have to prime every few minutes ?

[crui05]

well had the new/ replacement line back into the original tank. but i now have found engine stalling but needs to prime it after a few minutes on the wet stuff.
???

[Ribtecer]

Have you opened the breather screw on the fuel tank?

[crui05]

i didnt know there was a breather screw on the tank. its a fitted ally tank. i understand abouth the breather on the plastic ones but ???

[Pikey Dave]

Originally Posted by crui05

i didnt know there was a breather screw on the tank. its a fitted ally tank. i understand abouth the breather on the plastic ones but ???

It sounds like an air leak somewhere. You’re drawing air in the fuel line. Check all the connections, also check you have the primer bulb in the correct orientation (arrow pointing towards the engine) Check the connector at the fuel line/engine is seated fully & locked.

[jeffstevens763@g]

I had a new bulb with a faulty non return valve so the fuel kept draining back into the tank.

[crui05]

many thanks to you guys for your input. i will check all of the above but i still am not aware of a breather screw on the tank as its a littkle like the tank on a car.

[Poly]

Originally Posted by crui05

many thanks to you guys for your input. i will check all of the above but i still am not aware of a breather screw on the tank as its a littkle like the tank on a car.

There won’t be a screw (but will be a vent somewhere - they can get blocked) but you can tell if there is a vacuum forming by opening the filler port. I think it’s more likely you are drawing air or have a load of crap in the tank blocking the strainer on the pick up.

[Pikey Dave]

Originally Posted by Poly

There won’t be a screw (but will be a vent somewhere - they can get blocked) but you can tell if there is a vacuum forming by opening the filler port. I think it’s more likely you are drawing air or have a load of crap in the tank blocking the strainer on the pick up.

I’d have thought that if it was a blockage/vent issue, the primer bulb would collapse.

[paintman]

You don't give any details, but presumably this is a new problem which has only started since the new fuel line was fitted?
If so then look at what was fitted or done & likely you'll find the problem.

Never assume that a new item isn't faulty.

Reminds me of someone (no, not me) who serviced his Range Rover Classic & immediately had a misfire.
Best part of £600 on bits later - incl ECU - & following forum advice he finally decided to refit the old items one at a time.
Refitting the old rotor arm solved the problem. New one was defective.

[crui05]

a new fuel line was re-installed after a marine "expert" told me the tank was full of crap. i payed a small fortune having new plastic tanks put in. but i noticed she had a hell of a job getting on the plane as the weighty tanks full at the rear was holding her down ( 40 litres)
so after much investigating the "dirty" tank, which wasnt dirty. we fitted new fuel line. (i always felt the marine"expert" wasnt ) so it was easier to install rear plastic tanks) he wasnt paying after all.
she ran fine for about 15 mins out there then just died. i managed to limp her back to port just on slight forward throttle.
i noticed the prime button had no pressure. so i primed it and it allowed me to increase speed.

[Pikey Dave]

Originally Posted by crui05

a new fuel line was re-installed after a marine "expert" told me the tank was full of crap. i payed a small fortune having new plastic tanks put in. but i noticed she had a hell of a job getting on the plane as the weighty tanks full at the rear was holding her down ( 40 litres)

so after much investigating the "dirty" tank, which wasnt dirty. we fitted new fuel line. (i always felt the marine"expert" wasnt ) so it was easier to install rear plastic tanks) he wasnt paying after all.

she ran fine for about 15 mins out there then just died. i managed to limp her back to port just on slight forward throttle.

i noticed the prime button had no pressure. so i primed it and it allowed me to increase speed.

Once the engine is running, the primer bulb won’t be under pressure, it will be soft & pliant. BUT it won’t be sucked in & collapsed. If the bulb is collapsed you have a blockage between the bulb & tank. If it isn’t collapsed you may have a blockage between bulb & engine. OR you may have an air leak allowing air to be drawn instead of petrol. If you pump the bulb hard & continue to squeeze, you will see any fuel/air leak between the bulb & the engine.
Or you may have a dodgy bulb.

[crui05]

if air can get then can fuel get out. the reason i ask is that there is no smell of petrol which you always get a strong wiff of on any leaks.

[Pikey Dave]

Originally Posted by crui05

if air can get then can fuel get out. the reason i ask is that there is no smell of petrol which you always get a strong wiff of on any leaks.

If the pickup is cracked in the tank, it will draw air & not fuel. You won’t get a smell.

[crui05]

i wonder if that is the original problem that caused someone to think the tank was blocked with crud.

[Pikey Dave]

Originally Posted by Pikey Dave

If the pickup is cracked in the tank, it will draw air & not fuel. You won’t get a smell.

You put a piece of clear tubing between the bulb & engine so you can see what’s going on. Once you’ve established the supply side is ok, you can then start looking at fuel pumps etc. Do the cheap easy stuff first.

[crui05]

thanks Dave. i will.

[Matt]

I sometimes use one of these clear plastic filters on smallish motors which is useful enough to see what's going on: https://www.ebay.co.uk/itm/164063979229

This one would fit 5/16" hose and is nice enough for the job - although I don't know what motor size you're running - suspect you may want a slightly bigger one, even if it's just a temporary thing on a short extension hose while you diagnose.

If the bulb can easily re-prime it, suggests probably not a pickup issue?
What is the motor - if it's a mechanical fuel pump running carbs, the diaphragm can fail sometimes.

[crui05]

its a mercury 90 two stroke.
done very few hours since a major service although that was in 2019. but hardly been out since as covid came along.

[Limecc]

Could you fault find using a borrowed 12 or 25l plastic tank and spare priming bulb and line? Would quickly isolate the problem.