weird problem...3L...need help

[oops!]

hi guys....

89. 3.0...(181 ci)...2 bbl ....points....

was crusing.....(trolling speed) for four or five hrs.

hit the throttle..(approx 3500 rpm....tach does not work properly)..was ok for a few mins...then it started bucking and spitting.....

low rpms were allmost stall.

changed the plugs to nkg 35 thou gap.....still the same...

the points are changed and set to 16. timing is 8 deg btdc....(timing light)

the wires were changed....the carb rebuilt.....(no water in the gas....( a beer bottle full)...the carb filter is fine.....have not found an inline filter)

the dist cap is worn ..(i cant find a replacment) the rotor is new.

the intake manifold was checked....gasket replaced....there seems to be no pressure loss between the exaust side and the intake side of the manifold.

a compression check has not been done......(i need some one to turn the key when i watch the gauge)

it starts bang on........and seems fine till approx 2500 rpm.

the problem is....at a higher rpm....approx 2500 and over, it misses......under power....it has hardly enough power to get on plane....and is spits when it is.......(no back fire thru the carb or other)

any suggestions where to look?

the cap is badly worn at the rotor connection.....i hope to find one tommorow....but i cant see a cap being the cause at higher rpms?

thanks guys...

cheers
oops

(gotta go uodate my thread now.... been a week since i been on here)

 

[buggiedad_67]

Re: weird problem...3L...need help

hi guys....

89. 3.0...(181 ci)...2 bbl ....points....

was crusing.....(trolling speed) for four or five hrs.

hit the throttle..(approx 3500 rpm....tach does not work properly)..was ok for a few mins...then it started bucking and spitting.....

low rpms were allmost stall.

changed the plugs to nkg 35 thou gap.....still the same...

the points are changed and set to 16. timing is 8 deg btdc....(timing light)

the wires were changed....the carb rebuilt.....(no water in the gas....( a beer bottle full)...the carb filter is fine.....have not found an inline filter)

the dist cap is worn ..(i cant find a replacment) the rotor is new.

the intake manifold was checked....gasket replaced....there seems to be no pressure loss between the exaust side and the intake side of the manifold.

a compression check has not been done......(i need some one to turn the key when i watch the gauge)

it starts bang on........and seems fine till approx 2500 rpm.

the problem is....at a higher rpm....approx 2500 and over, it misses......under power....it has hardly enough power to get on plane....and is spits when it is.......(no back fire thru the carb or other)

any suggestions where to look?

the cap is badly worn at the rotor connection.....i hope to find one tommorow....but i cant see a cap being the cause at higher rpms?

thanks guys...

cheers
oops

(gotta go uodate my thread now.... been a week since i been on here)

looks like you started throwing parts at it before you knew what the problem was, you set the point gap but did you set the dewell and then retime it? you say no water but then you say about a beer bottle full??? if that is water that is too much a couple of tablespoons full i wouldnt worry about, you say cap badly worn, napa can or may have one or they can order you one, a good compresson gauge will hold its pressure after you spin the engine over, then record it and move on to the next cylinder, before anyone can help much you have to get right what you have already did, you may have had a simple problem and have now compounded it into a bigger one.

 

[Bondo]

Re: weird problem...3L...need help

the cap is badly worn at the rotor connection.....

Ayuh,....

Please explain this Wear,....
Is it from laterial movement of the Distributer Shaft,..??..??

If so,... You probably need a New, or another Distributer....

 

[Silvertip]

Re: weird problem...3L...need help

Setting the point gap IS setting the dwell. Using a feeler gauge is merely another method of accomplishing what would normally be done with a dwell meter. Dwell adjustment is more accurate but properly done with a feeler gauge results in nearly identical gap.

If you have a dwell meter, connect it, start the engine and then blip the throttle. The dwell meter will jump erratically if there is a worn distributor shaft or bushing. A dwell meter should hold steady regardless of engine rpm.

 

[Don S]

Re: weird problem...3L...need help

the carb rebuilt.....(no water in the gas....( a beer bottle full)...the carb filter is fine.....have not found an inline filter)

Way too much water, carb is probably full of water too. Time to consider installing a water seperating fuel filter

a compression check has not been done......(i need some one to turn the key when i watch the gauge)

http://forums.iboats.com/showthread.php?t=183904

the cap is badly worn at the rotor connection.....i hope to find one tommorow....but i cant see a cap being the cause at higher rpms?

If the button in the cap that the rotor pushes on is bad, it will cause week or no spark.

List of possible causes of low WOT. Look especially at #3

Engine Won't Reach Operating RPM. Check

• Fuel condition. Type and Octane possibly old fuel
• Propeller pitch or diameter, damaged blades
• Restricted fuel pickup tube or anti siphon valve Fuel System Test
• Crankcase oil volume, high oil level can cause aerated oil and lifter collapse
• Marine growth on hull and outdrive
• Wrong gear ratio in outdrive
• Restricted carburetor air intake (clogged flame arrestor)
• Restricted exhaust system (broken exhaust shutters/flappers) in engine transom shield or drive
• Poor cylinder compression Compression Test
• Carburetor defective, or wrong type.
• Fuel pump pressure and vacuum
• Boat overloaded, improperly loaded, or improperly trimmed.
• Engine Overheating
• Engine timing and ignition system operation
• Remote control cables and linkage for proper travel to open throttle plates fully.

 

[Maclin]

Re: weird problem...3L...need help

I must disagree in point with this statement...

"Setting the point gap IS setting the dwell. Using a feeler gauge is merely another method of accomplishing what would normally be done with a dwell meter. Dwell adjustment is more accurate but properly done with a feeler gauge results in nearly identical gap."

Setting the points gap is just that, setting the gap. It is a starting point only, it is not an accurate measurement of the actual dwell angle or percentage achieved. Dwell angle or percentage tells you exactly what the coil "sees" and reacts to as it builds then delivers the spark charge thru the secondary circuit. Using a dwell meter is the only way to be sure the ignition contact points are set correctly.

If you are just setting the gap and not checking the dwell afterwards then any mechanical deflections or deviations are not being accounted for and the actual dwell may not be in tolerance. That definitely affects how much spark is delivered. You must also check distributor timing with a points setup, changing the gap will move the timing around enough to need it checked or adjusted.

One incentive for checking and setting/resetting the points gap using a dwell meter is this: If the dwell can be set to exactly what it was the last time the timing was checked/adjusted then the timing will most likely not need to be adjusted this time. This does assume the distributor is in reasonably good mechanical condition.

 

[Maclin]

Re: weird problem...3L...need help

The cap could be a contributor to the problem, it could be allowing crossfiring at those rpms, or that rotor connection could be actually adding gap in the loop so to speak and slightly changing when the spark plug gets the charge.

 

[danond]

Re: weird problem...3L...need help

hi guys....


the wires were changed....the carb rebuilt.....(no water in the gas....( a beer bottle full)...the carb filter is fine.....have not found an inline filter)

He means he filled a beer bottle with GAS and there was no water present.

 

[oops!]

Re: weird problem...3L...need help

He means he filled a beer bottle with GAS and there was no water present.

yes, the above is correct, sorry for the confusion.

im at the store, the boat is in the back, so i will be checking all of the above suggestions.

it seems we have a prestolite dist, not the stock one, so thats why finding a cap is problematic.

 

[oops!]

Re: weird problem...3L...need help

Ayuh,....

Please explain this Wear,....
Is it from laterial movement of the Distributer Shaft,..??..??

If so,... You probably need a New, or another Distributer....

the cap terminal is just burnt, there seems to be no slop in the shaft, its tight.

 

[oops!]

Re: weird problem...3L...need help

compression seems to be good, with the lowest being 140 ish, highest is 150,

i forgot to mention a resistance test was done on the wires last night.

the spark seems to "dissappear" at around 2500.

the fuel, is good. lots coming in, the beer bottle was pumped full with good clean gas in a second or two.

however i will check the fuel system again as don suggested in item #3.

thanks guys
oops

 

[Don S]

Re: weird problem...3L...need help

Did this start just after new points were installed? Did you forget the spring for the points?

 

[Don S]

Re: weird problem...3L...need help

Read this thread.

http://forums.iboats.com/showthread.php?t=261063

 

[oops!]

Re: weird problem...3L...need help

Did this start just after new points were installed? Did you forget the spring for the points?

no....ii was running fine, then it just seemed to stop intermittently at high rpm. 3000 to 0 for a second, then instantaly back to 3000.

after the problem started, thats when we started the tune up process.

the dist cap is badly worn.....(the rotor contact) im tring to find another, but it is a prestolite dist. i am having a really hard time cross referencing the numbers to find the right cap.

thanks, for the help. im going to read the suggested thread now.

 

[chiefalen]

Re: weird problem...3L...need help

Is this a omc? IF yes disconnect the esa and run it. Could be bad. Would give the symptoms you describe.

 

[oops!]

Re: weird problem...3L...need help

Is this a omc? IF yes disconnect the esa and run it. Could be bad. Would give the symptoms you describe.

mercruser 181 cid or 3L 140 hp.


thanks for that thread don. the points were supposedly "professionally installed" (he didnt even use the grease for the shaft contact)

so ill double check the pionts, even, get a new set and start all over installing them.

(im doing this in between coustomers at my store)

 

[JustJason]

Re: weird problem...3L...need help

oops....
You say the gas is fine.... but try splicing in a piece of clear vynil line before the fuel pump and look for any air bubbles......

The other immediate thing i'd look at is the ignition coil... classic symptom of that as well.....

Just run down Don's list... the answer is absolutely in there somewhere.

 

[oops!]

Re: weird problem...3L...need help

heh heh heh....i have been running down the list....

we swaped out the coil for a new one.

 

[Don S]

Re: weird problem...3L...need help

heh heh heh....i have been running down the list....

we swaped out the coil for a new one.

And ????????

 

[oops!]

Re: weird problem...3L...need help

just waiting for the new dist cap don...

i may have found one at a local marine store.....60 bucks !!!!!! (just the cap)
(they took the old one for compairison)

it should be arriving soon. so ill let you know asap.