Problem with fuel delivery

PeteDeer · 11 March 2007, 19:25

Hi,

I have a ribeye with a Yamaha F80 outboard. On a number of occasions the engine has stopped running due to problems with fuel being delivered. When this happens, the primer bulb is completely flat. The steps I have taken so far to rectify the problem are as follows.

1. Firstly remove the pipe from the primer bulb which leads directly to the engine and check if it is blocked. It does not appear so.

2. Replace this pipe and then remove the pipe before the fuel filter which leads directly to the fuel tank. I have blown and sucked down this pipe and cannot "feel" any bubbles (although I am not sure I would), or receive any fuel.

3. I have then used an air pump (which I use to inflate the tubes) and blown through to the tank. This seems to work and the engine will then work.

This often happen when the sea is choppy, and on the last occasion the tank was almost full. It could be something in the tank, but the tank is built under the deck.

Any help or advice would be very much appreciated.

Thank you

Pete.

al40 · 11 March 2007, 19:56

When the boat stops and primer is flat, does it remain flat or slowly re-inflate?

If it remains flat it sounds like there is a complete blobk between the primer bulb and fuel tank. If it slowly re-inflates, there is a partial block (stating the obvious I guess).....

The fact the primer bulb goes flat would suggest hose to engine is OK and problem is after bulb (or valve on the bulb itself).

See http://rib.net/forum/showthread.php?t=18171 for similar issue I am having.

Fact it clogs when it's rough suggests sediment in the tank (as fuel gets picked up from bottom of tank so if there is crud at the bottom it'll get sucked into the tank outlet). Do you have an inline filter? This could also be blocked

jyasaki · 12 March 2007, 00:48

Could also be that something is resting on the fuel line (or nearly so; moves when it's rough), or the fuel line is kinked at a corner somewhere.

jky

PeteDeer · 12 March 2007, 08:48

I am not sure if the primer bulb remains flat, but I did decide to change the bulb over the weekend, just in case this were part of the problem.

Turning to the hose, it is carried under deck, and I can't see how you can get access to it. I think you are right, it could be debris in the tank, but given that the tank is not accessible (I think), any ideas ?

It does have a filter located between the primer bulb and fuel tank. I have replaced the filter, it is one of those Yamaha cylinder shape filter of 3 inch diameter and stands 4 inches high.

Is there anyway of inspecting the tank or cleaning it with such limited access.

Thanks... Pete

fast fred · 12 March 2007, 11:27

check the vent of the tank.

jwalker · 12 March 2007, 11:36

If you are sure it's debris in the tank, can you insert a tube through the filler to the lowest point in the tank? You may be able to lean the boat over in some way to bring the debris towards the filler for easier access.

al40 · 12 March 2007, 22:10

I assume the flow rate on the filter is OK? The filter size is measure in microns and there is usually a flow rate (or max HP - which is a kind of guide) stamped on the filter body.

If the filter is too fine and can't deliver proper flow, then at WOT, the engine could be sucking more than the filter can deliver. I'm guessing that this would not necessarily cause the bulb to go fully flat tho and it would recover quite quickly.

As already mentioned, the air breather could also be blocked (potentially by something moving around in the tank?). This would make it worse if tank was full.

When the engine stops, do you have to blow through the fuel pipe (between filter and tank) to get it to go again? If so, the issue is limited to tank, said pipe or breather.

PeteDeer · 13 March 2007, 08:20

I believe the problem lies between filter and tank, as the bulb is completely flat, however the bulb did feel quite weak when squeezed.

When I used a hand pump and blew air directly down the pipe to the tank it did seem to clear the problem, although that might have been just luck !

The tank was probably 3/4 full when it happened on Saturday, and the engine was at high revs.

Pete.

fast fred · 13 March 2007, 10:35

had similar problem once, was the vent of the tank. the bulb got Sucked flat,cuzz the vac' bilt up in the tank is more than the pump can pull.