Logo
FULL SITE MENU

2004 BF200 Surging/ Fuel Issues-Advice Needed

At idle, the Helm shop manual says the fuel pressure should be 41 to 48 psi with the vacuum line to the fuel pressure regulator disconnected - page 5-73.
 
Thank you.
I should also note that when I first tried to drain the vst, before having the shop change the hp filter and screen, no fuel came out. I didn't put two and two together at the time, but in hindsight, that's obviously a sign of low pressure in the fuel system...
 
That is not necessarily a good indicator. You need to charge the HP fuel pump first by turning the key switch on for 2 - 3 seconds, then open the set screw to see if fuel comes out of the VST. If not, blow some compressed air pack through the tub to see if you can move the blockage.

Can answer about the fuel pressure regulators. There has been little or no discussion about them on the Forum as best as I recall.
 
I blew into the vst drain, sucked a little until i could see fuel halfway down the tube, and turned the ignition on both with the drain screw open and closed, and nothing came out...
 
In that case the VST likely needs to be removed and cleaned and the float and float valve checked. Did you screw out the set screw about 3 turns?
 
Yes on the set screw. That was before I took it in to have the HP Filter and screen underneath changed. They checked it and said everything looked good. I think that must be an indicator of low pressure in the system...
 
Hard to tell. Best to have them check the pressure.

However, all of this started with surging and a code 1 on the MIL light. Have you retested it on the water lately?
 
No, I plan to retest in the water on Friday. We'll see how it goes, but I wish I had a better idea of what to look for, whether it's between the fuel tank and the engine or a problem with the engine itself.
 
Also, it occurred to me that after I cleared the coeds and ran it, the MIL light stayed on solid when I went to check the codes again. I didn't think much about it at the time, but when I went back to look, the code sheet says that could be a short or a bad ecu. Should I be concerned about that?
 
Randy,

I received your e-mail and video and viewed it carefully. I also went back over all your posts here. You definitely have an air leak in the fuel line somewhere between the fuel tank and the engine, even though you said all of that was replaced. And clearly, that is the source of your problems with surging and low top-end rpm's.

In the video it appears that the air bubbles are not consistent. That indicates to me that the suction from the low pressure fuel pump is drawing the air in through a very small leak. As the leak relieves that pressure, the fuel goes back to a normal flow until there is too much suction again.

If your flow meter is still being erratic while running, that indicates that the problem is between the tank and the fuel flow meter. Since all the fuel lines were replaced with new ones, then it is doubtful that there is a pin hole in those, so the possibilities are the connections at the fuel/water separator, connections at the primer bulb, or the connection going into the fuel flow meter. The other possibility, and the one I would check first is either the seal on the fuel-water separator or the drain spigot for the fuel/water separator. If it is not difficult to do, try bypassing the fuel/water separator and see if the air bubbles go away. If so, then just replace the entire fuel water separator.
 
CHawk, thank you again for your reply.

I went ahead and swapped out the O2 sensor yesterday morning since I had it and I wanted to be sure that fuel pump was pulling the appropriate amount. I spliced in about 18" of clear pvc directly in front of my engine and drove it about 30 minutes over to my mechanic. The video I sent was about 10 minutes into during this first ride. It shows significant pocket of coming through clear hose about every 30 seconds to 1 minute. I talked to my mechanic some and got the service connector that was left at his shop and told him about the problem. I had already replaced the fuel water separator assembly beforehand. From there, I bypassed the fuel water separator, fuel flow meter, and pump up bulb individually all with the same results. I would have taken another video, but they all looked the same. After taking turns doing each of those, for the ride home, I plugged the fuel line straight into a portable 5 gallon tank I brought with me. After purging the air in the system within the first minute, it ran perfectly with no bubbles coming through. I should also note that with the normal setup, bubbles only came through when it was on a plane, around 3500-4000 rpm, and more when I ran it a little faster. At idle, no air ever came through. I ran out of time at the end of the day, but I think I eliminated everything in my aft box that holds the water separator and all. The next logical step is something at the fuel pickup, although that was replaced at the same time as the fuel line a few weeks ago. Overall, I'm encouraged that I'm narrowing down the potential problems, and at least I know it's a problem between the tank and engine, not the engine itself. I didn't think about it at the time, but I should have bypassed all of that stuff at once and gone straight to the engine, then I could really say it's got to be at the tank if I still saw air coming through. I'm open to suggestions of what it could be, but I'm going to keep plugging away next time I get a chance. Thanks ya'll!
 
I'm sure you are relieved that the problem is NOT with your engine.

Good move on plugging into a separate 5 gallon tank.

As I noted before, this is a strange problem that only reveals itself when there is a high demand for fuel, so you are looking for a very small, intermittent air leak - the ones that are the most difficult to find.

If your mechanic replaced the fuel pick up tube, I would direct my attention to the point where the fuel hose connects to that pick up tube. If I understand your previous posts, that is all new fuel line Then there seems like there is something screwy at that connection. At this point it's simply eliminating each possibility. First, retighten each clamp.
 
Ok, I was able to run the boat some over the weekend. First, I replaced the fuel pickup just to be safe. I noticed that the old one had a little bit of an "s" to it that indicated it had been hitting the bottom of the tank. I measured the depth and cut the new one to length, and re-assembled everything with generous portions of pipe dope, hopefully ensuring that the connections at the tank were air tight. Afterwards, I was able to run the boat for about 2.5 hours. I ran it a various speeds still with the clear tube in front of the engine. As always, idle speed was fine, no bubbles coming through at all. I noticed that there was some air coming through immediately after getting on a plane and sometimes after hitting some wake. As a reminder, and I know it's not ideal, this is a 62-gallon tank (5' long) with the fuel pickup located about 9" from the front end of the tank. I'm thinking that the pickup gets air when getting on a plane and the bow comes up and fuel rushes to the aft end of the tank. The engine ran fine and was obviously able to purge this amount of air. In fact, the fuel flow meter never showed anything out of the ordinary. The fact of matter is, it may have always been getting this amount of air, but we would have never known because the engine ran fine and we never put any clear tube in the system. I would have never known there was any air coming through on Saturday without the clear tube. Of course, I would like for there to be none and I'm hesitant to say it, but I think it may be fixed. I guess I just need to put some more hours on it to regain my confidence. Once again, I'll keep everybody posted.
 
A 62 gallon tank, five feet long? HOLY COW!!!!! AND THE PICK UP TUBE IS UP FORWARD???? I would consider that a SIGNIFICANT design flaw.

Anyway, it looks like you found the problem. Good for you and all that that persistence. Keep it topped off as best as possible and keep as much weight forward as you can. Also, if you don't already have them, trim tabs may help by keeping the bow less elevated.

Of course the real fix is to cut out the tank and turn it around. But I suspect that is not in your cards.
 
I got to thinking about this overnight. I was just wondering if there is some way to extend the pick up back towards the rear of the tank. I've never tried doing anything like that, but maybe someone else on this forum has.

You might post this issue on the Robalo discussion forum: http://forum.robalo.com/
 
I thought about that as well, but I'm sure it would be very tricky, almost impossible. There are two baffles in the tank, and I'm not sure the exact shape of them and how I would route fuel pickup around them. I was thinking about what could be done to install a pickup at the aft end of the tank while there's fuel in it. Is there a fitting that can be screwed in like the fitting of a sending unit with gasket? Is it even possible to cut a hole and drill screw holes with fuel, sounds kinda sketchy...any thoughts?
 
I would NOT even think about cutting a hole in any fuel tank while it is still installed. The only way I know of safely doing that is to remove the tank, drain it completely, open all openings, hook up a blower to one of the openings, then cut only after all fumes have been purged.

Still, I would post this issue on the Robalo forum and see if anyone else has found a work-around.
 
This would just be dropping in sender/fuel pickup into a pre-existing hole where I had the mechanical gauge installed. I think it might be a good solution given my situation...
 
Sorry I didn't see your last message before posting mine.

Obviously I can't eyeball the set up, so it is hard to judge. If the fuel pickup will fit properly and can be properly sealed in the aft opening, that would likely help eliminate air getting into the fuel line. However, the link that you sent is just a sender, and it does not look like it would also accommodate the pick up tube. Or did I miss something there?
 
It is a sender with a "diesel return" fitting that could also be used to install the fittings for the fuel pickup (if I'm interpreting it correctly).
 
Back
Top