Mechanical Fuel Pumps (1.9 WBX) - Broken Again!

[T25Convert]

Hi,

Five moths ago the original mechanical fuel pump gave up the ghost, as the lever that pivots up and down bewtween the pushrod and pump diaphragm had worn its way through the arm it pivots on.

I fitted a replacement from GSF - one of their 'higher quality' german lines rather than the cheap south American one.

Yesterday the new pump packed up. On inspection the same lever and pivot had worn through.

Is this just coinicindence / low quality GSF parts, or can anyone come up with a bright suggestion as to some deeper underlying problem? The pushrod appears to go straight up and down as it should, and is the correct length (100mm). Is there some special magic grease I should be using on the arm, or is standard high melting point the right stuff?

Only ask as a new one is being shipped to me (via Brickwerks this time though) and I don't fancy having to replace it in 6 months time!

Cheers,

Alex

[kevtherev]

Hi mate!
I have never used grease on the pushrod or the arm

could you post a picture of the damage?

[bigherb]

No special grease, just pack the housing with multi purpose grease.

[T25Convert]

Hi mate!
I have never used grease on the pushrod or the arm

could you post a picture of the damage?

Hi Kev,

To be honest I didn't use any grease on the one thats just failed - I assumed that any lubrication necessary would have been dealt with by the oil that escapes up the push rod - the base of the pump is always pretty oily.

I'll dismember the pump and post a couple of pics.

No special grease, just pack the housing with multi purpose grease.

Excellent - that was my plan this time to try and get more than 2,500 miles out of it!!

Cheers all,

Alex

[T25Convert]

Hi,

Finally got to fit the new pump and dismantle the old one.

First pic shows the arm and pivot that link push rod to pump diaphragm - not arm hole is now oval, and pivot scored, so that the motion is more side to side than up and down, leading to no petrol coming out the pump:



Second pic is close up of pivot showing how deep the scoring is after less than 1,500 miles:



The whole lot was nice and oily, so its not a lubrication problem, so can only assume its rubbish quality.

I won't be buying another one from GSF, and suggest that others might also want to steer clear.

Fingers crossed my new one lasts longer (it looks more solid at least!)

Cheers,

Alex

[kevtherev]

Ah quality issue ..I thought as much.
great pics mate .. thanks

[T25Convert]

AHHHH!

Its not as simple as it first seems!!

With the shiny new Brickwerks pump (which looks like some piece of space machinary!) installed it was working fine for a couple of trips.

Today though it cut out again - same problem, no fuel at the carb (accelerator pump squirting air not fuel) and pipe from pump to carb is dry. Plenty of fuel at pump, and pump works if the arm is pushed with your thumb. However, pump doesn't work when bolted to the engine.

Measured push rod ant is 98 mm, only 2mm shorter than the spec, but looks like this is enough to stop the whole lot working.

Can only see new pushrods on JK and GSF, but worry that if I get either they will be made of cheese and wear down in a couple of months. Anyone got any hints of places to get a quality replacement??

I think that this will sort the problem, but any other ideas (the cam that operates the push rod seems fine - I peered down the hole with a torch and it doesn't appear scored / chipped etc)?

Cheers in advance,

Alex

[batmangb]

Hi Alex
Is the plastic/bakelite base that the pump bolts to ok? I ask because mine had cracked low down where you couldnt see, and was causing to pushrod to miss the cam on the pump. It was confusing as when dis-assembled the pump looked fine. Good luck with it!
Ben

[Ian Hulley]

Measured push rod ant is 98 mm, only 2mm shorter than the spec,

This MUST be 100mm, critical.

[EarthWormJim]

Just a thought (maybe not a good one but here goes) could you put a blob of weld on the end of the push rod and file the end to tidy it up and make it 100mm exactly??

[VERAT25]

HI,
are you sure that you have no air leaks in the supply pipe,
i had the same probs as you. and after fitting new pump//no fuel//...found air leaks in supply pipe near carb...
re newed pipe/and cured problem.

as for the wear?? have you an alignment problem????????????

verat25(cardiff)

[T25Convert]

Hi,

Thanks for all the comments / suggestions.

I have purchased a new push rod from GSF only to find that it is only 98.5 mm new, which was dissapointing to say the least. It is also a slightly smaller diameter, meaning it wobbles in the plastic support guide (which can only lead to further problems) and appears to have been reproduced by someone who had never seen the original!

I'm sure that there are no air leaks or problems with the fuel lines, as the pump works fine if you use your thumb instead of the push rod. The plastic guide looks fine.

As a temporary 'fix' I have replaced the two thick paper gaskets with a little liquid gasket, which has gained me almost 1 mm in effective rod length, and gently tidied up all the mating surfaces, so all in all I'm closer to the magic 100mm.

Plan to try VW Heritage as they list both rod (reproduction) and guide (genuine VW), all for about a tenner - any experiences?

Cheers for the help,

Alex