Club 80-90 Forums

Just finished an AAZ swap. All runs fine once it's going, done about 500 miles so far with no probs. however everytime I start it it takes 30 seconds of cranking before it stumbles to life. Glow plugs are new. I have checked all the fuel pipes and banjo fitting seals, all looks good there. Swapped the return line banjo bolt for te jx one, and still I have to essentially fill the pump by cranking every time. When I switch it off I can see the fuel drain back down the fuel pipe to the filter and I can just hear a light hissing from the injection pump for a few seconds. No fuel leaks while running however.

So what do we think? Have I for a duff injection pump? Anyone run into this in the past? Ideas as to what I should check? Or am I now in the hunt for a new injection pump, or at least a rebuild kit?

Cheap option is to fit a non return valve in the fuel line, diesels won't be able run back then. Will give you a bit of time to save up for a pump rebuild

You won't see any fuel leaks as the leak is on the suction side. Replace the washers on the inlet banjo or heat the current ones to glowing and allow to cool to resoften them and remake the joint.
To test for exact location of the leak you will need to pressurize the fuel line from the filter so that fuel is forced out of the leak.
Pump rebuild is a bit drastic!

I have just replaced all four of the banjo fitting sealing rings and annealed the new rings before fitting them. No difference. I suppose I will have to rig up a way to force diesel into the pump and see where it leaks out? How I am going to do that I don't really know, but i'll give it a try tomorrow. Feel free to offer any other suggestions as to where this can be leaking.

Cheap - bicycle pump, blown up prophylactic / balloon / rubber glove, more expensive - airline, purchase a hand rubber bulb type.

Sorry, should have mentioned it, I am a mechanic by trade. And VW factory trained no less. So have access to shop air and tools ect. I have not had much experience with these old IDI engines professionally as nobody takes them to the dealer anymore, and I left the dealership two years ago to work for a firm that specialises in muscle cars. So all the tools in the world, but we are all stumped by an old diesel. Sad I know.

All I meant is I will have to devise a way to feed it a pressurised supply of diesel ie: mock up some cobbled together fittings to a hand pump. Although I just read on another forum that te pump should hold vacume fine, so I'll do that first with a mitey vac and at least confirm the leak is in fact in the pump.

Right. I have capped off the outlet and drawn vac on the inlet side and it is in fact leaking. Sounds like it is coming from the pulley, but hard to really tell. The pulley end of the pump at least. Tried to apt pressure to it but got no real result. No leaks to be seen and when I relieved pressure all the diesel that was in the pump came back up the line. So, the pump leaks. Local place wants £200 to "reseal" it. If I was to buy a rebuild kit, is this the sort of thing a reasonably competent person can do? Or are there loads of specialist tools required? Or better still, is there one seal that commonly leaks?

Bu**er!
In that case the cheap remedy is to fit a non - return inline valve as Lloydy says, this fix would do you for years until another seal goes that makes it worthwhile spending 100's of £££s on overhaul/replacement.

E D I T:
there's an AAZ pump on Ebay starting at £80 at the moment. HERE or a seal kit is £16 but a full strip down for all the seals calls for scrupulously clean work bench and knowledge of workings - there must be a guide out there somewhere, I know there was a good writeup on a NA pump on the Brickyard some time ago.

Having just fitted the engine I may actually go against my better judgement and just fit a one way valve. I don't really have the energy to fight this much longer. I'll watch that injection pump on eBay but I seem to remember hearing in the past that there are others that may do the job better. A Renault unit seems to ring a bell. But for the moment, I'll just bodge it and ignore it fit a while.

Anyone have a recommendation for where to find a non return valve? eBay like everything else? Off to look now....

And thanks so much for the help, really made a difference knowing I was not going crazy alone.

I feel your pain - I spent two years off and on trying to find an air leak on my boat engine fuel line - still haven't found it and as it takes two or three weeks to leak down I just use the manual lift pump if I haven't used it for a while. I have even pondered the possibility of a porous casting on the fuel filter holder!

Re-sealing the fuel pump isn't as bad as it sounds as long as you have a clean work area and some patience (and good eyesight). I just did mine to replace the big rubber o-ring at the distribution head. Although I have lots of mechanical experience including engine building (289 SBF as well as VW's ) I had never been near a diesel pump!

All went fine really, following this guide http://gnarlodious.com/vanagon/bosch_pump/-Rebuild#84

There is also a few links on this thread https://club8090.co.uk/forum/viewtopic.php?f=12&t=105691 which I started a while back but didn't get much take up on.

HTH,

MM

Bringing this back from the dead as I was going thru my old posts and realised it never got answered. In the end it was the seal right behind the pulley on the injection pump. Bought a full rebuild kit, but just used that one seal. Wasn't hard to replace, and totally solved the problem.

Then I sold that bus, then I bought another, and next week I am picking up another AAZ to start all over again.

In any case, should anyone else come across this in future, it's a reasonably easy fix.