Delayed Start for M20 Problem (Master Tech needs help)

[cobraken]

Hey,

My friend has a 90 325i that has 68k on it. Its really in mint condition. It does have one problem though, it has a delayed start that he cant trouble shoot. The starter will turn the engine over for 10 seconsds or so and then finally start. The there is a strong smell of fuel. AFter its started it runs fine.

He has changed the Crank Position Sensor.
We have swaped computers.
The car has a complete tune up.


Any thoughts?
Thanks,
Ken

[jlevie]

The first actions should be to have a smoke test run on the intake to locate any intake leaks and run through the suite of fuel system tests in the Bentley manual.

[jeffw]

check the gate on the afm maybe its not opening at the right speed so it takes a bit to start. ten seconds seems a bit long for that but you never know

[Adrian_Visser]

I have a similar problem. It's only hot starting though and doesn't happen everytime. Seems like it floods itself if you don't crank it enough before you let the key off of start, only way to start it is to floor the gas pedal and crank for like 20 sec.

I am gunna throw a coolant temp sensor on there and see what happens.

The problem persisted after I put a MarkD chip and 19lb injectors and 027 AFM in so I don't suspect that in my case it was the injectors or AFM causing this

It kind of came to a high point this morning when my battery crapped out half way through cranking it. Grrr, and in front of like ten people I work with. It totally made my e30 look bad.

[tim88325is]

I had the same problem, the coolant temp sensor cured it. Colds starts were fine for me but warm and hot starts were a problem. Obviously, if the computer thinks it is cold, it is going to "choke" the mixture. My car has been starting instantly since the swap.

I also checked and tested the AFM, TPS, replaced the valve cover hose, replaced a leaking hose that went to the charcoal canister, and made sure all intake manifold fittings were tight. Also, I had the throttle body off and cleaned the inside.

[cobraken]

Those are both good ideas, possibly the coolant temp sensor or the AFM. The coolant temp sensor really sounds lilke a possiblity.

[SmokeE30]

test the fuel pressure at the rail, if it is losing pressure after it shuts off it may take a couple seconds for it to build back up again, make sure its not leaking somewhere and losing fuel pressure.

[peerless]

test the fuel pressure at the rail, if it is losing pressure after it shuts off it may take a couple seconds for it to build back up again, make sure its not leaking somewhere and losing fuel pressure.

Smart call. Also the fuel pump has a check valve in it that is supposed to keep pressure in the rail. Common for this to fail so that when you turn off the vehicle the fuel pressure immediately drops to zero and has to rebuild line pressure again, thus delaying the start.

There is a replacement inline check valve that is supposed to be available but I do not have a part number for it or if it is even available anymore.

You can verify with a fuel pressure gauge as mentioned above.

C/Ya

Robert
E30 Motor Werks

[ikkitousen]

M5X swap FTW!

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DAMN MEANINGLESS POSTS!!!

[fyfee]

I had the same problem, the coolant temp sensor cured it. Colds starts were fine for me but warm and hot starts were a problem. Obviously, if the computer thinks it is cold, it is going to "choke" the mixture.

Pardon my ignorance, but if the coolant temp sensor is failing would it affect the gauge on the instrument cluster?

[tim88325is]

Not the sensor that sends info to the ECU which would affect starting, there is a another sensor for the gauge. I replaced that sensor at the same time and tightened the nut on the back of the cluster gauge and my temp needle has been very stable, after years of weird jumping around.

On my 325is car, both sensors are located near/on the thermostat housing, the ECU sensor has a blue-color plastic top and the gauge sensor was brown-colored. Easy to replace and fairly cheap, the test specs are in the Bently manual.

Hope this helps!!

[gw ix]

Chech your main ECU relay.

[txtorquemade]

In case your pondering, and can someone tell me if IM correct.

It would not be the O2 sensor because the ECU reads the coolant temp sensor at start up and not the lamda (O2) sensor.

Possible culprits:

Coolant temp sensor
Fuel pump
FPR
ECU
ICV??

main ECU relay...is a good idea too.

[cobraken]

From Plano hu, my friend who this post is for lives in Lubbock.

In case your pondering, and can someone tell me if IM correct.

It would not be the O2 sensor because the ECU reads the coolant temp sensor at start up and not the lamda (O2) sensor.

Possible culprits:

Coolant temp sensor
Fuel pump
FPR
ECU
ICV??

main ECU relay...is a good idea too.

[Republic]

I've been having similar issues as of this winter and now spring.
I would run my battery dead trying to get it started. As I would start the car, it would quickly flutter and die before I get my hand off the key. At this point, I know I am screwed. So, I have another car push my car and let off the clutch... starts with no problem.

However, this is getting old. I work in the fricken ghetto rehab places and I don't need to be the white target whose car won't start.

I can try the coolant temp sensor; however, I replaced that 2 years ago when I build this thing.

How do you check the fuel pressure? Any specialized tools needed?

Is there any thing else I can try?

This issue rarely, if ever, occurs when it is warm outside. It happens almost always when it is cold out, less than 40 degrees.
thanks!