2006 Volvo 5.7 GI-F surging @ 4000 rpm and cant get above that

[mtymax]

hoping someone can help... i have a 2006 stingray 250LR. it has a volvo 5.7L GI-F engine. the boat runs great up to approx 3600rpm or about 2/3 throttle... if i try to throttle up anymore or go to WOT, the rpm's get to about 4000 (without going any faster) and thats it... also, the sound of the engine changes as i put the boat to WOT... the boat can get up to about 28 knots (used to go 45)... after doing that speed and rpm for about 5 seconds, the boat begins to "surge"... it goes for approx 1 second and dies for 1 second and goes back and forth... i had a mechanic look at it and he told me it needs new gas (water in the tank) and a tune up and it would run perfect... i ran the boat on a temp gas tank and it did the same thing. then i replaced the spark plugs (that were pretty black) but the boat is still doing the same exact thing. i have added "sea foam" to the tank (in the beginning) as well to help the water issue... any thoughts of where to go next? everything on the boat is stock... no new props or anything like that... thank you!!

 

[mtymax]

Re: 2006 Volvo 5.7 GI-F surging @ 4000 rpm and cant get above that

quick update... i ran the boat pretty much empty of gas... just this weekend i replaced the distributor cap and rotor (volvo parts). the dealership told me that i didnt need new wires as they should still be ok (so now it has new plugs, cap, and rotor) I put 25 gallons of fresh fuel with StarTron. the boat is still doing the exact same thing. it really feels like it is starved of gas... does anyone know if a lack of enough fuel would cause it to backfire? i guess i am going to call the mechanic again today and have them look at it again...

 

[Bondo]

Re: 2006 Volvo 5.7 GI-F surging @ 4000 rpm and cant get above that

does anyone know if a lack of enough fuel would cause it to backfire?

Yes,....

I see No mention of changin' the fuel Filters...
When ya do, inspect the contents for Water, 'n Crud...

 

[Don S]

Re: 2006 Volvo 5.7 GI-F surging @ 4000 rpm and cant get above that

Have you done any fuel pump pressure testing on the pumps? That should be your first priority.

 

[mtymax]

Re: 2006 Volvo 5.7 GI-F surging @ 4000 rpm and cant get above that

Yes, i have changed the fuel filter twice now this year... i didnt dump it out and check the first time but i just replaced it for the 2nd time last night and dumped out the old filter and let it settle... i dont see any water but there was some dirt/sand looking stuff coming out... i dont know how much dirt is too much but i was definitely surprised to see that (i will try and get a pic and post it)... another note, i called the mechanic who looked at it last time again and he told me that my carb needs to be rebuilt... am i wrong in thinking that i dont have a carb? i am almost positive my enigne is fuel injected (which would mean there is no carb, right?)

Don S. - i just bought a vacuum gauge and am trying to find the right fittings to fit my fuel line and pump (lowes and HD didnt have the right one... the hose that the vacuum gauge came with is pretty small (so i need a "T" with the straigt sides bigger for the fuel line and the T part smaller to fit the gauge)... i bought the one from sears that is listed in your post about fuel system checking... i am going to try and follow your directions and test the ability to creat a vacuum this weekend. i personally think its a fuel pump issue which would be 100% covered under warranty <fingers crossed>

thanks for the help guys! very much appreciated!

 

[mtymax]

Re: 2006 Volvo 5.7 GI-F surging @ 4000 rpm and cant get above that

Another update, just hooked up the vacuum gauge to the fuel line (boat side) and started it up... at idle and warmed up the gauge read 1 Hg of vacuum... i took the boat out and opened it up... I had clear line tapped into the fuel line and while going, there wasnt 1 bubble to be seen... once the boat started to bog down (about 10 seconds after WOT) I pulled back the throttle and the fuel pumps began to whine and the vacuum gauge jumped to about 3 Hg and then i saw a lot of bubbles going backwards (weird?) from the fuel pump towards the fuel tank for a couple of seconds and once the boat began to "catch" again and start going, the bubbles were gone and the vacuum gauge went back to 1 Hg... any thoughts? im getting to the point where nothing is working to fix the problem and i am going to open up the checkbook and let the pros figure it out but i would love to figure it out 1st.

 

[gbeltran]

Re: 2006 Volvo 5.7 GI-F surging @ 4000 rpm and cant get above that

You need to check the fuel pressure on both the low and high pressure pump when this is happening, like DonS suggested. Sounds like the low pressure pump isn't able to draw enough fuel to keep the high pressure pump fed with fuel. It's an expensive pump, worth spending the time to properly troubleshoot the system.

 

[mtymax]

Re: 2006 Volvo 5.7 GI-F surging @ 4000 rpm and cant get above that

I am guessing the way to check the high pressure fuel pump is to check the "engine side"??? i dont see those instructions in Don S's post on checking fuel pump pressure. it notes in that post that this is for the "boat side" testing... should i just unscrew the metal fuel line coming out of the fuel pump and tap on another clear line to that? do i need the pressure gauge? if so, what readings should i see if it is good or bad... or should i just look for bubbles? the fuel pump is under warranty so i am hoping that is the issue but the mechanic that is looking at it keeps telling me that its not the fuel pump ( i feel like he doesnt want to do warranty work and just wants me to pay for some "other" fixes first before he does that)

thanks for the help guys! I REALLY appreciate it!

 

[gbeltran]

Re: 2006 Volvo 5.7 GI-F surging @ 4000 rpm and cant get above that

Yes, you will need a pressure gauge. If you look on the fuel pump you will see two fittings with a cap that look like tire valves. The gauge will go there, one at a time. It needs to be one for testing fuel injection stuff. Don't unscrew the metal line coming out of the pump. You can test it static by hooking up the gauge and turning the key to the run position. But it really needs to be tested under load in the water. At the top of the forum page is a post labeled adults only. Click on it, you can go to the volvo information link, and you will find another link to the service manual for your engine. I don't know what the pressure should be on that model. The low pressure side, which will be the lower port should have about 6psi at idle and about 5 when running all out. You will have to find the other pressure number in the manual, or someone might chime in with it.

 

[mtymax]

Re: 2006 Volvo 5.7 GI-F surging @ 4000 rpm and cant get above that

awesome, thank you gbeltran! i was wondering what those fittings were that look like tire valves... i will try that and uupdate my post with the results... thanks for the quick response!

 

[mtymax]

Re: 2006 Volvo 5.7 GI-F surging @ 4000 rpm and cant get above that

Also, another note i wanted to mention is that last time i was at the boat, i checked the oil level and it was significantly over the full mark on the dipstick...(the dealership has done the oil change every year since buying the boat brand new) Do you guys suggest i try to pump or drain a quart of oil out of the engine and see if that fixes the problem or will i be wasting my time? i have read a couple threads where they say to much oil in the enigne and restrict the "moving parts" from moving enough... any thoughts???

thanks again!