All Kinds of problems, Help?

[kwrigg]

I have been searching this forum for the last couple of weeks and have found it very useful, but im at the end of thoughts. I have a1986 bass ski with a 3.8 Buick v6 Omc drive in it and ran great until I go it from my dad for the summer. <br /><br />Well I have been having a fit trying to get this boat running right so I can use it but have ran into alot of problems and still doesn't run right.<br /><br />The first problem was that the boat had no low end power, couldn't idle but when it got on to plane it would haul *** like usual. Well I replaced the fuel pump and in the process burring up the points, I have replace every ignition component on the boat. After that I started it up and it started and ran fine but then it wouldn't get pass 3000 rpms an if it does it can hit 5500 rpms but is very iritic and can jump 500 rpms in a second.<br /><br />I have checked the timing, and the timing advance is working right. Undid the fuel pump and put the old one on, which helped none, and then put the new one back on. Doubled checked the points I replaced and all the connections. I'm pretty sure I can rule out the ignition and fuel delivery system. Opened the tank to make sure the vent is working, it is. And every thing else on under the sun.<br /><br />When the boat is in the water, it has good acceleration until 3000 rpms and then just bogs down and sometimes backfires. When it is out of the water, it can get up to 5700 rpm but the rpm gauge is like a jumping bean an jumps between 3000 and 5700 rpms in seconds. It doesn't seem fuel related because the jumps are fast and the sound pitch of the motor is very unchangeable during this rpms jumps. Also when it is at full throttle it sounds like a very "dry" power and backfires sometimes.<br /><br />Oil pressure is normal and the temp is at 150 or lower most of the time during testing.<br /><br /><br />Only thing I haven't one is rebuild the carb because all this time the carb seemed to be working right. But I guess that's my only option right now.<br /><br />Any sugestoions.

 

[Blk-n-Blu]

Re: All Kinds of problems, Help?

k, have you checked the operation of the choke? how bout listing the parts you have changed,It kinda sounds like coil or condenser and possibly cap.Im sure you changed the fuel filter in the carb as well.Yes?

 

[kwrigg]

Re: All Kinds of problems, Help?

Items changed:<br /><br />Fuel filter in carb.<br />Water condenser.<br />Coil<br />Plugs<br />Plug wires<br />Points<br />Condenser<br />Fuel Pump<br />Siphoned gas, new gas ( this my dad did before I got the boat, couldn't imaging fresh inland gas doing this)<br /><br />Every thing on the carb seems to function, when the motor is off and your push the throttle forward, you can see the jets squirt fuel into the primary barrels, and coke works and is open in normal operation. The only thing im not sure of is I have the two lean screws set at 2 turns out, but when I messed with them, any direction, in or out, didn't help the situation. Also on the secondary barrels, when I have it a full throttle the top choke plates only open 1/4 of the way and when I force them open it just sucks more air and doesn't do much to the motor.<br /><br />I also had a squirt bottle of gas that I tried squirting into the carb at full throttle with no change in rpms or sound when did it.

 

[Blk-n-Blu]

Re: All Kinds of problems, Help?

k, I don't see the distributor cap/rotor mentioned in the parts changed.Look at this before pulling the carb.<br /> http://www.boatered.com/forum/topic.asp?TOPIC_ID=51329

 

[kwrigg]

Re: All Kinds of problems, Help?

for some reason, any form of that link you posted is sutting down my internet explore ofn this piece of crap mac.

 

[hoot]

Re: All Kinds of problems, Help?

recheck timing and need to measure volts at ignition coil + terminal when it is running good and after it starts giving problems. tach reads from the coil and since it is acting strange, i would lean toward ignition.

 

[kwrigg]

Re: All Kinds of problems, Help?

Ill do that. When i measured the voltage across the + and -, i had something like 6 volts when it wasnt running, i thought it was alright. Also i have changed the coil twice in fact with the same problem.

 

[Bob_VT]

Re: All Kinds of problems, Help?

Maybe slighly off topic but isn't 5700 rpms too high for that set up?<br /><br />Bob

 

[kwrigg]

Re: All Kinds of problems, Help?

If i rember right, at top speed on the water i could hold 5000 with trim. 3000 rpm cant get me out of the hole in the water.

 

[Blk-n-Blu]

Re: All Kinds of problems, Help?

k, Here is the story behind the link you couldn't open. I am not the author.<br /><br />Before Replacing/Re-building the Carburetor<br /><br /><br />We often blame the carburetor for: POOR PERFORMANCE and/or a POOR RUNNING ENGINE. Although this does happen, it is not the most likely reason for engine problems. The carb has very few moving and or wear related parts. If a carb has gone bad, it is usually caused by some other reason other than wear and tear.<br /><br />The following items should be checked before replacing/re-building the carburetor.<br /><br />Fuel System<br />1. Adequate fuel pressure at all operating RPM and loads.<br />2. Dirt in system - Is the fuel filter and/or water separator clear and free flowing?<br />3. Clogged, pinched, or kinked fuel lines.<br />4. Clogged fuel tank pickup and/or anti-siphon valve.<br />5. Water in the fuel.<br />6. Quality of fuel.<br /><br />WARNING:<br />Gasoline is very flammable and highly explosive under certain conditions. <br />Service a carburetor only in a well ventilated area away from lighted cigarettes, open flames, or sparks. Use care not to spill fuel.<br />Clean up any spilled fuel immediately.<br /><br />Flame Arrestor<br />1. Is the flame arrestor clean and free flowing?<br />2. Is the flame arrestor properly sized for the engine?<br />3. Is it bent or damaged?<br /><br />Engine <br />1. Does the engine need a tune up? - Points, spark plugs, condenser, plug wires, cap & rotor. <br />2. Battery, battery cables, and charging system condition.<br />3. Electrical connections.<br />4. Overall condition of cooling system.<br />5. Cylinder Compression and vacuum leaks.<br />6. Seizure and/or binding in the drive train?<br />7. Over or Under sized propeller? In good condition?<br /><br />Boat<br />1. Is the engine room ventilation clear and properly sized for this engine?<br />2. Is the boat bottom in good condition.<br />3. Can water drip onto the engine due to clogged and/or poor drainage?<br />4. Is there excessive water sloshing around in the bilge?<br /><br />Protect Your Efforts<br />MOST CARBURETORS FAIL BECAUSE OF:<br />· Dirt in the fuel system - Dirt is the #1 cause of carburetor failure.<br />· Dirt in the flame arrestor - Air flow is blocked, causing poor performance and/or rough running.<br />· Over tightening when installing.<br />· Clogged, pinched, or kinked fuel lines.<br />· Water entry from fuel tank and/or dripping onto engine from above.<br /><br />BEFORE REMOVING OLD CARB:<br />· Disconnect batteries.<br />· Shut off fuel supply<br />· Identify, tag, and disconnect all fuel lines, electrical lines, and linkage.<br />· Note carb base gasket condition and type.<br /><br />BEFORE INSTALLING:<br />· Flush fuel lines.<br />· Install a new fuel filter and fuel water separator.<br />· Compare and match the new carb base gasket to the old one.<br />· Clean the flame arrestor and housing.<br />· Service PCV valve if equipped.<br /><br />BEFORE STARTING ENGINE:<br />· Change engine oil and filter if the reason for carb service was flooding.<br />· Check for free movement of throttle linkage.<br />· Ventilate engine compartment.<br />· Connect batteries<br />· Open fuel supply.<br />· Crank engine and then check for leaks.<br /><br />AFTER STARTING ENGINE<br />· Check for leaks.<br />· Check choke operation.<br />· Re-check linkage movement.<br />· Bring engine to operating temperature.<br />· Check and adjust idle timing in neutral and in gear. **<br />· Make final mixture adjustments to carb, in gear. **<br />· Lake test unit and verify operation through out RPM range.<br /><br /><br />** If idle is electronically controlled (such as current Mercruiser, Volvo, Crusader, and other engines), install jumper to disable computer control, before attempting to adjust timing and or idle mixtures.<br /><br /><br />Note: The above information should only be used in conjunction with your owners and service manuals and should not be your only source for servicing your engine and/or it's carb. <br /><br /> <br />George Van Parys,

 

[Blk-n-Blu]

Re: All Kinds of problems, Help?

Originally posted by Blk-n-Blu:<br /> k, I don't see the distributor cap/rotor mentioned in the parts changed

 

[kwrigg]

Re: All Kinds of problems, Help?

i checked the cap and rotor, and they look preety good.<br /><br />If i rember right, when this started to do the backfiring is when i set up the new points. Are there big differences in points? the new points i got waas all steal with insolater betwwen the arm and base. the old one had a plastic arm.<br /><br />Also i was reading one of my care mannuals and it says that the coil needs to have 0 or close to 0 resistance in the coil, bot new coils i have that have been on the boat have around 6 ohms. is this considered close to 0?

 

[ron7000]

Re: All Kinds of problems, Help?

One word... Pertronix. Junk the points and condensor setup and get a pertronix electronic ignition. Points are just too acient and high risk, do yourself a favor and spend $70 for the pertronix module. It's a non maintenance item, after two seasons you'd send close to that in points anyhow. It should fit in your current distributor under the cap, call a Pertronix dealer with your engine and distributor info. Last I checked, you can get the pertronix ignitor II (better than their original ignitor I), their coil, and spark plug wires for around $120. I got mine from CBS Performance Auto a few years ago, but you can get them from boatus or west marine I think, also check Jegs, summittracing, JCW, etc.<br /><br />Knowing that the ignition system isn't the problem, the symptom of no power at 3000+ rpm sounds like the power valve in the carb, and may also cause backfiring at high rpm's if the motor isn't getting enough fuel. However, if you get high rpm's, like 3000 or more, and the motor seems to want to run but will backfire occasionally, that's an indication of a bad valve. Grab a vacuum guage and follow the directions, that'll help pinpoint a lot of problems!<br />You mentioned when you got the boat, at first you had problems idling and no low end power but when you did get it on plane it'd haul. That sounds like a valve seal problem, and it'll get worse with time... eventually backfiring at high rpm more and more then no power at all. A vacuum guage would pinpoint this. Depending on the amount of hours on the motor (1986?) you're probably do for a valve job so don't feel too bad if that's the case.<br /><br />FYI, points should only have around 6V across them, which is so they don't burn up quickly. If you have full ignition voltage, 12-14 volts across them, then something is wired wrong. You're either missing the resistance wire from them to the coil or have the wrong coil. A bad coil can also be part of your problem. It is not uncommon for them to heat up at high rpms and fail, causing intermittent loss of spark, but then heal itself as rpm's lessen and it cools down. <br /><br />Some coils, like the pertonix, have 0.6-ohms or 1.5 ohms across there +/- contacts, this has to do with coil design and their power output. Some coils can have higher resistance, up to 6 ohms like you said. That doesn't mean they're bad, and if I remember right most coils used with points have higher internal resistance which is to limit current flow because of the points.

 

[hoot]

Re: All Kinds of problems, Help?

Adding to ron7000's post, my coil has the 1.5 ohms resistance across the +/- posts and 9000 ohms across the +/secondary post. With 12.5 volts at the battery, i have 7.5 volts at my + post on the coil with the switch on, not starting. Two other items to look at are alternator output and any blockage in the exhaust system. my understanding of points is that the current travels from the - post of the coil to the contacts to ground thru the arm that has the moving contact. if your arm was plastic, how does the current get grounded?

 

[kwrigg]

Re: All Kinds of problems, Help?

***UPDATE****<br /><br />I fixed it. The problem was the points. The old points had a plastic arm but was grounded by the spring. The spring and the light weight of the arm let it work corectly. But when i got the new points which was metal, the spring wasnt strong enough to keep the spring on the shaft. so at high rpm's thepoint would skip because of the high force hitting the point and the backfiging was probably caused by the point hiting the set screw by being thrown to far by the shaft. Put in a stronger spring and problem is fixed.