|I have a 88 mastercraft with the 351w engine and it doesn't want to start when it is hot. When I first get in the boat and start it it fires up first try with no problems at all. Once the boat is hot if you turn it off for like 1-2 seconds it starts back up no problem. If it sits more than a few seconds it doesn't want to fire back up. It will turn over fine but doesn't start. Sometimes if I turn it over for a few seconds and then let off of the key it will start up even though it didn't sound like it was firing yet, kind of hard to explain that one.I thought maybe it wasn't turning over good enough so I replaced the battery with a 800cca battery and still the same thing. Here are a few other things I have tried and still no sucess. |
Replace points with solid state ignition.
Check timing and tried different timing settings when it is hot and having a problem starting.
Replaced fuel filter.
Vent is working on gas tank.
Tried adjusting the card fuel/air screws.
Choke is fine on the carb.
My next tries are going to be replace the plug wires, cap and rotor even though they look ok. Then maybe the coil, then if that doesn't work try rebuilding the carb.
If anyone has any other ideas I would appreciate it, this is driving me insane. It was running totally fine and then all of a sudden one day it started acting up.
|my boat did the same thing.turns out it was the coil.go figure.|
|Make sure when the engine is shut down after running that fuel is not still "dripping" from the carb into the intake manifold causing the engine to flood. If it is, try adjusting the throttle return (linkage at the carb) to shut of any excees fuel. Tap around on the float bowls also to make sure a float is not stuck open. Try the simple things first... |
(Message edited by kcsideways on September 22, 2004)
|Make sure when the engine is shut down after running that fuel is not still "dripping" from the carb into the intake manifold causing the engine to flood. If it is, try adjusting the throttle return (linkage at the carb) to shut of any excees fuel. Tap around on the float bowls also to make sure a float is not stuck open. Try the simple things first...|
|Here are a few things to do to help narrow it down. In general, these types of problems are the result of either no spark, no gas, or too much gas. |
As Rick pointed out it is possible that the engine floods due to gas slowly leaking past the float valve. Start it up again real soon and it hasn't had time to flood. Wait a long time and the gas evaporates out, clearing the flooded condition.
If the engine is flooded then when it eventually does start there will probably be a lot of soot and smoke plus a smell of gasoline.
The opposite case is that there isn't enough gas. When you shut the engine off the heat from the engine can cause the gas in the line from the fuel pump (and in the fuel pump itself) to evaporate and "boil away". This can leave the fuel pump attempting to pump vapor instead of liquid, which they aren't all that good at. If the fuel pump is a little weak then it can have a lot of trouble getting a prime again.
A good way to see if you have any fuel at all is to take the flame arrester off the top of the carb and sight down the opening while someone pumps the throttle. You should see a good spray of gasoline from the accelerator pump as the throttle is operated. No spray means no gas!
CAUTION! DO NOT look down the carburetor while someone tries to start the boat!
You could also try spraying a bit of "starter fluid" into the flame arrester intake and see if that makes it fire off. If the problem was no fuel the starter fluid should make it start right up.
If the problem isn't fuel then it is probably spark. The coil is certainly a possibility. It is also possible that the ballast resistor and/or resistor bypass relay is not working properly.
Check the voltage right at the coil. If you have a ballast resistor type coil (most common) then you should see around 7 volts on the coil when the engine is running. When you go to crank the engine, however, the resistor should be bypassed and you should get 11 volts or so at the coil while it is cranking.
|If you haven't already, next time it acts up open the throttle up at least 3/4 with it in neutral, and crank the engine, until it starts or 15 seconds pass. This will clear out the motor if it flooded. If helps start the motor turn the mixture screws in a 1/3 of a turn.|
|I had a boat with a 302 that ran like crap when the boat was warm and had difficulty starting, it was a faulty coil.|
|I have a 87 same engine. I don't know if you are giving any throttle when starting, but I know sometimes my gets "vapor lock". I am pretty ignorant about engines, but a guy I ride with is pretty handy. He said it is common in old motors like that. May not be problem but might be helpful. I just give some throttle and it starts right up. This may be another simple idea but is kill switch working properly? I replaced a starer after burning mine up because lanyard was not pushing in button completely. Never had a boat with kill sitch, so I tried for a while to get it going. Probably not problem, just some thoughts.|
|Thanks for the input evertyone. I think my next step is going to be replacing the coil to see if that works. I am pretty sure it is the original coil anyway so it is probably due to get changed. If that doesn't do the trick I will start looking more into the fuel system. I have check the funtion of the carb a little and it seemed to be working ok. I didn't have anyone else in the boat at the time so I was trying to work the throttle and look at the same time. Again thanks to everyone for the input I really appreciate the help. |
If you are going to replace the coil anyway, make sure you get one made for electronic ignition. When you do that, you will also be able to eliminate the ballast resistor, if you haven't already. Check out: http://www.tmcowners.com/teamtalk/index.php?
Good information there. There is a guy there with the screen name Jimn who knows almost everything about Mastercrafts and their engines.
|Another possibility is "hydrolock". If your exhaust manifolds are leaking water and it is making its way into a cylinder, that will cause this problem. You should notice water in the oil but it will be hard to tell. When this was happening to my Centurion, the water never did mix with the oil, I only found out when I drained it into a mason jar. The water will generally come out first. |
Another sign that you have a leak is if the coil is making popping sounds when the engine is running. That indicates high compression which can be caused by water in a cylinder.
|As a devout Ford guy, I would say replace the coil. They heat soak and dont work sometimes. Stay away from Accel products. MSD blaster coil works great and costs the same as a stock replacement and fits the stock mount. Use Motorcraft or Autolite stock plugs, cheap ones NOT platinum. The distributor is probably a Prestolite with mechanical advance, damn nice part. Make sure you have the right points in there, www.skidim.com Set the timing to 10 deg BTC, and the dwell to 31 deg with a dwell meter. Good 2 go. If it still won't run, take the holley off, find the nearest fence, and throw it over. Get a brand new one. They're good carbs when they're new, junk when they're old. If you're selling it, you could try to get the carb rebuilt. If you want to go wakeboarding, replace it. In most cases, you can bolt one on and it will work perfectly. I have rarely had to even adjust float levels. |
|Rereadin your first post, Stan, you might try checking the timing. If it is a little high, say 12-14 BTC, it may kind of "back up" on the starter, or crank kind of wierd before it starts. Timing should be around 10 deg, but the boat will run like stink if you put it at about 13. I put them as high as they will go before they back up on the starter. Usually between 11 and 13 deg. Stock is either 8 or 10 depending on which cam is in there. |
I worked on a Ski Brendella of my pals last week, his (351) timing was set to 31 deg BTC by my dealer. The boat still ran great. He got 10 mph more top end when we got done tuning his boat. Same stuff I just mentioned. I used to outrun him in my 22' Toyota with 1500 of weight in it. Not anymore!
|Thanks again for the advice. I replaced the coil this past saturday before my run and it ran like a champ all day long. I was so happy to have a boat that started again after turning it off.|