Classic no-start with a twist

[83Zel944]

I'm new here and hope that a fresh take on the problem will result in success.

I have a problem. After testing compression I put the fuel pump fuse back in and tried to start the car and it wont start. It cranks but has no fuel. I am not sure what else could have happened.

I pulled the plug wires and boots. Then pulled the fuse, cranked and read the readings. Now no start.

Pulled nut at the end of the fuel rail with catch rag and LOTS of fuel shot out. Much more than I expected for the operating pressure of 38-40psi.

Using Clark's-garage methods tested the following:

AFM - OK (input and output V+ in range and smooth transition when barn door opens)
Fuel pump Relay - OK
Speed / Reference Sensors - OK (within resistance values)
DME - OK (pins 35 to 5, and pins 18 to 5)
Fuses - OK
Fuel Pump - OK (operates using DME "Y" jumper wire I made)
Injectors - OK (12V+ on one leg of injector harness 0 on other)
Plugs - OK (Gapped and changed)
Wires - OK (Cleaned and close to resistance specs)
Cap - OK (PO must have changed cap before i bought it)
Spark - OK (Spark on all plugs - bright Cool)
Vacuum hoses - I have check all the hoses between AFM and throttle body since those would likely make a lean condition all ok including those running under intake though they could use to be changed anyways.
Battery - recharged and ready to crank - terminal clean and tight

It ran for a bit on starter fluid so I think it's the injectors. I am not sure how I may have damaged them while cranking for a compression test.

While looking under the dash i have noticed a wire that looks like it should be attached to the back of the fuse panel. It is Black with a red strip and has a female blade connector at the end.

Ok I am running out of ideas and seriously dreaming of scrapping the POS 2.5 in favor of a V8 of any sort just to remove the archaic engine management and get back to enjoying the car.
I need help pretty bad here folks.

[John_AZ]

83Zel,
Hello,
If your car was running before the compression test...

My, you have done your homework and made many more checks and tests than I could have thought of. Well done. You have much knowledge and experience.

I do not know what the wire is for on the back of the fuse panel on the '83 944. It has happened that while pulling and replaceing the DME relay, the wires and rear connections separated.
Your checklist did not include the reference sensors. Does the tach bounce a tiny bit when you crank the engine. It should. This tells us if the sensors are sending a signal.
If not, check the connection of the sensors at the top-rear of the engine for good connection. Check the wires for cracks. Begin at the bell housing and follow back to the computer. At the computer see if you moved any wires and wiggle the big in wire.
You know Clarks-Garage troubleshooting:
http://www.clarks-garage.com/shop-manual/ts-01.htm

Here is one from member many944s:
http://www.benms.com/944nostart.html

Why do you think it is the injectiors? Have you checked for fuel pressure at the end of the fuel rail? You checked the pins at the DME relay...have you tried your spare?

GL
John_AZ
1988 924S + 1987 924S

[83Zel944]

The tach bounces so i assumed the sensors were ok.

While under the dash replacing the DME Relay I noticed the fuse panel was not secured. I am sure who ever loosened it couldn't figure out how to put it back in properly so they left it sort of in the metal housing. I did figure out the panel mounts and remounted it and replace the hold down bolt.

Because the car ran for a bit on starter fluid and I have fuel in flow I assume the injectors are not firing. I pulled the plugs after an attempt at starting and smelled no fuel.

Does any one have a 83 944 wiring diagram?

[ae1969]

If your FPR has failed it tends to fail causing a high pressure situation....

The injectors will not fire in that situation. Unplug one injector and attempt to start it. If it runs on 3 injectors it is probably the FPR.

I would verify using a fuel pressure guage.....

[John_AZ]

It is a frequent problem. Here is another current post and a couple more solutions--begin at post 31...
http://forums.pelicanparts.com/porsche-924-944-968-technical-forum/447266-87-924s-sputtered-stop-post4395498.html#post4395498

GL
John_AZ

[83Zel944]

WEll I pulled an injector connector and it didn't start so i'm going to try and figure out where the wire mentioned above goes and check the connections to the rear of the fuse panel are tight.

I pulled the DME and all things look and SMELL good. no burnt smells or cracked solder joints. Still not start though

[legoland951]

Check your injector pulse with a noid light. Having voltage is meaningless. You cannot check pulse with a multimeter. They are fairly cheap at any auto parts store and you can't use anything else other than an oscilloscope that I know of.

[83Zel944]

i'll try and find one.. but my local Autozone doesn't carry them. Any way to make one? I am good with electronics.

[legoland951]

http://motors.search.ebay.com/noid_Parts-Accessories_W0QQcatrefZC12QQdfspZ1QQfromZR40QQftrt Z1QQftrvZ1QQsabfmtsZ1QQsacatZ6028 You can find a set for less than $15. Its totally not worth your time trying to make one.

[paper1122]

Did you make a jumper wire per Clarks for the DME relay? My relay looked good and tested good but was still bad.

[legoland951]

This is a fuel issue. I believe a bad DME or relay will get no spark so starting fluid would not have worked.

[83Zel944]

i did make a jumper and the fuel pump is operating. In fact i used the jumper to test flow at the rail. With the jumper in it wouldn't start. I also tried disconnecting 1 injector to test if the FPR was shot and it still didn't start.

What's funny is that I plan to rebuild the engine since i know it will need rings and after the compression test it won't start. It ran before i did the test and now nothing. This thing is making me a bit grumpy and i think this thing is trying to test my manhood.

[legoland951]

Trust me, check injector pulse and I can try and help with the next step.

[83Zel944]

I'm waiting on my ebay set of noid lights. I hope they come quick.

[83Zel944]

Noid light indicates that the injectors are pulsing. The light blinks they way I think it should. No solid or no light symptoms on the noid light. Just blinks as the car turns over.

[legoland951]

If you got pressure and pulse then it can't be a fuel problem unless the pressure is off. I have never seen a no start problem when there is pressure with pulse and a car start with starting fluid. I almost have to see it to believe it.

[TibetanT]

Originally Posted by legoland951

If you got pressure and pulse then it can't be a fuel problem unless the pressure is off. I have never seen a no start problem when there is pressure with pulse and a car start with starting fluid. I almost have to see it to believe it.

Hello There Everyone:


I have SEEN this condition before. It happens when the reference sensors connections become loose, or one is not connected completely. The connection point is where they meet the wiring harness within the engine compartment. Make sure they are snapped on tight. If loose, use some electrical tape or tie wraps to hold them together. Check for corrosion there as well as the ground points.

Just a thought to throw out there.

legoland951 is right though...this is very, very unusual to see happen.

[legoland951]

The reference sensor is working since it runs on starting fluid. Everything including DME, DME relay, crank sensor, reference sensor, cap, rotor, and coil are ALL working since it runs on starting fluid. He has compression, timing, correct spark/timing, but no fuel. He has fuel pressure and pulse so it SHOULD run as these are the only things any engine require to run. I can't imagine all 4 injectors spontaneously getting plugged up simultaneously. Low fuel pressure is the only thing I can think of. Heck, even if he forgot to plug in the AFM it should run for a second before it shuts off again.

[TibetanT]

Okay, good!

Now, check the battery voltage with a volt meter. Voltage at cranking must be at 12.5 or higher for fuel injectors to fire.

[83Zel944]

I will recheck the battery. I simply trusted that the battery was charged fully because my battery charger said so. I did pull apart the connectors on the firewall and they were tough to pull apart but clean. I will hit them with contact cleaner tomorrow. I'll update tomorrow.