M30B35 Swap No Power to Fuel Pump

[sebastianroher]

Verified relay is good and even bypassed it with a fused jumper. Still won't get voltage to the pump. I can run a hot wire to the battery and the car will start. Does anyone have any ideas on what could cause this? 1989 325i w/ M30B35 out of a 91 535i

[D3R3K]

89 only has one fuel pump, you need to trace your wire back from the relay to the fuel pump and find where is may be bad/damaged, you may have a new wire. you can try to diagnosis the wire using a multi meter and see if you have power coming out of the relay, or if you actually have a bad wire, this site has the wiring diagrams you need

https://www.armchair.mb.ca/~dave/BMW/e30/

[sebastianroher]

89 only has one fuel pump, you need to trace your wire back from the relay to the fuel pump and find where is may be bad/damaged, you may have a new wire. you can try to diagnosis the wire using a multi meter and see if you have power coming out of the relay, or if you actually have a bad wire, this site has the wiring diagrams you need

https://www.armchair.mb.ca/~dave/BMW/e30/

Yeah there is power coming out of the relay (verified with a test light as my multimeter is broken). It's just not making it to the fuel pump fuse for some reason. The worst part is that it's intermittent and doesn't happen all the time. I'm about to wire in a painless fuel pump relay and be done with it, but I'd prefer to retain the factory wiring if possible.

[D3R3K]

Yeah there is power coming out of the relay (verified with a test light as my multimeter is broken). It's just not making it to the fuel pump fuse for some reason. The worst part is that it's intermittent and doesn't happen all the time. I'm about to wire in a painless fuel pump relay and be done with it, but I'd prefer to retain the factory wiring if possible.

only way would to follow the wire all the way back and find the bad spot and repair it

[sebastianroher]

only way would to follow the wire all the way back and find the bad spot and repair it

I know and I will do that once I get a new multimeter. With a larger walboro pump, would you just recommend running a new relay and wiring to the pump instead?

[D3R3K]

I know and I will do that once I get a new multimeter. With a larger walboro pump, would you just recommend running a new relay and wiring to the pump instead?

i installed a wallboro 255 for a friend on the factory wiring with no issues, dont think its necessary, unless your going with bigger pump than that

[sebastianroher]

Yeah I think it's actually a little smaller than the 255. I don't intend on going bigger as this motor is just NA with headers and a chip.

[D3R3K]

Yeah I think it's actually a little smaller than the 255. I don't intend on going bigger as this motor is just NA with headers and a chip.

you should be fine with the stock wiring setup, as long as you get it squared away lol

[It's Soda Not Pop]

check fuse #11. If you using a walbro 255 then you'll need to run a bigger fuse than the 7.5a that's in there(15a is what I use). Also if you have a 13 button OBC that might causing your no fuel while cranking issue. Check all your grounds on the engine as well. There has been few guys on here with similar issues as of late. So if you search around this forum you'll find them. Some guys had a main relay issue(I had this issue along with popping fuse #11), some guys had a OBC related issue, some guys had a grounding issue.

[sebastianroher]

check fuse #11. If you using a walbro 255 then you'll need to run a bigger fuse than the 7.5a that's in there(15a is what I use). Also if you have a 13 button OBC that might causing your no fuel while cranking issue. Check all your grounds on the engine as well. There has been few guys on here with similar issues as of late. So if you search around this forum you'll find them. Some guys had a main relay issue(I had this issue along with popping fuse #11), some guys had a OBC related issue, some guys had a grounding issue.

So I figured my issue out. First was that the previous owner switched relays so I was jumpering the wrong damn relay Once that was sorted I discovered a loose/slightly corroded terminal on the power distribution block. I removed them and wire wheeled them and re-installed them. After that she fired right up!

So I had been having a high issue (1100-1200 rpm) so I found some information on a TPS adjustment. I did that and she idles much lower now but has a slight hesitation on acceleration so I'm wondering what else I can look at to try to clean that up some. I love old cars, fix one thing and in the process you find something else that needs to be addressed!

[It's Soda Not Pop]

So I figured my issue out. First was that the previous owner switched relays so I was jumpering the wrong damn relay Once that was sorted I discovered a loose/slightly corroded terminal on the power distribution block. I removed them and wire wheeled them and re-installed them. After that she fired right up!

So I had been having a high issue (1100-1200 rpm) so I found some information on a TPS adjustment. I did that and she idles much lower now but has a slight hesitation on acceleration so I'm wondering what else I can look at to try to clean that up some. I love old cars, fix one thing and in the process you find something else that needs to be addressed!

The hesitation could just be the AFM. I'm not saying it's bad. I'm saying that if you are used to more modern cars and/or engines then the primitive AFM is going to feel slightly sluggish.
I use SSSquid tuning's MCK (maf conversion). At least for me I feel that the throttle response is a lot better(on a M20 that is). These are old engines that are bit lazy.

[sebastianroher]

The hesitation could just be the AFM. I'm not saying it's bad. I'm saying that if you are used to more modern cars and/or engines then the primitive AFM is going to feel slightly sluggish.
I use SSSquid tuning's MCK (maf conversion). At least for me I feel that the throttle response is a lot better(on a M20 that is). These are old engines that are bit lazy.

I was reading that it's basically the same setup for m20/m30.... do you really feel like it was worth the money spent?

[It's Soda Not Pop]

I was reading that it's basically the same setup for m20/m30.... do you really feel like it was worth the money spent?

I do. Give them a email and they will give you the rundown of it all. But for me I feel it was worth the money, especially if you are staying with the stock DME.