Author Topic: Guess it is worth a shot. (Read 6046 times)

Jimmy Lewis · « **on:** January 26, 2009, 09:45:13 PM »

Hey guys, here's the most recent story of my little M42. I'm having trouble putting my finger on the issue. Here goes.

About 2 weeks ago on my way home from college my fuel pump decided to take a shit about 1/2 mile away from my house in a nice convenient spot to leave it overnight. The next day, I installed the new fuel pump and I was on my way. I drove the car to and from school a few times that week and everything seemed just fine. After those few days I decided to fill the car up because in the process of installing the new pump I somehow damaged the fuel sender. Got a new fuel sender from my buddy Eric and it worked like a charm. That night after filling the car up and installing the new fuel sender, I went out to go pick up some take-out and low and behold, the car wouldn't start.

I have ruled out just about everything there is to rule out in terms of getting these cars to start and run right. I think I have a pretty good knowledge of such and anything that I am not sure of Eric always has an answer for. The following are items that are commonly at fault that are known working.
-Ignition system works as it should, car gets spark on all cylinders and the plugs are brand new, wires are also only a few months old.
-Fuel pump is running, pumps fuel all the way to the hard line in front of the booster, just as it should.
-AFM checks out because the car can be run on starter fluid into the intake track.
-ECU has been swapped with no change, so that cannot be the issue.
-Fuel Pump relay is known to work and has been swapped with other known working units.
-No fuses have been blown and all fuses are as they should be.
-FPR was one of the first items I replaced when the issue arose, it is brand new.
-Injectors, do not fail in batches of 4 as far as I know
-Coils, also tend to not fail 4 at a time

Now onto things that I believe it could possibly be, I would love to hear anything else you guys have to say about this.
-Crank position sensor could be bad, I have access to a known working sensor, but if any of you know how to test it with a multimeter that would be great.
-Cam sensor, not sure if this would cause a no start issue, but I guess its a possibility, let me know.

So in short, the car is getting fuel to the rail and getting spark, so my only conclusion is that the injectors are not pulsing. Once I ruled out the ECU, I'm left with these damn sensors. What are your thoughts? Note: the engine is not hitting on a single cylinder, it simply is not getting fuel into the engine.

B318M42W · « **Reply #1 on:** January 27, 2009, 04:36:00 PM »

it is possible to test them. not exaclty sure what pins to check, but you sould get around 540 ohms for the crank and 1250 ohms for the cams. (#'s from bently manual)

Jimmy Lewis · « **Reply #2 on:** January 27, 2009, 07:00:42 PM »

Yeah I have one of each known to be working, I'm going to swap them in, in the morning. I will report back, but by now I'm almost positive that it is the cps. We shall see.

rallyegolf · « **Reply #3 on:** January 27, 2009, 07:15:34 PM »

Quote from: Jimmy Lewis;65473

Yeah I have one of each known to be working, I'm going to swap them in, in the morning. I will report back, but by now I'm almost positive that it is the cps. We shall see.

one of the sensors should be 1280 ohms and the other is like 540. Test the center and left pins on both of them.

Does the car crank, but not start?

good luck.

Jimmy Lewis · « **Reply #4 on:** January 27, 2009, 07:19:38 PM »

Quote from: rallyegolf;65475

one of the sensors should be 1280 ohms and the other is like 540. Test the center and left pins on both of them.

Does the car crank, but not start?

good luck.

Yeah I know what they are supposed to ohm to, but I knew that Eric had both of them and figured it would be easier to just swap them out rather than sit out in the cold and test them. Thanks for pointing out which pins they are, I wasn't sure.

Jimmy Lewis · « **Reply #5 on:** January 28, 2009, 09:34:56 AM »

Well great. I swapped out both the cam and crank position sensors and its a no go. Car still isn't getting any fuel into the motor. This has to be an electrical issue and there isn't anything I can think of it being. At this point I know it has to be something stupid and simple, because all of the obvious and common problems have been addressed.

I guess I still need to test the ones I swapped in to make sure they are good, but I have class in 20 minutes and I'm too frustrated to go out and mess with it anymore.

Does anyone have any ideas of what could be causing this, because at this point I'm open to even the most absurd of ideas.

xwill112x · « **Reply #6 on:** January 28, 2009, 10:22:34 AM »

maybe your injectors are messed up?
i read somewhere that if you ran completly out of gas, it would possibly trash the injectors...or its not good on them atleast.
maybe your fuel pump issue gave them the same sort of condition and it trashed them?

swap a diffrent set in and see what happens.

might be a good opportunity for a 4pintle conversion

B318M42W · « **Reply #7 on:** January 28, 2009, 08:17:32 PM »

here are some ideas... fuel filter- partially clogged engine ground strap- not there

if you're bored, you could unplug the lower fuel line and then from the fuel rail divert the flow to a bucket. you will see if there's enough pressure for the injectors. also... maybe try to unplug the fuel sender... or reinstall the fuel pump (remove, inspect and re-install)
good luck

peerless · « **Reply #8 on:** January 29, 2009, 02:00:55 AM »

Maybe you should pull that seat back up and check your fuel pump and sending unit installation. Is it possible the wire connection came loose or broke. Have you actually tested for power at the fuel pump with a simple $5 test light?

In addition, you may have pinched the feed line when you where installing the pump. The fuel pump may have come loose in the tank. I say you start right back where you where just at.

Quote

So in short, the car is getting fuel to the rail and getting spark, so my only conclusion is that the injectors are not pulsing. Once I ruled out the ECU, I'm left with these damn sensors. What are your thoughts? Note: the engine is not hitting on a single cylinder, it simply is not getting fuel into the engine.

[/B]

And I find it odd that in your original post you say you have fuel all the way to the rail, yet you also say in yet a different sentence that the engine is not getting any fuel.

So which is it?

Are you getting fuel or are you not?

Fuel pressure gauge/tester works great in a situation such as this.

I love all the wild guess's people throw out.

Good luck with it.

Jimmy Lewis · « **Reply #9 on:** January 29, 2009, 09:57:55 AM »

Believe me, the fuel filter was checked, it is brand new. The way I knew there was fuel getting into the hardline was by pulling it and pumping fuel into a jug, flow is good and is as it should be. I did have the sender out just prior to the issue, but I don't see it being related.

To Peerless:
As I said, I've had the back seat out of the car for weeks now, I have pulled the sending unit a few times prior, and surprisingly I got that working. The pump has also been out of the car, checked my connections, everything is good. I have verified that the pump is getting 12V, believe me.

I believe my next step is going to be to jump the main relay on both the fuel pins, and maybe check the fuel pressure just to be sure. Eric thinks that if the coolant temp sensor was completely dead, the car wouldn't start, but I'm not sure.

Edit: I forgot to address peerless' questions about the fuel issue. The idea is that fuel is getting to the rail, but the injectors aren't pulsing. Plugs are dry upon cranking. There is also a large amount of pressure in the return line after cranking.

txleadfoot · « **Reply #10 on:** January 29, 2009, 03:22:59 PM »

Disconnect the fuel pump wiring and hook up an external power source. I used a cordless drill battery. If it starts, you know it's something between the fuse block and the pump. Did you check voltage for the fuel pump relay and main relay as instructed in the manual? Mine was having the same problem and come to find out it was something really stupid....the fuse was blown.

B318M42W · « **Reply #11 on:** January 29, 2009, 04:30:45 PM »

there isn't supposted to be any large pressure in the return fuel line... maybe you are getting tooo much fuel pressure??? maybe a pinched return line?

nicknikolovski · « **Reply #12 on:** January 30, 2009, 05:28:01 AM »

Wasn't there a check valve modification as well for the E30 fuel pump's?

txleadfoot · « **Reply #13 on:** January 30, 2009, 09:08:10 AM »

After rebuilding my M42 I accidentally reattached the fuel hoses to the wrong pipes at the engine, creating a no-start condition. IIRC the bottom hose at the bracket is the high pressure feed.

Quote from: B318M42W;65581

there isn't supposted to be any large pressure in the return fuel line... maybe you are getting tooo much fuel pressure??? maybe a pinched return line?

JP 91iS · « **Reply #14 on:** January 30, 2009, 02:29:27 PM »

Quote from: txleadfoot;65611

After rebuilding my M42 I accidentally reattached the fuel hoses to the wrong pipes at the engine, creating a no-start condition. IIRC the bottom hose at the bracket is the high pressure feed.

Sounds plausible.

Also you mentioned that it may be an electrical issue and that none of your fuel injectors are firing. Have you checked your fuel rail wiring harness? I had a no start issue once that ended up being a corroded connection at the main engine harness. The connections were all green with corrosion, a good clean-up got the car running again - but this was on a 325i.

Good luck!