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xsquared_uk · 02-13-2010, 04:32 AM

Hi all! I wonder if anyone could help me out a little, I'm new to the forum and also to the E30. I bought an 89 325i Touring last week, it's a great car but the one problem seems to be the fuel economy. I filled the tank to halfway and only got about 75 miles from it! Even our 4.2 Jag does better than that. I haven't yet investigated, but I wondered if there were any common faults or things to check on this engine? It idles smoothly but I think it is idling too fast, but only a little. The exhaust does smell a little of petrol, perhaps it is running too rich. When you set off from a standstill and put your foot on the gas, it sort of hesitates for a second before the power kicks in - I think this is the engine rather than the auto box. Oh, and the temperature gauge doesn't work at all, I read online that if the thermostat is faulty then the engine management might be thinking that the engine is cold all the time and overfuelling? I know this is a bit of a vague question, but I'm still relatively new to mechanics so I'd like to learn how to do this kind of diagnosis and any help gratefully received!

**Blackice** · 02-15-2010, 02:22 PM

I have heard that this can be a bit of a headache to sort out.....

The first thing I would check, is the seal on the fuel pump, remove the rear seat and have a look for leaks on the pump as well the fuel lines.....

Does the car smell rich ?

You could also try lifting the pedal off the floor, at lest once in a while

xsquared_uk · 02-21-2010, 07:56 AM

Hi, thanks for the reply! The exhaust perhaps smells rich, but there isn't any fuel smell in the cabin or coming from the engine bay - my Alfa had a split fuel line and you could smell that a mile away. I think after further driving that the exhaust might be blowing, that could have something to do with it.

Shocka · 02-23-2010, 01:18 AM

Id check your 02 sensor. Try unplugging it while running and see if there is a noticeable change. If so, id replace it. Hows the maintenance stuff, airfilter, plugs, cap,rotor, oil? You should buy a bentley manual for it. It will save you thousands of dollars and hundreds of hours. Theyre pretty user friendly cars to work on.

02-13-2010, 04:32 AM	#1 (permalink)
xsquared_uk newbie Name: Jimmy Joined: Feb 2010 From: Bradford Posts: 2 iTrader: 0 Thanks: 0 0 Times in 0 Posts	Poor fuel economy - E30 325i Hi all! I wonder if anyone could help me out a little, I'm new to the forum and also to the E30. I bought an 89 325i Touring last week, it's a great car but the one problem seems to be the fuel economy. I filled the tank to halfway and only got about 75 miles from it! Even our 4.2 Jag does better than that. I haven't yet investigated, but I wondered if there were any common faults or things to check on this engine? It idles smoothly but I think it is idling too fast, but only a little. The exhaust does smell a little of petrol, perhaps it is running too rich. When you set off from a standstill and put your foot on the gas, it sort of hesitates for a second before the power kicks in - I think this is the engine rather than the auto box. Oh, and the temperature gauge doesn't work at all, I read online that if the thermostat is faulty then the engine management might be thinking that the engine is cold all the time and overfuelling? I know this is a bit of a vague question, but I'm still relatively new to mechanics so I'd like to learn how to do this kind of diagnosis and any help gratefully received!

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02-15-2010, 02:22 PM	#2 (permalink)
Blackice Moderator Name: Dave Joined: Oct 2007 From: North Vancouver Posts: 1,088 iTrader: 0 Thanks: 43 47 Times in 46 Posts Blackice's pictures '91 BMW 318i '91 BMW 318IS	I have heard that this can be a bit of a headache to sort out..... The first thing I would check, is the seal on the fuel pump, remove the rear seat and have a look for leaks on the pump as well the fuel lines..... Does the car smell rich ? You could also try lifting the pedal off the floor, at lest once in a while

02-21-2010, 07:56 AM	#3 (permalink)
xsquared_uk newbie Name: Jimmy Joined: Feb 2010 From: Bradford Posts: 2 iTrader: 0 Thanks: 0 0 Times in 0 Posts	Hi, thanks for the reply! The exhaust perhaps smells rich, but there isn't any fuel smell in the cabin or coming from the engine bay - my Alfa had a split fuel line and you could smell that a mile away. I think after further driving that the exhaust might be blowing, that could have something to do with it.

02-23-2010, 01:18 AM	#4 (permalink)
Shocka Senior Member Joined: Jun 2008 From: Vancouver Posts: 362 iTrader: 0 Thanks: 4 11 Times in 10 Posts	Id check your 02 sensor. Try unplugging it while running and see if there is a noticeable change. If so, id replace it. Hows the maintenance stuff, airfilter, plugs, cap,rotor, oil? You should buy a bentley manual for it. It will save you thousands of dollars and hundreds of hours. Theyre pretty user friendly cars to work on.

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Poor fuel economy - E30 325i