Volvo Penta 4.3 GXi stalls at slow throttle up

[Sparky_1988]

Hey, gang. Thank you in advance for any pointers you provide.

Here's my dilemma... I just purchased a used 2003 Larson 190 LXi with a Volvo Penta 4.3 GXi-B with less than 60 hours on it. Boat seems to run well at idle and cruising speeds, but stalls and dies when slowly throttling up from idle (500 RPM) to around 900 - 1000 RPM. If I'm on the lake and quickly throttle up, it stutters for a couple seconds, but then takes off and seems to run well throughout the rest of the throttle range.

Other info:

Not sure, but the exhaust MAY smell a little rich, but I'm not sure.

Slowly backing down to idle from 900 - 1000 RPMs is smooth with no stutter. It also seems somewhat better if I throttle up under load vs. in neutral.

It has 3/4 of a tank of gas from last year that was stabilized when professionally winterized. I also put an injector cleaner in it and ran it about an hour in the driveway with the muffs on it with no change.

Any ideas? Do I just need to run it a bit? Thanks!

Volvo serial number: 4012080831

 

[Sparky_1988]

Update: I disconnected the IAC motor since I'm seeing similar problems resolved with a new IAC motor on other sites. This has no effect what so ever. Should I expect to see any changes when doing this? I've both disconnected while running and while off. Same exact performance.

Could this be a bad IAC motor or a bad enough MAP sensor or intake manifold leak that the IAC can't compensate (resulting in no change when disconnecting the IAC motor?)

Any advice would be appreciated. Thanks!

 

[Sparky_1988]

Another update: I took the flame arrester off and watched the IAC operation. It slowly moved in and out a tiny bit in accordance with an RPM swing up and down at idle so slightly that the dash gauge was barely registering the change. I am not sure how much travel it should have, but am going guess that it's not much.

I think tomorrow, I'll pick up a pressure gauge and see what my fuel rail pressure is doing.

Again, hoping some folks with experience weigh in here.

Thanks!

 

[Sparky_1988]

Update: I hadn't received any input here and my work travel has been picking up, so I've brought it in to the shop to be sure it's ready for the water when I am.

 

[ddbyrd3]

Sparky_1988 Any updates on your issue???

 

[Sparky_1988]

Hey, ddbyrd3.

Weather and work travel hasn't allowed me much time to focus on it. But, here's where it stands...

Turns out the fuel gauge was stuck at 3/4 when there was only a couple gallons in the tank. I put a full tank of 91 octane non-oxygenated fuel in it to give it some fresh gas and it runs much better, but not perfect.

I'm guessing between the stabilizer the dealer put in during winterization and the sea foam I put in this spring (all based on the assumption of 3/4 of a tank of gas), it was running on a pretty funky fuel cocktail. All bets are off.

Now that it had fresh fuel, I put about three hours on it making sure to get some good time idling, slow cruising, full throttle and resting. When I put it in, I had a hard time keeping it running. By the time we loaded up, it was doing 90% better. Hooking it up to the muffs the next day, it was still 90% better from a cold start.

I'm hoping it gets even better after a bit more run time, but was thinking of replacing the fuel filter for good measure.

 

[Bondo]

but was thinking of replacing the fuel filter for good measure.

Ayuh,...... Good idea,..... Inspect the Contents of the take-off filter for water, 'n crud,....

 

[ddbyrd3]

At least you are heading in the right direction....

I am chasing off idle stalling as well.. But I can smell my motor is running really rich.. I am doing a 4bbl carb swap this week... No more 2 barrel...

 

[Sparky_1988]

Update... Chasing for year two, now. It won't idle until warm. I've replaced the throttle positions sensor based on research elsewhere. Now, it runs right from start up, but idles at 1,000 to1,200 RPM. Wondering if the dealer tried to adjust idle up to compensate for bad TPS? I've checked to be sure the throttle cable was not pre-loading the throttle... It was not. Don't know if you can even adjust the idle on a 4.3 Gxi

 

[Sparky_1988]

Final update! Late last year, I finally brought it in to another dealer. They had it for a couple hours and replaced the fuel pressure regulator. There was over 90 psi on the fuel rail! Wish I had bought that fuel pressure gauge when I thought of a while ago. This boat runs great ever since.