Last week my previously reliable st4 wouldn't start. After about 30 minutes of re-trying it did. This week it won't start at all. I have taken the plugs out and determined no spark. It cranks over fine and all the electrics work. Have checked all the fuses and all seem fine. I have a datatool veto plus alarm on it. Normally if it wont disarm, I cant turn the starter. The battery voltage was low on the keyfob so I have changed that, but no difference. Two questions: 1) Any suggestions as to where/how to troubleshoot? known common problems etc. 2) I dont really see the point of an immobiliser on a bike that's not worth a lot of money, and the previous guy had problems with (there is no audible alarm on it). I've seen threads on removing datatool s4 alarms. Is the veto plus any different. Anyone removed one?
A good aftermarket immobilisers usually breaks 2 circuits to prevent the bike starting, the starter circuit and the ignition/fuel circuit. So even if it allows the starter to operate it may be interfering with the ignition circuit. Does the fuel pump run at switch on? If it does it is unlikely to be the immobiliser that is preventing it from starting. Immobilisers usually prevent the fuel pump relay from operating as this kills the fuel pump, injection and sparks. If the immobiliser was active the pump wouldn't run at switch on. Can you hear the pump running while the engine is cranking? If not the problem could be the crank sensor. I have also seen no spark due to a poor battery. The bike cranked but the voltage dropped such that the ECU shut off, so the relay didn't operate with no sparks, pump nor injectors.
Thanks for the input guys. I have swapped the battery, and jumped it from my car battery, still no sparks, so I don't think its a battery issue. When I switch the ignition on I can hear the fuel pump go for a few sconds then go silent. I'm guessing that's normal. I'll look in my service manual about the crank sensor. Is it a known problem. After it wouldn't start the other week it then ran perfectly for the 25 mile ride home. My intuition tells me thats an intermittent (electrical fault), hence my suspicion about the alarm, but if the fuel pump and ignition are linked it may rule that out.
Looking at your second question I think you are totally right, and they are fairly easy to remove. Often the worst part of it is removing panels and manoeuvering the loom for access and reinstating/repairing. As the loom wires are obviously colour coded, it makes matching up the alarm system targeted intersection joints quite easy. You might need some additional wire of similar quality to the loom wire and of course some good quality heat shrink tube. I must have done over half a dozen by now and have all been straightforward, completed within around an hour at a leisurely pace.
In most cases removing an alarm is a relatively straight forward job. The alarm will have connections to earth, battery 12V, switched 12V and right and left indicators. These will be Tee-d into existing wires and can be cut. There will also be connections to the starter and ignition (fuel pump) circuits. These break the existing circuit, route into the alarm and out again. In this case you need to find both ends of the original wire, cut out the alarm connections and re-instate the original wire. Attached is a colour wiring diagram for the ST4 that you might find useful.
Sorry if I seem to have offended you. Apart from the first sentence, every thing I said was additional information which I thought could be useful to the OP.
Id have to say pull the alarm also....ive never seen anything apart from bad stuff when alarms are fitted....every year for the last 6 years of going to the TT at the ferry port theres always : 1. A bike sitting on its own with the alarm going off 2. A bloke messing around with his bike, with the alarm going off. 3. A Bloke try to start his bike as the alarm has flattened the battery. Any bike ive bought that has had a alarm fitted - the alarm has been removed the next day....the last bike I bought (my evo sp) the bloke I bought if off said after id bought it "you'll probably want to remove that mate as its been more hassle than its worth" Just trace all the wiring from the alarm and desolder the added wire, stick a heatproof shield on, resolder, and then seal with a hairdryer. I found in the past it depends on whose wired it in and to what extent - my z1000 took about 30 mins to remove (about 6 wires or so) the hyper was a nightmare (10+ wires) and he'd stripped the loom right back and wired it all in really difficult to get to places so that was almost half a day plus I had to order some of that canvas tape to reseal the loom back up.... The only thing I think alarm wise might be barely acceptable is a factory fitted integrated jobbie....if you want something to make a noise if its moved then I would say a disc lock with the alarm on it, that kind of thing, something that's independent of the bike...2 cents in..
Thanks for all the advice guys. I removed the alarm/immobiliser this morning. Took about 20 minutes with the bodywork off. The veto connects into the wiring looms at plug junctions, so not even any wires to solder back in place. Took about 20 mins. There are now sparks to the spark plugs and runs great. Still don't understand why the fuel pump worked but the ignition didn't as the wiring diagram shows it as off the same feed. Ayone after a slightly dodgy used veto plus immobiler?.....
Think I spoke too soon. I Made 2 successful short trips yesterday for which it started. Third time 15 miles from home it wouldn't start again. I tried repeatedly and at about 10 minute intervals, and after about the 4th interval it burst into life, just like a few weeks ago, and has been fine since, so it appears I have the dreaded intermittent electrical fault, Maybe removing the immobiliser was a coincidence. Any thoughts on how to diagnose, or narow it down greatly appreciated. I'm nervous to take it out now for fear of being stranded....
Derek, For £17 that may be worth a try. My st4 is a 1999 model. are all crank sensors the same do you know? I've read on a fiat forum about them failing when engines get warm, but that's kind of the opposite to the pronblem i may have. I've found the sensor on ebay Engine Crankshaft Position Sensor Fiat Punto Panda Doblo Cargo Bravo Brava Crank | eBay Is this the right one?
Have you checked the wiring to the stand . Mine wouldnt start one day and a help full watcher on fiddled with the stand wiring and it fired straight up . Had it fettled properly and it was ok from then . That was on a 2000 st4s . Whilst I had the problem starting was very intermittent sometimes it would start and sometimes it wouldn't .
As far as I can tell, there is no wiring or sidestand cut out switch, not sure if my nodel came like that or if it's been removed.
