No power under load


larry1954

New member
I have a 1997 271 Fastech. The boat was running fine a year ago, but today when I took it out it would not rev above about 2000 rpm when in gear without stalling. In neutral there was no problem - revved it to 3000 rpm without any hesitation. But under load it will stall.Could it be a blocked fuel filter? Mechanic told me to replace it after last service (a year ago) because the fuel tank had some rubbish in it, but have run the boat very little and thought that it could be run some more before replacing the filter. But are these the symptoms of a clogged fuel filter? Any help much appreciated. Engine is 454 Magnum MPI.
 
Start with the easy stuff. As you mentioned. Fresh fuel and change the fuel filter. I have read many problem threads sounds like the same thing. Always point to s loss of fuel pressure.
 
Thanks for the advice. I would be pretty sure that it is a fuel problem. Boat was fully serviced about a year ago and we used it only once after the full service and it ran great, but we have not used it between then and now.

When we were out yesterday it also twice stalled just above idle when in gear. Started again no problem. It generally ran ok between 1000 and about 2000 rpm, but above that it would not rev, but would just die and then pick up again and then die and then pick up again, etc.

I would rather not empty the tank of fuel if I can avoid it because it is almost full (400L) and the fuel would not be that old, well, it would be about a year old. Maybe just start with the fuel filter?
 
I put the sea foam in my tank. I have never had any problems. I would treat your fuel add some fresh and change that filter and see what happens.
 
I removed the old filter today and poured out the fuel inside it into a clean container. There was quite a bit of particulate matter, mostly very fine but also some relatively large bits corrosion. I installed a new filter and I am thinking that perhaps I should pump out the fuel tank into a couple of 44 gallon drums with a filter in the line and then pump to another couple of drums, again through a filter, and so on until nothing more is being picked up in the filters, and then pump back to the boat fuel tank and add some fuel system cleaner (probably Wynn's fuel system cleaner - cannot get Seafoam here in Australia).

Fuel smells all right - not like stale fuel. I only hope that injectors are not clogged.

One problem with this boat is the fact that the previous owner let it sit for quite a long time with about 150 liters in the tank before I eventually bought it. There was a fair bit of rubbish in the tank including some sort of bacterial growth. I was not aware of this problem when I bought the boat.
 
Does not sound like injectors but when a motor has been sitting for a long period of time with untreated fuel it never hurts to clean the system and have the injectors bench tested. Let us know what happens after you clean the fuel and treat it. Maybe try and run it with the new fuel filter and see if it clears up before you do through all the trouble to empty the tank.
 
Sorry for the delay in replying. I have been waiting for another opportunity to get the boat on the water.

Took the boat out this afternoon and it ran fine for the first ten minutes or so. I could rev it out to 3500 rpm with no problems. Then I had it idling for about 5 minutes while I was trying to check out why the boat was leaning to the starboard side a bit when planing. Could not figure that out. Thought it must be that I needed to adjust the trim tabs. Anyway started off again and it did start to stumble again, but only over about 3200rpm. Ran it for about 20 minutes at about 3200 rpm and then loaded it back on the trailer.

I am thinking that I will have to take the filter off again and probably replace it again. As well as replacing the fuel filter before, I also pumped the fuel, with a small electric pump and then through a fuel filter, from the fuel line coming from the tank and then back into the tank. I did that for about 4 hours (pump rate of about 100L/hour) so that I could filter the fuel by that accessory fuel filter. Do not know that it had much effect though because it looks like that the new fuel filter has blocked after only about 10 minutes or so of running.

What do you think?

Could not figure out the trim tab problem but eventually got the boat going level, but only with the starboard trim tab lower than the port side by almost an inch to correct the lean. Not yet sure why that is.
 
I had a similar issues years ago on a boat with twin outboards. Ran fine under 2500 rpm, but would bog down or stall above that. Drove the mechanic nuts, kept trying different things. I went out on a test ride with him and he brought a small portable gas tank and hooked it up. Then everything ran great. The shop had a guy come in with a pump / filter device. Put a hose into the tank through the fuel level float hole, and pumped fuel out of the tank, through his filter machine, and returned to the tank through the filler hose. Ran it for almost a full day. Every so often he would stir up the tank. When he was done I was amazed at the brown crud that came out of his filters. When wet it was like a thick mud, after it dried out it made me think of ultra fine rust particles. Turns out it was clogging the screen on the fuel pickup tubes inside the tank. After that the boat ran great, until I through a rod through the block down I the Keys.
 
If it is the screen on the fuel pick up line then maybe my filtering the fuel by running it through the electric pump and an accessory filter and then back into the tank did do some good. Maybe I just need to run it through that filter some more some more? Or maybe I need to pump the fuel from the tank directly by sticking a tube down into the tank, by removing the sender for example and putting the tube down there, rather than using the normal fuel line coming from the tank, so that I by pass the screen on the fuel pick up line?
 
Maybe try and blow some air down through your pick up tube if there is anything stuck to the end it will get it off. But issues is still stuff floating in the tank. You dont want to leave a big open hole for fumes to come out. Maybe get a separate gas tank and try to run it off that and see if your problem goes away. Just like Mike stated they did above. Then you narrow your issue to the tank if it runs great.
 
Yes, would be interesting to run off a separate tank and if it runs all right then you certainly would know where the problem was.

I will let you know how I get on.
 
I spoke to some one from the local marine shop today and he says that there has probably been condensation in the fuel tank and that is the source of the problem. A bug grows in the fuel and the filter gets choked with water. He says that the cheapest way to fix it is to add methylated spirits to the tank of fuel (he suggested about 3 litres to 400lL of fuel and just keep changing the filters when they clog up until it runs all right. He pumps out tanks and filters the fuel, but only diesel not petrol. So he was not prepared to do mine.

He also said that there will only be a gauze on the pick up line if the pick up line is not removable from the tank. Does any one know whether the pick up line in a 1997 271 Fastech has a gauze or not on the fuel pick up line in the fuel tank?

I did apply compressed air to the fuel line back into the tank a few times and there seemed to be no problem doing so.
 
All pickup tubes have a screen/gauze on them. I don't see water in the fuel being the problem, so adding more alcohol is not going to help. If you did have water in the fuel you would have seen some what you dumped the contents of the filter and noticed the crud. Just run it off a remote tank as mentioned
 
Many thanks for the advice. But it does look to me as if the most likely problem is the fuel/fuel tank. The boat ran better after I filtered the fuel and replaced the fuel water separating filter. And there is a black soot like substance in the fuel in the tank. When I changed the fuel water separating filter, the old filter had fuel in it which had this 'soot' in it and when I pulled the sender out, you can scrape this black soot off the bottom of it. I am thinking that it may be some sort of bug growing in the fuel.

We live in a warm tropical climate and before I bought the boat it had been sitting for probably 2 years with a half a tank of fuel. After I bought the boat I did empty the tank of the stale fuel and refilled it with fresh fuel, but there obviously still is this black 'soot' in it.

What is the black 'soot'? Any ideas?
 
My guess on the black soot is just gas which has gone bad for some time. I would suggest maybe the cheapest way to fix the problem is pump all the fuel out. Then remove the fuel sender, and insert a power washer nozzle into the tank and try to blast away all the crud with some cleaner solution. This will now be water and solution and can be pumped back out with a water pump and onto the ground. Repeat the process until it is cleaned out.

Pump out, then use other methods to get the water out, and refill with gas
 
Thanks for that advice. I just cut the old fuel/water separating filter open and it looks to me like it has not had any water in it - no sign of rusting in the bottom part, on the spring for example. Also, I think that is right that if it had had water in it, I should have seen it when I poured the fuel out of it when I replaced it with a new filter.

When I look now at the clean containers, into which I poured the fuel that was in the old filter, now that most of the fuel has evaporated, it is tarry. So I think that you are probably right that it is just petrol which has gone bad from sitting for so long.

Is there no other way than by blasting the inside of the tank with water and cleaner solution? Nothing that perhaps can be added to the tank to dissolve the crud? If not, then I certainly will try what you suggest.
 
Don't know of anything which will break up stuff and make it burnable. If anything breaks it up, it will just head for your motor and if it gets past the filter, well then your fixing the motor.

I mention water only because the environmental impact will be a non-issue. There are other chemicals which will do it faster but then more clean up.

Only other way I know of is replacing the tank, but that will be more costly

Just my opinion, maybe some else will have other ideas
 
I took the contents of the old fuel/water separating filter to the marine shop yesterday and showed it to the mechanic who had worked on the boat before and he said that it was just old degraded fuel. He suggested emptying the tank and spraying into it Johnson Engine Tuner, letting it soak in for a while, and then adding some fuel and pumping it back out, noting the colour. Then do the same thing again until the pumped out fuel looks normal colour.

I am wondering whether it would be useful to get an inspection camera so as to be able to get a look inside the tank via the hole where the sender goes. That way I would know exactly the state of things inside the tank. I have put down a stick of wood through the hole where the sender goes to reach the bottom of the tank and tried to scrape along the bottom of the tank and then look at the end of the stick to see what is on it. It does not feel like there is a guey sludge there and nothing much comes up on the end of the stick. I am wondering whether the old degraded fuel is simply suspended in the newer fuel which is in the tank. I pumped the tank about a year ago to get all the old fuel out, but I pumped via the fuel line so I might not have got every last drop, so that when I added more fuel there was still some old fuel there.

Any way, I thought that an inspection camera would tell you exactly the state of the tank. What do you think?
 
By all means do NOT use an inspection camera in a tank that contains gasoline and/or remnants of gasoline unless it is explosion proof!

Traditionally the pick-up tube is ~3-5" from the bottom of the fuel tank. As such, I have a feeling that you may have had more of the "old/tainted" gasoline than you think.

Any free-water will be in the bottom of the tank. As such, go to your local Auto Parts store and purchase a tube and/or jar of Gasoline water-finding paste. Smear some of it (3-4" high) on a wooden dowel and lower the dowel down to the bottom of the tank. Let it sit there for ~1-minute and then bring it up. "If" there is any free-water in the tank the water-finding paste will turn a different color i.e., either purple or red depending on what brand of paste you purchase. This will determine if your challenge is water-related of not. If you don't get a defined water-cut then most likely your challenge is, in fact, old/tainted gas-related. Pump out the tank once and you should be good to go.....

Water-finding paste can be found at: http://www.amazon.com/Kolor-Kut-Oun...sr=8-1&keywords=kolor+kut+water+finding+paste
 
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