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Posted by: tabs914 Oct 16 2009, 01:58 PM

Hello all... I have been trying to trouble shoot my non-starting 914(just cranks). I figured I would start on the fuel injection system, making sure the ECU is getting the proper signals. Here is what I have checked:

MPS
Vacuum: Holds 5 Min. +
Main Coil: 56 ohms SPEC: 90
Secondary Coil: 348 ohms SPEC: 350

Injectors: SPEC 3 ohms for all injectors

Inj 1: 3 ohms
Inj 2: 3 ohms
Inj 3: 2 ohms
Inj 4: 2 ohms

Throttle Position Switch Idle Contact: Spec .5 ohms

.68 ohms

Head Temp Sensor: SPEC 2k ohms Also it is new...

3k ohms

I cleaned the trigger points (I don't know if it was a fluke, but this sparked a stummble for one second, only once)

New cap/rotor/points
Checked Spark from coil wire (Good)
Checked Spark from cap (good)
Checked Spark at plug (good)

Fuel Pump Primes when key is turned

Checked the injectors for pulse (when cranking) Good.

New fuel filter and lines (the pump is installed correctly I have checked several times

The AAR warms up if connected to 12 volt. warm closes and opens when cooled down. (not sure if it should do this if I just turn the ignition on? - doesnt seem to warm up if I do.)

New vacuum lines backed up with clamps on all connections

I can't check fuel pressure - I don't have a guage nor for compression either. Anyone in Portland, Oregon or Vancouver, Washington I can borrow from?

Maybe someone in the area that can help me out, would be very cool. I am learning alot, but this has me stumped.

I haven't had her on the road yet, but I had this baby running pretty well. I was messing around with the head temp sensor when it died. I thought maybe the wire lead became damaged within the sensor casing? Bought a new sensor with no effect. I have three ECU's and I know two work (no effect) The triggers seemed to sparked a stumble, they look ok... any way to test them?

Thank you for your help.

Tab

Posted by: type47 Oct 16 2009, 03:15 PM

Trigger points are just basically on-off switches, little to no adjustment. You can make a fuel pressure gauge with a gauge from the plumbing dept of Home Depot or Lowes or whatever your hardware store is. Get the barbed fitting and whateverelse is needed to screw the gauge into and a piece of FI hose and you're good. But, if it was running good before, I doubt the pressure changed. Definately need the head temp sensor to start though, needs to be ~3k ohms cold decreasing to low resistance (single digit ohms?) when hot

Posted by: underthetire Oct 16 2009, 03:22 PM

Harbor freight sells a fuel pressure tester. It's usually on sale for 7 bucks or so. Has the barbed fitting and a bunch of other adapters. Good home garage tool. Hell, you can barely make one from hardware store parts for that.

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=92699

Guess it's not on sale this week, it usually is, but here is a coupon for 15%off.

http://www.harborfreightusa.com/usa/common/displayCoupon.do?week=4209&campaign=RetailB&page=4209_retailB.html&r=6265_949704&cust=78096260905&keycode=0000

Posted by: tabs914 Oct 16 2009, 03:24 PM

QUOTE(type47 @ Oct 16 2009, 02:15 PM)

Posted by: tabs914 Oct 16 2009, 03:25 PM

QUOTE(underthetire @ Oct 16 2009, 02:22 PM)

Posted by: aircooledtechguy Oct 16 2009, 03:35 PM

QUOTE(tabs914 @ Oct 16 2009, 02:24 PM)

Posted by: tabs914 Oct 16 2009, 03:58 PM

QUOTE(aircooledtechguy @ Oct 16 2009, 02:35 PM)

QUOTE(tabs914 @ Oct 16 2009, 02:24 PM)

3k at the sensor or at the ECU?

Disconnect the sensor from the ECU and test the sensor by itself. Positive test lead in teh spade, negative test lead to the base of the sensor. You may also test the difference to the head where it screws into. If there is a big difference, you have corrosion in the threads (I've seen this once). These keep the motor from running and can strand you if they go bad. I recommend my clients carry a spare (since they are so cheap).

Posted by: type47 Oct 17 2009, 08:27 AM

2-3k ohms according to:

http://www.914world.com/bbs2/index.php?showtopic=99524&hl=CHT++resistance

as directed above, you disconnect the CHT sensor from the harness; you don't want to see resistance from the ECU. 'course, what has not been discussed so far is replacing the CHT Disconnect the CHT at the sensor and measuring resistance takes like 2 minutes.

Posted by: John Jentz Oct 17 2009, 08:44 AM

The D-Jet "Bible" http://members.rennlist.com/pbanders/ . Go here and all will be explained

Posted by: BMXerror Oct 17 2009, 10:06 AM

This may be way basic considering tests that you've already done, but an engine needs four things to run; air, fuel, spark, and timing. It sounds to me like you've got the first three covered. I would recommend taking some time to double check your connections and base settings. Make sure your plug wires are in the right place. Set the 'bench timing' on the ignition (lemme know if you don't know how, and I'll tell you). Also, make sure that your point gap is set right.
Just some things to think about. And it's not a commentary on your skills, because I've done all the same things.
Mark D.

Posted by: sean_v8_914 Oct 17 2009, 10:29 AM

...did you check for spark at a plug?

Posted by: swl Oct 17 2009, 11:55 AM

QUOTE(John Jentz @ Oct 17 2009, 06:44 AM)

Posted by: tabs914 Oct 17 2009, 12:07 PM

Thank you all for your suggestions... I really appreciate it. Well going to the store and buying some more testing equipment has narrowed my search for the culprit...

I tested the compression. I could only do this on a cold motor of course, but here are the results:

1: 145
2: 148
3: 148
4: 145

...looks like fuel.

I hooked the fuel pressure gauge to the test port... turned the key and heard the pump prime then continued to crank the motor for 8 seconds or so... zero on the gauge. Second attempt same thing. I pulled the gauge and it was dry. It doesn't look like there is a valve on the port so it appears that there is a supply issue... and yes I have a 1/4 tank of fuel.

more things I can try?

Posted by: swl Oct 17 2009, 12:13 PM

sounds strange. if you hear the pump it should be moving fuel.
Have you done any work on the fuel lines?

Posted by: swl Oct 17 2009, 12:23 PM

one thought...

The three port pumps have a fail mode where they wind up pumping through the return port rather than the delivery port. Way too much of a coincidence for that to happen when you are working on electrical stuff but i guess stranger things could happen.

Do you hear any gurgling in the tank when you turn the key on without starting the car. The pump runs for a second or two with key on. Do that a couple of times and you should hear the return being dumped back in the tank.

Posted by: tabs914 Oct 17 2009, 12:29 PM

QUOTE(swl @ Oct 17 2009, 11:13 AM)

Posted by: tabs914 Oct 17 2009, 12:30 PM

QUOTE(swl @ Oct 17 2009, 11:23 AM)

Posted by: tabs914 Oct 17 2009, 01:36 PM

I can't hear any gurgling...

Posted by: Jacob Oct 17 2009, 01:51 PM

Can you pull the lines leading into and out of the fuel pump? I think the the fuel pump just runs for four seconds regardless of whether or not you have pressure. It would be nice to see if fuel is even getting to the pump. Might be a plugged line.

Posted by: tod914 Oct 17 2009, 02:07 PM

You should be able to peek in the tank with a light and see if the filter sock is clogged. The AAR works off of the same fuse as the pump. But, it would more than likely blow the fuse if it was shorting out. Couldn't hurt to unplug the AAR to test. Sound like a clog or misrouteing. You mentioned in the other thread the fuel system was removed. You can try swapping the lines inside the engine bay by the battery tray where they attach to the plastic lines (feed and return). If they are swapped, you will not get pressure. Pelican has a fuel routing diagram too if you need it.

Posted by: BMXerror Oct 17 2009, 02:22 PM

When you checked for injector pulse, did you actually pull the injectors and check for fuel coming out? If so, then you can eliminate any 'no fuel pressure' theories. Go back to basics. Air, fuel, spark, timing. Try to steer clear of wild, convoluted theories. They're usually bunk.
So has the engine not run in 20 years, or was it running before you messed with the CHT sensor?
Mark D.

Posted by: BMXerror Oct 17 2009, 02:37 PM

Sorry. Didn't see your post about not being able to register any fuel pressure on the gauge. The 'keep it simple' advice still applies. How did you check the injector pulse before?
Mark D.

Posted by: tabs914 Oct 17 2009, 04:41 PM

QUOTE(BMXerror @ Oct 17 2009, 01:37 PM)

Sorry. Didn't see your post about not being able to register any fuel pressure on the gauge. The 'keep it simple' advice still applies. How did you check the injector pulse before?
Mark D.

Posted by: tabs914 Oct 17 2009, 04:43 PM

QUOTE(tod914 @ Oct 17 2009, 01:07 PM)

Posted by: swl Oct 17 2009, 05:04 PM

QUOTE(tabs914 @ Oct 17 2009, 02:41 PM)

QUOTE(BMXerror @ Oct 17 2009, 01:37 PM)

Sorry. Didn't see your post about not being able to register any fuel pressure on the gauge. The 'keep it simple' advice still applies. How did you check the injector pulse before?
Mark D.

Mark... I checked the pulse with a LED light. But I did find a kink in the line under the car. I went to the store and purchased a coupler and added some more line. I do have pressure now, but it will still not start. Should the fuel system maintain pressure when turned off? The gauge went to 55psi or so and then dropped to zero in about 5-8 seconds.

Thanks...

Posted by: tabs914 Oct 17 2009, 05:14 PM

I'll go check again... should the pressure drop suddenly like it is?

Posted by: swl Oct 17 2009, 05:34 PM

yep - nothing to hold it up.

Posted by: tabs914 Oct 17 2009, 05:42 PM

Sorry miss read...28-29 and the gauge has a small leak...

Posted by: tabs914 Oct 17 2009, 06:24 PM

GOOD NEWS The spark looked a little weak, so I replaced the coil and she started right up. Seems to be running a bit rich though. I checked the plugs and they are covered with carbon powder. I have only checked one of them so far...

Posted by: BMXerror Oct 17 2009, 06:36 PM

QUOTE(tabs914 @ Oct 17 2009, 05:24 PM)

GOOD NEWS The spark looked a little weak, so I replaced the coil and she started right up. Seems to be running a bit rich though. I checked the plugs and they are covered with carbon powder. I have only checked one of them so far...

Posted by: tabs914 Oct 17 2009, 07:11 PM

QUOTE(BMXerror @ Oct 17 2009, 05:36 PM)

QUOTE(tabs914 @ Oct 17 2009, 05:24 PM)

GOOD NEWS The spark looked a little weak, so I replaced the coil and she started right up. Seems to be running a bit rich though. I checked the plugs and they are covered with carbon powder. I have only checked one of them so far...

That's awesome news! If spark was your problem, she may just need to blow some excess crap out of the engine. Take her out and run her a bit and the exhaust may clean up some. And enjoy!
Mark D.

Posted by: swl Oct 18 2009, 06:39 AM

If the cht was failing that might account for the richness. You may have already fixed that with the new one.

You might find 'Just free the rear brakes' more than a quick fix. If they are the brakes that have been sitting for 20 years you really need to rebuild them.