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dlski
07-17-2010, 08:41 PM
My temperature climes as high as 200. On about the third start (on these warm days) the does does not want to start. I have replaced the impeller, I have replaced the fuel filter and I have a new thermostat on the way.The transmission was rebuilt in 2009 Tonight I was stranded for about 15 minutes. I left the engine cover up (temp was only 150) and finally got the boat started. Could this be a fuel pump problem?? .What are the symptoms or fuel pump failure? Any other thoughts on what my problem might be?

JimN
07-17-2010, 09:01 PM
My temperature climes as high as 200. On about the third start (on these warm days) the does does not want to start. I have replaced the impeller, I have replaced the fuel filter and I have a new thermostat on the way.The transmission was rebuilt in 2009 Tonight I was stranded for about 15 minutes. I left the engine cover up (temp was only 150) and finally got the boat started. Could this be a fuel pump problem?? .What are the symptoms or fuel pump failure? Any other thoughts on what my problem might be?

So, it cranked but wouldn't start, right? Make sure the connections at the starter are clean and tight. Also, make sure the grounds are clean and tight at the rear of the motor. Do a wiggle test of any main wires to make sure of the integrity of the wires. If any wire breaks, crimp and solder the replacement terminal. Just crimping them is a good way to have the same problems later.

Which motor?

TLR67
07-17-2010, 09:18 PM
Run it without the thermostat and see what happens.... Might be locked up...Also check your debris screen...

oldairboater
07-18-2010, 12:01 AM
Vapor lock---maybe. Is this boat engine turning over like normal when hot but just not starting up? If it turns over normal then your problem might be vapor lock that has been described here before. Your engine is running too warm for my taste. I would install a new marine thermostat and wonder about your impeller. I think you need to cool that engine down.

JimN
07-18-2010, 02:45 AM
Vapor lock---maybe. Is this boat engine turning over like normal when hot but just not starting up? If it turns over normal then your problem might be vapor lock that has been described here before. Your engine is running too warm for my taste. I would install a new marine thermostat and wonder about your impeller. I think you need to cool that engine down.

Vapor lock isn't a hot engine that won't start, it's a hot fuel line that caused the fuel to boil and create a gap in the liquid. That void isn't combustible, so that motor won't start. If the fuel pump is on the motor and the void causes the fuel to be pushed back to the tank, it's trying to draw air to the motor, which won't work. Vapor lock was common with low pressure/low volume pumps but when the pump is in the tank, pushing the fuel at high pressure, vapor lock doesn't occur.

hester
07-18-2010, 07:13 AM
After taking a few sets in my 91 PS 190 it would not start. Not sure what yours is doing but mine acted as if the battery was completely dead. You would turn the key and get a click or two but it would not turn over. Sat with cover up for while and it would crank again. Tried a bunch of stuff and replacing the starter finally fixed the problem for good.

Jesus_Freak
07-18-2010, 08:14 AM
Vapor lock isn't a hot engine that won't start, it's a hot fuel line that caused the fuel to boil and create a gap in the liquid. That void isn't combustible, so that motor won't start....

Actually, the void is combustible. It causes problems because it not metered properly by injectors and jets. Typical engine metering (mass flow proportional to square root of driving pressure) systems are obviously set up for liquids. One could, theoretically, inject gasoline solely in vapor form, but the risks and storage/pumping costs are likely prohibitive.

oldairboater
07-18-2010, 08:50 AM
This boat carbed or FI???? I assumed it was carbed. All I know is that it is running hot and will not start till it cools down for 15 minutes. Hot fuel system on a low pressure carbureted boat will vapor lock if the fuel system gets hot from the carburetor back to the fuel pump. Hot engine--hot day---hot cowling--vaporized fuel. He didn't mention his starter dragging when the engine is hot--so I am not thinking starter or timing yet.Vapor lock isn't a hot engine that won't start, it's a hot fuel line that caused the fuel to boil and create a gap in the liquid. That void isn't combustible, so that motor won't start. If the fuel pump is on the motor and the void causes the fuel to be pushed back to the tank, it's trying to draw air to the motor, which won't work. Vapor lock was common with low pressure/low volume pumps but when the pump is in the tank, pushing the fuel at high pressure, vapor lock doesn't occur.

JimN
07-18-2010, 10:54 AM
After taking a few sets in my 91 PS 190 it would not start. Not sure what yours is doing but mine acted as if the battery was completely dead. You would turn the key and get a click or two but it would not turn over. Sat with cover up for while and it would crank again. Tried a bunch of stuff and replacing the starter finally fixed the problem for good.

According to the profile and first post, it's a '94, so it's injected and that was the first year MC went without carbs.

If it doesn't turn over at all, a bad starter can definitely cause that. If the starter was cranked with a battery that was almost dead or it dies completely while cranking, you can just about expect a year until the starter needs to be replaced. That also takes a big toll on the solenoid.

JimN
07-18-2010, 10:59 AM
Actually, the void is combustible. It causes problems because it not metered properly by injectors and jets. Typical engine metering (mass flow proportional to square root of driving pressure) systems are obviously set up for liquids. One could, theoretically, inject gasoline solely in vapor form, but the risks and storage/pumping costs are likely prohibitive.

OK, OK, I know it's combustible but I meant that it won't make the motor run because it's air with a bit of gasoline vapor and we're discussing vapor lock in a 15' fuel line, not a steady supply of it.

Gasoline in vapor form vs propane or CNG- the Coast Guard would never see the benefits.

dlski
07-18-2010, 03:43 PM
So, it cranked but wouldn't start, right? Make sure the connections at the starter are clean and tight. Also, make sure the grounds are clean and tight at the rear of the motor. Do a wiggle test of any main wires to make sure of the integrity of the wires. If any wire breaks, crimp and solder the replacement terminal. Just crimping them is a good way to have the same problems later.

Which motor?

I believe it is a 350 indmar. Yes, it will crank and not start as though it is not receiving fuel I will have the guys help me check your list since I am not a mechanic, but learning quickly! Thanks

dlski
07-18-2010, 03:48 PM
Vapor lock isn't a hot engine that won't start, it's a hot fuel line that caused the fuel to boil and create a gap in the liquid. That void isn't combustible, so that motor won't start. If the fuel pump is on the motor and the void causes the fuel to be pushed back to the tank, it's trying to draw air to the motor, which won't work. Vapor lock was common with low pressure/low volume pumps but when the pump is in the tank, pushing the fuel at high pressure, vapor lock doesn't occur.

The fuel lines were getting hot! I have isolated them and replaced the fuel pump (which was totalled!) Vapor lock has been mentioned by my ski buddies. We are still perplexed.

dlski
07-18-2010, 03:55 PM
After taking a few sets in my 91 PS 190 it would not start. Not sure what yours is doing but mine acted as if the battery was completely dead. You would turn the key and get a click or two but it would not turn over. Sat with cover up for while and it would crank again. Tried a bunch of stuff and replacing the starter finally fixed the problem for good.

I cannot actually remember if it turned over with the first attempt, but definitely bythe 3rd or 4th attempt I was begining to blame my old battery. But, I am curious , does heat affect a starter? This seems to be a heat related issue.

Boat mechanic in training!

dlski
07-18-2010, 03:56 PM
I have insulated NOT isolated the fuel lines!

JimN
07-18-2010, 04:26 PM
I believe it is a 350 indmar. Yes, it will crank and not start as though it is not receiving fuel I will have the guys help me check your list since I am not a mechanic, but learning quickly! Thanks

I meant, TBI (looks like it has something similar to a carb) or the LT-1 (says 'Corvette' on the fuel rail covers)?

They're similar, but have enough differences to matter.

You should have a black plastic cover on the rear of the motor with a red breaker button. Inside of that, you'll see a round relay with the battery cables connected. The base of that needs to be grounded. Also, if the motor was cranked when the battery was almost dead or it died completely while it was being cranked, the relay, solenoid and starter are probably history. Low voltage means high current and lots of heat for the contacts.

If you have the TBI motor, it's easy to see if it's getting fuel- look into the throttle body while you crank it. Don't look from directly overhead (safety issues if it backfires).

dlski
07-18-2010, 08:11 PM
JImN,

the battery has not died, but it is old. We put a charge on it each Spring. I will check on your recommendation tommorow. Thanks.

JimN
07-18-2010, 08:20 PM
JImN,

the battery has not died, but it is old. We put a charge on it each Spring. I will check on your recommendation tommorow. Thanks.

if you're going to a parts store, have the battery load tested. A real test, not the clamp-on kind. It needs to be fully charged for this and the test involves applying a load, seeing how far/fast the voltage drops and how it recovers.

Jesus_Freak
07-22-2010, 01:39 PM
OK, OK, I know it's combustible but I meant that it won't make the motor run because it's air with a bit of gasoline vapor and we're discussing vapor lock in a 15' fuel line, not a steady supply of it...

Hope I didnt get your knickers in a twist. :D

harv559
07-23-2010, 12:40 AM
My 82 S&S got too hot today and wouldn't start back up. The boat has always had a tough start up after running hot. Always tackes a few cranks. I suspect today was the old battery which I had forgotten to charge since the winter. After a few cranks it just got slower and slower. When I thought I still had juice I used starter fluid into carb...but that didn't even get a kick start...so I think I wasn't getting any spark from starter/battery crank....I've been using a DieHard Gold 34 with 660CCA's. I'm restricted on size in battery well...can I get a better (higher CCA#) crankiing battery that will fit by well??? An earlier post questioned whether the starter might be the issue in the heat...I would like that answer also. Another question I have is what the thermostat does (or does not do) in starting process...how does it affect starting. Thanks for all your helps!
????

JimN
07-23-2010, 11:08 AM
My 82 S&S got too hot today and wouldn't start back up. The boat has always had a tough start up after running hot. Always tackes a few cranks. I suspect today was the old battery which I had forgotten to charge since the winter. After a few cranks it just got slower and slower. When I thought I still had juice I used starter fluid into carb...but that didn't even get a kick start...so I think I wasn't getting any spark from starter/battery crank....I've been using a DieHard Gold 34 with 660CCA's. I'm restricted on size in battery well...can I get a better (higher CCA#) crankiing battery that will fit by well??? An earlier post questioned whether the starter might be the issue in the heat...I would like that answer also. Another question I have is what the thermostat does (or does not do) in starting process...how does it affect starting. Thanks for all your helps!
????

The thermostat doesn't have anything to do with the starting process. It just needs to open and close at a certain temperature. However, the motor gets hotter than the gauge indicated while it was running when it sits for a while and this is called 'heat soak'. It's basically heat from the hottest parts transferring to cooler parts and averaging the temperature.

If the motor cranks slowly and not smoothly after it sits, it could be that the timing advance is excessive or it could be gas leaking from the carb, into the intake manifold.

oldairboater
07-23-2010, 09:46 PM
I am not a master mechanic but I learned a long time ago that hot engines have a tendency to make starters drag, especially if the timing is a little off or timing chains/ gears are worn. I don't know about the rest here but my battery is about three to four feet from my perko switch which is about another foot from my starter. All that battery cable and connectors add to the resistance which cause a voltage drop. These boats need good, hot, batteries with clean terminals. I will be installing another battery under my front passenger seat. I run two batteries in all my other boats with a dual perko switch.

jetlife
07-24-2010, 12:31 AM
This may sound like a long shot, but it may be worth a try. Heat affects electrical components as well as everything else. With this in mind try changing the ignition coil. You may not be getting enough spark when it gets hot. As it heats up it looses conductivity. It sounds like you've got the fuel flowing better than ever, this may be worth a try.

Jay

dlski
07-25-2010, 08:09 PM
I replaced a very corroded thermostat last Wed. The temp has stayed at 165 and below and the boat has started every time! I placed the old thermostat in boiling H2O and it barely opened. I cannot explain why the new thermostat (for a whopping $8.33) helped, but so far so good.

JimN
07-25-2010, 09:27 PM
I replaced a very corroded thermostat last Wed. The temp has stayed at 165 and below and the boat has started every time! I placed the old thermostat in boiling H2O and it barely opened. I cannot explain why the new thermostat (for a whopping $8.33) helped, but so far so good.

Think about it. A thermostat that sticks closed will never cool the motor the way it should and the temperature will stay high. Re-read the posts about overheating- the fuel needed to run a hot motor is a lot less than a cold one. Also, any fuel that may have been ingested into the cylinders will have expanded, due to the higher than normal in-cylinder temperatures. It's harder to crank against the added pressure. Also, if the ECT sees high enough temperatures after the motor heat soaks, it thinks the motor has overheated and will only deliver fuel to one bank of cylinders, either by toggling between the two injectors on a TBI or a bank of injectors.

oldairboater
07-25-2010, 11:16 PM
Marine thermostat for 8.33? Never wondered why a hot engine was hard to start --just always new they are. I always assumed it was a timing and friction issue at the same time as a symptom of the heat.I replaced a very corroded thermostat last Wed. The temp has stayed at 165 and below and the boat has started every time! I placed the old thermostat in boiling H2O and it barely opened. I cannot explain why the new thermostat (for a whopping $8.33) helped, but so far so good.