1990 Golf Gti 16v Bad Fuel Consumption

dhillman · #1 11-30-2005, 09:27 AM

Hi, we have two gti 16v's both 1990. Both run great but one gets 35mpg all the time, the other one just 25!!!!!! Any ideas what I can check, we are no mechanics and do not trust the VW dealer on older cars!

veedubmechanic · #2 11-30-2005, 04:16 PM

you done tune ups on both? plugs wires, cap rotor. fuel filter air filter.

how about timing belt?

dhillman · #3 11-30-2005, 05:23 PM

Thanks for this. Both are totally unmodified but one has very low mileage and has had timing belt done (good fuel consumption).
Both run a bit rough when cold but only for a few seconds.
Will check fuel and air filter, and that the timing belt is OK. One more thing you might know. On mine, when warmed up the revs drop below 500 when you depress clutch and brake ie in traffic. Sometimes they shoot straight back up to 1000 and then stay there, other times it stalls!
Was fine til local garage did plugs etc (hence my reticence about going to VW dealers!).

GTI325 · #4 12-08-2005, 04:02 PM

Quote:

Originally Posted by dhillman

Thanks for this. Both are totally unmodified but one has very low mileage and has had timing belt done (good fuel consumption).
Both run a bit rough when cold but only for a few seconds.
Will check fuel and air filter, and that the timing belt is OK. One more thing you might know. On mine, when warmed up the revs drop below 500 when you depress clutch and brake ie in traffic. Sometimes they shoot straight back up to 1000 and then stay there, other times it stalls!
Was fine til local garage did plugs etc (hence my reticence about going to VW dealers!).

The fluctuating idle sounds like a Fuel Pressure Regulator, specifically the diaphragm type that's next to your fuel dizzy on top of the air box. It's cylindrical in shape and has a line running out the back of it, and into the side of it. If your car is a 2.0L 16V, which I believe it is in 1990, then it's got the motronic ignition, and that part costs a pretty penny, I'd suggest finding a used one.

dhillman · #5 12-09-2005, 04:43 AM

I think you're right about the regulator thing! I am trying to get a new one as we speak, £150!!!!

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