine struggles and dies often. When opening the throttle the timing advances until the throttle cam touches the roller which opens the butterflies on the carbs. At this point the motor dies very quickly. I adjusted the linkage between timing and throttle cam backwards and forwards and it makes no difference when the motor is cold, it just wants to die when the butterflies start to open, they are completely closed when at idle or start as per the lynx and sync.

To get going when cold or from shore i used a combination of idle lever to raise idle and sometimes it would then accept throttle input and then on other occasions a few pumps of the fuel bulb would yield a result and we would take off. I also used the idle screw to raise the idle in the water


When I got home and flushed the motor on muffs, 3 hours and about 40 miles from the lake,it started on the first crank and idled beautifully without a stutter and would rev using warm up lever without any hassle. Idle was a little high (i think due to no back pressure on exhaust or the adjustment I made while at the lake)

I don't know if it's flooding or starving when cold. to try and solve I am going to test fuel pump as per above details and dismantle, clean and reassemble carbs with kits I have on hand, including cleaning the jets. I'll also replace the in inline fuel filter and make sure there are no blockages between the tank and fuel pump (the fuel supply connected from the filter to the fuel pump, the connectors on the motor cowl was removed when I got the motor due to leaks)

If I've missed anything or there's something else I should look at please let me know, i will post again when I have had chance to water test again, thank you again all for all the assistance and advice.

Good day people.
I note with interest your engine problem, which is similar to a problem i have.
I have posted it here some weeks ago and given similar advice regards the carbs, which i did, and today i put the boat back in the water and managed to actually get some revs on the engine (before it would not even get any revs on)
I assumed that there was still something in the crabs so removed them and cleaned them agaian (putting wire up jet as first told)
I noticed that the inner jet is off set, is it supposed to be off set or is it supposed to be central (see pic) all 3 of my carbs inner jet are off set.
I also overhauled the fuel pump, as well as removing each fuel line one at a time to each carb and petrol was being pumped.
My engine is an evinrude E70ELCNB
Thanks

That is the idle feed tube and every one I ever saw was installed like that at the factory !

Thanks for that, i can assemble and try again.
I did not notice any blockage, or indeed any signs of dirt which might cause a problem. Is there anything i should be looking for in the carbs which may cause this problem? Also, what next if these are not the cause?
Thanks
Peter

Just so we are clear on this , the " tubes " in your pictures are not the fuel metering jets !----They are found elsewhere in the carburetor.

Mmmm! So where are they then?
Peter

Hollygolly (Peter).... It would be best if you went back to the previous page so that you could enter your post under your own forum name and post title. As it now stands, your post is listed under another members post, is considered hijacking and results in confusion for everyone. Hwoever, while I'm here, the slow speed jets are in the top of the carburetor, in back of the screw plug you see at the top front portion of the carb.

Hi all.

removed and tested fuel pump today, no leaks, all seemed in order. Took it apart, cleaned and re-assembled. Will replace gasket between pump and block as that appeared to be bad.

Also tore down carbs today. Found very little dirt, but they are soaking before re-assembly with new kits. Removed jets to confirm sizes and found main jets are 63c, which is correct for my altitude. The low speed jet however is 0.035 and not 0.038 as per the manual for my altitude. Would this have something to do with the problem I'm having and do I need to change these to 0.038?

i also found the 0.035 jets installed at the top of the carbs in what I would describe as the "intake Venturi" before the butterfly valves.

the,main jets are in the lower orifices on either side of the float bowl. In the top orifice of the float bowl there are jets that are 0.029 in size.

Are these the idle jets and are they the right size for my altitude and are they in the right place above the main jets?

thanks.

Hi All. So I managed to confirm all jets are ok, completed carb rebuild today and re-assembled. Noticed that I had many gaskets missing (for example between carbs and silencer plate and between plastic cover and silencer plate, replaced all of these to eliminate possible issues. Put new hose clamps on all fuel lines, flushed fuel tank and replaced fuel,filter. No air of fuel leaks now for sure. Lync and sync completed. Also dropped lower end and checked water pump and impeller while I had the carbs off. All ok.

Had chance to water test this afternoon. The problem when cold is gone, engine will rev from start up and accelerates when given throttle. So that's done now.....however the engine has started to "tremble" or shake at mid throttle and wot doesn't appear as high as it used to be, not as quick out of the hole either. Idles fine but is running rough and feels like it's starving or flooding. I fiddled with the primer solenoid lever position and the linkage between timing advance and throttle cam with mixed results but the problem remained.

I carefully checked the floats when assembling carbs, making sure they were parallel with the carb bodies, but I have niggling feeling my problem might be there. Any ideas on trouble shooting or solutions anyone?

I will start a new post of required. Thanks

Quick update. Pumping the fuel primer bulb while under way made no difference at all.

Hi All. As quick update. I removed carbs and changed floats in line with Joe Reeves advice on other posts, to eliminate this being a fuel starvation issue.
I ran the engine on the muffs and checked all cylinders sparking at idle, lent my spark tester to someone, so will use that at the end of the week and do a water test this weekend and confirm results. P.s I pumped the primer bulb on the motor after shutting it down on Saturday and it was still hard this morning, no air or fuel leaking anywhere in the system, so I am confident I haven't over adjusted the float levels.

Hi B.

I use 93 Unleaded in the motor. I'm in South Africa and my fuel choices are limited to 93 Unleaded or 95 unleaded premium. Most service stations have stopped supplying LRP all together and I was advised that Unleaded 93 is ok to use, but that a lower octane would have been better, such as 87, which is no longer available. I also only use fuel from BP (British Petrolium) as down here it has the lowest Ethanol content or so I have been told, I have tried to find out officially, but run into dead ends on this. I steer away from the brands which advertise that their fuel "cleans your engine as you drive" or "adds power"

I will re-check all ground and other electrical connections before the water testing on the weekend. It really surprises me how much care these motors need, but after 32 years of service I suppose it deserves it.

Hi kimcrwbr1. I got the trailer sorted by moving the boat and "nose stop" forward about 4 inches. This sorted out the sway increased tongue weight, without having to move the axles. The trailer sticks out a bit at the back of the boat, but that doesn't bother me at all. I also converted the lights to waterproof LED's, saving me the effort of removing them everytime I want to launch.
I will be re-spraying the whole trailer in my winter and will give the bearing buddies a try as part of this process. Thx

Hi all. Quick update. Took the boat out this weekend after all my work on the carbs, lync and sync and having worked the wiring over. Didn't get chance to run on the muffs before hand. Got it in the water and the damn thing wouldn't start. Fuel bulb hard, primer solenoid working, fuel in tank, spark ignition all good as per my usual numbers. Got the thing back on the trailer and brought it home.

Was about to start tearing everything down again, when I notice the fuel pipe that leads from the primer bulb directly to the fuel pump (connector on motor cowl was leaking so removed it some time back) was kinked due to way I had put it back in the cowl and after removing and replacing the wiring so it completely shut off the fuel supply.......feel like such an idiot.

so the primer bulb was getting hard and seeming to work and fuel already in the system was supplying the primer, but no where close to enough to get her started......

removed fuel pipe and reinserted properly without kink and started right up on first crank on muffs. Going to be a few weeks before I can get her back in the water so, I will update all on the experience mid Feb.

Hi B. I got her out and problem with the bogging dissappeared, but the engine developed an intermittent miss, which I traced to a faulty power pack. I replaced the pack and it was a lot better, but still not 100%. Through further trouble shooting and the use of ,y home made spark checker I discovered that one of the brand new coils I put on 3 months ago was bad. Put one of the coils back and all now seems well. Here's the link to the thread i started after tracking down it was a bad power pack http://http://www.marineengine.com/boat-forum/showthread.php?405820-Powerpack-failure