Volvo Penta 2005 5.0 GXI-E 3809255, 4012156127

[Gatekpr2002]

Hello everyone. I am having a problem with my engine hard starting while hot. Engine is Volvo Penta 2005 5.0 GXI-E 3809255, 4012156127. At the dock completely fine in the mornings while fishing and still a bit cool out engine starts fine hopping from spot to spot. Run for a while during day as the ambient temps rise harder to start especially when it was hot and humid a few weeks ago. The thermostat on the dash seems to be reading fine. After doing some research online I have found others with Volvo penta engines (not same as mine) with what seems to be very similar problems. They were pointed to the coolant sensor.

From what I can see on the schematics online there is a part #3850397 described as a switch, part #3852029 described as Sensor coolant water temp, part# 872068 described as a temperature sensor coolant water temp dual station.

I can not find out what parts do what or even where the parts are located if I even have all 3, I do not know.

The link below has the only schematics i could find.

Has anyone experienced a similar issue or can help in anyway?

Thank you,
Rob

 

[alldodge]

3850397 = coolant temp switch, when motor gets above 200 degrees it switches ON (grounds lead from ECM) and the ECM turns on an alarm horn/buzzer and sets a code

3852029 = is a single temp gauge sender which shows the temp of the motor

872068 = does the same thing as the single one above, but is used when the are 2 helm stations (such as a boat with a fly bridge) and therefore 2 gauges using the same sender on a motor

Your issue sounds like vapor lock (VL). VL is caused by to much heat in the engine room on hot days. You can reduce this by using the blower more, run it after you stop for a while. Open the engine hatch cover, idle longer with blower running before shutting down.

The true fix is to change the fuel return from going to the canister filter, and run it back to the tank

 

[Gatekpr2002]

AllDodge, thank you for your reply. This has never happened in previous years. The boat always turned over on the first turn of the key. Hot days no problem. When it does not want to start it cranks I give it a few seconds cranks give it a few seconds and when it does start it barely catches maybe even chugs and goes right to normal. The only thing I can think of that has changed was rerouting the vent hoses so they go to the bottom of the sump. They used to just dangle around by the engine so I pushed them under the cargo net that sits beside each side of the engine to force them to stay down. The cargo actually creases them a little. Could this cause this vapor lock to happen? And vapor lock happens on fuel injected engines? Sorry I’m a really good parts changer not the best mechanic. Also the fuel pump was changed at the beginning of the season mid April.
Thanks for all help.
Rob

 

[alldodge]

In the marine world VL only happens with fuel injected motors. When the fuel lines get heat soaked the fuel boils and the liquid gas is replaced by vapor. The vapor expands and creates greater pressure in the system and displaces the liquid thru the fuel pressure regulator.

When the motor is restarted, it starts by can maybe idle for just a bit, and when trying to take off there is not enough liquid gas to keep the motor running, so it dies. When cranked again, some times it will cough a bit but will not run. Given long enough time, the motor cools more and allows liquid to come back.

To see if it is VL, the next time it does it find the Shrader valve on the fuel rail. Have a rag and someting to push in on the valve (wear eye protection). Press in on the valve after the fuel pump stops pumping and see if you get any air with some fuel. You should have only fuel and no air

 

[Gatekpr2002]

Thank you and I will definitely do this when we go out next. To be clear the next time I try to crank the engine and it does not start then with the key off and fuel pump not running I push in on shrader valve to see if I have fuel or fuel air mixture. Another thing I thought of when I first bought this bought a few years ago two of the vent piping that goes to the bottom of the engine we’re taken off I wonder if the previous owner did this to allow for more ventilation?

 

[alldodge]

To be clear the next time I try to crank the engine and it does not start then with the key off and fuel pump not running I push in on shrader valve to see if I have fuel or fuel air mixture.

Yes
You can also, with the motor off and not starting. Turn the key ON again and after pump stops (2 second prime) push again

The vent tubing is blower hose (3 to 4 inch and lloks like dryer hose) and the hose should be low because gas vapors are heavier then air. If there is gas fumes/vapor in the bilge the hoses are there to push it out before the motor is cranked.

 

[Gatekpr2002]

thanks again AD we are not due to go back out for a couple weeks... work uggggg... but I will definitely post back with results. Thank you again.