Fuel Starving??

#1

Ok here is the rundown. I have an 87 325is. I just got back from 3 days at Shenandoah at Summit Point. I think I have a bad fuel pump. Im getting what seems to be starvation after making hard right hand turns. ( 3 places on that track) I know exactly when it will happen and how long it will last. Like clockwork. Sounds simple. It is worse with less fuel but will still do it with a completely full tank but not until late in the session when the car is hot. As the car gets hot and the session goes on it gets worse, in the same spots on track.

Once the car cools down, and I go out for the next session it runs flawlessley until it gets hot again and then it happens again in the same 3 spots, all after right handers, and without adding more fuel. The car just falls on its face for a few seconds and then kicks back in. It does it at WOT or partial, dosent matter.

Car drove home fine no issues, and runs fine everywhere on track. My question is does this sound reasonable? Could this be an electrical problem? Second, is there a better fix (other than fuel cell) for replacing the stock pump? I would rather fix this only once and I have heard the 87’s have this tendancy with their fuel pumps.
Thanks
Brian Jones

Post edited by: Jones, at: 2006/05/30 09:46

#2

Brian,
This is a common problem, and I’ve fought it with just about every single E30 (M3, 325e, 325i) that I’ve owned.

Your car is an '87, so you probably have the smaller fuel tank, and dual-pump system (one pump inside the tank, and one outside - located under the driver’s side, above the fuel filter). Fuel is siffoned from one side of the tank to the other via a small tube inbetween the saddles of the tank.

The short term solution is to replace both pumps, which will probably cost you a couple hundred (if you get a discount.) It’s my experience that new pumps do a good job, but you might as well view them as wear items. While you’re in there, replace your fuel filter - you never know if it’s clogging the system up.

I really don’t like the idea of replacing the stock tank with a fuel cell. The original design may be crap, but it’s location is money. The rules are open on fuel pumps, and if you’re lucky enough to have the later style fuel tanks, then a dual-in-tank-pump system can really do the trick.

I’ve though about using an aircraft style pickeup, which moves with the liquid. They use tubing that sits right under a float, so the tube moves with the fuel…no experience with these…just ideas.

Good luck!

-Vic
SO #325

Post edited by: victorhall, at: 2006/05/30 10:19

#3

victorhall wrote:

[quote]Brian,
This is a common problem, and I’ve fought it with just about every single E30 (M3, 325e, 325i) that I’ve owned.

Your car is an '87, so you probably have the smaller fuel tank, and dual-pump system (one pump inside the tank, and one outside - located under the driver’s side, above the fuel filter). Fuel is siffoned from one side of the tank to the other via a small tube inbetween the saddles of the tank.

The short term solution is to replace both pumps, which will probably cost you a couple hundred (if you get a discount.) It’s my experience that new pumps do a good job, but you might as well view them as wear items. While you’re in there, replace your fuel filter - you never know if it’s clogging the system up.

I really don’t like the idea of replacing the stock tank with a fuel cell. The original design may be crap, but it’s location is money. The rules are open on fuel pumps, and if you’re lucky enough to have the later style fuel tanks, then a dual-in-tank-pump system can really do the trick.

I’ve though about using an aircraft style pickeup, which moves with the liquid. They use tubing that sits right under a float, so the tube moves with the fuel…no experience with these…just ideas.

Good luck!

-Vic
SO #325<br><br>Post edited by: victorhall, at: 2006/05/30 10:19[/quote]

I have one of the newer style tanks that someone can have free if they want it. It does have a small dent in it, no leaks and came out of my whacked 89 325i. I live near Summit Point 'cause shipping is out of the question
Conventional wisdom is the transfer pump , being cooled by fuel, suffers over the years by having the tank low on fuel, and the pump getting hot. Bentley has procedure to test the volume of the pump displacement but Vic is right about the replacement. Apparently there is a walbro pump that can be made to work in the E30 but I have no personal experience with that.

#4

I was facing the exact same problem last year in my '86-bodied 325i. I verified that the exterior pump (the one on the driver side) was working (or at least sounded like it was working, lol), then i replaced the in-tank pump. The old in-tank pump had a rubber tube (about 1/2&quot; diameter) connecting its lower and upper parts… this tube was located at about the half-full level in the tank, and I believe it was deteriorating. When I replaced the in-tank pump, my starvation problems disappeared.

#5

Thanks for ther help guys. Ill be pulling stuff apart this week to see what I need and check on which tank I have.

Sean, thanks for the offer, Ill look at what tank I have and let you know.

#6

if you look under the car from the rear…look to see if there is a metal tube connecting both sides of the saddle…that is the early tank. I would be happy to see the tank I have sitting around do someone some good.

#7

nasaregistrar wrote:

According to Carter, if your car came from the factory with a two-pump system, swapping to a newer style tank is illegal. (Guess how I know the answer to that question…)

The best trick about the tanks, especially the early ones, is to make sure that you have at least &frac12; a tank at all times. At VIR, with 1/3 of a tank, going down from the rollercoaster into hogpen, my needle swung from half to empty and back again a couple of times. I freaked out and pulled into the pits thinking I had a severe issue (or that I was out of fuel).

#8

Obviously, the fuel tank is not a performance part…but strictly speaking, the car must have it’s original style tank.

Plus, why go to all the trouble of swapping tanks when we all end up racing with the tank about 80% full anyway?

I’m replacing my brake master cylinder and yes, I’m ordering a master cylinder for an '89 325i. I’ve been told that there are different style master cylinders (some might work better for racing) but my car is an '89 so that’s what it gets.

Carter

#9

Brian, did you ever solve the fuel problem? What was the &quot;final answer.&quot;

I’m having the same problem with a '87 car and have replaced the in-tank with new and the exterior pump with a used part. So far , no luck. Any other insights?

New exterior pump on order. But testing a new car/ new ful parts on race day is not smart.

Regards, Robert Patton

#10

I did solve the problem. I ordered new OEM parts. In tank transfer pump, main fuel pump, filter and a few lines. Car has worked great ever since, no problems.

Hope this helps,

Brian

#11

Brian, thanks for the response. With the new exterior pump on order I’m hopeful that is the answer. Now, I just need some long sweeping, fast right hand turns to test. Guess the test will have to wait till ???Any one got a three car hauler?

Regards, Robert Patton

#12

Robert,

The same thing worked for my 87’. I replaced everything; both pumps and the filter per Brian’s suggestion and have not had a problem since.

I was starving at 3/4 of a tank before replacing the pumps.

JP

#13

Jones wrote:

[quote]I did solve the problem. I ordered new OEM parts. In tank transfer pump, main fuel pump, filter and a few lines. Car has worked great ever since, no problems.

Hope this helps,

Brian[/quote]

Encouraging news. I experienced the same problem with my '87 325is on it’s maiden voyage. That darm Feb event is a killer, I jsut ran out of time getting everything ready. I plan on doing the same as you and replacing all of the components.

#14

Since these cars are 20~ years old, I would highly recommend checking the condition of the inside of the fuel tank as well.

As mentioned in another post somewhere, you could have some nasty stuff in there, I think the quote from the thread was &quot;it seemed like the car was trying to pump mud through the fuel system&quot; or something to that effect.

Take a look inside the tank when you are replacing your in tank fuel pump. I used a flashlight, wouldnt recommend using an open flame to illuminate the situation.:frowning:

It would be a good idea to check inside the old fuel filter also to see what you find. I personally havent done this but I am curious as to a safe way to cut this open. Anyone?

The in tank pump does have a mesh screen at the pickup point but fuel pumps and such arent exactly chump change (for me anyway) and I would hate to ruin new ones prematurely because of sucking up the &quot;mud&quot; again.

#15

Walbro makes pumps that seem to be a valid replacement for the OEM stuff

#16

nasaregistrar wrote:

I have a Walbro 255lph in my turbo 5er and it does well (it buzzes a lot though). I had to modify the mounting a little bit b/c it was longer than the one it had, but you could probably find one that’s right if you don’t need the high volume.

#17

Thanks to all…A look inside the fuel tank reveals that it is clean and the baseball bat insures that there is clearance inside the tank. The filter is clean, too.

Mike, where did you get the Walboro pump? Price as compared to the BMW unit which is about $150. A different p/n for a 325i?

Regards, Robert