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Mar 21, 2007 21:33:15 GMT
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As mentioned in an earlier thread, my father-in-law has brought himself a 1987/8 E-reg BMW 520i, he phoned me this morning saying it seems a little heavy on fuel and it's a bit hesitant when pulling away from junctions. Having just got back from driving it (about a 10 mile drive) I can confirm both the above problems, along with a definite whiff of petrol from the exhaust, I also noticed that the temperature guage is not working, although the engine is hot (Normal) but nowhere near to the extent of overheating. There are two sensors on the thermostat housing, the brown topped Temperature sender unit and the blue topped Temperature sensor, am I right in thinking one or both of these might be causing the choke to stay on therefore causing the over fueling problem, or is it something else?  |
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bobz
Part of things
Posts: 343
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Mar 21, 2007 21:54:57 GMT
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Well.... These cars are curse word on fuel anyway, I ran one a bit back and rarly saw 20mpg. The fuel tank itself is huge, about 80 lt IIRC (or 100 Lt if it's got a touring fuel tank) Put a tenner in and watch the needle stay in the same place  It'll be worth checking all the vacuum hoses around the throtle body, and check the dizzy cap hasn't furd up inside. A new cap and rota will cost in about 90 quid, all the hoses are fairly cheep (usaly about 12) and still easy to get from BMW within 2 working days. Have a look on realoem.com/bmw/ it's great for looking up part numbers for all BMWs  |
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Last Edit: Mar 21, 2007 21:56:34 GMT by bobz
Don't plan anything, it'll start raining!
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Mar 21, 2007 22:24:49 GMT
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Well.... These cars are curse word on fuel anyway, I ran one a bit back and rarly saw 20mpg. The fuel tank itself is huge, about 80 lt IIRC (or 100 Lt if it's got a touring fuel tank) Put a tenner in and watch the needle stay in the same place It'll be worth checking all the vacuum hoses around the throtle body, and check the dizzy cap hasn't furd up inside. A new cap and rota will cost in about 90 quid, all the hoses are fairly cheep (usaly about 12) and still easy to get from BMW within 2 working days. Have a look on realoem.com/bmw/ it's great for looking up part numbers for all BMWs Thanks for that, but I still reckon its down to either one of those sensors, if one of them is faulty, it would be causing the choke to stay on and causing the over-fueling. I've driven several BMW's with the M20 engines, in the past and not experienced the hesitation symptoms when pulling away from junctions. I appreciate that they are heavy on fuel, but to use nearly 1/4 of a tank of fuel on a 32 mile round trip with normal driving is a trifle excessive.  |
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bobz
Part of things
Posts: 343
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Mar 21, 2007 23:19:08 GMT
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If it's those 2 sensors that are on the thormastat housing, it'll (IIRC) be the smaller one, I think the bigger one goes to the gauge on the dash, the other to the ECU. might be part number 13621709966, about 20 squids but get the dealer to check  |
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Last Edit: Mar 21, 2007 23:20:28 GMT by bobz
Don't plan anything, it'll start raining!
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brown sensor is temp. gauge.
blue sensor is fuel injection temp. sensor. not going to be a lot from euro car parts or german & swedish.
might be worth checking the timing properly. most places are scared to do it properly, as it should be timed at 5000 revs (yes, really!).
most likely cause of overfuelling is the fuel pressure regulator. take the return pipe off and run the car, fuel should honk out, if it trickles or none comes out, its duff. beware taking it off though, it'll probably have about 5/6 bar of fuel pressure behind it!
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Mar 22, 2007 21:27:36 GMT
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brown sensor is temp. gauge. blue sensor is fuel injection temp. sensor. not going to be a lot from euro car parts or german & swedish. might be worth checking the timing properly. most places are scared to do it properly, as it should be timed at 5000 revs (yes, really!). most likely cause of overfuelling is the fuel pressure regulator. take the return pipe off and run the car, fuel should honk out, if it trickles or none comes out, its duff. beware taking it off though, it'll probably have about 5/6 bar of fuel pressure behind it! As you've said the sensors are cheap, I'll get them any way, at the start of the thread I said that the temperature gauge wasn't working, hopefully this will cure that problem, but I'll check the fuel pressure regulator out at the same time, when I'm up there again next week. |
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Mar 22, 2007 21:33:20 GMT
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if you're still getting stuck after that, feel free to holler my way. I've been an independant bmw specialist for 9.5 years now |
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Mar 22, 2007 21:45:18 GMT
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if you're still getting stuck after that, feel free to holler my way. I've been an independant bmw specialist for 9.5 years now Thanks for the offer, will be going to see the Outlaws ;D towards the end of next week. Will keep you posted. |
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