Heat/Fuel Issues

[Threehz]

My E30 does not like the heat. I've been trying to pin down this problem since earlier this year with no luck, but I have the symptoms pretty narrowed down now.

If my Bimmer sits in the sun (especially if facing the sun) on a hot day (every day here) she often times has a rough start. RPM will bounce between 500 and 900 almost sputtering dead when it drops low, but eventually settles at a nice 750 to 800 idle. She idles perfectly and drives flawlessly after that.

But, if I do a long run with the AC on (or before I had AC working anytime I worked her super-hard like 30 miles with four passengers in 117 degree heat) in the hot heat she will run fine, but when I go to start her back up, the past week she's been sputtering down and dying. The only way to start her is give her heavy gas while she cranks then use the throttle to keep for at about 1000 RPM until she does the bouncing and steadies out.

Yesterday I did a long run, in blazing heat with the AC on, stopped and had real trouble getting her started, then proceeded to drive up an entire mountain and had to make a stop to let some friends catch up with me. I could get her running if I tried, but the second I tired to take off she would die. I let her cool down for five minutes and she ran flawlessly after that.

The most important thing to note is that the fuel pump was whining like a banshee (low and high variable whining) when she wouldn't run, and I could tell she was bogging when I tried to take off from lack of fuel.

The fuel pump is brand new because the last one gave me similar problems in the exact same circumstances. Recently I've had bogged down power when taking off on occasion and my fuel pump whines like hell when it's hot and she's been running a while or with the AC on. These are the same symptoms that my last fuel pump had before it was really experience bad problems and was replaced.

I occasionally get a 1222 CEL after ten seconds of idle, but that points to about 50 different possible problems..

So far I've cleaned the AFM, ICV, replaced the fuel pump, replaced the fuel filter twice, replaced the spark plugs twice, checked the CPS (looked good, not sure what I was looking for), cleaned every electrical connection under the hood, cleaned the TB, every fuse is fine, and the plug by the firewall is unplugged before someone mentions that ;) Forgot to mention O2 sensor is new as well.

I need help... I have a feeling my new fuel pump is on its way to death (if I don't fix the problem), but I don't think the pump is the problem. I believe the fuel pump's symptoms must be from another cause and the engine's troubles are with fuel delivery from the suffering pump.

Every suggestion will be MUCH appreciated. Thanks.

[Dj Buttchug]

i remember this from another thread. What about your evap system that controls fuel vapors. Is your charcoal canister and corresponding vent lines working properly? high heat might cause vapor lock??? did we talk about this already?

[Threehz]

You know, for some reason I thought vapor lock only happened to carbureted engines, but that makes total sense. Would a bad FPR most likely be at fault?

Any ways to check charcoal canister? I heard about blowing on the line that goes back to the fuel tank to see if it's clogged..?

What should our fuel pressure be at (I see the FPR is rated at 45 PSI), should it be 45?

[mr ilia]

I you problem think is related to gas vapor ventilation.

Try this when necessary, before starting car, open gas tank. The air should in the gas tank and gas lines should start circulating more easily providing necessary ventilation.

Do this test several times just to make sure...

Please report back after.

[Threehz]

I've actually been thinking about doing this, as well as getting my hands on a stock gas cap. For some reason my mind keeps telling me that the cheap aftermarket cap isn't stabilizing the pressure properly, but then I'm asking myself is that even possible?

Thanks for the tip, I'll try it as soon as I have a chance.

[jlevie]

I think you have two problems. The first would be intake leaks, which would be consistent with a rough idle, difficulty in starting that is helped by opening the throttle, and the 1222 fault code. Hoses get softer with increasing temperature and what may be a minor leak when the engine is cold could turn into a major leak when hot. Additionally the DME will command a richer mixture as the engine temperature is lower, compensating somewhat for the intake leak. A smoke test of the intake is the only sure way finding any and all intake leaks, regardless of where they are.

A whining fuel pump is one that is worn or or one that is having to work too hard. This being a new pump (and OE part, right?) we can assume that the pump isn't worn out. But an obstruction in the fuel lines could be causing the pump to have to work too hard. Or the tank may have rust in it, which can clog the pump's intake filter and/or the fuel filter. Pull the level sensor and pump. Then use a penlight to look in the tank while you scrape the bottom of the tank with a stick. If there's a layer of rust you'll feel & see it. The fix for a rusty tank is to remove the tank, acid clean and seal it, or to replace it. Rust is highly abrasive and can kill a pump short order. So the tank is rusty you fix that before replacing the pump.

[Threehz]

I suppose doing a smoke test and completely ruling out a leak is the first priority.

Pump is Beck Arnley (BEC1520993) exact fit replacement, and it is the entire assembly not just electric pump part. I have to assume it's being worked too hard because when I first start the vehicle, before it gets really hot, it doesn't whine at all. The only time it whines is after a really long hard run.

As a note, when I removed the old pump the intake filter on it was pretty clean. I'm nearing an empty tank of gas though so I'll do a check for rust, or debris.

Thanks for all the help and advice!

[eLKuRLy]

Reviving old thread.
I'm having same fuel pump noise/whine when weather is hot. 90 plus degree weather (Vegas). Late mode car with single pump
Fuel pump is an aftermarket pump, about 6 months old. It will be super loud when a/c is on and weather is hot.
No sputtering , just feels like low power on take off. Heavy fuel smell.
There is no rust in the tank. No fault codes.
Any help will be greatly appreciated.
TIA