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.


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[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.