fuel pump or fuel filter?

[cjromero77]

I have a Tige 22V 2005 with a Marine power 350 MEFI GM VORTEC engine. My problem occurs after the boat has been running for a 1/2 hr or so. At first the engine runs fine then it loses power intermittently. Eventually, it wont go any faster than 8 mph at full throttle.

I've tried changing the distributor, but that didn't work.

Any ideas? I'm at a loss

[da.bell]

1) What type of gas are you filling your boat with? Ethanol is not good for the engine.

2) Have you checked the fuel/water separator? Could have water in there.

Doesn't sound like the pump is the issue.

[chpthril]

Ethanol fuels are typically mandated by the EPA, due to emission levels, for a specific area and not sold voluntarily, therefore, avoiding it may not be possible. Either way, I believe that that that year model engine was built with fuel system components designed to tolerate ethanol blended fuels. Older fuel systems are a different story.

Sounds like "Limp"mode to me. What does the engine sound like what at WOT and 8mph? Whats the RMM's? Check the knock sensor connector. Make sure it's not the PP setting

[cjromero77]

I'm using gas from a marina that services only boats, so I'm not sure if that's the issue. I do buy the fact that condensation could have contaminated the fuel. However, the Fuel Water separator is difficult to open. The mechanic at the dealership says it needs to be opened with a vice grip. I tried but its too hard. The filter is not like an oil filter where it screws off. In discussing this with the mechanic, he believes I should first check the low pressure fuel pump. He suggests reversing the wires on the pump clear out the low pressure pump filter and see if that at least clears it temporarily. He says if this is the case I may need a new pump as the filter in the pump is probably toast.

>Sounds like "Limp"mode to me.
what is "Limp" mode?
> What does the engine sound like what at WOT and 8mph?
I don't know what the acronym WOT stands for but the engine sounds like it normally does at 8 mph. The abnormality is that the throttle is at full and the boat won't go any faster.
>Whats the RMM's?
You mean the RPM? I'm not sure, what the RPMs are, but they are fairly low, when this happens so it's not drive train connection.
>Check the knock sensor connector.
What am I checking for?
>Make sure it's not the PP setting
Should not be the problem unless it's PP is taking control when it is not supposed to. I definitely have this turned off.

[R&T Babich]

"Limp" mode is what happens when the computer determines there is a system deficiency that could physically harm the engine. The engine is restricted to a minimal power output condition.
WOT stands for Wide-Open-Throttle or pedal to the metal.
Check the knock sensor connector to ensure it is still connected. It is easily knocked off.

What is the fuel pressure when the power loss occurs?
Try again to get that fuel/water separator off. Pour the contents into a glass jar and see if there's any water. Our old boat would lose power at higher speeds and it progressively got worse. When it finally would only idle the separator was full of water. The gas came from a marina pump over a couple of days. Haven't used marina gas since and no more problems.

[TeamAllen]

You can't control the ethanol in the fuel but you can try this Marine Formula STA-BIL.
http://www.goldeagle.com/brands/stab...marine_formula

[whitlock87]

I have a Tige 22V 2005 with a Marine power 350 MEFI GM VORTEC engine. My problem occurs after the boat has been running for a 1/2 hr or so. At first the engine runs fine then it loses power intermittently. Eventually, it wont go any faster than 8 mph at full throttle.

I've tried changing the distributor, but that didn't work.

Any ideas? I'm at a loss

I have the exact same problem on my 2004 switch –v (20 V)
I have the 38 gallon tank in my boat, and it turn out to be the check valve mounted on the tank. The check valve would not open completely. So after the reservoir on the full pump was empty, I could not over 2k rpm. If I ran at an idle, then I could go WPT for about 35 seconds. If I turned it off a then back on (letting the key sit in the on position for about 1 min before starting), I could run for a few min before it would start acting up again.

I tried changing the fuel filter, and it did not solve my problem. In the proses of checking everything, I notice that I had a hard time getting fuel out of the tank. Once I removed the floor, I found the check valve. After cleaning it out, I could get the fuel to flow much better. I still have not had a chance to take it to a lake yet, and I am trying to get a hold of Marine power USA to see if I even need the check valve.

[R&T Babich]

... I am trying to get a hold of Marine power USA to see if I even need the check valve.

I don't think Marine Power USA are the right people to ask.
That check valve is an anti-siphon valve required by the Coast Guard that the fuel tank manufacturer installs.
When a fuel line dips below the fuel tank outlet an anti-siphon valve is required to prevent fuel being siphoned into the bilge if the fuel line leaks.
It is just a check ball in the fitting that can stick or get clogged.
Don't know what the insurance would say if it were removed.
I carry a spare and a straight thru for testing.
Also, a small fuel pressure gauge mounted in the fuel rail could tell you the fuel pressure is low.

[whitlock87]

I was told that it is requiered by law like R&T said.
Also they said with out it it could burn up the fule pump. I am going to add a filter between the tank and the check valve.

[R&T Babich]

...Also they said with out it it could burn up the fuel pump. I am going to add a filter between the tank and the check valve.

I don't see how not having an anti-siphon valve could burn up a fuel pump.
If the fuel lines did not get routed below the fuel tank pickup the anti-siphon valve would not be required.
The anti-siphon valves are sized to be non-restrictive to fuel flow rates above a trickle.
The fuel pump pulls from the tank and builds up pressure in the fuel rails where the fuel waits for an injector to open. Any excess fuel is routed back to the fuel supply lines as in our 2000 Merc or back to the fuel tank in later designs. The pump is constantly running.
Adding a filter would keep an anti-siphon valve from getting clogged from debris, but it wouldn't prevent dried fuel scum buildup from long layups.

[JGR]

Just purchased a 2004 22V as a repo so I had no history. Had the boat inspected and serviced prior to using it. Had the same problem. Would run fine up to about 10mph or so then would starve for fuel. Has the 350 mag mpi with two fuel pumps. The low pressure pump was getting very hot and after spending several hours diagnosing the problem. We determined that the low pressure (boost) fuel pump was failing. Replaced it and works like a charm.

Simple to check if you have same fuel delivery system as mine. Simply find where fuel line from tank comes into first fuel pump. Leave enging running for a few minutes and check to see if the pump is hot to the touch. It uses fuel to cool itself so it should not become very hot at all if functioning properly. You can then turn engine off and disconnect the other end from the pump. Be very careful doing this......... Now turn ignition on and see if you have a decent flow from the pump. If not, it's bad.

Hope that helps..........

[whitlock87]

JGR
where did you get the new pump from?
Is your engine a gray Marine power 350?
is the first pump small, and the second pump has the filter in it?
thanks
David

[JGR]

David I found the pump at a Merc dealer. All they need is the motor s/n which should be on the engine bonnet, at least that is where mine is. My motor is black and I believe it's a 350 Mag MPI. It has two fuel pumps. One is high pressure and water cooled and below the motor on the stbd side. The other is low pressure and is gold in color and easy to find at the rear of the engine on the port side. It has two wires that come out and go to a modular plug. The fuel pump was about $240. It's pretty easy to verify if it's bad. It will become very hot after only a short while and will only dribble fuel if you disconnect the outlet side. You may also want to make sure your fuel filters are in good shape and nothing plugging the screen on the input of the pump. On my motor there is a pre filter inline, then the low press fuel pump, then the screw on filter, and then to the high press pump. Hope that helps.

[whitlock87]

Thanks JGR for your help
I have a marine power engine, so everything was a little different.
I took the boat out and neither pump would get hot. When I disconnected the house from the low pressure pump to the high pressure pump, I did not get any fuel to come out. I could feel slight sucking on the inlet to the high pressure pump. It turned out that the red wire on the low pressure pump was corroded, and the low pressure pump was no running at all. I removed both wires cleaned them / crimped them and reinstalled (I crimped them to make sure they would have a snug fit)
Hope that was it
Thanks again for everyone’s input, even thought this was not my thread.

Here a few pics
DW

[JGR]

Good job and glad it was an inexpensive fix!