Gonzotiki_666

Hey RL gang,
My 81 has gone from a nicely thrumming beasty to a no starty sadness. Last drive was roughly a week ago. Went on a nice 100 mile drive. Battery is new, as is the ground strap. Grounds on the rear are tidy. It cranks but won't catch.

Today I've jumpered the alarm so that wonky thing is ruled out. No start. (Although it sorta came alive for a second and immediately died before I could tap the gas.)
Jumpered the FP relay & could hear it humming away. No start.
Replaced the FP fuse. No start.
There is a bit of exhaust aroma from the rear and the oil pressure guage goes up while it cranks.

It's back on the trickle charger overnight now.
I've read a hundred no start threads today. They all scare me.
I'll make it a point to dive into the 14 pin and some other grounds this weekend--but what would the next recommended tests be from the 928 gurus out there? Not a mechanic here, but I'll need to get this resolved myself.
As always thank you for your insights.
cb

ammonman

If you are sure you're getting fuel to the fuel rail via the pump the next thing to check is see if you have spark. No start is always a lack of either fuel, spark, or compression in the right proportion.

Mike

Landseer

On the 81, which is L Jet engine control, there is an ignition relay that can be jumpered with a three-ended wire. 30 to 87 to 87a. or 30 to 87 to 87 depending on what you are referencing (diagrams or relay printing). I've had two fail in 84 cars with similar setup. Jumper and try to start. Alternately, don't jumper it and hook up a noid light in place of one of the injector plugs. The light will strobe with start attempt. If it doesn't, put in jumper and try it. DR/Wally/Jeannie have a great chart of relay positions on their Specialsts site.

Beyond that, there are two very important grounds, on the engine for 81, both on passenger cam cover.
One is hidden from easy view by the an emissions valve that must be removed for proper ground cleaning.
These grounds are for the ignition system on the car and the O2 sensor so they are quite important --- the computers ground there. The injector harness essentially grounds through this.

Green wire linking distributor and spark box on fender can have flaky failed plug ends -- look at it but try not to disturb, its how the car knows when to fire. If somebody or something chewed it, could be a problem.

Big vac leak can cause problem, too. Nice thing about 16V is visibility to most hoses. If too much vac leak, the barn door of the AFM doesnt' swing open, so the car can't get the air it needs to run, and the potentiometer within the AFM doesn't send the right signal to the computers.



Nice thing about California is less moisture to mess with all the electrical stuff, too. I've made replacing the temp/time switch part of my "initial list" of things that automatically get replaced in the first round of massaging on any L Jet rescue car due to no start issues I've had.


This thread might help, too, as other potential no start issues are mentioned during the discussion.

https://rennlist.com/forums/928-foru...next-step.html

Back to grounds cleaning, this rambling thread shows some of the grounds that apply to your car. It is especially good at showing the passenger side cam ground positions scattered in the first half dozen pictures or so. Yes, its a Euro LH 16 v car, not L Jet, but most of the grounds are the same, esp. on cam cover. (and yours has the green wire / the euro uses a crank position sensor, so ignore that part).

http://forums.pelicanparts.com/porsc...-16v-euro.html

Mrmerlin

nice post Chris

86'928S MeteorGrey

If you have spark and fuel present...

Could be your temp II sensor.

Try turning on the ignition, hear the fuel pump get to pressure, then pull the fuel pump relay and see if the car starts.

If this causes a start condition, check your temp II sensor..... Have seen this recently.


If no joy,
Check your fuel pressure regulators for fuel passing into the vacuum and directly into the throttle body.

Gonzotiki_666

Thanks for the tips guys. I should have some time to grab some provisions (noid light/spark tester) & try some stuff this weekend. Where is the time / temp switch located? Also how do I test for fuel at the rail? Might seem like a dumb question-but I've not done it before and I don't want to burn down my garage!

Landseer

If you have gas in the tank, and pump runs, I think its ok to skip the fuel volume test for now.

Temp/time switch runs axially into water bridge. Most other sensors up there on front of motor run vertically.
I read somewhere the test method for checking time/temp functionality.

But am wondering right now about the ignition relay.
Also the ignition switch.

So many things can go wrong. Be patient.

Gonzotiki_666

Quick update had some time to noodle around. Made a jumper for the ignition relay, but turns out I didn't really need it-the relay in mine was identical to the horn-so popped that in and no start. Tried the hose in the barn door (that just sounds kinda wrong ) and that didn't do the trick either. Both fuel pump regulator vac lines smell gassy, as does the dampner vac line.
Too much traffic in town right now to run out for noid light/spark tester/fuel pressure guage (parade for the Petaluma little league-they came in 3rd for LLWS).
Digging into 14 pin and man is it UGLY in there, the casing is brittle and cracked. From below it looks like it slides to free it from the housing that's holding it in place, is that correct? I don't want to make it worse and destroy it.

Here's pics of 14 pin and fuel pressure regulators for the car so other noobs like myself can get an image result when we search.

Landseer

Colin,
What do you mean the ignition relay is same as horn relay?
I think this is wrong. The LJet ignition and fuel pump relays are very different from each other and from the horn relay on the Ljet cars. The picture on the side of the ignition relay needs to have two 87's on it. Ignition relay is 928-615-119-00 and it needs to be in position # XVI. It has extra pin on it.

Horn relay is 928-615-117-00. Like a standard 24 or 53 relay in terms of contact position.

Can you show pictures of each relay and relative postions on the CE panel.

Lets make sure this is right.


Good find on the 14 pin, that's a mess, roger or mark can supply new ones.

Do you have the wiring diagrams, if not, we can map it for you.
Yes, it slides, but there is a thing to depress underneath to allow sliding. Regardless, you need a new one.


Somebody has replaced at least one of the 50mm long injector feed fuel hoses, but used a hose clamp that can cut the hose. I think you will want to take an opportunity here to change fuel lines throughout.

Gonzotiki_666

Good grief. Of course you are correct Chris! I only looked at the raised numbers on the bottom & saw one "87" stamped--for both male plugs I presume. It's clearly stamped on the side. I feel like a dumba$$. Thank you again for your help.
I did get all the emissions stuff outta the way to clean up those cam cover grounds. My hands arent even that big and it was way tight. My dogs learned a few choice new curse words.
I'm leaning toward having a shot at cleaning up that 14 pin connector. I need to save some coin to have the fuel lines done by a pro or a RLer in the bay area that's done it before. Any volunteers??

Gonzotiki_666

Found this broken vacuum line nipple last night. I wonder if this a 928 specific part or if can I snag one at AutoZone? It doesn't look like a generic vacuum connector to me, but it's most likely my culprit here I hope.

And yeah I agree that motor is FILTHY. Ima do some cleaning today too.

Lizard928

That broken vac line will not cause a no start issue.

Jumper that fuel inj relay with a 3 pin jumper as described.

WallyP

Kneel by the rear bumper. Have someone turn the ignition switch on. Listen for the fuel pump to whine or buzz. Have the helper try to start the engine. Listen for the fuel pump to whine or buzz. No fuel pump, no start.

The most common problem is a poor connection at the fuel pump fuse.

Gonzotiki_666

I will but is that vac connector a universal item? Thanks.

Gonzotiki_666

Finally had some time to address this annoyance. Turned out it was the two pronged vacuum part. I ordered a used (new is of course NLA) one from 928 Intl. All the relays were fine. As long as I was getting filthy I replaced some vacuum lines w/new silicone ones. Those lines were most definitely original as several actually snapped in two while I was mucking around. It Fired right up.

Broken culprit is in the picture.

Next up= fuel lines!

Thanks to all who chimed in.
CB