Author Topic: fuel pump/non-start issues - been doing lots of research, still NEED HELP... please > (Read 44065 times)

318i91 · « **Reply #60 on:** May 30, 2008, 09:20:51 PM »

The good news is I may just found the culprit. The bad news is that the problem may be serious.

The compression in the 4 cylinders reads:
cylinder 1: 40psi
cylinder 2: 75psi
cylinder 3: 32psi
cylinder 4: 35psi

Then I did a "wet" compression test with cylinder 4. With some 10w-30 oil to seal the rings, it read 80psi.

That tells me that I may have:
worn piston ring and/or cylinder wall, or
worn piston ring, cylinder wall and valves

I remember reading an article that for an engine to start there need to be at least 65psi pressure in cylinders. So low compression caused the no-start issue?

I would think that a worn engine would develop chronically aggravating driveability issues long before it fails. Yes, the car did not accelerate quick. but it constantly gave 25-30 GPM fuel efficiency. Shouldn't a worn engine turn much worse MPG? Besides, the engine just passed 155K mils mark. I have heard a lot of bimmers with 200K+ miles on them and still running great. So is it normal for this one to be so worn

So the puzzle is why the engine ran well on Saturday and suddenly stopped working next Monday? One possible explanation may lies on what happened on Saturday. I was checking the brake pads and had to roll the car up and down the driveway a couple of times trying to find a good jacking base. Each time the engine ran for a few seconds. In doing so unburnt fuel might flooded
the piston and washed off the oil. As I mentioned above, Cylinder 4 reads 35psi in "dry" compression test and 80psi in "wet" test. Assuming it's true that the engine need at lease 65psi to fire up, the oil being washed away removed the seal b/w the rings and cylinder wall and reduced the compression below 65psi threashold thus cause the engine not to start, even though everything else works normal.

But every time I crank the engine, Shouldn't oil be pumped to the piston rings and cylinder walls and seal where they contact, thus restore compression? Anyone have a good explanation for this?

Another thought is that if the above is exactly what happened, may be I could revive the engine by changing to thicker oil like 20w-50 and feed a tea spoon of oil through each spark plug hole. The risk is that every time I let the engine sit for a couple of days, I may not start the next morning.

Anyone have experience fixing a low compression problem? Does that require special tools/equipment, skills and a lot of hours? How much could it cost to have a repair shop open the engine and change rings, pistons or both?

What to do now? Any suggestion is welcome here. I am still not ready to give up.

Cobra Jet, I saw you started another popular thread on #87 gas. I have used #89 for the past 3 years. But after going through these compression diagnostics, I guess an older engine with lower compression can probably use #87 safely simply b/c the low compression won't detonate the lower-oct gas. Do you agree?

RED IS 91 · « **Reply #61 on:** May 31, 2008, 06:47:42 AM »

I find it hard to believe that one day it runs good then the next day won't start with no compression.
How did you perform the compression test ?
Are you sure your compression tester o ring was good ? I would try another tester to be on the safe side .
It just doesn't add up ..............................I may be wrong though:confused:
good luck

318i91 · « **Reply #62 on:** May 31, 2008, 07:32:40 PM »

Quote from: RED IS 91;50353

I find it hard to believe that one day it runs good then the next day won't start with no compression.
How did you perform the compression test ?
Are you sure your compression tester o ring was good ? I would try another tester to be on the safe side .
It just doesn't add up ..............................I may be wrong though:confused:
good luck

RED IS 91 -

I tested the compression with a brand-new compression tester from Advanceautoparts for $25. The tester come with an extension hose so I can reach down the deep plug hole. With all plugs, main relay and fuel pump relay out, and the tester fitting screwed in (o-rings seated well at fitting-to-hose connection), my neigbour cranked over the engine while I watched the tester dial until the pressure reading stables, after about 5-6 revs.

You raised a good question: How did the engine run ( I forgot to mention that it had never burned oil) with such low compressions. As I mentioned in the last post. The "wet" compression test raised the compression from 35psi to 80psi, right above the minimum ignition compression of 65-70psi. Maybe the car kept running just b/c I never let it sat off road for too long so the oil helped sealing the worn piston rings by pure luck for so long? But it still doesn't explain why it didn't burn oil with all the worn rings. I plan to put some thicker oil in each cylinder tomorrow and see if it make some difference.

Another possibility: maybe a skipped timing chain (Just like Cobra Jet suspected) messed up with valve timing so the valves are partially open in the compression stroke so the pressure is low?

Have anyone heard of M42 very-low-compression issue before and know how to diagnose/fix it? I am all ears.

318i91 · « **Reply #63 on:** June 02, 2008, 08:33:02 PM »

No one can offer some ideas?

vatos_p · « **Reply #64 on:** June 03, 2008, 02:21:24 AM »

you must check what is wrong with the compression...It is too low...i do not believe that you have a problem with the pistons or the piston ring , you should check for a crack in the cylinder head...There is no way the car worked fine and imidiatly droped pressure from the pistons...check your timing , remove the valve cover , and read from a manual about timing and where all the parts should be , check it and see if you have any timing issues...

edit : if there is wrong timing , the valves would be open and no compression would be possible....

318i91 · « **Reply #65 on:** June 04, 2008, 09:56:45 PM »

Quote from: vatos_p;50518

you must check what is wrong with the compression...It is too low...i do not believe that you have a problem with the pistons or the piston ring , you should check for a crack in the cylinder head...There is no way the car worked fine and imidiatly droped pressure from the pistons...check your timing , remove the valve cover , and read from a manual about timing and where all the parts should be , check it and see if you have any timing issues...

edit : if there is wrong timing , the valves would be open and no compression would be possible....

Still googling on similar issues. One guy had a low-compression problem b/c no spark in two cylinders and the gas washed off oil sealing the rings. I may also have blown gasket.

Severe T-storm with wind gusting 60+mph this afternoon. my cherry tree in the yard was blown over. big mess.... Strong storm continues Thu and Fri...
Will open the hood after that.

applecran · « **Reply #66 on:** June 29, 2008, 01:32:28 PM »

We had a similar issue yesterday with a 91 318is.

Fuel pump died (whirring and whining and car eventually would not start). Swapped a new pump in - car won't start, cranks, but no start. Fond this thread which helped immensely.

the pump would not come on, even when starting the car. There was voltage at the pump connection when cranking though. We though maybe we got a bad pump. Pulled it and checked the wires just to be sure.

We swapped all relays from another car that was running, no luck.

We ohmed the crank/cam shaft sensor. Crank was 525 (same as our running car) and cam was 1000 (about 200 to low).

Next I jumpered the fuel pump relay and immediately heard the pump fire up, and could here fuel coming into the rail.

Went to start the car, and it started, but ran really rough.

I think the bit of fuel from jumpering the pump got it started, but not sure.

Now I swapped the cam shaft sensor, and it started up and smoothed out. Swapped in a new o2 after that and took her out. Runs great and idles great. Hopefully we got it all figured out.

Good luck to anyone else that finds this thread (it should be stickied, really great explanation of how the entire startup works).

Thanks!

Colo318IS · « **Reply #67 on:** July 07, 2008, 01:56:07 PM »

Status update on my M42 Non-start issue�

First, sorry for the delay, I accepted a new job and with packing and the move, had to table working on the car for a few weeks�

I went through all the tests above (Testing pump, FRP, CPS, Cam PS, etc) and came to the conclusion the pump went out. I had removed it and jumped it from the battery and got nothing. I ordered a new one and put it in last weekend, but now a new issue has cropped up...

After installing the new pump, I tried to start it several times. At first it started, idled for about 45 sec then started to show signs of what it did when the original pump went out--that is, it sputtered and even when pushing the gas down it wouldn't go over 800 rpm then finally died. On several repeat attempts over a couple days, it would sound like it was just about to start right when I turned the key, but then would just crank.

One thing I noticed that I thought was strange was the new pump was not turning on with the key on, engine off. It would only turn on as I was trying to start the car. Any thoughts?...isn't the pump supposed to turn on when the key is turned on? My thought was that's why it's not starting b/c the pump isn't priming the system thus not gettin enough fuel to the engine to turn over. It would also turn on if you jump it from the battery. Voltage is good at the harness.

The other thought was is this a fuel mixture issue which is separate from the pump issue?

Thanks for any insight...

RED IS 91 · « **Reply #68 on:** July 07, 2008, 06:09:27 PM »

did you change the fuel filter recently ? You should check the fuel pressure at the pump .You should have 42-43 psi.
It sounds like something is telling the fuel pump not to start :confused:
You could disconnect the line that goes into the fuel filter ,stick it in a jar and see if the pump will pump fuel when you turn the key to the "on" position.
Be careful doing this.If it does not then the pump is not getting a signal to start.
When you turn the key to the on position do you have 12 volts at the pump?

Colo318IS · « **Reply #69 on:** July 08, 2008, 02:48:48 PM »

Yes I did change the fuel filter prior to the new fuel pump. I haven't checked the fuel pressure but will.

I did actually disconnect the line into the jar...what happened was no fuel came out when the key was turned to on...fuel would only come out when either tryin to start the car or jumping the fuel pump. Also, there wasn't voltage at the pump when the key was turned on...only when you tried to start it would it read 12 volts...weird...so yeah somehow something is telling the pump not to start but other thought I had was that aside, when looking back at my starting the car when it did run...probably 98% of the time I put the key in and start it w/o giving the pump really any time to prime...started wondering if maybe it was a spark issue then? I did replace the plugs, but only tested a couple for spark so maybe a coil is bad?

Cobra Jet · « **Reply #70 on:** July 09, 2008, 10:32:41 AM »

Colo - did you do the pedal stomp test to retreive any stored codes? If you did do this already, are you able to get any codes?

When you turn the key to "on", can you hear the fuel pump prime? You should be able to hear this audible priming instantly. Pull the rear seat cushion out and listen closely when you turn the key to on.

Also, make sure that when you installed the fuel pump connector back onto the fuel pump that you installed it properly, because IF the connector was reversed, the fuel pump will NOT pump fuel towards the engine, it will be pumping in "reverse" (basically not pumping it through the fuel lines to the engine)... check that connector to make sure it's making proper contact at the fuel pump, do the "wiggle test" when trying to start the car.

It sounds to me like the car only ran on the available fuel that was left in the lines, then died after there was no more fuel source.

What was your CPS results after testing it?

Another thing to check would be the ICV valve. Have you cleaned or checked your ICV valve? If the ICV is not operating 100%, you will experience hard cold starts, hard starts when hot and/or rough idle, stalling, etc. The ICV needs to be operating at nearly 100% in order for the engine to run or idle properly. If the ICV is not operating 100%, it's not allowing the proper air flow into the engine for idle or when driving, therefore the engine will experience irradic idle, the inability to run properly or it can or will stall out.

RED IS 91 · « **Reply #71 on:** July 09, 2008, 11:20:53 AM »

fuel pump relay

??

colin86325 · « **Reply #72 on:** July 09, 2008, 08:23:40 PM »

The fuel pump doesn't prime when the key is in the on position. It turns on when the ECU detects that the engine is turning over via a signal from the crank position sensor. The noise you hear is probably your antenna motor activating when the key is in the on position.
There's a check valve in the fuel pump that prevents fuel drain-back so that the fuel line stays charged.

RED IS 91 · « **Reply #73 on:** July 10, 2008, 04:48:47 AM »

When you turn the key to the on position you should hear the fuel pump relay click on .It is located on the fire wall ,drivers side (usa), behind the plastic cover.

Colo318IS · « **Reply #74 on:** July 23, 2008, 01:48:53 PM »

Another update on my end.

First again sorry for the delayed response, was out of town for a couple weeks...

OK...

Cobra Jet: I did do the pedal stomp a few times...it comes up 1444 (No fault)...

REDIS91: FPR is good, it does click on. CPS is good.

I think I'm getting closer to a culprit now, which I think is the ICV. I did check the connections on the fuel pump and they are good, but I decided to check the fuse again (I had checked the fuse long ago when I first encountered my no start). As you'll likely know and to my knowledge there are two main fuses for the fuel system (#10 & 11)...10 amongst other things is for the fuel gauge and 11 is for the pump)...I know there are several ways to check a good vs. bad fuse, but what I thought was helpful was to put in a known good fuse in 11 and put the fuse from 11 into the 10 slot...when i did that, got nothing on the fuel gauge telling me the fuse I had in the 11 slot was bad. So I replaced the 11 fuse.

The car fired right up and did what it did a few weeks ago when we replaced the fuel pump. It ran for about a minute, then couldn't maintain power and died. I then removed the ICV based on Cobra Jet's comments and other research, cleaned it with carb cleaner, tapped it, etc..reinstalled. Oh before I reinstalled, I checked it...Ohms read 9, which it's my understanding it should be 20, another sign the ICV is bad. It didn't start. I then started thinkin about the fuse again, so I checked it. Blown fuse. I put another one in, it fired right up, ran for a minute, died. checked the fuse. Blown again.

So just curious your thoughts on this...my current thought is the ICV is bad and too much fuel is getting into the engine...it's overloading the system and blowning a fuse which is shutting the pump off which is why it dies. Any thoughts?

As to the ICV...like I said, I did remove it and clean it, but don't know whether I did a good enough job on this or tapped it enough? I obviously didn't want to damage it, but did give it slightly more than a gentle tap, tap, taparoo. When I did tap it, I felt like I could feel a slight vibration as a sign it wasn't clogged anymore. Also, when I cleaned it with carb cleaner...not a ton of "gunk" came out? Is that normal. Thought about trying to clean it again before breakin down and ordering a whole new ICV. Lastly, after it is cleaned, should it read 20? I never did retest it after I cleaned it.

As always, thanks so much for your thoughts.

Jay

Author Topic: fuel pump/non-start issues - been doing lots of research, still NEED HELP... please > (Read 44065 times)

318i91

Problem found

RED IS 91

fuel pump/non-start issues - been doing lots of research, still NEED HELP... please >

318i91

fuel pump/non-start issues - been doing lots of research, still NEED HELP... please >

318i91

fuel pump/non-start issues - been doing lots of research, still NEED HELP... please >

vatos_p

fuel pump/non-start issues - been doing lots of research, still NEED HELP... please >

318i91

fuel pump/non-start issues - been doing lots of research, still NEED HELP... please >

applecran

fuel pump/non-start issues - been doing lots of research, still NEED HELP... please >

Colo318IS

An update on My non-start issue.

RED IS 91

fuel pump/non-start issues - been doing lots of research, still NEED HELP... please >

Colo318IS

fuel pump/non-start issues - been doing lots of research, still NEED HELP... please >

Cobra Jet

fuel pump/non-start issues - been doing lots of research, still NEED HELP... please >

RED IS 91

fuel pump/non-start issues - been doing lots of research, still NEED HELP... please >

colin86325

fuel pump/non-start issues - been doing lots of research, still NEED HELP... please >

RED IS 91

fuel pump/non-start issues - been doing lots of research, still NEED HELP... please >

Colo318IS

fuel pump/non-start issues - been doing lots of research, still NEED HELP... please >