View Full Version : Boat still stumbles
6ballsisall
07-16-2005, 12:26 AM
Ok my brain is fried as is the guy working on my boat (i got to pissed off and had to hand it off to someone else) Compression check came back fine, all cylinders at 110 or just above that, all are close to equal. At this point the boat is completely rewired and totally dialed in. The points have been reset and triple checked for gap. Brand new plugs (NGK) 2 different carbs have been tried, boat has a brand new coil on it. Yet with all this the boat still stumbles all over itself and just won't run with a darn.
Need advice or I may take up smoking!! Help!
redmike
07-16-2005, 12:57 AM
will it run at all? I mean will it free rev and die as soon as you put it in gear?
6ballsisall
07-16-2005, 12:58 AM
It will run. At idle it is all over the place and no matter how much you tinker with it it won't idle smooth. Give it some throttle and it shakes like a mother
redmike
07-16-2005, 01:01 AM
may sound goofy, but check the distributor shaft for play side to side with the cap off...had one go bad on an old truck of mine, same thing...
redmike
07-16-2005, 01:03 AM
it will goof up points (dwell) and timing will jump all over the place...not for sure it is it, but it is easy enough to check for it!!!! once again, good luck to you!!!
6ballsisall
07-16-2005, 01:10 AM
Thanks Mike I recommend that to the mechanic tommorrow. I gather he is stuggling too. I kinda hope that fixes it in a way and in a way I don't, its a nearly new (1o hour old) Mallory Marine Distributor. I do have to say there was a sigh of relief when the compression test proved ok
redmike
07-16-2005, 01:14 AM
ok, new dist. throws a wrench at my theory, but it could be...anything else new since it last ran good? or is the whole motor new?
6ballsisall
07-16-2005, 01:18 AM
Nothing else new since last go round except an identical Edelbrock Carb right out of the box. I still have both. I tell you at this point I am completely stumped. The mechanic is too I think, he builds race car motors quite a bit and really knows his stuff but this one has him frustrated
redmike
07-16-2005, 01:31 AM
ok, forgot all about your carb issues! if I remember, you stuffed a 750 right? is it getting enough fuel? could the carb have gotten sh@# in it?
At idle it is all over the place and no matter how much you tinker with it it won't idle smooth. Give it some throttle and it shakes like a mother.....
either the timing is jumping/ or the carb has one circuit plugged imho. try running it with a timing light on it (check for it jumping around) and then go to the new carb is what I whould do.
6ballsisall
07-16-2005, 09:35 AM
We'll be giving it a shot soon! Heres a question, even if compression tested out ok could one still have a bad cylinder? Say a contorted piston or burned up fuel bowl on the piston head but still have good compression?
6ballsisall
07-16-2005, 09:37 AM
ok, forgot all about your carb issues! if I remember, you stuffed a 750 right? is it getting enough fuel? could the carb have gotten sh@# in it?
At idle it is all over the place and no matter how much you tinker with it it won't idle smooth. Give it some throttle and it shakes like a mother.....
either the timing is jumping/ or the carb has one circuit plugged imho. try running it with a timing light on it (check for it jumping around) and then go to the new carb is what I whould do.
Did the timing light thing and yes the timing light jumps all over the place quite a bit. You can't even really attempt to time the motor as you can't get a consistent idle no matter what :mad:
If the timing indicator jumps around, make sure the shaft doesn't wobble(this would mean the bushing is bad) and make sure it's bolted down securely & the distributor ground is good. Loose connections could cause jumping around, too.
Was there any rust or chipped gear teeth on the original distributor? If so, the gear on the cam could have the same thing and would need a new gear. You can look at the drive gear on the cam by removing the distributor and looking into the block, rotating the crank manually.
6ballsisall
07-16-2005, 09:52 AM
JimN, thanks so much for the advice! I hadn't thought of the cam gear! I'll give it a whirl
the legend
07-16-2005, 11:08 AM
May sound trivial but have you checked your ignition signal to the coil?
JEREMY79
07-16-2005, 11:37 AM
pretty stupid question, but maybe would you have water in your gas?
6ballsisall
07-16-2005, 12:42 PM
Well the electrical saga continues. The whole motor wiring harness has already been rewired and triple checked for accuracy. However, somehow the key switch is getting mad hot and apparently the moron who owned the boat before had played with the wiring in the dash. The dash lights come in when the key goes in the on position etc.. (I never noticed this as I use it in the day light) We finally got the motor running half way decent but after a few minutes at idle it shuts itself off. The points are burning themselves up and the new coil is getting warm. Something tells me more rewiring is about to take place. Man some people shouldn't mess with stuff if they don't know what the heck they are doing, hind sights 20/20 but I should have paid more attention to the wiring of this boat when I bought it last fall. It's like 20 different guys have "fiddled" with it! :mad:
Edit: Cam gear and Distributor are a-ok
redmike
07-18-2005, 01:41 AM
if I remember right, you said you can't find a ballast resistor...right, well, if you are getting 12 v to the coil, it will get too hot, and fry the points.....here is my suggestion for now, go to your local auto parts place, and ask for and internally resitsted coil (the ballast resistor is in the coil) put it in the boat with a new set of points, and see if that helps. I run these all of the time in the race cars to eliminate the ballast resistor. I hope this has helped, and gets ya back on the h2o!
Leroy
07-18-2005, 01:56 AM
If you have the resistor is should be bypassed when you start and then back in circuit when running. Agree with redmike, sounds like you are getting 12 volts all the time. Remotely, could be bad condensor or bad connection to it.
Agree, electrical wiring issues are the worst, especially as boats and cars get more wires!
zberger
07-18-2005, 09:31 AM
Has anyone bothered to check for crap in the gas tank?
bad fuel?
Fuel Filter?
bad spark arrestor?
Tried siphoning the fuel out of the gas tank and putting fresh in? even using race gas maybe..
Ever heard of Sea Foam?
What will race gas do for it? It wasn't made with that in mind, so it would be better to use a substitute gas can(with fresh gas in it) as the fuel source and see if it runs better. Get the can above the motor and if it runs right, it could be bad gas or a weak fuel pump diaphragm. Or both.
Since it hasn't been mentioned yet, what were the compression numbers(this was done warmed up and dry, right? If it wasn't dry, it's really not valid)? Did you take a fuel sample or check the fuel pressure? HAve you inspected the fuel lines, fuel/water separator and/or fuel filter? What about the fuel pickup in the tank? Fuel shutoff/anti-siphon valve? These have all been mentioned in other driveability threads. How old are the plug and coil wires?
6ballsisall
07-18-2005, 09:52 PM
Hey all, thanks for the idea'rs. The tank is clean and I actually threw a can of seafoam in there the other day. The boat now runs good and apparently the point (even though new) were caput. Boat has a new key switch in it and that solved alot of problems.
JimN, compression was done once warmed up and she is between 110-116lbs. in all cylinders. The oil had quite a bit of gas in it and we changed that. Apparently even this motor just can't quite a 750cfm carb on it so went back to a 600cfm Holley marine.
We got her running like a champ and all was great for a few hours and then she died and won't restart. Dummy me forgot to add the Ballast Resistor which was off the boat and that should solve that problem (along with another set of points :rolleyes: )
I don't want to get to excited but I think we got this things by the short and curlies now :D
I don't know if I should be proud to say this or not but I was awarded "the boat that kicked my mechanics butt in 2005" award. I think he was VERY glad to see me gone!! :D
Was that 110-116# with the gassy oil? Most of the time, this should be around 140-160#. If you used a compression gauge that doesn't screw in, this could be the reason. Otherwise, low compression = low vacuum and this makes it hard to tweak the carb for all conditions. How is your oil consumption? Any smoke in the exhaust or major amounts of smoke when you remove the oil filler cap?
6ballsisall
07-18-2005, 10:57 PM
Was that 110-116# with the gassy oil? Most of the time, this should be around 140-160#. If you used a compression gauge that doesn't screw in, this could be the reason. Otherwise, low compression = low vacuum and this makes it hard to tweak the carb for all conditions. How is your oil consumption? Any smoke in the exhaust or major amounts of smoke when you remove the oil filler cap?
To be honest, I don't remember if that was before oil change or not. I wasn't around for the compression test so I don't know what kind of gauge he has. I drop the boat off this week and I'll ask him about the gauge. Boat has absolutely zero oil consumption and doesn't smoke at all.