Fuel pressure problem

Disturbed · #1 09-03-2012, 04:02 PM

I thought I had this problem figured out, but I guess not. When I'm cruising along at any speed under 30 mph, the engine is fine. When I go above 30 for an extended period, I get an alarm, followed almost immediately by the engine sputtering due to lack of fuel.

I shut down, check the fuel ball and its not flat, but you can tell there isn't any pressure there. I pump it a few times, start back up, and no problems for a while until I go above 30.

I've already replaced that line with a new one, and I can't find anywhere that it appears to be collapsing. I replaced the fuel/water separator about 2 months ago.

What am I missing? It runs great all the time at all speeds until I hit high speed that demands fuel.

On an unrelated note, I still have the DAMNED rooster tail from the transducer on my new fish finder. It is angled properly and at the bottom of the hull. It reads perfect, but it still shoots water straight up and all over the engine. WTF!!! Any suggestions would be great as I'm now starting to lose my mind. I don't want to keep drilling holes in my boat.

tsubaki · #2 09-03-2012, 04:31 PM

We had a similar issue with a Mariner after a line degraded and filled the filter with the hose linings.
Replaced the hoses and filter and it acted like it was lacking in fuel again at high rpms.
After scratching our head for a few weeks checking the lines and filters, we replaced the Marpac filter with a Sierra filter and the problem went away.
We cut open the Marpac filter and found nothing wrong. Only thing we could figure was the composition of the filter severely restricted the fuel flow.
The Marpac was a 10 micron and the Sierra was a 21 micron.

If the transducer is performing well at the speeds you want it to, just make a plate out of plastic cutting board material and place over it or better to mount to. Something similar to this.

Disturbed · #3 09-03-2012, 04:46 PM

Thanks tsubaki. I really like the idea for placing something over the transducer. I had pondered around with that thought but having the visual definitely makes me want to do it. Just wish I could figure out why it does it when the other one in the same spot never did.

I will look into the filter issue. When I replaced mine, the one that was installed was one that you can find in Walmart. I changed it out to one for West Marine, and for the life of me without looking at it, I can't remember what the name was. I do remember it had a smaller micron size. I went with the logic that having smaller foreign particles caught was a good thing right? Maybe I need to switch back to the other one. It's cheap enought to try it out.

tsubaki · #4 09-03-2012, 04:50 PM

You don't know how hard we beat our head on our problem.
We took apart everything from the pickup tube out the fuel tank all the way to the fuel rail.

Oh, don't leave out a possible vent problem.

Disturbed · #5 09-03-2012, 05:06 PM

The vent is a bit corroded. We were about to replace that and the fill tube anyway. The fuel cap is cheap plastic and we want to upgrade it all to stainless. Sounds like a project for the upcoming weekend.

phatdaddy · #6 09-03-2012, 06:14 PM

saw this on tht and thought it was a good idea

http://www.thehulltruth.com/boating-...er-engine.html

tsubaki · #7 09-03-2012, 06:32 PM

phat, that's easier, cheaper and neater than what I was suggesting!

Disturbed · #8 09-04-2012, 10:33 AM

I may just have to check that out. I know that I mounted it exactly per the specs. I may try filling in the space with silicone first to see if that gets rid of it. If not, this is an excellent idea. Thaks Phat.

THEFERMANATOR · #9 09-04-2012, 10:53 AM

If your hearing an alarm before it runs out of fuel, then that is the fuel restriction alarm going off. It takes about 3-4 inches of vacuum to set it off, so that is a pretty noticeable restriction. Check your vent, lines, and filters out for the restriction.

Disturbed · #10 09-04-2012, 11:18 AM

Thanks Ferm. Let me ask you this.

I'm going to try and describe this accurately. When I pull the engine cowl off, I'm staring at the black air intake, that says V6 on it. When I'm looking aft from the boat, on the bottom right corner is what appears to be a vent line. I was having problems with that line a few weeks ago being cracked. It appears to me that it may be kinked now. Could that one line be causing the issue?

The issue immediately goes away when I pump the gas ball and turn the engine back on.