Starting Issue: Need Help

[Johnny V]

So I looked into Witchhunter and they have instructions on removing the fuel injector hoses, and I found writeups on replacing those hoses as well. Good news! Since my car was running fine not even two months ago, the probability that they can be successfully serviced by Witchhunter and given new hoses is very high. They will be sent out this week for sure.

[Niles]

That connector looks like it is for the air conditioning compressor clutch.

[jstobo]

The resister on the temp sensor is a "fix" for a bad running condition. It adds resistance to the signal which richens the mixture from the computer. The car probably had bad cold starts and or cold running issues. Dirty injectors could cause both problems. Check the sensor with an ohm meter at various temperature. You can pull the sensor out and use ice water and then heated water to test. The WSM has resistance ranges for different temperatures. If sensor is bad -replace. If good -continue to fix injection components.

[Johnny V]

Thanks fellas! I pulled the temp sensors and thermoswitch and will be testing shortly

[Johnny V]

Got my injectors back from WitchHunter today. I highly recommend them. I dealt with their second shop in Kansas. All of the injectors have new filters, gaskets, caps, and two of them had cracked insulators which were replaced. End result is that all 8 are perfectly matched and flow like new



I can now check off one more thing from my list of culprits.

[Fixer]

Really seems like the typical #2 fuel pump relay failure 911s go thru.

Fuel injected 911s of the same period have a fuel delivery relay located under the driver's seat that when fails will start briefly they die.
Just as you are describing.

Most people do not know there is an additional relay, i did not after 10 years ownership.

I would look into whether 928s also have a second fuel delivery relay.

[Maleficio]

The injector computer's ground may be bad. You need a noid test light to visually check for pulsing.

[Johnny V]

I checked all eight connectors with a noid light and all eight made the light pulse

[Maleficio]

Isn't the O2 sensor wired up with the fuel pump? I've heard about bad O2 wiring disabling the fuel pump before.

[Johnny V]

Not sure, but I have jumpered the fuel pump relay and it still won't start/stay on. I may be on to a lead that I will check on tomorrow. Hopefully I'll post back with good news.

[Johnny V]

Ok, spent a lot of time of the car today. Here is the list of what was done:

-Reinstalled injectors onto rails and then onto car
-Cleaned injector harness ground
-Replaced two large vac plugs on passenger side of throttle body (one had a huge tear)
-Replaced small vac line connection to throttle body (hose had a cut right where it met the TB)
-Removed strut tower brace (for stripping and polishing)
-Reinstalled Temp II sensor, Thermotime sensor, and Temp sensor (cleaned them)
-Visually went over every vac line I could see, found no more issues

I jumpered the fuel pump relay so I could fill the rails and lines with fuel first. Once that ran for a bit, I removed the jumper, replaced the relay and gave it a shot.

Unfortunately, the results are the same. The car hesitated for a bit (shaking off the cobwebs from sitting for about a month), then started. It stayed on for about a minute or two(ran pretty well), and then choked up and died. I tried it again, started for a second, then died. After this, it just cranks with no start. Also,if I press the gas pedal at any time while its running, it chokes and dies. If I let the car cool for a while, and try again, it starts then dies quickly after.

So, my next step is to order a new thermotime sensor, temp ii sensor, and green distributor wire. I'm also going to order a new battery ground strap since I peeled back the insulation and it looks like this:



I really thought it was going to stay on after fixing those vac leaks and getting my injectors serviced. Sucks that it's still fighting me, but I guess I can check a few more things off the list of suspects..

[riber.bentsen]

I'd say you've found the problem - it's the ground strap! Replace that before anything else, it matches your symptoms very well. Ie. "works fine, works fine, suddenly goes wrong"

[Johnny V]

Lol, we'll see in a few days when it gets here

[Maleficio]

Yep. May want to replace the engine ground cable, too. $8 at Autozone.

[SanDiego928]

Replaced my battery ground strap today. Easier starting.

Tried out an emergency start today learned at RL. Yellow wire in 14 pin to jump post to by pass the ignition switch since mine has been giving me some grief. I think that is a good thing to know.

I hope you figure out your issue(s). We all have them at some point.

[JK McDonald]

Hey Johnny - From following your problem, it looks like you have checked off most of the basic issues that might have caused your problem. Have you actually placed your crankshaft at top dead center and then cross checked the cam timing marks to be sure they are still set correctly. You would probably find it easier to line up everything by using a large socket/breaker bar on the crank bolt with the plugs removed. Naturally you must make sure to be on the #1 cylinder compression stroke.

I have seen several cases where a running 928 was shut down only to jump a tooth or two on the cams because a new timing belt had not had the follow-up adjustment performed after replacement. Just a thought -

Good Luck, Michael

[Johnny V]

Thanks for the tip, Michael! I actually have not performed that check. I assumed my timing was fine since it runs smooth for the minute or so before it dies, but I'll check regardless

[Johnny V]

Ok fellas, my new sensors came in today and of course they sent the wrong one for the thermo switch. However, temp II and the temp gauge sensor were the right ones. I replaced those two and I also installed the new ground strap for the battery.

I tried to start it and same as before, it would try, start and then die. I then wedged the barn door open and tried again. It started right up and ran like dog $hit, however, it did not die. It even allowed me to rev it up. Once I got off the gas and let the rpms settle, it ran like it was misfiring, but it ran. I then removed the wedge I had in the barn door and the car died almost immediately. I disconnected the AFM completely and tried to start her up. She starts every time and runs horribly, but doesn't die. Again, when it's running, it lets me rev it up without dying, but runs BAD.

I also noticed my dash voltage gauge is reading much more stable with the new ground strap and my courtesy lights on the doors are way brighter.

PROGRESS!! I'm now going to get the correct thermo switch sent to me, as well as look into replacing my AFM. I'm assuming the running like crap is normal with a disconnected/dead AFM.

Seems as if those sensors were never the issue, but I'm glad I have new units regardless.

I'll update once I get my AFM situation resolved.

[Maleficio]

Your thermotime switch is working fine. It controls your cold start valve. Save your money.

[Maleficio]

You may need to open up your AFM and increase or decrease the spring tension, and clean up the slide and arm. You may have too much resistance between the arm and the slide screwing everything up.