Author Topic: Fuel pumps (Read 2911 times)

Ramblin MAn · « **on:** August 10, 2009, 02:39:57 PM »

Hey guys, I'm finally going to be an "official" member. Picking up a white on black 91 318iS this weekend that is practically being given away. Police auction special.

They could not figure out the fuel pump arrangement and so the previous owner it never got titled. I went and had the title work done and the docs sent to me. As soon as they arrive we will go do the exchange.

Anyway, my M42 docs that I got from here last year show the in tank pump and the external pump which is what I'm used to seeing with my e21s and my 84 e30. However, everywhere I look I only find in tank pumps unless I look for the number which was refferenced to the 635's pump on one of the parts sight I looked at.

Did they eliminate the external pump and go with just high pressure in tank pump or do I need to find the correct external pump and does anyone have any recommendations.

thanks

I'll post some before and after pics after I pick it up.

twright · « **Reply #1 on:** August 11, 2009, 08:39:49 AM »

Yes. The later E30's only had one high pressure fuel pump in the tank.

SonomaGTLN2 · « **Reply #2 on:** August 11, 2009, 03:37:56 PM »

Ironically I was able to purchase a 318iS pump at my local auto parts store and fabbed it up to fit on the original E21 in-tank mount with little pain. If you need a replacement pump, Autozone or Advance should have one that shouldn't be too expensive.

alphaphaedrus · « **Reply #3 on:** August 11, 2009, 08:08:19 PM »

I'm glad someone finally posted a fuel pump issue like this one. I had a failing fuel pump in my 91 318i and I sourced an aftermarket pump from autozone (trying to cut costs). The pump looks entirely different and I don't have a fuel pump gauge to tell if it's pumping at a lower pressure (but I think it is). The brand is Airtex. it's an in-tank pump like the oem, but it seems like a smaller motor and lacks the odd in-line bellows on the output. OH and I realized after some hair pulling that the intake and outlet barbs are reversed. I have tried to rig it up (switched lines at the pump, changed electrical connection) to work but it seems it won't. Any ideas (I'm at the point of just biting the $250 bullet and getting a proper oem one. I get spark, smell fuel after quite a bit of cranking, have verified fuel coming out of the line at the rail. Stupid problem to end up in for a hundred dollar difference but money is tight. Anyone ever run into this?

Ramblin MAn · « **Reply #4 on:** August 12, 2009, 09:39:11 AM »

Sounds like you have the high volume low pressure feed pump for the two pump setup. The book says 3bar which is 42-45 psi. I don't remember how many liters per hour.

You can make yourself a fuel pressure gague pretty cheap for testing. Put it in line back at the pump just to get your readings. Home Depot or Lowes will have all the parts you need except the gague which you can get at any autoparts store.

Also if you have a Harbor Freight Tools I got my fuel pressure tester for something like 12 dollars on sale. It was a no brainer.

For what it's worth, I have never had to replace a quality part like a bosch fule pump. I would expect VDO to be the same way. If you plan onkeeping the car it might save you in the long run.

Ramblin MAn · « **Reply #5 on:** August 12, 2009, 09:47:45 AM »

So here is the 300 dollar question. Can I take the two pump assembly I have on my 84 and fit it to the 91? Are the mounts for the external pump on the later cars? The 84 has enough other issues that I think I can part it out and be ahead at the end.

alphaphaedrus · « **Reply #6 on:** August 12, 2009, 10:50:22 AM »

Thanks for the tips. I'll check on it. I have some ebay auctions that should go then I can just get the right pump.