Weird - hard to start on hills

[monkeyodeath]

My 325i starts great, except when it's on any kind of incline. Then it takes a lot of cranking to get it to fire up. Also have noticed a bouncing idle sometimes when I've just gotten it started up and am on a hill, facing either up or downhill.

Does anyone have any idea what this could be? I was trying to figure out my intermittent starting issues, then it dawned on me that every time it was difficult to start, I was on a hill. Could it be a bad AFM flap that has no spring tension left?

[Kershaw]

my eta did this. i threw a crap ton of new parts at it for another issue and this one eventually resolved itself. so... no help for you. but at least you know you're not the only one and it's fixable. haha.

[jlevie]

Park the car on a hill and run the fuel system tests in the Bentley manual. That will tell if that is where the problem is. I sort of doubt that the cause is the AFM. Most anything that could be wrong with it will cause other problems.

[nomansland92]

Just a thought but maybe the check valve in the pump, If the front of the car is uphill it could make the gas run back into the tank and making it harder to start because it has to prime itself. Do a full pressure test.

[monkeyodeath]

Should also mention that the car also seems really down on power when I start on hills. Easy to kill just trying to get moving.

It's also really intermittent - kind of hard to replicate.

[Adrian_Visser]

How often do you start it on hills? Intermittent problems can be hard to troubleshoot, how often would you say it happens and how sure are you that it is ONLY on hills?

[monkeyodeath]

I live in a hilly neighborhood, and I noticed that it ran fine when I first bought it and test drove it in a normal, flat area.

Then a couple days later, when I had goten it home and was trying to move it on my inclined street, it started easily, but bogged badly, died when I tried to move it, then was a bitch to get started again. I needed to wait like 5-10 minutes or so to be able to get it to start again.

I noticed, though, that when I was working on it on a flat part of my driveway, I had no issues of the sort. The issues come when I'm trying to back out of my steep, short driveway - it bogs, dies on the way up, and can be hard to start again.

The only other time I've had this issue was when I parked on a hilly street somewhere else, spent 2 minutes out of the car, then tried to start it again. Same symptoms. Otherwise, in 2-3 days of driving on flat streets, I haven't had any starting issues.

Otherwise, it doesn't seem to matter whether the car is hot or cold, or whether the ambient temp is hot or cold. The hill thing seemed to be the only connection between each time my car died.

So to sum up, on hillsides (as far as I can tell), the idle bounces, the engine bogs really easily, and once it dies, it's hard to start up again. I'm not 100% sure it's only on hills, but in maybe 35 or so starts, the only time I've had issues is on hills.

[monkeyodeath]

I think check valve is OK, doesn't seem to bleed off any pressure over the course of 10-20 minutes.

[monkeyodeath]

Now I'm having a hard time getting this problem to happen at all. Still able to make the bouncing idle happen for 10 seconds or so on startup, but unable to kill the engine. Maybe it has more to do with ambient temp than I though...will try tomorrow in midday to get it to happen.

Dunno if this has any bearing, but on my recently passed smog test, I had HC's right at the limit.

[monkeyodeath]

Ok, some more clarity.

First of all, I'm realizing that this is not a hills only thing. Sigh. It just seems that way because, for some reason, the car seems really down on power right after firing up - it seems to happen more when it's warm out. And because on hillsides, I'm applying more power to get going, it's easier to kill the car, which reveals the starting issue.

First of all, I don't think it's related to fuel pressure. When the car's idle is bouncing, as it does when I first start it, the fuel pressure rises and lowers, but it' doesn't dip below 36-38 psi. When it's hard to crank, the fuel pressure is still at 44 psi, so it's not being starved of fuel in these conditions.

So to sum up, car starts fine, is low on power and easy to kill, then after that is hard to get started again. Cranks for a few seconds, seems to catch at a really low idle speed, then surges to the normal idle speed, or bouncing. The bouncing really seems to happen when I actually move the car a few feet and then idle, not if I've been idling for a while.

Any ideas out there?

[AT-JeffT]

I'm having similar problems. I believe the cause is sediment in the gas tank.

[nomansland92]

I had i sorta similar problem, with mine it would have a hard time starting like 15secs of cranking and it would be real low on power for a minute or so and had a real bad idle. turns out my 5th injector was leaking in to the cylinder and flooding the car.

[billybobjoseph]

Sediment in the tank could get through an old injectors filter and plug it up - causing it to leak; I saw a DIY on how to rebuild your injectors and where to get the kit.