V4 1987 Looper Low Compression & Backfire In One Cylinder

Riley C

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Gents,

Regarding jets, does the intermediate jet work at idle?. If the intermediate orifice numbers between port and starboard are not in the exact position. Say No.20 jet which is for Port was swapped with No.16 jet which is starboard. Would this cause a misfire or sneeze?

I will double check this, sure its all in place

All the idle air ones are the same size for each engine. So cant be that.

Just want to eliminate possible causes.
 

Riley C

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Dec 23, 2018
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239
haven't got any faria tacho tachos so can't say what it should be set at,

the other issue sounds like a low battery problem but...

Thanks Tas. I hate the gauges really, trim and fuel don't even work. Could buy OMC ones for $40 second hand, but more $ trying to avoid.

Volts are good above 12v and not over 14. Battery brand new century.
 

Faztbullet

Supreme Mariner
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Mar 2, 2008
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15,589
Regarding jets, does the intermediate jet work at idle?
No.....most boggs on these motors is the outer covering(clear) has came off roller and roller to close to cam.

Say No.20 jet which is for Port was swapped with No.16 jet which is starboard. Would this cause a misfire or sneeze?
There are two jets you can see on front of carb, The top one should be smallest number and the bottom one biggest number.
 
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Riley C

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No.....most boggs on these motors is the outer covering(clear) has came off roller and roller to close to cam.


There are two jets you can see on front of carb, The top one should be smallest number and the bottom one biggest number.

Thanks Fazt.

The came roller is now 3mm clear away from the cam at idle, previously 1mm.

Yep it's got that definitely. No: 30 on top and 45 on bottom.

Cleaned carbs down again last night, some slight black particle in the fuel bowls not much. Should have the two fuel filters caught it... May swap the water separator one out if it keeps letting black particle through.

Search continues.
 

Bosunsmate

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If those particles a big enough to block a jet or its passages that can cause the problem. It may be that the hoses downstream of your filter are deteriorating.
When i meant dry i didnt mean not enough oil, more not enough fuel oil mixture getting in that cylinder.
If you dont have a lanyard line just ground out the Black wire with yellow stripe from the power pack as that kills spark.
I think you really need to do that test thoroughly. CLean all spark plugs, put one into the engine and test and then remove, inspect and try the next cylinder. They should have a nice wet covering, if not they are running dry
 

Riley C

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If those particles a big enough to block a jet or its passages that can cause the problem. It may be that the hoses downstream of your filter are deteriorating.
When i meant dry i didnt mean not enough oil, more not enough fuel oil mixture getting in that cylinder.
If you dont have a lanyard line just ground out the Black wire with yellow stripe from the power pack as that kills spark.
I think you really need to do that test thoroughly. CLean all spark plugs, put one into the engine and test and then remove, inspect and try the next cylinder. They should have a nice wet covering, if not they are running dry

Thanks Bos,

Yes I understand now, the mix is too lean resulting in dry and not enough fuel. Carb/air mix related and not timing then?

I will get on to this. When I pulled down the carbs the bowls mix looked pretty good (See photo).

The particles weren't a lot and about size of hair thickness max and black.

So could be rubber OMC line from primer bulb to inline filter at motor, or the smaller hoses after fuel pump? Non are perished or anything externally. Guess anything possible.

I noticed when I pulled the air box off there was a lot of oil residue in there and the throats. Is this normal? Blowback through carb do this? Got me beat why the blowback happens.

Thanks for the wire ground advice, I'll do that.

I will do test tonight.
 

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Riley C

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If those particles a big enough to block a jet or its passages that can cause the problem. It may be that the hoses downstream of your filter are deteriorating.
When i meant dry i didnt mean not enough oil, more not enough fuel oil mixture getting in that cylinder.
If you dont have a lanyard line just ground out the Black wire with yellow stripe from the power pack as that kills spark.
I think you really need to do that test thoroughly. CLean all spark plugs, put one into the engine and test and then remove, inspect and try the next cylinder. They should have a nice wet covering, if not they are running dry

I bet the previous owner ran Ethanol on old hoses, this would explain rubber particles downstream of fuel filters?

Also, if the mixture is lean result in the dry plugs would this be carb air inlet issue? Fuel Starve? Weird can go WOT and speed. If so where would you adjust this...

Get this test happening.
 

Bosunsmate

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I bet the previous owner ran Ethanol on old hoses, this would explain rubber particles downstream of fuel filters?

Also, if the mixture is lean result in the dry plugs would this be carb air inlet issue? Fuel Starve? Weird can go WOT and speed. If so where would you adjust this...

Get this test happening.
It may just be one cylinder running dry on the low speed orifices so you get the sneeze at low speeds but not at high speeds but itl still be running slightly dry from that at top speed. You will notice that with my test done at low cranking rpm.
Cant see anything in the glass, you will need to judge on that but lines can do lots internally and look harmless externally. They may be alright.
As for timing or carb. That test will tell you but its more likely fuel related.
There is coincidentally another boat with a similar sounding problem to yours at the moment
https://forums.iboats.com/forum/engi...pro-200-issues
The timing test you have to also do is the max advance one to check pistons are not burning up but thats nothing to do with the sneeze dryness test
 

Riley C

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It may just be one cylinder running dry on the low speed orifices so you get the sneeze at low speeds but not at high speeds but itl still be running slightly dry from that at top speed. You will notice that with my test done at low cranking rpm.
Cant see anything in the glass, you will need to judge on that but lines can do lots internally and look harmless externally. They may be alright.
As for timing or carb. That test will tell you but its more likely fuel related.
There is coincidentally another boat with a similar sounding problem to yours at the moment
https://forums.iboats.com/forum/engi...pro-200-issues
The timing test you have to also do is the max advance one to check pistons are not burning up but thats nothing to do with the sneeze dryness test

Thanks Boss,

Yeah ill pull the carbs down again to make sure that black isn't in the indeterminate brass bit as per photo. If that's blocked could be idle starve issue on one cylinder?

Doing test tonight, fingers crossed.
 

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Bosunsmate

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I dont know those carbs but anything blocked is bad news on a carb. Sometimes you cant even see the blockage as its not in a jet its in the labyrinth of canals that go through the carb taking the air/fuel through to where its destined to go out.
So what i do is i get a can of crc/wd40 and i use that little straw that comes on the lid. I then blow the crc/carb cleaner whatever down each hole and make sure it comes out another hole as fast as easily as its going in. Only doing that have i found some elusive reasons for a sneeze. Bathing in carb cleaner isnt my method, you really need to blast, some people use compressed air.
Good luck with the test, hopefully it shows one is running a bit dry and that you quickly find the cause
 

Riley C

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I dont know those carbs but anything blocked is bad news on a carb. Sometimes you cant even see the blockage as its not in a jet its in the labyrinth of canals that go through the carb taking the air/fuel through to where its destined to go out.
So what i do is i get a can of crc/wd40 and i use that little straw that comes on the lid. I then blow the crc/carb cleaner whatever down each hole and make sure it comes out another hole as fast as easily as its going in. Only doing that have i found some elusive reasons for a sneeze. Bathing in carb cleaner isnt my method, you really need to blast, some people use compressed air.
Good luck with the test, hopefully it shows one is running a bit dry and that you quickly find the cause

Thanks Boss,

I haven't heard much good news about these carbs.

Yeah originally used carb cleaner with the straw like you and soaked the jets. Blew it all down with comp air.

Im thinking if this black matter is the hoses post filter, that really sucks.

Also, regarding recirculation valves, if they are not working can this cause a lean issue? Or being post reeds it would have an affect....

Fingers Crossed.
 

Bosunsmate

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re circ valves, i dont know what the hook up system is on yours. Normally they suck out and into the manifold from the bearings etc (scavenging) and have a one way valve too which you can check by blowing and sucking to check it only works sucking i think.
I suppose they may lean it out a bit if there were issues in their piping system. You can always temporarily block them off if you want to test them
 

Riley C

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Just to update guys.

I have replaced all the carb fuel lines and pulled down the carbs. The specs were in the bowls, and blocking one of the intermediate holes at the throttle valve hole. Dont know if this was the idle issue, but god it was a pain in the arse clear out. These carbs have been pulled down three times now.

The old OMC hoses were cracked alittle, especially going from primer to motor.

Another weird thing is the new RSP (Aus made) 5/16 fuel hose I hadn't installed yet, also had specs in it when I would put it in heated water to flare over fittings. The 3/8 hose to motor is gates and fine. It has driven me bonkers! Could new hose not fitted have specs from not being flushed through yet?

Think I might need a new filter.

I have also clear through alot of black carbon in the recirc lines.

I found the tacho to be on setting four and not setting five like Faria manual states. Maybe will get proper revs!

Ready to complete the plug test Bosuns instructed.

Oh yeah I managed to pickup two hard copies of genuine OMC manuals for $20 off a guy selling a whole catalogue. Best deal yet of this money pit of a machine. I can provide his details if anyone in Brisbane needs a manual.
 

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Riley C

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New compression numbers from my friends gauge.
1# 110, 4# 120, 2# 115 & 3# 115psi

kills that one!

The big issue of the black bits, found it to be the codon hose from super cheap auto. Put all gates hose in now. All hoses are new.

Going to really hand it to super cheap tomorrow. Reason for pulling carbs down three times.

started it up this afternoon noon on muffs. Started missing so put my hand on throat and found the black bits in there. Has done it again after 5min.

will take out tomorrow under load to do boss test.

getting close!
 

Tassie 1

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Supercheap = Supercrap
Only buy oil and degreaser spray can...when on sale... there now,
too far away as well
 

Riley C

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Should I start a new thread?
I think it’s an electrical issue I’m having, but can’t I know for sure.

Yesterday I went on water, with all new filter and hose and clean carbs. Ran terrible and no power, felt like two cylinders out. It would rev spike alittle but back down. Now can’t get over 3.5k revs.

put new plugs and coils in, saw some goop on back of some coils.

Cleaned carbs again, fuel is ok, still small specks , even after draining the tank started fresh fuel this morning. I flushed tank a month ago, something got in there.Ran ok initially at idle for 10min, couldn’t get revs over 3 again. Engine just died suddenly.

cant be link if last week same setting got me full WOT. Lean sneeze gone though, so weird.

Found zero spark while trying to crank. The engine is now the worse ever. Degraded over three weeks.

Can power pack or stator do this? So different to the issue last week of sneeze.


I got it home it started flush easy. WTF

Bloody really over this thing. It’s broken me.

i wish to thank everyone that has replied to me on the thread.
 

Riley C

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Dec 23, 2018
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Put the skeg in the esky to test with muffs also.

Found the the two new coils had no spark, how can this be??

I put put the old ones in and got a blue spark on both. Then used tester which had red light. Got me beat how two new cdi coils could not work on startboard side. Are they number in a way that would affect operation?

Can an someone tell me more I should look at for electrical issues. Symptoms of power pack failure?

see Dropbox link below.

https://www.dropbox.com/s/09cqk53meed8aaa/Video 20-1-19, 5 37 34 pm.mov?dl=0

Thanks guys
 

Riley C

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Dec 23, 2018
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Is there water coming from your tell tale? It doesnt look like it
Why did you replace the old coils if they were working?
Have you asked the shop who sold them to you?
Dont start a new thread
This is the easiest and best troubleshooter for the electronics
http://www.cdielectronics.com/troubleshootingguide/

Sorry Bos, Yeah water from the tell tale is great, even better than before thermos. However on just that video run just then when I stated there a abit of a kink in the hose from going into esky on muffs, I stuffed up there. need a wider flush tank. I'll send a better video today.

I replaced them as on Saturday I was down to two cylinders, I saw ooze coming from one Coil and cracks in the rubber backing of the other. However, the resistance test was at 255ohm for both.

The seller are happy to issue a refund. I just don't want to drive 40min each way to hand it back for $50.

Idle sneeze and missfire is gone though, so that's why I was thinking electrical.

Ill look at the ad, thanks boss.
 
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Bosunsmate

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Not sure what you are trying to solve now as since you have put the old coils back on dont you have spark everywhere?
The specks in the fuel would be top of my concern. My lines are old but the fuel comes out pure
 
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