Mechanical air cooled fuel pump.

[dwt25]

Guys, got a problem, has anybody had the same issue.
Fuel not pumping, but the pump is ok.
I have tested the pipes , all seem clear,fuel passes through the the filter ok.
Push rod not worn ,about 140 mm long.
Had the pump off, and have manually been able to pump petrol through it.
However petrol not getting as far as pump. Could there be an air lock?
If so how do you get rid.

[BOXY]

Could be debris / rust blocking the outlet of the tank. Try putting an air-line in the tank outlet and blowing it through. It won't be a permanent fix but if it solves the problems in the short-term you could try flushing the tank.

[CovKid]

With an old pump. I often found you can get it to operate off the vehicle quite happily but not in situ even if pushrod length is OK so I wouldn't necessarily pass the pump as OK unless its new. The diaphram/valves gets tired after so many years and it may be needing greater travel to get a proper pump cycle. It just becomes too weak to pull the fuel from tank to carb/s.

However, have you tried dribbling a little fuel into carb/s to get engine started and seeing if (once it starts) the pump is able to work on its own? Chances are it will if line is primed.

[dwt25]

Cheers guys will give both ideas a go.

[CovKid]

Generally, if the line is somewhat dry, turning it over on the starter won't get the pump running fast enough to pull the fuel through but it should do if you actually get it running even if only for a few seconds each time with a dribble of fuel in the carb/s. That said, if you have other issues it makes the whole thing that more frustrating. If you get repeat problems of dry lines (ie it runs back to tank every night), then an electric pump should cure it. Its generally the best option if a replacement mech pump proves elusive, which I gather is the case now on Aircooled models.

[dwt25]

Ok, so put fuel into carbs, turned over ,after a few goes, started to work on its own. so does that suggest that the old pump is now wearing out and needs replacing
Also, could I fit some kind of non return valve ?

[CovKid]

As long as it starts every day. leave it be. It just needed those fast revs to get the pump moving fast enough to pull the lot through. When it goes, fit an electric one, or buy one and keep it onboard as an emergency spare. As I mentioned, I believe the mech pump is no longer available for that engine.

[BOXY]

If I don't run the van for a month it can struggle to fire up. Normally I pump the throttle three or four times to get whatever the accelerator pump has got left, into the inlet, and then let it turn over on the key until it catches. That's worked for me so far. Pushing the pedal to the floor also sets the chokes which helps

[CovKid]

The tank run-back can be a pain in the proverbial if its a daily driver and been parked for the weekend in hot weather. I became so cheesed off with it I couldn't see any choice but to go electrric. At least it'll pull fuel through without the engine firing.

[Sir Brixalot]

Is that a simple job?

[CovKid]

Yes, relatively. Depends how you wire it. Mine is simplified as its powered by the blue alternator wire (there are better ways using a purpose designed relay). Essentially the pump goes underneath just after the fuel filter and instead of fuel line terminating at mech pump, it goes straight to carb. The potential pitfalls are a worn carb float valve (bear in mind pressure is increased) which may cause carb to flood requiring a carb overhaul kit, and fuel line needs to in excellent order to avoid any leaks. If you search for 'facet', much has been covered already. I had umpteen fuel issues with random loss of power (with MUCH frustration) and its been great since going electric. That said, a good mech pump can last many years and does a great job. Cost-wise the Facet low-pressure pump is about £30 but best to factor in a new fuel line and possibly carb kit if valve can't deal with constant fuel supply. The electric ones push fuel whereas a mech one sucks fuel.

[Sir Brixalot]

Thanks for the detailed reply.