Help Required From the Epic Gods

[ktdust]

Need help diagnosing a problem.

Two weeks ago we were out on the lake for about two hours wakeboarding with no problems. Turned the boat off to do some swimming for about a half hour. Started the boat and it fired right up. Immediately after the rmps started to drop. When we tried revving it up in neutral it would feel like it was stalling out so we put it back in neutral. Engine eventually died.

Knew the fuel pump was on it's last leg so I replace it. Boat fired right up again with no fluctuation in the rmps.

Went wakeboarding for about two hours today with no problem. Turned the boat off to do some swimming for about a half hour. Started the boat and it fired right up. Rpms started to fluctuate again and the boat stalled out again. Wound up getting towed back to the boat launch.

This time I did notice that the oil pressure was lower than normal. It was 5 psi. I know when idling it drops just below 20 (around 18), but it's never been this low. Tried starting the boat in the driveway and it fired up again, but the oil pressure was 2 psi and stalled out after about 2 seconds.

I'm pretty sure it's not vapour lock with the new fuel pump and all, but I'm not sure why it runs fine for such a long period of time and then stalls out totally. Is it the oil pressure sending unit or something else. Do I rent the scan too to try and figure it out? Any help is appreciated.

Thanks
Todd

[wakejunky]

when was the last time you replaced the fuel filter? did you clean both fuel pump intake screens when you replaced the pumps? and was that one pump or both? what octane fuel are you running? what do the tips of the spark plugs look like? are they carbon fouled? is the check engine light on? i know its a lot of questions but it helps narrow down the possibilities.

if the filter is fairly new, the screens were clean, and the spark plugs arent fouled i would start with a fuel pressure test before going any further. tap into the fuel rail at the banjo fittings. report back with fuel pressure.

[ktdust]

The fuel filter was replaced mid June. Only 20 hours on it so far. Both pumps were replaced, screens were cleaned. I used a 94 octane from Chevron last fill up (half tank) and I had a half tank of 91 from the time before (as it was all I could find).

All plugs look good, clean, no oil, no carbon. Check engine light never came on, before, during or after.

Not sure how to check the fuel pressure. Kind of a mechanical idiot. Can you drop me a pm when you have time.

Much appreciated.

[lilfoo2225]

hmm. just sounds more sensor related.

[ktdust]

Lilfoo,

Wouldn't the check engine light come on if it was a sensor?

[lilfoo2225]

you would think that but we get a CEL when (nothing) is wrong. so i dont trust the system at all. it just seems like the only logical thing. cant be fuel if both pumps, and all filters were replaced like u say. is the engine oil full?

[lilfoo2225]

oh werent you having this issue before? i saw other threads from you and it sounded like the same problem again.

[ktdust]

Lilfoo,

You are correct, it is the same problem again. I was just wondering if the light should have tipped me off. The oil and trans levels are also fine.

I believe the complete fuel pump assembly comes with new filters as it's all in one. I checked the pump at the tank and it looked clean also.

At the beginning of the year I had a problem with a knock in the engine/trans after which the boat stalled. Thought I lost my tranny. Topped up the oil from 3/4 to full and the problem was gone. I'm now thinking all these problems are related.

In talking to wakejunky, I'm wondering if it's the plugs. Bought the boat about a year ago and don't know if the plugs have ever been changed. So I think I'll try that on the weekend...and clean the mass air flow sensor just in case.

Not sure how to nail down the problem as it only seems to have problems after running solid for a few hours.

I'll keep you posted.

Thanks for the advice.

[lilfoo2225]

yeah this is real strange. but like you say if it was a plug or two you should get a CEL for a misfire. maybe that light isnt working.

[ktdust]

Tried the boat on Saturday morning and it fired right up again. So, I'm positive it only has trouble after running for a few hours.

Cleaned the spark arrestor and the MAF sensor. There was a bit of dust, but not much.

Pulled the fuel circuit relay and it works as it should. When you hook up/disconnect power to the terminals you can hear the relay open and close and the continuity/resistance is as per the engine manual.

Primed the fuel rails and the pulsation dampener pops up. Check the fuel pressure just after the pumps and it's within the range noted in the manual.

Pulled the spark plugs and didn't notice any fouled plugs. I did notice a tiny bit of oil in each plug cylinder. The amount was the same through out all 8 cylinders. Didn't have a camera, but it's maybe a quarter of what is shown in the 'Change spark plugs' maintenance section. Cleaned the oil out and put in new plugs. Checked threads in the forum and it says the leaking oil may be from a gasket (head gasket or spark plug cylinder seal). Also noted that the 'Change spark plug' section says to tighten plugs finger tight plus 1/8 turn, which is what I did in the spring. Another thread says 13ft/lbs, which I confirmed with a Lexus mechanic. Finger tight plus 1/8 turn is no where near the 13ft/lbs.

The boat ran fine last year and didn't have this problem until this spring (after winterizing when I fogged the cylinders).
I'm wondering if the plugs weren't seated properly or tight enough and that allowed the bit of oil to leak into the cylinders and is also causing my problems.

Weather was miserable all weekend and couldn't get the boat out to test, but until I get the chance I 'm wondering what you all think.

Thanks for the help.

[blindside]

Sounds to me like you are experiencing the dreaded Ethanol fuel symptoms. Make sure you add "Sea Foam" fuel additive every time you gas up.

[ktdust]

When I filled up w/ 91 octane I used Shell V-power as it was all I could find while on vacation. Searching the internet, half the links I found said it contains no ethanol, the other half say it contains 5-10% ethanol. The Shell website doesn't say.

I'll try sea foam and let you know.

[blindside]

One of the guys here was having the problem with his supra. removed the fuel line and it pumped out about 6 oz of water with 1 gallon of gas.

[wakejunky]

I'm guessing you found the problem. i agree that the oil in the spark plug tubes is from not properly seating the spark plugs. if the crush washer isn't "crushed" the plugs aren't sealing properly. if you had one or two spark plug tubes full of oil it would most likely be the spark plug tube seal at the valve cover. there's no way all the seals are leaking.

Good news on the fuel pressure. At least you can eliminate the fuel system.

not real common but its possible you may have a carbon buildup problem. Next time your out if it stalls again have  a can of brake clean or carb clean with you. spray some in the intake while cranking if it fires up and runs fine chances are you have carbon buildup on the intake valves or the combustion chamber.

guess i should explain that one. when you start up a cold engine the computer compensates with a longer injector pulse to help get the engine going. just like a choke on a carburetor. but when you fire up a hot engine it doesn't compensate because it knows via the coolant temp sensor that the engine is at operating temp. here comes the kicker when you have carbon buildup on the intake valve or combustion chamber and the engine has ran for a while it s hot and dry and it works like charcoal and absorbs some of the fuel being injected into the cylinder and keeps the engine from firing up properly. The brake clean will act like extra fuel and help start the engine.

Sounds like you have it figured out, if not try the brake clean. it's really common on a lot of the newer Lexus engines but still can affect these too.

[HCollado]

Holy crap Wakejunky, you know your crap about these motors 

Stay tuned, you'll be a great source for info.