proper glow plugs

[91surflux]

hey there. i have a 91 2.4 turbo surf. my problem is it wont start. lately its a bugger to start in the morning unless its been plugged in for a few hours(night). when it isnt plugged in it will eventually start after alot of turning it over.but it will run really rough and smoke alot. i mean an embarassing amount of smoke. usually a few minutes. but when plugged in it fires up no problem and no smoke.but the other morning it didnt start at all, and it had been plugged in all night.turned it over till the battery died. so i figure(hope) its the glow plugs. the ones i pulled out are bosch 7v . are these the right ones or should they be a 12v.
thanks in advance.

[NiftyNev]

Should be 11V in a '91. 19850-54090 genuine or Bosch GPT223. NGK also have glow plugs that will suit. There's cross reference info on the site somewhere I think.

Nev