Symptoms of a faulty CDI unit ??

[fredperrybruce]

Hi all,, could you guys give me some idea's of some symptoms of a faulty cdi please.

Scooter want's to die on me when slowing down and coming to a stop ,, only after the scooter has warmed up!!

Changed the stator and checked all the wiring throughout the scooter all seems Ok

New plug/cap/ coil changed also !

[henri]

other than metering it the usual diagnostic of a cdi is to swap it for a known good-un . your symptoms sound more carb/fuel related to me ,with a timing check 1st to rule that out .H

[fredperrybruce]

Cheers H ,,, I'm sure its not a fuel issue now!!

I've changed the fuel tap and pipe and gave the carb a quick boil in the pot along with the jets and gubbins .

The problem seem to start when I left the scoot outside in a real heavy downpour of rain and the wind was blowing the rain into the side where the CDI sits.

My rubber cover for the cdi is pretty knackered so rain getting in there would have been pretty easy .

[sime66]

FPB, I've sort of followed your problems, here and on FB, and it is all sounding very similar to the “is-it-fuel, is-it-elec” conundrum I tackled a couple of years ago. I haven't got time to re-read my threads or go back over yours thoroughly to see how relevant mine are, but here's the two that spring to mind, where you might find some ideas (there's a wealth of info in old threads on this forum; you don't have to start from scratch with every problem encountered – reading old threads is a good way of finding helpful info):

vespa.proboards.com/thread/3724/cutting-out-idling-revving-own

vespa.proboards.com/thread/3831/stator-overhaul

As a side note, I'm sure water up the CDI was at least a contributing factor; during my investigating and solving it (with a new CDI and stator in the end), I came across a tip to smear Vaseline around the top of the CDI; it's a messy solution, but I've been doing it a couple of years now and not had a repeat of the problem.
On your other thread on the same subject, pxguru suggested you check your wires for continuity; here Henri has suggested you check your stator and CDI for resistance with a Multimeter – there's several recent threads on the subject where you can find the readings if you look for them. Their advice will get you well on the way to finding it or dismissing possible causes.
Sorting these problems is a systematic working through of the possibilities until you find the cause; that's what you should be doing, whether it is fuel or elec.
Hope you find it sooner, rather than later; it is a frustrating problem I know.

[fredperrybruce]

Cheers Sime for the info/links ,,


I read your previous threads and by the looks of things I can certainly eliminate some things which you have mentioned.

It's a total ball ache for me as I'm totally impatient and hate fart arsing around.

I took the scooter out 4 times today and after 10 mins of each ride the scooter just stopped almost like it's ran out of fuel but when I pulled the plug it was dead dry and not an ounce of wetness to be seen , but after every engine fail I also checked the spark and it was always there!! ALWAYS

I did notice one thing today my carb tray was totally warped and so was my carb body which was definitely not helping matters that's due to me being over zealous on the socket set.So I swapped them both for better ones and it sounded better with a better idle .. Was gonna take the scoot out again but then sods law I realized I had a flat back tyre !!! Bloody great ... Until next weekend I cant do anymore .