Hard start troubleshooting

Hi again,
Just looking for some thought on my '90 325I and this issue I have starting it up.
The car usually takes five to ten seconds of cranking to start-- and when it finally starts it takes two or three seconds to reach an idle rpm.
The hesitation to start is more evident when the engine is cold, but it seems that even when its warm I can leave it sitting for ten or fifteen minutes and it still hesitates to start.
So I think the starting problem is probably fuel/air related, and not so much coolant temp and so on (as per Haynes).

If you've had a similar issue with resolve, i'd love to hear it.

Thanks in advance,
Chris

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fuel is probably draining back into the tank. but cleaning the icv and checking for vacuum leaks isnt bad either

Why and how would fuel be draining back into the tank?

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after it sit for a few hours, take the fuel line off of the inlet of the fuel filter or fuel rail. if fuel is present and under pressure, its something else

What will I need to change if there is no pressure?

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add a check valve. someone on here sells a kit. it was over 2 years ago so i cant remember a name

Downhiller, you're awesome. That is exactly what it was. I disconnected the fuel line at the rail, and no fuel. I looked everywhere for the check valve kit - that steve haygood fella is out of business or something, but I found the kit on BMAParts.com - I hope someone else can use this thread too... here's the info:

Buy ($7) from:
http://www.bmaparts.com/item.wws?sku...r=BMW&weight=1

Part type:
bmw retrofit check valve kit 16 14 9 068 988

Resolved from original Steve Haygood part: check valve p/n 16149068988 (no longer available from haygood?)

im sure any 3/8" fuel injection check valve will work.

Got the kit, installed the check valve, and fuel now sits at the fuel rail (as expected) but it still takes forever to crank over...
Fuel pump is audible when I jump the relay
Fuel pump relay tests good
I replaced the purge valve
Oxygen sensor has really stiff wires, and looks oldish
the time-temp probe for the cold start injector (in thermostat housing) does not have continuity between its two terminals. So I think this may be it?

This thing is a headache.

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Thermo-time switch*

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I checked the idle air stablizer valve's electrical harness; and the manual says there should be about 10v between the center conductor and either of the outer conductor. One reads 9v, the other reads 3.9v. I pulled back the boot and it is the beige color, yellow stripe wire. Now the next step says "if there is NO voltage have the idle speed control unit or ECU checked at a repair shop" it has voltsge, just half the normal amount. Should I keep diagnosing or pay to have em checked?

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whats your battery CCAs?

Cranking amps: 875
Cold cranking amps: 700

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Also replaced oxygen sensor and the thermo-time switch. Nothing

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Had similar issue and was told and I was convinced it was fuel pump. After a lot of mis-diagnosing on my part, ( thinking it was coolant-temp sensor, cold-start injector--I have an 87 325e) etc. It ended of being Crank Position Sensors, of which I have 2 on bell-housing but your car has only the one towards the front of the engine. Anyway, may be worth checking out. Since I replaced mine, no starting issues, car idles much better and my gas mileage greatly improved as well. I had a good indy do the work and car runs much better, now. Good luck.

I actually was just looking at that yesterday, I had noticed that someone had 'self-wired' it and there was a cut wire on it. That is absolutely amazing. I need to figure out how to wire it, then I will replace it. Thank you so much for your input!!!

-chris

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Ok, so I unplugged the harness and the car wouldn't start at all(inconclusive?)... also tested the [sensor side] for an ohm reading. The first two are 550ohms, the middle and third are infinite (OL). Which according to bentley is good. But there IS evidence of a problem [in the broken wire], so I will post a picture to show you the sensor.
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I took the sensor off and found that it wasn't a broken wire, just the braided shielding had come off. So there is probably reason to replace it. Agree?

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I would replace it for good measure. There could be some moisture getting in there causing issues and inconsistent starting. Keep going, you'll figure it out eventually! I also replaced my fuel pump relay, main and oxy sensor relays and that made things even better. Best of luck.

I picked one up at a junk yard in similar condition, but I figured it would unlikely be bad too... it didn't work. Should there be power at the harness (not on the sensor side) if so, what would I test for?

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I'm not getting a voltage reading at fuse 11...

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There is continuity (when ignition is off) between the pump relay (78) and fuse 11. There is also continuity between chassis ground and fuse 11....



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Oh wait... it reads 13v when the car is on. (Reads 0 when the key is in ON position)

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Ok, so I found another forum that suggested fuel injectors leaking... so I pulled the fuel line off the fuel rail (after my new check valve) and there was fuel present, under no pressure (not sure if that's good)
Now, before I put in the check valve, there would be no fuel at all at the fuel rail, now there is. But when i'd pull the line off a few minutes after the car had been off; fuel would spray out.
My car has been sitting [off] for about an hour.

Does this really tell me anything?

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Thats good. Thats means theres no leaks in the fuel line. Thats how its designed. Leaking injectors may cause a rich or lean fuel mixture depending on where its leaking at (like o ring or the body

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