fuel pump advice -87 325i - BMW Forum

crabbdaddy · 09-10-2010, 07:26 AM

hello,

i have a 87 325i that has a fuel problem when the fuel tank/gauge shows just below 1/4 tank. it starts to loose power, like fuel starvation and the check engine light comes on. you can "feather" the gas pedal and it will pick up a bit but its hit or miss.

if i fill the tank up it runs great and the check engine light turns off, until below 1/4 tank. i have only owned the car for 2 fuel tanks, so just learning the symptoms.

so - from the parts look up the 87 325i has an in tank fuel pump?/!l so i would guess either the fuel pump is getting hot with no fuel to keep it cool, or trash in the tank getting sucked into the screen.

any suggestion or ideas?

im thinking i need to replace the pump! any upgrade suggestions?

appreciate everyone's time...!!!

leadfoot · 09-10-2010, 10:48 AM

I would add two other possibilities: the breather is obstructed and creates too much vacuum in the tank to the point that the pump can no longer suck up the fuel, or the sucking hose is broken and therefore once the gas level reaches the broken point it starts sucking air. Either one would light up the CEL. The vacuum issue is easy to diagnose because you would feel it when you open the tank for refueling.

crabbdaddy · 09-10-2010, 11:23 AM

Quote:

Originally Posted by leadfoot

I would add two other possibilities: the breather is obstructed and creates too much vacuum in the tank to the point that the pump can no longer suck up the fuel, or the sucking hose is broken and therefore once the gas level reaches the broken point it starts sucking air. Either one would light up the CEL. The vacuum issue is easy to diagnose because you would feel it when you open the tank for refueling.

cool... ill check it this weekend. thanks for the idea leadfoot!

crabbdaddy · 02-17-2011, 08:08 AM

revisiting this problem - no pressure or hissing when opening the gas cap --
the problem went away for a while seems due to cool weather, now on warm days its as it was. also have a gas smell in the cabin intermittent. fuel pump is loud.....

today the car will barely idle, Ill try to replace the fuel filter today and then look for a replacement fuel pump.

anybody have a fuel pump replacement write up? cant find my repair manual..

is the fuel pump in tank or external?

i have replaced in tank pumps before, just not on a bmw..

crabbdaddy · 02-18-2011, 06:17 AM

ok - i replaced the fuel filter, lots of discolored fuel came out... throttle response is much improved as well as idle. a 10 mile test drive with no problems, today will be a good test with warmer than usual temps and a 65mile round trip.
one thing, their is a small device just after the fuel pump, almost looks like another filter but its shape is like a enclosed breather cap that's about 1.5".... is this another filter?

terry717 · 02-24-2011, 10:17 PM

at least on my 90 325i the pump is in the tank. I also have changed a few in tank pumps..usually a long process..draining and unbolting the tank, but looking up R & R on this bimmer, you take out the bottom of the back seat pull back a tag of carpet, unbolt a plate and it's all accessible inside the car. Should be a pleasant change from most chevy's I've worked on.

subnoidiloverlode · 02-25-2011, 02:23 AM

look i no this sounds crazy but it worked on mine pull it out of the car it takes 5 min. hook your jumper cables up to your bat. then hook it up in neg. to poss. then poss.to poss. do this back and forth like 5 or 10 times this will free up a frozen or gummed up pump most of the time dount get gas in your eyes it will have 4,5,oz. in them when thay brake

crabbdaddy · 02-25-2011, 06:31 AM

thanks for the replies... i wish i would have read them before dropping the car off at the shop...

a quick update - the fuel filter did not solve the problem. it did improve the throttle response, but on a warm day 78+ after about 35-45 miles the system starves or goes into vapor lock. if you then shut the car off and restart, it may get another 15-30 miles before it does the same...

i was in training all this week so i dropped the car off at a local euro shop before i left to get checked out. ill hopefully find out more today.

so if they have not touched it... ill be pulling the back seat and checking a few things...

crabbdaddy · 03-26-2011, 05:25 PM

ok -- picked up the BMW today and its running 10 times better. had the fuel pump replaced along with related gaskets. no gas smell in the cabin at the moment, the fuel injectors have quieted down... don't really understand that part... and zero hesitation at all throttle positions.

ill be driving it several hundred miles next week, so we will see how she holds up. but, at the moment, very happy with the replacement bosch pump.

im looking forward to 25mpg vs the 15 i am getting in my F150......