Help with trouble starting Volvo Penta 5.0 GI

[Rlreed207]

1999 Four Winns Sundowner 205
Volvo Penta 5.0 GIPWTR
SX-M Drive

My boat sometimes is difficult to start while launching on the ramp(acts flooded). The boat always starts fine at home on the muffs prior to leaving to the lake. Typically a three hour drive to the camp ground and then launch in the morning. Similar elevation and temperature to my home. Once started it runs great all weekend. This started happening over the summer and I'm hoping to fix it before using again. Advancing the throttle seems to help get it started for the first time but it's fuel injected so that does not make much sense to me.
I tested and replaced numerous things with no change.
New fuel filter
New Fuel
New Spark Plugs
Checked pressure on high and low pressure pumps and them met specs
Checked vacuum reading from tank at WOT and it's in spec. No restriction
Cleaned flame arrester
No evidence of TB fuel injector leak down or wet throttle plates prior to start up on trailer

What's funny is that is has no problems at home and only during the first start up after getting to the lake. I have noticed a slight amount of soot residue on the transom. Very slight. Fuel economy has not changed and it does not smell rich.

Any IDEAS??

 

[John2037]

Re: Help with trouble starting Volvo Penta 5.0 GI

I see new plugs but have you checked the cap? Latley every cap I've pulled has been in rough shape -

I'm reaching here! Maybe you have a miss (added backpressure while in the water adds load to starter, lowers volts while cranking - miss due to heavy deposits on electrodes - flooded) like I said, an idea and free to check.

 

[wrench 3]

Re: Help with trouble starting Volvo Penta 5.0 GI

I've been racking my brains on this for a couple of days and hoping some one else would solve this for you. Since it hasn't been solved yet, here's my two cents worth. Assuming your running a raw water cooling system, the only thing I can think of that would be different when you first launch it is less water in the top of the engine. On a cold start the coolant temperature sensor should be at ambient temp, so the lack of water in contact with the sensor should not be a problem. But stranger things have happened. The only way to test it would be to get the readings off of the sensor under both conditions.

 

[Rlreed207]

Re: Help with trouble starting Volvo Penta 5.0 GI

The back pressure combined with a weak spark due to a corroded distributer cap is a great idea and I will order a cap and rotor just for good measure.

The coolant temperature sensor is new but I have not water tested since replaced.

If the problem persists, I will start the boat with the drive trimmed up. The prop is out of the water then and the raw water inlet is submurged. If that works it would confirm a back pressure problem.

Thanks for the ideas thus far. It has me scratching my head too.

 

[wrench 3]

Re: Help with trouble starting Volvo Penta 5.0 GI

Don't try starting it with the drive trimed up too far or you might damage the "U" joints.

 

[Rlreed207]

Re: Help with trouble starting Volvo Penta 5.0 GI

I did not realize that. Thank you

 

[Tail_Gunner]

Re: Help with trouble starting Volvo Penta 5.0 GI

If you have access to this now. Muffs on cold start. Take a neon lght and watch the spray patterns. Smooth and no drips. Both starting and @idle.

When you advance the throttle your off the iac valve. That says a lot.

 

[Rlreed207]

Re: Help with trouble starting Volvo Penta 5.0 GI

I will have to wait until I for spring to check the spray pattern on the injectors. I have look while it running but never on actual start up. Seams to have a good pattern, no drips

 

[wrench 3]

Re: Help with trouble starting Volvo Penta 5.0 GI

If the IAC is gummed up it will usually give you low idle when cold, all the time. But like I said before stranger things have happened. However advancing the throttle will help compensate for a poor fuel mixture.

 

[Rlreed207]

Re: Help with trouble starting Volvo Penta 5.0 GI

I'm not sure where the IAC is located. Anyone have a picture or advice on where to look to locate it? Is it something that can be removed and cleaned? Thanks.

 

[Jammer864]

Re: Help with trouble starting Volvo Penta 5.0 GI

Unfamiliar with that model but does it have a fuel pressure regulator on the fuel rail? If so, pull the vacuum line from it and check for gas in the line. Im going on the idea that at home the gas has had time to dissipate and it starts right up. But after running it then shutting it off and heading to the lake, the gas has leaked thru the regulator and into the intake manifold. So its real rich starting it up a short time later. Opening the throttle valve adds more air and allows it to fire up. Just a guess.

 

[wrench 3]

Re: Help with trouble starting Volvo Penta 5.0 GI

I'm not sure where the IAC is located. Anyone have a picture or advice on where to look to locate it? Is it something that can be removed and cleaned? Thanks.

The IAC should be on the starboard side of the throttle body to wards the rear corner. It can be unscrewed and cleaned with intake cleaner. To do a good job of cleaning you need to remove the pintal to get at the threads, but I don't know how to do that without a scanner.

 

[Rlreed207]

Re: Help with trouble starting Volvo Penta 5.0 GI

Thank you all. I'll look into these areas over the next few weeks and let you all know the verdict when I put in the water mid May.