Author Topic: Both CPS? at the same time? (Read 16165 times)

sfinsf · « **on:** February 27, 2012, 08:18:23 PM »

during some spirited driving on a twisty mountain road, my little german decided to hesitate under heavy acceleration and then completely give up and stall after reaching the summit within about a 1/4 mile after the hiccup. It would start after cranking and lots of pumping of the accelerator, but then stall within 30 seconds. It did this three times and finally, after no signs of coming back to life, I decided to neutral coast down to a resting spot. That's fun w/o the power assist brakes!
stomp revealed 1244
Had it towed home

after much reading....
FP relay making activating sound, Fuel Pump sadly quiet
pulled fuel pump, tested, in working order, leads me to Crank PS, no continuity, so I check Cam PS just to see that I'm doing it right... nothing.
Is it likely that they retired together as a team? Does this indicate or imply a larger ill? Am I a retard noob and failing a simple continuity test? :confused:

DesktopDave · « **Reply #1 on:** February 27, 2012, 09:16:31 PM »

You're not failing the continuity test at all. You'll get better results with ohms.

680 or so on the crank pins 1 & 2...and 1240 or so on the cam pins 1 & 2. Pins 1-3 and 2-3 should be very high, min 300k ohms IIRC.

Geoff · « **Reply #2 on:** February 28, 2012, 06:04:02 AM »

also, these fuel pumps can die in situ, or appear to, then come to life when removed, or even tapped hard with a wrench..sometimes it is flakey connections on the pump, and sometimes the pump is going bad, but will work after being moved or tapped on. if this is the case they may do this a few times before they die for good.
Geoff

sfinsf · « **Reply #3 on:** February 28, 2012, 08:11:13 AM »

dave, not sure I'm following you. thought I was testing for ohms/resistance by doing the following

This is from my meter manual:

7. Resistance/Continuity Measurement For resistance and continuity testing POWER MUST BE OFF:
1) Fully seat the test leads in the input jacks.
2) Set the function/range switch to the Rx1K position (resistance indicated multiplied by 1000) and short the test leads together. Using the zero ohms adjustment dial, slowly turn the dial until the needle indicator reads -0- ohms at the right end of the ohms scale. If the needle will not zero, replace the internal battery with a new 1.5 volt AA size battery (see Battery Replacement).
3) Touch the test leads to the resistance or non-energized circuit to be measured. Measure the value of the reading on the green ohms scale and multiply the reading by 1000. If you’re making basic continuity tests, the needle indicator should move all the way to the right side of the ohms scale if continuity exists.

After performing this test with both of the sensors pulled out, no matter what lead I touch to there is no response on the needle (its an analog meter)

wrong setting? wrong test?

Geoff, not getting 12 volts at pump when turning over engine, makes me think that the relay is not getting its signal to close and power the pump. I focused on solid connections while I had it out.

sfinsf · « **Reply #4 on:** March 04, 2012, 09:12:25 AM »

not sure what happened to my other post, still unclear what I did wrong to test the cps, but went at this issue again with the DIY no start from an old post and bavauto

http://www.bavauto.com/newsletter/2007_n407_newsletter.pdf

after some time with my multi tester discovered that my fuel pump relay is dead, ordered a new one, waiting to see what happens next.

DesktopDave · « **Reply #5 on:** March 04, 2012, 09:51:12 AM »

Sorry - missed your earlier post. It was moderated, I approved it for you. I didn't know you were using an analog meter.

Did you jump the fuel relay socket to test the pump? IIRC it's pins 30 & 87 with a short bit of wire. I have one with male spades in the car just for such testing.

sfinsf · « **Reply #6 on:** March 04, 2012, 07:25:35 PM »

I did fuel relay jump and it proved that the pump is happy and the relay is not. Hoping that the relay is the only thing that is dead this time around. Learn something new every week with this sweet little car. Thanks!

DesktopDave · « **Reply #7 on:** March 04, 2012, 09:11:28 PM »

If it's not the relay it's likely the CPS. Without the crank sensor signal the computer won't turn on the relay, so no fuel pump.

On the crank sensor wire, pins 1 & 2 need to be about 640 ohms, pins 2 & 3 and 1 & 3 should be very high, like 300K ohms or so. I looked at your earlier post...you did test the sensor, right? Not the harness heading back to the computer, right? If so, don't do that. Doing a resistance or continuity test on the harness can damage the computer.

I'd advise getting a cheap multimeter at Radio Shack, Sears or Harbor Freight. They're self-calibrating, do many tests, and are very reasonable. I bought a few of the $4.99 HF units (along with some of those cheap LED flashlights) just to have in the cars. You never know when you'll need one!

sfinsf · « **Reply #8 on:** March 11, 2012, 10:16:43 AM »

some progress made, still no start.
- bought digital meter
- Cam PS tested - 1240 ohms between pins
- tested for voltage on each of the four connections on the coil block
- new Fuel Pump and Main Relay
- retested fuel pump with jumper wire, it hums away and plays nice
- started pulling out hair so I pulled fuel line just before fuel filter under car, no pressure, no fuel squirts out when I perform jumper at relay
- pulled pump out of tank, it makes noise, but doesnt pump any fuel.
now this sounds dumb, but does the pump run and not pump if there are issues elsewhere, or is this pump ready for the ball peen hammer burial process?

sfinsf · « **Reply #9 on:** March 18, 2012, 09:17:01 AM »

Am I being punished? Two posts now and nothing is showing up?

sfinsf · « **Reply #10 on:** March 18, 2012, 09:19:02 AM »

wanted to let you all know the latest on this issue.

keflaman · « **Reply #11 on:** March 18, 2012, 10:15:26 AM »

I don't know, but I was on the forum several times between yesterday afternoon and this morning and there was nothing showing when I hit new posts. An hour later I refreshed the page and had half a dozen new posts from the preceding 12 hour period.

Cyber-space lag?

DesktopDave · « **Reply #12 on:** March 18, 2012, 10:26:32 AM »

It's more of a Dave-lag...I missed that post. The "new posts" link doesn't seem to work as I'm assuming it does. Not sure why, but it misses updated posts all the time for me. Combined with the uptight spam filter, it makes moderating a bit of a chore.

Anyhow, what's the results of the crank position sensor resistance test? The cam sensor looks good. That crank sensor is a very common no-start problem. If there's zero resistance on pins 1 & 2 of the CPS, it's dead (internal short) and the DME won't receive a signal. Then the DME refuses to signal the fuel pump relay...and you get no fuel pump power at all.

Jump the fuel pump relay socket pins 30 & 87. The pump should power up when you turn the key. You should hear the pump...and likely the sound of fuel flowing through the rail & FPR. The car might even be able to start...I ran my car that way when I bought it for a little while, just pulled the jumper wire out after diagnosing so I didn't kill the battery.

sfinsf · « **Reply #13 on:** March 18, 2012, 04:24:14 PM »

the fuel pump runs, but does not pump fuel. disconnected just before the filter, same thing. disconnected at the connection under rear seat, still no fuel but it engages electrically. Now I'm not super bright, but I'm gonna say my fuel pump is dead.
But just to make sure, has anyone ever run into this before? Is there a sensor that would tell the pump to run, but not move any fuel thru it? That seems a bit over the top, but we are talking about german engineering here!
I really dont want to drop coin for a new FP at over $250 bucks

DesktopDave · « **Reply #14 on:** March 18, 2012, 07:11:34 PM »

Might be that the pickup screen is plugged. You can fit a generic fuel pump if its bad. You can verify it if you borrow a fuel pressure gauge...usually an Advance or Pep Boys will loan them if you leave a deposit.

The gauge should see about 43psi running off a tee, or up to 80psi if you dead-head it with the gauge.

Worst case scenario, just buy the pump, not the whole OEM assembly. Walbro makes one and some members have reported success with cheaper TRE pumps. Here's a thread about the TRE 340 fuel pump. That lists for only $70 here, you just need to be a bit handy to install it.