M42club.com - Home of the BMW E30/E36 318i/iS
DISCUSSION => Engine + Driveline => Topic started by: achtungE30 on April 19, 2006, 02:56:49 PM
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I noticed that if I let the car sit awhile, it will crank for a good 5-8 secs before starting. I'm wondering if the starter or a failing fuel pump could be the culprit?
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what's awhile?
have you checked the loaded voltage on the battery
(turn on the lights for a minute with the car off, then meter the battery?)
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will try that
a while = more than 2 hours sitting. i mean once in a while, it'll crank 2-3 times then start, others it'll take 5-7 seconds to start, lots of cranking.
*edit*
I just had the car parked not even 20min and it took 8 secs to crank this time...
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I also notice I hear my fuel pump audibly at idle...
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Sounds like a leaking fuel pump check valve most of these screw into nose of bosch fuel pumps. replacements available from mercedes or vw dont know part#s and could not find in my bmw etk.
hope this helps
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I also notice I hear my fuel pump audibly at idle...
Mine is audible too. From what I've read, it appears this is fairly normal and they they can run like this for a long time.
The fuel system is pressurized, so the pump only runs when the system needs pressure, then it shuts off. So if it runs all the time there might be something wrong.
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Nooo way can this be normal...I know if I bought this car in 1991 brand new and that thing was audible, i would not be a happy camper...
Anyone have a pic of the check valve...I was considering going to autozone to pick up a generic brand fuel pump compatible for the car since the OE ones are crazily priced.
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Nooo way can this be normal...I know if I bought this car in 1991 brand new and that thing was audible, i would not be a happy camper...
It is normal to hear a hum:
http://www.esatclear.ie/~bpurcell/318isfaults.html#fuelpump
http://www.bimmer.info/forum/showthread.php?p=67867
Humming pumps can go for hundreds of thousands of miles. That's not to say that yours is ok; if its crazy loud or you hear it all the time then you might have a problem. Otherwise, I would start looking for a problem somewhere else, or else you will be wasting your money. Most guys who have a problem like this and replace the fuel pump find that it does not solve the problem (I would guess the check valve or a leaky injector). Also, if you do end up needing to replace the pump, I would stick with Bosch. Word on the street is that generic pumps only last a few months.
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I believe I remember that this is also a sympton of whatever it is called in the FI (pressure accumulator???) that provides high pressure fuel to the injectors for the first several cranks ....
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...I was considering going to autozone to pick up a generic brand fuel pump compatible for the car since the OE ones are crazily priced.
I would highly recommend spending the cash on the Bosch pump if you need one. I went through this crap last year with my son's VW. I thought I would save some $ and by a generic pump. The Bosch puts out ~65-70 pounds of pressure and the generic only put out about 20 lbs which is no where near enough pressure to open the injectors. I found this out after about a week of looking for another problem that didn't exist. I ASSUMED that since the pump was new that it was good and the proper one. BMWs are quality cars and deserve quality parts.
Sorry to preach but I hate to see others make the same mistake as me.
Just my 2 cents, Dan.
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Where did you find a Bosch fuel pump? All the pumps I seen have been VDO units.
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As a retired BMW + MERCEDES tech, I can tell you the aftermarket pumps dont work well on our cars. do you have a Pick n Pull or like wrecking yard in your area? if you go to a self serve yard & look at the pumps on cars that use the same type of injection as your 318 (VOlVO, SAAB, AUDI, VW PORSCHE, MERCEDES) it is amazing the number of new or slightly used pumps you can find. just match up injection type, fitting size etc. The pressure/volume specs for bosch pumps really dont differ that much and the m42 being a small displacement 4 cyl is on the low volume side of the scale, so most others are higher volume anyway. A higher volume pump wont affect anything really because the injection only meters a timed pulse to the injectors which can only flow a preset amount based on pressure, any excess is rerouted back to the tank. As for noise, these pumps made noise when they were new, they got noisier when hot, when they get a little wear in them they do get louder though. Not sure which check valve your car is using, as there are at least 3 different versions of bosch pumps that were installed in m42's. Look at the outlet side of the pump there is probably a short fitting that screws into the pump and the lines attach to that if so pull it out and look at it, it will have a ball bearing and spring in it, that is the check valve, some pumps use a valve built into the pump but have a provision to add the screw in type. I have put many screw in valves in pumps that already had an internal 1, it wont hurt anything. back to Pick n Pull, a check valve out of almost any bosch pump will work if you have the afformentiond type. As to a fuel accumulator, it is merely a diaphragm and spring that takes out the fluctuations in fuel pressure and acts as a reservoir for fuel pressure, they rarely go bad in my experience. but if there is no working check valve to keep the pessure on the accumulator, the accumulator wont work.
hope this helps
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Thanks for the input guys....I have a hookup at a shop that has an account with worldpac, picked up a VDO pump new for about $170, threw it in and the sound went away. Also the car starts about 2-3 cranks less than before, but still a little long. Gonna look into cleaning the injectors while I have the intake manifold out and see where im at after that.