82 928 no injector pluse

KC Steve · 05-20-2012, 03:20 AM

Hi to everyone
I am working on a 82 928 for a friend been sitting for two years when it arrived @ my place it had no fuel pump & the fuel supply line was crushed. Got a fuel pump installed new fuel filter & fuel supply hose flushed ot the fuel tank & supply line & rail to the motor Fresh fuel in the tank. I have good fuel pump pressure @ the rail It starts & dies restarts & dies hooked up a noid light found it has no injector pluse If you spary carb cleaner in the air intake it will run I looked around under the hood for wiring cocerns such as broken wiring or wires being chewed by mice Not finding anything jumping out at me saw the article about the 14 pin connector under the hood could this be why I have no injector pulse & where exactly is it? What the best way to diag the no injector pulse . I relize a car sitting for two years is not good possible crank sensor or wiring issue ? I found the computer connected to the harness but not mounted just loose under the panel like someone had been in there not finding any obvious isses there did find with key on the fuel pump relay clicks off & on tried a know good relay soes the same thing. is this normal ?would appreciate any insight & suggetions find out why it has no injector pluse
KC Steve

924CarreraGTP · 924CarreraGTP's Garage

Disconnect the battery before working on electrical components. Check the fuel injection relay and fuses. Clean the contacts to the Jetronic and your grounds. Clean the 14 pin connector. It's right behind the jumping station just beside your right headlight in the engine bay. Make sure the Jetronic is plugged in correctly. If nothing happens try to source a new Jetronic brain. That may be why it was unplugged. If you get a pulse and get her started run a small amount of B12 chemtool in the new fuel to clean up the fuel system. This really sounds like fuel injection relay though.

Danglerb · 05-20-2012, 01:35 PM

Green wire?

Maleficio · Maleficio's Garage

Bad Jetronic main ground. It's under the supplemental air valve on the passenger side valve cover. It's invisible, and the screw is probably loose. Remove the ground terminal, add more wire, relocate the terminal to the open screw hole on the forward side of the valve cover.

stepson · 05-21-2012, 07:52 AM

Relay relay relay

The fuel injector relay for this YM 928 is specific to this function. No other relay can be swapped in to check function. (XVI...4th relay from the right on the top row)

BUT....you can remove the relay temporarily and fashion a three pronged jumper to bypass the relay function. On the prong side of each relay next to each prong is a number (30, 86, 87 etc) Use a male spade and wire to connect the 30 terminal to each of the 2 87 terminals. This will remove the fuel injection relay from the circuit. If the car now starts and runs, you will know that you need a new fuel injection relay. (928.615.119.00) Be sure to remove the jumper when you are done testing.

stepson · 05-21-2012, 08:03 AM

On another note Steve, Did you know that the 928 Owner's Club International Convention will be held in Wichita July 13, 14, and 15th?

Details at www.928OC.com

See you there.

wallstreet · 05-21-2012, 08:32 PM

Is the Jetronic the silver box near the 14 pin?

Quote:

Originally Posted by 924CarreraGTP

Disconnect the battery before working on electrical components. Check the fuel injection relay and fuses. Clean the contacts to the Jetronic and your grounds. Clean the 14 pin connector. It's right behind the jumping station just beside your right headlight in the engine bay. Make sure the Jetronic is plugged in correctly. If nothing happens try to source a new Jetronic brain. That may be why it was unplugged. If you get a pulse and get her started run a small amount of B12 chemtool in the new fuel to clean up the fuel system. This really sounds like fuel injection relay though.

wallstreet · 05-22-2012, 08:51 AM

I see the harness 10mm bolt ground at the injector. You mention a screw (NOT bolt) hehind the air injection valve. Correct?

Quote:

Originally Posted by Maleficio

Bad Jetronic main ground. It's under the supplemental air valve on the passenger side valve cover. It's invisible, and the screw is probably loose. Remove the ground terminal, add more wire, relocate the terminal to the open screw hole on the forward side of the valve cover.

924CarreraGTP · 924CarreraGTP's Garage

It's been a while but the Jetronic brain is near the relay box I believe. My memory is not what it used to be. Here is a link to a company that fixes 928 brains. It also explains what your potential problem might be if you don't figure it out by replacing or jumping the injection relay. Still try that first. Bosch LH 2.3 ECU Repair - JDS Porsche

stepson · 05-23-2012, 12:34 PM

Quote:

Originally Posted by wallstreet

Is the Jetronic the silver box near the 14 pin?

No. That's the ignition box. (Sorry. I have CRS and can't remember the correct name presently)

KC Steve · 05-30-2012, 04:03 AM

Hi
First I would like to thank everyone for there input
Here what we have did have a bad fuel injection relay XV! corrosion coming out of one of the terminal spades & two bad fuses replaced the fuse& relay. I know it is a specific relay I used a known good relay the wiring schematic on the side of the relay matches the the old one but will try the jumper method. still starts & die starts & dies no injector pulse, Cold start valve just squirting during cold start? can I get to the computer main ground wire without removing the pass side valve cover? just to tap into it to make sure i have a good ground. would also like to confirm powers & ground @ the computer harness by load testing them . Does anyone have a veiw of the connector face of what pins are what & the configuration .I have part of a schematic but only give pin #.s not where they are in the computer harness connector what was the suggestion of the ***green wire**? where is the location of the crank sensor if it has one which I assume it does. Unfortunate I do not have a spare computer sitting around to try. the reason I am leaning to wiring issue s is my 944 has the exact same problem good fuel& spark no injector pulse& it was the connector for the crank sensor had deteriorated & came apart.
once again thanks to all for the input for my concern in helping get this 928 back on the road.
KC Steve

KC Steve · 05-30-2012, 04:05 AM

Hi again
forgot one thing I did check the 14 pin connector& removed the shell to check the wiring inside all looks good
KC Steve

KC Steve · 05-30-2012, 04:08 AM

Sorry re-read about the main ground under air valve on the valve cover I will check that next
thanks
Steve

stepson · 05-30-2012, 08:04 AM

Steve,
'82 doesn't have crank sensor like the '84 Euro and up.

The fuel injection relay is specific to that function. No other relay can be substituted. It is good that your 14 pin connector is corrosion-free.

The computer main ground is above the computer on the passenger footwell firewall. The wiring harness ground is on the passenger cam cover.

lfausty · lfausty's Garage

green wire, comes out of distributor follow across to pass firewall broken/brittle/wires showing?

fuel inj relay a must to replace, sometimes even buying new it needs to be replaced, there touchy.

bump eng for each inj connector with noid light and no light? connector broken/brittle? can buy set of new on ebay pack of 20bucks resolder or crimp method.

inj them self not spraying, send out to witch hunter 100bucks 7/10day turnaround.
orings on inj large and small seated good? leaking or dried?

fuel pump going , fuel filter and or its checkvalve?

lfausty · lfausty's Garage

fuse relay chart on 928gt.com under tips links by model check to be sure right ones in right place. clean relays clean fuses clean grounds clean contact on parts,switches,components clean .... miracles will happen.

924CarreraGTP · 924CarreraGTP's Garage

I agree that you must keep emphasis on the fuel injection relay. Get a new one, go to your local Porsche shop and try to dig up a used relay, or both. It's good to have a couple anyway. I also agree that if that doesn't work, you may have clogged or bad injectors. Hopefully you cleaned out the tank and fuel lines really good before trying to start the car. An extra computer would tell you a lot in this case, but it may still be a wiring connection or the relay. A blown fuel injection relay will do just what you're talking about. I had some clogged injectors one time and I made sure the injection relay was in working order, and then ran Berrymans B12 Chemtool in the fuel letting the engine fire by bumping the starter over and over until it finally fired and ticked over. You may have a combination of connection problems and clogged injectors. Keep cleaning and make sure the relay is working. Also clean the XV relay pin inputs (female) in the relay board that you spoke of. You can maybe wedge a small wire brush in there to get the most of the corrosion out of the plugs. This will give you a good contact to the new relay without having to move the whole relay board and risk unplugging something important. Jumping will work to get the car started, but you should get a proper relay for it after it's running.