Fuel pump dying?

[thayerplay]

Before I spend the money on a new fuel pump, I am hoping someone can offer some incite into my issue. I have an apparently common e30 problem: a quick blip of the throttle causes the engine to dip then it catches but then dip again before leveling off at idle. With my rear seats and cover plate removed, I can hear the buzz of the fuel pump dip when I hit the gas. I don't think it's the relay.

TIA!

[BergerNJ]

Search this forum please. Im a noob compared to EVERYBODY here and i know all of the answers you are looking for, BY SEARCHING.


Common mistake: simply throw parts at the car.
Another common mistake: post a thread without searching.

Smoke test the car or else you're wasting time.


SEARCH BUTTON SEARCH BUTTON SEARCH BUTTON SEARCH BUTTON SEARCH BUTTON SEARCH BUTTON SEARCH BUTTON SEARCH BUTTON SEARCH BUTTON SEARCH BUTTON SEARCH BUTTON SEARCH BUTTON

[Quadrajet]

If after your search, if you cannot resolve your problem, state model and year of E30, it really does help.

[thayerplay]

I've actually searched the hell out of this issue. The problem is there are 100 different answers, but nothing definitive. Before jumping into new parts, I wonder if anyone can diagnose this specific problem. I've already changed the plugs, o2 sensor, injectors, fuel filter, ICV, and cleaned the fuel pump mesh. I have had a smoke test done with no leaks. The TPS was giving me problems, but I adjusted it so I hear it click now and it idles fine. Car is a 1991 325i m20 engine


Check out this video for the exact same symptoms I am having.

https://www.youtube.com/watch?v=Sa2HnJ4EYgg

thanks!

[Fusion]

Fuel filter and fuel pump relay are a couple bucks and atleast you won't be as surprised as I was when the 25 year old relay died. Also take the fuel pump out and have a look at the filter sifter thingy on the bottom of it. Could be crudded up and the fuel pump can have a har time picking up fuel.

[Quadrajet]

I could be a long shot, but I didn't see you mention it. Did you check the cap and rotor? What kind of plugs are you running? I found when I had my eta, that it definately did not like platinum plugs.

[thayerplay]

I could be a long shot, but I didn't see you mention it. Did you check the cap and rotor? What kind of plugs are you running? I found when I had my eta, that it definately did not like platinum plugs.

The cap and rotor don't look too bad, perhaps I should replace them for good measure since they're not too expensive. I had this problem before replacing the plugs, but they are cheap autolites.

Fuel filter and fuel pump relay are a couple bucks and atleast you won't be as surprised as I was when the 25 year old relay died. Also take the fuel pump out and have a look at the filter sifter thingy on the bottom of it. Could be crudded up and the fuel pump can have a har time picking up fuel.

I tried a few relays from junk yard cars, but maybe some new relays can at least rule out that being the culprit before I did into my pockets for a fuel pump. I took the fuel pump out and cleaned the pickup filter, no improvements.

[Quadrajet]

Autolites are best left to blue oval products.

[jlevie]

That sounds like a sticky or bad ICV, but it could just as easily be a bad or misadjusted TPS or even a bad DME.

[thayerplay]

That sounds like a sticky or bad ICV, but it could just as easily be a bad or misadjusted TPS or even a bad DME.

I replaced the ICV with several used ones to cross check that it wasn't the culprit. I cleaned the current one well and it vibrates before starting the engine. I have a donor TPS that I can try, but I doubt that's the problem. At this point I might take it in to a shop to have it diagnosed...

thanks for the help, though, guys!

[ff_medic]

on the e30 there are 2 fuel pumps. another that runs along the frame. i had that one die on me

[Quadrajet]

He has a 325i, which I believe, only have the in tank hi pressure pump. That's why I asked him to state his model earlier.