Engine "Missing"

[Ferrariiwish]

Hi all,<br />I have a 1993 Force 90Hp 3 cyl.The engine was fine last year but when we started it for the start of this season we came across a few proplems ie. new impeller, bad starting,plenty of smoke, the usual at the begining of the season.I fitted new plugs, leads,checked compression which was very good.Removed carbs for clean up, jets ect.Now it "missing". I can remove 1 plug lead at a time and it will still run the same so its not down to one cyl.I adjusted the 3 carbs adjuster screws in all the way and then brought them out 2 full turns each.Thanks in advance.

 

[Yepblaze]

Re: Engine "Missing"

Do those screws again while it's idleing and make sure each one of them acts upon the idle condition. If one of them doesn't make it react, suspect the idle circuit needs attention in that carb.<br /><br />Here, this might help.

 

[Ferrariiwish]

Re: Engine "Missing"

Yepblaze,<br />Thank you very much for your reply.I tried what you said to no avail.The carbs are absolutley spotless.I dont think i mentioned it gives a backfire now and again.It also makes an effort to clear itself ie. will sound great for a nanno second.then it will have a splutter and a good fart before conking out.like meself after a few pints i suppose.Thanks again.

 

[jim dozier]

Re: Engine "Missing"

Perhaps I misunderstood your initial comment, but if you remove a spark plug lead and it continues to run unchanged that would indicate that cylinder you unplugged had not been firing. A good firing cylinder would cause a decrease in rpm when unplugged. However, despite that it does sound from your other description like it is running lean and I would look for obstructions in the fuel flow or air leaks in the lines. Does pumping the fuel bulb help, does choking it help or hurt?<br /><br />Someone on another post suggested putting 2 fingers in the throat of each carb (1 carb at a time, this selectively enrichens that carb) if it improves that carb is running lean for some reason.

 

[Ferrariiwish]

Re: Engine "Missing"

jimd,<br />Thanks for the reply.When I take the plug leads off 1 at a time it makes little difference.I took 3 off 1 at a time and the RPM drop is very little.<br />I can assure you there is a good spark at the leads as my neigbours can tesify after I took them off by hand.Their children are using language they never heard them speak before.<br />I will try putting my hand over the carb and see what happens.That will certainly richen the mixture.<br />Thanks.

 

[Ferrariiwish]

Re: Engine "Missing"

I am still having trouble with this engine.It seems like at this point it might be the carbs.Number 3 cyl. is perfect so I took the lead of that one and put it on the other two cyl. to eliminate plug leads.I have the carb adjusters screwed out to about 2 turns.When I rev. up the engine it backfires and tries to clear itself.Any ideas please.Thanks in advance.

 

[jim dozier]

Re: Engine "Missing"

The backfire may be an indication of a lean condition. By what method did you determine that cylinder 3 is perfect? The recently electrocuted neighbor is not a reliable indication of the quality of spark in the cylinder. Pull the plugs and ground them on the engine away from the hole and turn the engine over, you should have a strong blue spark. Better yet, get a spark tester, it should jump at least 1/2 inch with a strong blue spark. After you determine you have 3 strong sparks you can start to narrow down the fuel situation. Have you tried the 2 fingers (not whole hand the idea is to restrict not close off the carburetor) method mentioned earlier. Also when it starts missing try selectively spray pre-mix gas/oil from a spray bottle into 1 carb at a time and see what happens. If it speeds up or smoothes out that carb is running lean. My guess is you are going to need a complete carb cleaning and rebuild with a carb kit. Keep us posted as you narrow it down.<br /><br />After re-reading your post I see that you already worked on the carbs. How did you clean them, completely disassembled and soaked in carb cleaner and cleaned with compressed air or just spray cleaned on the outside? Floats readjusted or not?

 

[Ferrariiwish]

Re: Engine "Missing"

Jimd,<br />You are making a lot of sense to me now.<br />Just to get this out of the way first.I grounded all three plugs a have a good blue spark.How I think Number 3 cyl. is ok is when I pulled off that plug lead with the engine running the engine cuts out. With numbers 1 and 2 it does not cut out when you take them off one at a time but does when you take off both.<br />Now, the carb situation,I pulled the carbs off and striped them down one at a time.I used carb cleaner aerosol first and then compressed air.I did NOT adjust anything internal.I will try what you said with the spray of gas/oil.That sounds like the best idea yet.I Did NOT adjust floats.What way is that done?<br />I am an auto mechanic by trade and have no experience with 2 stroke engines.A different beast altogether.Many thanks Jim.You have been a gem.

 

[Ferrariiwish]

Re: Engine "Missing"

Jimd,<br />Just back from this engine again.I started from scratch.<br />I stripped carbs again to make double sure they were ok.I bent the little "stopper" on the float to let more fuel in.<br />Its still the same. I replaced all three plugs even though they were new. I done the same with the leads.There is a bright blue spark from all three cyls.Its when you rev. the engine it breaks down.Also it wont tick over.A guy who knows nothing about engines made me think hard whe he said my fuel line might be to long.(I moved my tank from the back of boat to the front and its about 10 feet long)I gave up on it for today.<br />Trying to get a marine mechanic around here is like trying to get a brain surgeon to make a house call.Rare as hens teeth.Hope to hear from someone soon.Thanks in advance.

 

[gss036]

Re: Engine "Missing"

Maybe you have already done this, but thought I would add, use fresh fuel, makes all the difference in the world.<br />I got out my weed eater the other day, I had about 3/4 tank full of fuel in a qt container already mixed from last year. It would start when chocked but would not run. after 4-5 trys, I finally dumped the fuel and mixed a fresh batch, guess what, it ran just fine.

 

[jim dozier]

Re: Engine "Missing"

Ok, it seems you got 3 good sparks but 2 of 3 cylinders aren't doing much, gotta be the fuel system. Two strokes engines are just like 4 strokes, only different. Same spark/ignition issues, same fuel/air issues though they might be a bit more sensitive in the carb area. One common thread among many of the posts here is that there is cleaning a carb and then there is "cleaning" a carb. By that I mean many people do an incomplete clean/rebuild and don't correct the problem. In addition to causing the engines to run poorly, the lean condition from a clogged carburetor leans out the lubrication system and is associated with engine wear and/or damage.<br /><br />So you probably should replace the float valve and set the floats to the proper specs. You really need a manual to work on these things because they are all slightly different. I don't know your particular engine but I think most of the floats should lay level with the bottom of the carb when turned upside down. You gotta remove whatever necessary to visualize the main and idle jets and clean them well with solvent and compressed air. All new gaskets and seals. These mothers can be real sensitive to mixture. You also need a manual to tell you how far out for baseline to unscrew the idle jets from the seated position. Then you have to fine tune them from there. When the idle is best, back it out 1/4 turn (richer) more.<br /><br />Now about the long fuel line. When the motor is running is the fuel bulb firm or collapsed? If you pump the bulb while its running does it improve? If it improve you might need to rebuild the fuel pump. Even without a fuel pump, pumping the bulb should keep the enginge running. If the fuel line is adequately large enough in diameter it should probably be okay. But you also need to check the fuel hose for air leaks and check the anti-siphon valve and connections and any filters for air leaks. Best way to rule all this out is borrow a portable OB fuel tank an test it with that.<br /><br />It seems you've narrowed the problem down to fuel/air no you need to narrow the many fuel/air possibilities down. Keep us posted.

 

[Ferrariiwish]

Re: Engine "Missing"

Hi,<br />I got a full tank of new fuel.Thanks for that anyway.I am willing to try anything at this stage.<br />The bulb is hard all the time when the engine starts.Checked for air tight seals and replaced all gaskets which were ok anyway.I think "Jimd" is correct when he says fuel because when I stripped carbs again all 3 cyls. seem to be the same instead of number 3 cyl. been the best one.I also kept pumping the bulb to eliminate the pump.If you come up with any thing more please post it.I will try anything.Thanks again.This is the most helpful site I ever came across on the net.

 

[Ferrariiwish]

Re: Engine "Missing"

Jimd.<br />Is there any more you can come up with?

 

[Ferrariiwish]

Re: Engine "Missing"

^^^^^^

 

[Ferrariiwish]

Re: Engine "Missing"

^

 

[jim dozier]

Re: Engine "Missing"

Larry,<br />Did you have a chance to squirt some premix into the each of the carb throats while its acting up? I still want to verify whether it is running lean or not. That should help point us whether to continue fiddling with the carbs or whether to look elsewhere. If its not running lean and its got spark you gotta check the compression which you said was OK. What were the numbers? The other possibility and I don't have much experience with it would be a bad crankcase seal at either end of the crankshaft leaking pressure. Two strokes use the crankcase to suck in the mixture then pump it back into the cylinder for firing and if they leak you got problems.<br /><br />Also if you have not done so already do a search on this forum for Force engines and see what others have dealt with.

 

[Ferrariiwish]

Re: Engine "Missing"

Thanks Jimd,<br />Yes I tried the squirter. What puzzled me on that one was it made no difference at all.If it was running lean it would have reved up.If it was running rich it ought to flood and cut out?????<br />The compression test result was 90lbs per square inch which is very strong.Hopefully this marine mechanic should be here tonight.Thats a 3 week wait and he said he MIGHT be down to me.<br />I just want to go fishing.<br />Let you know what happens IF he comes.<br />Thanks again.

 

[jim dozier]

Re: Engine "Missing"

90 psi on the compression test is probably low. Should be over 100 psi. More important is the difference between the cylinders. Should not be more than 10-15% difference. It is starting to sound like you have 1 or more bad cylinders, that's why when you squirt the gas into the cylinder nothing much is happening. It is probably not firing. Now if you do if fact have a good spark like you indicated, maybe you got bigger problems in the cylinders. If you haven't already done all 3 cylinders on the compression check, do them and tell us what all 3 numbers are. Do it on a warm engine, all plugs out, full throttle. I'm curious.

 

[Ferrariiwish]

Re: Engine "Missing"

Warm engine. 3 plugs out.All 3 were 90lbs per square inch.This engine was running perfect last season.Thats what has me really peed off.I will keep you posted.<br />Thanks again for all your help.<br />You've been great.

 

[jim dozier]

Re: Engine "Missing"

I don't have much experience troubleshooting ignition woes beyond the obvious so someone else might have some suggestions here, I'm beginning to wonder if you don't have spark gremlins. You seem to have spark but maybe you are losing it at higher rpms. Since you've looked pretty good at the fuel maybe you should take another look at your ignition system. Do you have a manual? You could probably get one online quicker than you can get the roving mechanic. Manuals are really a necessity. Each outboard is a little different than the next.