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mtenda
08-01-2011, 08:09 PM
have a 95 prostar 190 350 tbi. after boat has warmed up have trouble restarting sometimes it seems like it vapor locks . if you wait 20 or so minutes usually it will restart. or you can pour a little fuel in the carb and it will restart. any help would be appreciated..

HDAVIS
08-01-2011, 08:30 PM
Are you using gas with ethanol???? Not sure if that would cause it or not. Just a thought. I once had a car that would do that. Not sure about boats!

mtenda
08-01-2011, 08:49 PM
yes my fuel has ethanol in it, i think it's tempature related

JDK
08-01-2011, 09:06 PM
TBI's can't vapour lock.
There's a bunch of TBI 'hard hot start threads' on here.
Summary of things to check;
1) plugs/cap/rotor/plug wires (helped mine quite a bit and not a bad idea to replace anyways))
2) thermostat - 142 degrees has helped a few people (this came in my boat)
3) possibly the coolant temp sensor

Instead of pouring gas in the throttle body, mine would start instantly when the plug was pulled off the coolant temp sensor (yellow and brown wire plug on the driver's side of engine, above the exhaust manifold))

HDAVIS
08-01-2011, 09:08 PM
The MC mechanic at the dealership says NOT to use gas with ethanol period. I don't know if it would cause a vapor lock in a boat or not. I know most marinas in this area do not sell gas with ethanol because of problems it may cause. I just know I don't use it and won't unless I have no other choice.

JimN
08-01-2011, 09:13 PM
have a 95 prostar 190 350 tbi. after boat has warmed up have trouble restarting sometimes it seems like it vapor locks . if you wait 20 or so minutes usually it will restart. or you can pour a little fuel in the carb and it will restart. any help would be appreciated..

When did you clean/check the flame arrestor last? How about your fuel filter? Did you check the anti-siphon/fuel shut-off valve to make sure it hasn't closed?

Check your fuel pressure.

mtenda
08-01-2011, 09:47 PM
plugs, cap, rotar, ecm ,and wires have all be replaced , haven't checked flame arrestor.. fuel filter last year... still had problems after i replaced filter. will check thermostat next i guess.. .. it only does it when the boat is warmed up.

JimN
08-01-2011, 10:20 PM
plugs, cap, rotar, ecm ,and wires have all be replaced , haven't checked flame arrestor.. fuel filter last year... still had problems after i replaced filter. will check thermostat next i guess.. .. it only does it when the boat is warmed up.

Why would you replace the ECM? That's about the last thing that should be replaced.

mtenda
08-02-2011, 12:01 AM
yea i changed the module in the distrubitor, and also the coil... i am going to check the thermostat tomorrow..

JDK
08-02-2011, 04:34 PM
yea i changed the module in the distrubitor, and also the coil... i am going to check the thermostat tomorrow..

A quick and easy check would be to remove the thermostat for the day.

mtenda
08-02-2011, 10:25 PM
okay so i changed out the thermostat.... still doing the same thing. after it is warmed up and you shut it off it won't re start. temp is at max 180 after shut down. i did notice that the carb was not shooting fuel . checked fuel pump and there is pressure at the carb. it's like there is something telling it not to spray fuel once it gets warm on a restart. spark arestor is clean, any other ideas... i don't know what tells the jets to spray the fuel into the carb, any help would be greatly appreciated.

mtenda
08-02-2011, 10:27 PM
it had the correct 143 deg tstat installed but the old one was sticking part open so i changed it anyways...

gr82bgreen
08-02-2011, 11:26 PM
okay so i changed out the thermostat.... still doing the same thing. after it is warmed up and you shut it off it won't re start. temp is at max 180 after shut down. i did notice that the carb was not shooting fuel . checked fuel pump and there is pressure at the carb. it's like there is something telling it not to spray fuel once it gets warm on a restart. spark arestor is clean, any other ideas... i don't know what tells the jets to spray the fuel into the carb, any help would be greatly appreciated.

180 is too hot when shut down. With a 140 thermostat mine runs at 150. With the 160 mine would reach 180 and not restart. How is your impeller, fan belt, water pump, ect. You are still running too hot for some reason.

JimN
08-02-2011, 11:46 PM
okay so i changed out the thermostat.... still doing the same thing. after it is warmed up and you shut it off it won't re start. temp is at max 180 after shut down. i did notice that the carb was not shooting fuel . checked fuel pump and there is pressure at the carb. it's like there is something telling it not to spray fuel once it gets warm on a restart. spark arestor is clean, any other ideas... i don't know what tells the jets to spray the fuel into the carb, any help would be greatly appreciated.

Any time a motor won't start, it's usually pretty simple- it needs compression (if it ran before, this shouldn't be an issue), proper fuel/air mix and spark. If you're missing one of these with a carb, the others are generally unrelated- a bad fuel pump (a mechanical one) will have nothing to do with no spark. If it has an electrical fuel pump, it's possible that the problems are related. That's with a carb, which you don't have unless someone disabled the fuel injection system, which they didn't.

Here's a pretty basic description of how these injected systems work-

Before the engine turns over, a few things have already happened- when the key is turned ON, the MAP sensor determins barometric pressure, the TPS has indicated the throttle's position and the ECT has determined the coolant, and therefore, the engine's temperature. The last time the engine was shut down, the ECM caused the IAC to close and then reopen to a pre-determined position. The barometric pressure is needed so the correct amount of fuel can be delivered. The coolant temperature is needed so the engine can run as efficiently as possible- a cold engine isn't an efficient engine and a hot engine doesn't need as much fuel as a cold one. The TPS lets the ECM know if it's at <2% throttle position (this means Idle mode) or > 2% (this is Rum mode). If the TPS shows 100% while cranking, the ECM won't run the fuel pump or open the injectors- WOT while cranking is how you would clear a flooded injected engine.

Under normal circumstances:
1) The starter cranks the engine and somehow, the ECM finds out that it's cranking, as well as how fast.
2) If the ECM receives RPM information, it tells the fuel pump relay to close. If there's no RPM info, the fuel pump won't be activated.
3) Assuming the ECM got RPM info, the ECM will turn the fuel pump on, it will trigger the ignition module to cause the coil to induce spark and the injectors will open/close when they should. Once the engine passes 300 RPM, the ECM switches to 'Run' mode and general control is handed off to the MAP sensor. The only times the TPS makes much of a difference is when the throttle increases or decreases by 20% or more, quickly. This only increases or decreases fuel delivery until the normal RPM is reached, based on the MAP and TPS readings.

If you have no fuel, check the fuse and relay for the fuel pump. If you hear the fuel pump buzz for three seconds when you turn the key to ON/no crank, these are OK. If not, find out why.

If the fuel pump buzzes (priming cycle), the ECM may not be getting RPM info. You can check for spark at this time. If no spark, use a stick pin to back-probe the purple/white wire at the distributor plug. DO NOT PIERCE THE WIRE'S INSULATION (there's a right and wrong way to do this- piercing the insulation is the wrong way). If you set a multi-meter to DC volts, you should see 1-2VDC if the IC (ignition control) module is good. The IC module's ground needs to be great, not just good. Also, in order for the distributor to operate properly, the connection of the distributor's base and intake manifold must be very good. If it's dirty or rusty, clean it. If the IC module was connected when the key was turned on, it's probably toast.

If you see 1-2VDC on the purple/white wire and you still don't see the injectors fire, post this.

JimN
08-02-2011, 11:50 PM
180F isn't too hot if it has been sitting for a few minutes- that's probably from heat soak. If it shoots up to 180 at any time, there's an obstruction, especially if the thermostat has already been removed. 180 won't keep the engine from running or starting.

Open the throttle a bit next time to see if it will start. If it does, post this.

mtenda
08-03-2011, 08:01 AM
thanks jim i will try that out today if possible

mtenda
08-03-2011, 09:34 PM
jim,


here is what i did i ended up changing out my battery as it was not holding a charge. i also took apart all the ground wires and cleaned all the connections.. i put it in and ran it and shut it off and restarted about a dozen times and it started up every time. i hope what i have done solves my problem it seems to as of now. Thanks for all the help...