Club 80-90 Forums

Hi all,
I've got a 2.0l Aircooled T25, which wouldn't start the other day and after spraying some easy start in the carbs, I think it's down to the pump. (It tried to start with the spray, but wouldn't continue after the easy start burnt off). After looking for a mechanical pump I have just discovered I have a Pierburg electric fuel pump. It's bolted onto a bracket on the alternator and power goes to a relay and then onto the coil. I found a replacement and am going to replace it, but wanted to ask a couple of questions if anyone knows anything about Pierburgs.

1. I've had the van for 10 years and never experienced any problems, but is this generally considered a good system.
2. Pierburg have advised me that max pressure is 5.5psi and is governed by the opening pressure of the card needle valve. Does that mean it's self regulating to whatever is required? Can I test/adjust it? I have twin Webers. They also advise that no regulator is required. Reading some posts on electric fuel pump conversions, it says to leave the pushrod in place, should that be done with the Pierburg as well? Need to check, but think it's been removed with the mech pump.
3. If the pressure is too high, could this lead to high emissions? Also on emissions, are catalytic converters available for the T25? Any other options to reduce emissions?

Hopefully replacing it will solve the problem so I can go away next month, but would like to make sure it's good in the long run. Al advice greatly appreciated.

Cheers,
Peter

Pierburg pumps are ok but it was mounted in the worst place electric pumps shouldn't be mounted on the engine due to vibration. Depending on which pump it is, the normal place for an electric pump is close to the tank.
3-4 psi is the ideal operating pressure which the original mechanical pump works at. 5.5 psi is really to high especially for Webers which should be closer to 3 psi.
If the mechanical has been removed then the pushrod should have been removed.

I will look at repositioning it when I get underneath. 5.5psi is the maximum pressure, don't think it operates at that. Pierburg talk about opening pressure of the carb needle valve, but I don't know what that is. Doesn't look there's any adjustment. Tried linking a photo but keeps failing, part number is 7.21440.51, if you enter that into google, it'll come up but it's just a universal pump.

peteinnit wrote:I will look at repositioning it when I get underneath. 5.5psi is the maximum pressure, don't think it operates at that. Pierburg talk about opening pressure of the carb needle valve, but I don't know what that is. Doesn't look there's any adjustment. Tried linking a photo but keeps failing, part number is 7.21440.51, if you enter that into google, it'll come up but it's just a universal pump.

The valve opening pressure is the fuel pressure that will overcome the valve shutting off and allow fuel to continuously flow into the carb flooding it.
That Pierburg type pump is meant to be mounted near the tank with a maximum height of 500mm above the bottom of the tank.
Facet Posiflow pumps are a popular fitment and work at the correct pressure.
http://www.ebay.co.uk/itm/Facet-12v-Low ... SwofxUfQ6d" onclick="window.open(this.href);return false;

OK I'm underneath now and have what is probably a silly question...... Noticed that the fuel filter is empty so no fuel is getting into the pump, does that indicate a different problem? I assumed the pump sent the fuel to the carbs, but does it also bring the fuel from the tank?

Thanks.

peteinnit wrote:OK I'm underneath now and have what is probably a silly question...... Noticed that the fuel filter is empty so no fuel is getting into the pump, does that indicate a different problem? I assumed the pump sent the fuel to the carbs, but does it also bring the fuel from the tank?

Thanks.

Yes it does but it cant suck from the tank as well as it can push it to the carbs hence the pump must not be more than 500mm above the bottom of the tank.

And ideally as close to it as possible. For the record, I ran out of petrol once with my posiflow electric pump and no matter how much fuel I put in afterwards, it wouldn't start, for the reason Big Herb has given. To get fuel in the line I pulled line down below tank until fuel appeared (minor blow to clear debris from tank outlet and gentle suck to encourage fuel to come out), shoved my finger over the end to hold it there then QUICKLY reconnected to pump and started it. Job done. Once the pump sees even a little fuel, it should clear any air bubbles and thats that.

If I was you, I'd think about replacing the fuel line with new, and move that pump as close to tank as you can get it (along with wires) or it'll come back to haunt you, just when you're in a suit and have ten minutes to get wherever it is you planned to go.

Relays aside, its also a good idea to include a switch somewhere so you can start the pump if ignition is off. It can save a lot of grief.

New pump on and started after a couple of turns, so all good now. Pump is almost level with bottom of tank and positioned over rear axle. Had the van for 10 years with no previous problem, so hopefully straight swap will be good. I will keep some old clothes n the back though just in case I am in a suit when it goes!

Thanks for taking the time to post advice,couch appreciated.