it is only my 2pence worth mate(from bitter experience !) sometimes new parts are not up to spec and of course you never think that may be cause of prob , something to think about ,good luck
If its FI find my FI literature thread on the how to and follow the VW troubleshooting guide. It will walk you through each part of the FI an tell you how to test and what to expect. The problem with FI is that when it doesn't work there are so many things it could be. Could be dodgy fuel pump, cold start valve, temp sensor, afm etc etc. If it does start sometimes, you've changed the whole ignition system, and the starter motor is working then it sounds like fuel starvation or bad wiring. Follow the troubleshooting guide and post the results. I've been through this with my van so now know the FI system inside out, (not really a claim to fame I know!).
When I've not got my daughter running around my ankles I'll post a how it works and a to do list for you. That should get a diagnosis and we can work from there. The wife and I were discussing a weekend away sometime soon, the offer of free beer might be tempting
If you can drink Doom Bar then I have a never ending supply. I shall eagerly await that list thank you. I know all about the kids, at the ripe old age of 30 I have 5 ranging from 6 to 18... oh the joys! ) I did, about 9-10 months back, run the van dry with fuel, ended up clogging the filter and having to replace it. I wonder if i've clogged anything up somewhere :/
At the risk of sounding like my dad , mate , my old fella would say (as he had seen me struggle with a "refusing to start vehicle" when i was a kid, " you only need 4 things " ignition, compression ,fuel , exhaust" and thing is those basics are still well, the basics , and now rather than overcomplicate my own bus probs , i still go back to those checks 1st, assure myself one system is ok , move on to the next , any good ?
No mate, that's fine, I appreciate every drop of advice, every day is a learning day! Ignition? Check Compression? (according to the garage) check Fuel (according to the garage) check Exhaust? Hmmm well it seems ok... I'm going back to fuel, I think it requires further investigating! If only it wasn't so damn complex this system lol
Right here goes... Before you even go into the FI Matrix, make sure you are happy that these are working. The FI is a rabbit warren of wrong turns and lies and once you delve into FI there is no going back I'll go through this as if you've not tried anything, it's easy to miss something...So: 1) Check ignition system before anything else. Common problems: Dizzy, coil, leads, is there a spark at the plug, battery etc Is the starter motor turning over when you crank the engine? Make sure you are 110% with this before anything else. Don't even read on until you are. 2) Happy that all of that is ok, well take the red pill and welcome to the wonderland that is FI. In a nutshell this is what happens within all the FI trickery: Turn the ignition to the first stage and power is given to the ECU, (the brains of the operation), and redies the AFM and injectors. Turn the key one stage further and this powers the starter motor which should crank the engine. At this point voltage comes into the double relay, this then passes power to the fuel pump and auxilliary air regulator, (AAR), and also the starter, (not the double relay), passes power to the cold start valve. We should now have power and the AFM has realised that the engine is running, and for as long as it reads air flow, this keeps power running to the fuel pump and AAR and essentially the FI runs... Got that? Lots of other things happen within the FI but that is the basic process needed to get the bus running. With that in mind, if your bus isn't running you need to do some tests: a) Check the hoses for leaks and that they are tightly fitted on. No cracks, holes etc. If you don't know which ones to check, check them all, but focus on the larger ones. The small ones, (3mm ish diameter), are the vacuum hoses and you only need to worry about them when the bus is running. Remember, no air flow through the AFM, no worky... All ok? b) Get a pressure gauge and connect it to the metal fuel line between the injectors on 3 and 4. There is a little valve you can unscrew and put the line on. Crank the engine and it should be about 35psi. If you can't do this, go under the van and find the fuel pump and filter. The filter should be nice and clear and you should be able to see the fuel in in, if it looks full of crud, change it. They are cheap and they stop any rubbish from the 40 year old rusty tank ruining the rest of the, expensive, system. Get someone to crank the engine over while you are touching the fuel pump, if it's working you will hear it whir and feel it vibrating. The best way I can describe it is it's feels and sounds like an electric toothbrush. You will know if it is working or not. If it's not working, that's your first, (and hopefully only), problem. Remember, no fuel, no worky. Let me know what happens and I'll tell you which road to go down next...
Oh, and if you don't know what any of the things I've mentioned are and / or what they look like or where they are, just shout!
Have you replaced the ignition switch?? they are prone to failing, and when the engine cranks the feed to the coil fails... causing a no start situation.. the FI on these old beasts is pretty robust... so I would rule out everything, before you start delving into it!!
Fearny - I'm grappling with a similar problem! I have a 77 2.0 type 4 engine with FI. MadFrankie - that guide you put seems very helpful. Apologies if I don't know the answer to certain things, or explain what's going on with my van like a dumbass, I'm only just starting to get to grips with engines. I know a very handy VW restorer who is in the process of rectifying things, but he is busy as a busy thing in a busy place, so any extra help or first hand experience is always welcome in helping me understand... I have sparking points and believe from what he said that I have sparks at my plugs, the starter turns every time, it just doesn't catch after running fine. One day - she say no. Now the fuel pump doesn't pump, but when directly bridged from the coil, it does pump reliably. He's taken my combi relay cover off to check out the innards as that is currently the suspect, with no obvious structural problems noted (though I guess in electricals that doesn't mean that it is working!). The beef is that the part (Part number: 071-906-059 @ VW Heritage) is pretty pricey! Wondering if anyone has had any problems with these relays, has a spare to test if this is the problem (I'll pay for postage here and back), or even buy if you can sell one? Finally - any other genius ideas from first hand that you've found out the hard way? Cheers guys Rob
If he's sure the pump isn't working unless you bridge it then it can only be one of 2 things. 1) you have a bad wire somewhere 2) double relay is duff As you said, you want to hope its 1 as 2 is expensive. However while 1 is cheaper it can be harder to find and more time consuming in the long run. Get him to detach the double relay, (or at least turn it round so he can get to the wires), connect a test light to terminals 88d and 85 and try to start the engine. - If it lights up but the fuel pump isn't working then you most likely have a problem in the wire to the pump. Next step is to connect a test light to the wire connectors going into the pump at the pump end, if no light, it's the wire, if you get a light then the pump is faulty. - If it doesn't light up get him to put a test light between 88y and 85 on the double relay. If it doesn't light up you've most likely got a bad wire to the battery from the double relay. If it does light up then connect a test light to 86a and 85, if it lights then the double relay is bad, if it doesn't light then you've got a bad wire from starter to double relay. Just work through the above systematically and follow each yes / no answer. You have to go step by step and what you are doing by putting a test light on is checking that the current is moving around the FI system. It needs to do this whole process to work, so any break in it will mean your bus doesn't start. Try it and let me know what you get at each stage.
But as mentioned above, check that you are 110% happy with the ignition system as it is what gets the FI going in the first place. Check ignition switch, dizzy, coil, starter motor etc. A spark from a coil isn't a guarantee it's all working. Trust me, I spend weeks searching only to find my ignition switch wasn't grounded.
MadFrankie - that's awesome - will hopefully be able to get this trialled in the next couple of days if he's got some spare time after Camperjam and I will deffo give you the info...
I found this on the last auto that I worked on... worked ok (apart from the dead engine) but I wouldn't have said it'd have lasted much longer... top is the old loom from the double relay to the fuel pump and the starter motor... bottom is me mid-way through making a new section up!!
