Before I start to strip the fuel system...

Hightower · 24 August 2008, 16:28

....I'd like to ask opinions about my soft primer bulb and fuel delivery.

Some of you will be aware that a few weeks ago that on a jouney down Wooten Creek the engine coughed and spluttered to a stop. After a few initial checks and a prime on the Bulb I managed to get the outboard started and continued on my trip.

Altho not conclusive I suspeced the primer bulb/fuel system.

The last few cruises I have been monitoring how hard the primer bulb feels after each stop and everytime I tried the bulb is soft.

Yesterday I primed at the begining of the trip only and after about 6 restarts during the trip (drifting for fish) I had the same symptoms as before (splutter and stop). The Bulb was soft as before and after priming the engine started fine.

I have the bulb between the tank and filter/seperator, should I try to move this to beween the filter and engine, the bulb primes fine so I think this is OK. The only other resons for air getting into the system is either from the pickup pipe bottom (which I doubt) or one of the pipe conections leaking air into the system whilst under vaccum when the engine is drawing fuel.

Any suggestions?

Nasher · 24 August 2008, 18:05

Andy

Sorry to hear you are having problems again.

It may be of no help at all, but:-
I hardly ever touch my primer bulb, and each time I have its always been soft, some engines just don't need it, so I'd check to see if your Rude needs it before stripping it all down.

I'd start by checking any fuel filter under the cowl.

Nasher.

m chappelow · 24 August 2008, 19:00

how about the air bleed screw on the tank not fully open or vibrates closed slightly,or how about the non return valve on the bulb sticking open ,other than that apart from what you have done checking fuel line connecters and what nasher said about the fuel filter it could be a small hole in the fuel pump diaphram or badly worn one ,suppose you could try a piece of clear piping between the bulb or carb or fuel pump and get a large syringe or blow or suck with something and see if any air bubbles appear .

Nos4r2 · 24 August 2008, 22:09

Might be worth checking the fuel hose where it joins the connector. I've had the inner of the double thickness hose crack and let air in which stopped the engine before. It wasn't visible til I removed the connector from the hose.

m chappelow · 24 August 2008, 22:17

could be an 0 ring thats worn in the fuel connecter or if its had some heavy usage the brass pin could be worn .if it has one .is there any really tight bends on the fuel pipe on the engine side ie filter ,pump ,carb as after a while the metel pipe ends may have cut through the rubber or not fit right and thats weeping air in ,

Hightower · 24 August 2008, 22:29

Thanks for your replys.

I pumped the bulb hard before flushing my engine today, started the engine and observed the bulb, sure enough after a couple of mins the bulb went soft again. At this stage the bulb was above the fuel filter and any hose bends so I can only assumm that either air is entering the fuel hose where it connects to the fuel tank and rising into the bulb or is entering some other part of the fuel system (filter being the a likely suspect).

There is no smell of petrol anywhere on my boat

PeterR · 24 August 2008, 22:35

Hi Do you have an inboard tank or external 25ltr ones .for the 150 you require large bore fuel hose from memory 3/8 if you havent you ru n the risk of fuel starvation and its asociated problems.Fuel filter as already suggested is a must.And for the cost definately the bulb only last month it was the cause of almost identical symptoms on a 90hp 2 stroke although carb mariner.check you are using the corect 2 stroke oil.I,ll think about it more and if i think of anything else will post

Hightower · 25 August 2008, 01:34

It is an inboard fully vented tank and all installations for the outboard is correct.

Nasher · 25 August 2008, 11:10

Quote:

Originally Posted by Hightower

Thanks for your replys.

I pumped the bulb hard before flushing my engine today, started the engine and observed the bulb, sure enough after a couple of mins the bulb went soft again.

Should the Bulb really be hard whilst the engine is running?

I thought it was only supposed to be hard before starting.
To be hard during running there would need to be pressure in the line.
Or have I got it all wrong?

Nasher.

Hightower · 25 August 2008, 11:24

Quote:

Originally Posted by Nasher

Should the Bulb really be hard whilst the engine is running?

I thought it was only supposed to be hard before starting.
To be hard during running there would need to be pressure in the line.
Or have I got it all wrong?

Nasher.

My Oil priming bulb is rock-ard. By my reconing if there is no air in the system then why would the primer bulb be soft?

Rigaud · 25 August 2008, 11:34

Quote:

Originally Posted by Hightower

My Oil priming bulb is rock-ard. By my reconing if there is no air in the system then why would the primer bulb be soft?

Not the same for the fuel line and no the bulb does not stay rock hard.

I just had a few problems myself this weekend with fuel delivery on a 1998 Yamaha 115 2-stroke. Both lower carbs had partially blocked jets with dirt in the float chambers even with an inline filter. I replaced all my fuel lines, took appart completely the carbs and fuel pump. Also I found a hairline crack in my fuel filter that pulled in some air.

Now after everything was put back in place it started on a half turn and runs like a race horse.

I opted to not try and chase the problem but instead just go through the entire fuel system. In the end it took less time and pain than chasing the problems or guessing it.

Good luck
John

Hightower · 25 August 2008, 11:46

My Yammi and Merc always had a rock hard primer bulb and I never needed to prime it. Surely if there is no air in the system then the bulb will be hard and resistance felt.

Downhilldai · 25 August 2008, 13:37

Quote:

Originally Posted by Hightower

I have the bulb between the tank and filter/seperator, should I try to move this to beween the filter and engine,

I have my primer bulb between the filter and the motor - the filter blurb said to do it that way, so may be worth changing it around.

Erin · 25 August 2008, 17:59

I had a fuel problem on my last boat when the primer was before the filter. After moving it to sit between the filter and engine all was well. No idea the logic or reason though. I have also had a similar problem when some debris made it up as far as the inlet to the filter and partially blocked the opening. The suction from the engine caused the bulb to deflate as the fuel couldn't get through to replenish the bulb. Once cleared all was well. I wouldn;t think the bulb would stay firm when the engine is running as the fuel is being 'sucked' by the engine lift pump rather than being pumped up from the tank (as in a car).

Hightower · 25 August 2008, 19:29

I must admitt that I haven't a clue as to whether the bulb goes before or after the filter, but will definatly swap it around when I tinker with it later this week. The other thing I could think of was when I first tightened the fuel hose to the outlet pipe on the tank last year it deformed the copper pipe as I overtightened it. I did reform it by sticking a former up the inside of the pipe, but would be worth checking out again and doubling up on jubilie clips.

So who else has the pimer between the engine and the filter?

willk · 25 August 2008, 20:13

Oddly, my twins are rigged both ways, differently on each side. I await the outcome here with interest.

osprey__viper · 25 August 2008, 20:14

Quote:

Originally Posted by Hightower

So who else has the pimer between the engine and the filter?

Mine was like this

Searider · 25 August 2008, 22:27

Mine's between the filter and the engine.

Had a Tempo bulb that collapsed a few times causing the engine to stop - which was a little worrying on the way to the Scillies!

Replaced it with a genuine Quicksilver one for about £10 and all well for the last 3 years.

If you've net renewed the bulb then this would be a place to start.

spartacus · 25 August 2008, 23:11

A marine engineer advised me to fit the priming bulb should be situated between the filter and the engine. Reason he gave was that this reduced the possibility of forcing through any impurities/water into the engine. Makes sense to me.

Hightower · 26 August 2008, 00:20

Quote:

Originally Posted by Searider

Mine's between the filter and the engine.

Had a Tempo bulb that collapsed a few times causing the engine to stop - which was a little worrying on the way to the Scillies!

Replaced it with a genuine Quicksilver one for about £10 and all well for the last 3 years.

If you've net renewed the bulb then this would be a place to start.

Mine is a genuine BRP one and was installed new last year, I'm going to resite this to after the filter first.

Thanks!