2006 5.0 GXI cranks but won't start

Larson 206

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First of all thanks to everyone who takes the time to help.

I just bought a 2006 Larson with a 5.0 GXI. On Sunday I forgot the plug and got some water in the engine compartment up to the middle of the crank pulley. Everything seemed ok once I got the plug in. We idled around for about 15 min to make sure everything was ok and off we went. About 5 min later I throttled back and it stalled. It never started after that.

Once the boat was back home I changed the fuel filter and dumped the fuel of the old filter into a glass jar to check for water. There was none. I've checked the fuel pump for pressure, 60psi on the high side and 15 psi I n the low side. I even blead the fuel rail. I also put a little gas in the throttle body and it fired right up until that gas was exhausted. So I have spark. I've pulled the spark plugs and they are dry. I have fuel up to the injectors,but nothing past that. My thoughts are crankshaft sensor or ecm. Can anyone tell me if spark rules out the crankshaft sensor?

Any help is appreciated .

Thanks
 

alldodge

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As a Non-VP guy I'll give it a try. What is the rest of the letters after GXI (helps me look at all parts on line)

All fuel injected motors need a signal from the distributer sent to the ECM when cranking. The signal tells the ECM it is cranking and then allows fuel to be injected at the correct time. When you crank the motor does the Tach show around 300 rpm?
 

Larson 206

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The engine engine is a GXI-F and yes the RPM gauge jumps to about 300. I have also replaced the distributor cap and rotor. Also checked the fuel pressure regulator. It was a little dirty so I cleaned the screen.
 

Larson 206

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Update: installed a new crankshaft position sensor and it didn't help. Also double checked the lanyard killswitch. All is good there too. My thoughts are the ECM. Why will it start if I manually pour gas down the throttle bony if it was the ECM that wasn't working?
 

alldodge

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Dang it sure is hot today, can't drink enough water, need it to be a little cooler for beer :D

Thanks for the gxiF, Looks like you have the same as Merc, crab cap (I call crap cap) and with the exception of a cam sensor (item 6). So the ECM should be doing about the same thing, it is not picking up that the distributor is working so no fuel.

https://www.marinepartseurope.com/en/volvo-penta-explodedview-7744830-28-8855.aspx

The ECM also uses the crank sensor with the cam to set/check timing.

Will the motor start if you give more throttle when cranking, maybe 1/4 to 1/3 throttle?
 

alldodge

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The motor will not fire unless I manually pour gas into the throttle body.

OK, you injectors are not being turned on, so that is either the ECM is not getting the signal, or the ECM is the issue.

Things that can keep the signal from making it, are the cam sensor, bad or broken connection, and if the ECM thinks the throttle is at WOT (do this when engine is flooded).

In any case there should be code showing up if the motor is scanned.

Check the cam sensor plug and if need be trace it back to the ECM
 

alldodge

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I think so, in post 5 there is a link for the gxiF and it is listed as item 6
 

bruceb58

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I don't have an 06 schematic in front of me but there is one relay for the fuel pump, that you verify works already,and another relay. In older models the injector power ran off that same fuel pump relay. May be worth verifying that.
 

muc

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might want to check the voltage at the injectors. ECM grounds the injectors. they should have power at key on
about all the cam sensor does on this engine is cut down the amount of time it takes the ECM to know where #1 TDC is. It can take up to 2 revolutions without the cam sensor. takes 1/2 revolution with it.
 

Larson 206

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Thanks guys! I will get at it again in the morning. I checked the wires from the cam sensor to the ECM tonight and everything was good. One thing I did miss in my description of the problem was that it had some long starts periodically when the engine was warm. Distributor cap was quite corroded also so I replaced it.
 

bajaunderground

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These guys are very good at on-line, distance trouble-shooting and their advice is sound.

But another area to look...

Did you check the fuel cell? I know you checked pressure, but how about flow? I'm betting it's fuel delivery issue (bad anti-siphon, corroded fuel lines, blocked screen in fuel cell or vapor lock?)

I had similar issues and replaced everything from the anti-siphon valve to the fuel cell. The regulator was new when I purchased. When I run lower octane fuel, it get's hot when we sit (being static) and can be a bear to start. I typically put the throttle in neutral and go WOT, once I have it started, I back it off real quick...running higher octane fuel makes a huge difference (boiling point is higher) as this all but goes away and it starts every time. I plan on having my injectors serviced this winter.

VP had issues with the coating in the fuel cell. flaking and blocking the screen, it's usually followed by a loud whine from the pump...did you hear that when you are running?

What are the hours on this boat and where do you boat (fresh vs salt)?
 

Larson 206

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Bajaunderground thanks for your comment. The pump dose have a bit of a wine. It's loud enough that you can hear it over the engine running when the engine compartment is closed. The pump looks like it was replaced or at least off, judging by the paint on the bolts. The name on the cell is Carter. Not sure if that is a factory pump. When I changed the fuel filter I looked at the underside where it screws on and there was no black paint. I also pulled the fuel regulator and the screen had some black junk in it so I cleaned it all out. I also order the e clip from Volvo to perform the service bulletin. From what I've read a plugged screen on the regulator can cause high pressure on the fuel rail, 90-100psi. When I checked mine it was 65 psi on the high. Once I cleaned it went down to 60 psi.

With regards to flow, after the pressure check was done I pressed the release button on the gauge and let a half a litre or so to run through to flush the line and to make sure no vapour lock. The odd part was that the fuel was very yellow compared to the fuel I dumped out of the fuel filter when I changed it.

The hard start on my boat was only after it had been run for awhile and it was very intermittent. Cold starts were great. From what I've read, if I go to WOT to try to start it, the fuel injectors will be shut off by the ECM.
 

Larson 206

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Also the boat is a fresh water boat and there is no hour meter. I was told the engine was new as the previous owner did not winterize it properly and cracked the block. About 50 hours on it so he said.
 

Larson 206

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Muc I checked the voltage at the injector. It has .02 volts when I turn the key to the on position. I did not try turning it over.
 
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