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Discussion Starter #21 (Edited)
First, thanks to all for the helpful posts and threads. My frustration with the situation can sometimes leak into posts.

Second, I got back to my car and installed the expensive big black relay in the trunk. Relay works--voltage is now present at the pump--but the pump did not come on. Old relay did not click. New relay does. No surprise. I already ordered a pump and filter and they just arrived. I plan to go back to the car for install tomorrow. Odd that both the relay and pump would fail unless the failed pump somehow also created failure of the relay. In all this the 25A fuel pump fuse is still intact. Makes one wonder if the current rating is best or if a lower current fuse should be used.

A couple of questions:

1. Unfortunately, I have a nearly full tank of fuel (I know a rarity in an E39 M5). How best to siphon it off? How much until it is at the level of the fuel pump cover under the seat--or can I just siphon from there? I seen videos that show siphoning from the fuel pump cover, but am not clear how high the cover for the fuel pump is relative to the tank overall. Looks to be easier to siphon from the fuel pump cover.

2. I want to get the beast home then install the fuel filter--about 23.5 miles from home (I know since I did the 47 mile round trip on my bike expecting to drive the car home after relay install). I think that install could wait until I get home unless there was some really bad gas I got. More than likely the fuel pump failed a normal old age death though (about 135,000 miles)


Thanks
 

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The relay should not click! It is solid state, no moving parts. Do yourself a favor and use that thread I linked you to.
Yes good idea to wait to put the filter in, unless it is totally plug but I doubt that. You should always run a pump for a bit into the old filter so any debris moves to the filter, then change it out, no sense making your new filter dirty seconds after install.
 

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Considering his was in fact dead how would he know? It was discussed later in the thread.... Wading through misinformation is a feat unto itself. Reading any thread through to completion is important in any forum. Never heard one click, never felt one click, although you can feel something, but it is not a click. There are several threads here where we pulled them apart and showed how they work, no click. There are other relays beside it that might click and confuse you, but there is nothing in the big black on to go click.
Although a normal relay is an electro magnetic switch, this device is not that at all.
 

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Discussion Starter #25
Thought I would close this out with the results. Not surprisingly, the issue was the fuel pump and the relay. The order of failure is not known. I also want to share a general comment about parts. As we know BMW sources parts from various suppliers that meet their specifications and standards (OE and OEM). As most know, the OEM fuel pump can be significantly more than a fuel pump that claims to meet the specifications of the OEM item. There are some places where that risk may be worth considering. This is not one of them, and I made a rookie mistake (that I full well know be now) to go with a cheaper alternative that included an adapter for the electrical connections. I am sharing this embarrassment to prevent someone else from making this error.

Red Flag #1: When the pump arrived, I noticed it was about 2/3 the size of the one I removed.
Red Flag #2: The adapter seemed like it would work, but this made the wiring longer, so to make it fit right, it needed to be wrapped around the hose.

Given my situation of being stranded, I decided to go ahead and install anyway. After install, the problem was not resolved. After frustrating review of other potential areas, I decided to pull the new pump out given that the connection showed it was getting power. The adapter terminal disconnected, I suspect during the yoga required to get the part in.

I immediately ordered an OE part and when it arrived, installed it. Car started after about 3-4 cranks.

Incidentally, I returned the small pump without issue.

Thanks again to the members on this board for the help.
 

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People want to save money on parts so they buy the cheap manufacturers instead of genuine or the original manufacturer. Then they come back to the forum saying the new part doesn’t work. I gave up stating why to the never ending amount of bmw owners doing this...

There should be a sticky on these forums saying “buy cheap parts equals wasting money and a car not operating correctly.
 
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RobertDenali
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