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Old 08-21-2010, 01:00 PM
Nvrgvup Nvrgvup is offline
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Boat: 1983 S&S
Location: Northwest Ohio
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Trouble Hot / Warm Starting

I continue to have trouble with warm starts on my 83' with a 351.

Everything seems fine in the driveway however it just doesn't like to restart warm in the water. I just don't trust it so we always leave it idling when we go out. Runs great other than that.

Carb is new, no change in hot start.
Adjusted points.
Plugs look good however I may change them.
Cap and rotor look good.
Wires look good.
Water temp is about 160F. Which seems good, from what others report.

Possibly vapor lock however I don't know the best way to determine if this is the problem and how to combat this other than go to a phenolic carb spacer or insulate the metal fuel line between the pump and carb. I just don't know if a phenolic carb spacer will help considering the thickness of the carb gasket is already 3/16".

I have been running Premium fuel which I believe vapor locks easier. I am going to try running some regular to see of this helps.

Maybe need of new battery?? However I cranks good.

Thanks for any suggestions.
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  #2  
Old 08-21-2010, 01:05 PM
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babymoore3 babymoore3 is offline
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When you run to your favorite ski spot do you shut down as soon as you get there? I had problems because the engine was hot and shutting down kills the cooling water to the engine. Try running and then idling few about a minute before shutting down to unload a skier. Two cents.
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  #3  
Old 08-21-2010, 02:06 PM
falconjeter falconjeter is offline
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Boat: mastercraft maristar 225 VRS, 1994 Corvette LT1
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I dont think vapor lock, since it is a carberated engine I doubt it will vapor lock. The carb bowl stays full of fuel and it would have to boil out of the float bowl. I would check the float height for proper adjustment. I would also remove the flame arrestor and try to start it hot by very carefully spraying some fuel into the carb throat. If it starts right up then you have a lean condition. Another option would be if the carb has a accelerator pump try pumping the throttle 3 or 4 times quickly while you turn it over, if it starts then you are not getting fuel or have a lean condition. this could be low float level or clogged main jets in the carb.

If this action floods it and it does not start you can look in the carb and see how much fuel is spraying in as you crank it when it is hot. Also check that the choke butterfly is WIDE open, On my brother in laws boat he had the same symptoms. when he shut down after a ski run the boat would not start, he got towed in several times, mechanic could not find any problems, I was with him on a trip and this happened so we pulled the flame arrestor and found the choke butterfly nearly full closed, his choke was a heated spring type and the spring was broke. I used a zip tie to hold the butterfly open and the boat started right up, never had a problem again. Good luck. BTW, his boat had a 5.7 chev with a rochester 4BBL carb.

Last edited by falconjeter; 08-21-2010 at 02:09 PM.
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Old 08-21-2010, 02:59 PM
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gr82bgreen gr82bgreen is offline
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Quote:
Originally Posted by Nvrgvup View Post
I continue to have trouble with warm starts on my 83' with a 351.

Everything seems fine in the driveway however it just doesn't like to restart warm in the water. I just don't trust it so we always leave it idling when we go out. Runs great other than that.

Carb is new, no change in hot start.
Adjusted points.
Plugs look good however I may change them.
Cap and rotor look good.
Wires look good.
Water temp is about 160F. Which seems good, from what others report.

Possibly vapor lock however I don't know the best way to determine if this is the problem and how to combat this other than go to a phenolic carb spacer or insulate the metal fuel line between the pump and carb. I just don't know if a phenolic carb spacer will help considering the thickness of the carb gasket is already 3/16".

I have been running Premium fuel which I believe vapor locks easier. I am going to try running some regular to see of this helps.

Maybe need of new battery?? However I cranks good.

Thanks for any suggestions.
If it cranks good the starter is not the problem. With it runnibg at 160 I would not think vapour lock. Does it try to fire or just crank without any firing. if so I would check ign system. I had the exact concern with my 95 tbi 350. It would crank endlessly but not fire. It turned out to be the coil. Could also be a bad coil wire. If I were you I would also convert Your points over to electronic ignition.
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  #5  
Old 08-22-2010, 01:39 AM
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Bellinghamster Bellinghamster is offline
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Boat: 1978 Stars and Stripes, PCM 351 (60hrs)
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I had chronic hot start/poor running after re-starting due to the fuel in the carb bowls boiling, causing the floats to sink and subsequently the bowls to overfill, dumping lots of fuel into the engine. I took the shotgun approach to fixing it: Used a thick carb gasket, and also removed the intake manifold and blocked off the exhaust passages that run under the carb. I've heard that you can get intake manifold gaskets that don't have the cutouts for that exhaust passage, effectivly blocking them off. I cut out small sheetmetal rectangles that fit in the gasket cutout but larger than the ports. RTV'd them in place. Never had a problem since.
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Old 08-22-2010, 08:19 AM
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Jim@BAWS Jim@BAWS is offline
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Boat: 1996 PS 190 LT-1/Powerslot
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"I dont think vapor lock, since it is a carberated engine I doubt it will vapor lock."

WHAT????????


Where is the Fuel water serperator located? Back in the day it was located on the side of your gas tank. I have seen folks remove and relocate it BAD IDEA! Here are some ideas that have help out other folks

a) After a long hard run...do not shut off the motor right away. Lift motor box, allow motor to idle for a few minutes and leave the motor box up. ALot of heat gets trapped under that motor box. The more it can breath, the better to disipate heat

b) See where and how your fuel line runs. It should run from the tank via your bildge. It normally runs strapped to one edge. It should go to the base of your fuel pump

c) See where the line runs from you pump to the carb. It should not touch the block anywhere and should run to your carb. Is is a metal line or a thick rubber line. Sometimes they need to be replaced.

d) Some older boat where equipped with a 160 DEG thermostat. Normally used for heaters. It gave a reading of approx 180 deg. Remove that thermostat and put in a Marine 140 DEG one. That will help Your new running temp will be 162 deg on your gauge.



There are alot of threads on this subject. This should help. Jim N can add his 2 cents if needed


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  #7  
Old 08-22-2010, 09:16 AM
ctjahn ctjahn is offline
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Boat: Own a 78 MC S&S
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Silly question

Silly question
Has it done this since you or someone else installed the new carb?
Cj
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  #8  
Old 08-22-2010, 10:22 AM
keith3613 keith3613 is offline
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Posts: 89
I had the same problem. I found out that the carburetor was set too lean. I progressively turned the idle/mixture screws out to about 2 3/4 of a turn and it starts like new. My carburetor rebuilder was concerned about exhaust stains on the transom. So, he set the mixture screws lean, yet where the boat idled fine. However, I discovered it will still idle fine and start easy if they are set very rich. My boat originally came with the mixture screws set even richer than they are now. I guess MasterCraft knew back then that a rich setting makes for an easy starting motor. I'll live with some transom exhaust residue to have the boat start easy.
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  #9  
Old 08-22-2010, 12:45 PM
falconjeter falconjeter is offline
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Boat: mastercraft maristar 225 VRS, 1994 Corvette LT1
Location: southwest
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If I had to lift the motor box and idle after every high power run I think I would sink my boat and get a different brand, boats are not supposed to require this. I guess it is possible that you are boiling the fuel out of the float bowl but I would try the simple things first, like is it getting fuel or is it getting too much fuel. this is easy to do out on the water. why should you have to change a T stat unless it is not the one that is suppose to be in there in the first place? Do you have a mechanical fuel pump or electric?
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Old 08-24-2010, 07:31 PM
Nvrgvup Nvrgvup is offline
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Location: Northwest Ohio
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Thanks for all the suggestions.

Because I am worried about it restarting I have only been testing it in the driveway and when we bring it back to the dock slip. In the driveway I had no problems restarting. However the motor cover was up and only idling and running cold tap water.

I have to power in slow to the dock so the engine is not hot. The engine really never feels or seems hot even after running fast.

I installed the new carb which came from Holley. Runs great. I originally adjusted the idle mix a little and eventually ended up where Holley had it set which is probably around 1 1/2 turns open. I can try to richen it up however I don't know if the restart issue is due to fuel starvation or flooding.

The previous owner removed the water separator and installed an in-line filter just before the fuel pump. I need to get a filter element and reinstall the water filter and remove the in-line filter.

I also need to pull the flame arrestor and see what the choke is doing on restarts and see if the carb is dripping any fuel into the manifold.

Also I am going to drop in some new plugs and eventually put in an electronic ignition and new coil.

When I bought new plugs the guy at Autozone really recommended against Autolites and said that the Motorcrafts are much better plugs. Said that the resistance on the Autolites is much higher and they run like crap. I just thought they were the same plug just branded differently. Guy is really knowledgeable so maybe there is something to it. Same price, going to give them a shot.

How do you look for vapor lock or determine if that is the issue?
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