engine and drivetrain Engine issue

[bmw2002tiidriver]

I have an engine issue and I cannot figure out what it is so here goes: When I start from a complete stop, in first gear and second gear, the engine runs fine up until about 3000 RPM. At 3K, the revs drop like the engine is about to stall. I put the clutch in out of reflex, and then work the revs back up and it is fine. This only happens in first and second acceleration from a stop. Gears 3-5 (Getrag 245) rev up perfectly fine. Has anyone else had this problem or know what is going on and how to fix it? Any help is welcome. Thanks in advance!

[Napes]

If you're running a carb on your engine let us know which one and we may be more able to provide tips.

Bob Napier

[bmw2002tiidriver]

Ah it's a 72 tii. I should have said that in the description. Could it be something with the Kfish pump?

[ray_]

Clean the fuel screens/filters, especially the screen in the tank.

GL,

Ray

[dubois]

I have an engine issue and I cannot figure out what it is so here goes: When I start from a complete stop, in first gear and second gear, the engine runs fine up until about 3000 RPM. At 3K, the revs drop like the engine is about to stall. I put the clutch in out of reflex, and then work the revs back up and it is fine. This only happens in first and second acceleration from a stop. Gears 3-5 (Getrag 245) rev up perfectly fine. Has anyone else had this problem or know what is going on and how to fix it? Any help is welcome. Thanks in advance!

The engine is loaded differently (at a given rpm) depending on the gear. But I think it is loaded more on 3,4,5 than it is on 1 &2 - so it has to work harder and would tend to stall more on 3,4,5.

The only thing that I can think of is that fuel is being used up rapidly on 1 and 2, and somehow the system is unable to keep up with the sudden increase. The acceleration on 3,4,5 is less dramatic (rpm wise) so you don't see the problem. It is a shot in the dark, but I would drive the car on an open road, where you can accelerate slowly on 1 and 2, and see if it happens.

If it turns out to be a fuel delivery issue, then look at the usual suspects: filters, fuel pump, etc. This is my wild guess...

[cxzsaq]

I have an engine issue and I cannot figure out what it is so here goes: When I start from a complete stop, in first gear and second gear, the engine runs fine up until about 3000 RPM. At 3K, the revs drop like the engine is about to stall. I put the clutch in out of reflex, and then work the revs back up and it is fine. This only happens in first and second acceleration from a stop. Gears 3-5 (Getrag 245) rev up perfectly fine. Has anyone else had this problem or know what is going on and how to fix it? Any help is welcome. Thanks in advance!

The engine is loaded differently (at a given rpm) depending on the gear. But I think it is loaded more on 3,4,5 than it is on 1 &2 - so it has to work harder and would tend to stall more on 3,4,5.

The only thing that I can think of is that fuel is being used up rapidly on 1 and 2, and somehow the system is unable to keep up with the sudden increase. The acceleration on 3,4,5 is less dramatic (rpm wise) so you don't see the problem. It is a shot in the dark, but I would drive the car on an open road, where you can accelerate slowly on 1 and 2, and see if it happens.

If it turns out to be a fuel delivery issue, then look at the usual suspects: filters, fuel pump, etc. This is my wild guess...

I think this may be a fuel delivery issue as well. In addition to the filters in the tank and in-line - check the banjo bolt in the k-fish - i think it also has a "last line of defense" screen - that you should clean out.

[TobyB]

yeah, the only 2 things that pop to mind are very marginal

electric pump pressure- junk in the gas tank floating around?

or something mechanical in the engine bay- the motor moves

around a lot more in low gears (more reactance torque)

than in high gears.

I once unplugged the Pertronix module that way- dumped the clutch, and

viola, no more spark...

But you'd think that would happen at clutch dump, not 3k...

t

[bmw2002tiidriver]

Ok so I have a new development in this problem.The other day, I was low on gas, but i knew I could make it to Costco an hour away to get a good price on gas. I barely made it there. The car ran fine until I got off on my exit, when it started acting up again with the same symptoms. But since I have filled up, it has been running great with no issues at all.

[bmw2002tiidriver]

Ok so I have a new development in this problem.The other day, I was low on gas, but i knew I could make it to Costco an hour away to get a good price on gas. I barely made it there. The car ran fine until I got off on my exit, when it started acting up again with the same symptoms. But since I have filled up, it has been running great with no issues at all.

[MrSharky]

Sounds like you've got some junk in your trunk. As c.d. always says - you want to run from full to 1/2 a tank, not below that. Increases the chances of pulling some low hanging junk into the fuel system.

Ok so I have a new development in this problem.The other day, I was low on gas, but i knew I could make it to Costco an hour away to get a good price on gas. I barely made it there. The car ran fine until I got off on my exit, when it started acting up again with the same symptoms. But since I have filled up, it has been running great with no issues at all.

[bmw2002tiidriver]

What is the best way to get the junk out of it?

[MrSharky]

Lots of tips on here - from what I can tell, most involve draining & removing the tank, then cleaning it with solveint. Something I might be doing this summer... doesn't sound like much fun, though.

try searching...

http://www.bmw2002faq.com/component/option,com_forum/Itemid,57/page,search/mode,results/?search_keywords=gas+AND+tank+AND+cleaning&search_terms=all&search_author=&search_forum=3&search_time=0&search_fields=titleonly&search_cat=-1&sort_by=0&sort_dir=DESC&show_results=topics&return_chars=200

[TobyB]

and put a pressure gauge (temporary) on your supply line.

I'd suspect the supply pump of being marginal.

t