930 Won't Start

[Farintosh]

I apologize for another "Won't Start" thread, I read through a handful on here but couldn't find anything quite like mine. I'd really appreciate some guidance from one of the Porsche gurus lurking here!

I admit I've neglected this car for a while - I've been working out of town so I don't drive it nearly enough, just a few times each year when I'm visiting. I'm finally back in town for good so I want to get everything right and get some miles on it moving forward.

It's been slow to start for a while, I have to turn the key and let what sounds like the fuel pump run for ~20 seconds (the sound changes and reaches a crescendo, almost like it's filling something) before cranking. It often cranks for a bit before it catches, but after the first cough of life if it's good to go. I let this nuisance slide for a while because I wasn't driving it much and it always went, but now I'd like to fix it.

I pulled it out of storage last week and after the usual song and dance I drove it to my new place. There was some condensation from the exhaust for a few seconds when it started, I think the tank must've been fairly low on gas when I put it away. I went to move it the next day and now it won't catch, just cranks away without any signs of starting.

I tried a better battery, cleaning the starter connections and grounding strap, and adding some fresh fuel to no avail. I've got it in my head that it must be a fuel issue based on the starting ritual but I can smell a bit of raw fuel in the exhaust when I crank it. I tried to siphon out the fuel that was in it before adding some new stuff but barely got any; I think it was super low. I think my next step will be to find a 17mm allen to drain the tank entirely in case it's old fuel, or maybe remove the intercooler and try pushing on the metering plate/plunger(?) to make sure there's fuel to the cylinders? I've also ordered a fuel filter and spark plugs just because they haven't been changed recently as is and I want to check for spark.

Any advice would be greatly appreciated, thanks for your time!

(It’s an ’85 with the engine and some bits from an ’87 turbo - there’s some sketchy wiring from the previous owner that probably isn’t helping)

[gsxrken]

There’s a sticky on the turbo board about no starts.
I’d check your fuel control pressures and system pressures first. You also need to verify spark with a screwdriver to a spark plug wire lead and holding an 1/8” away from a ground.
If you don’t have spark, that’s a lot of reading to do.
Come on over to the turbo board for more help.

[Farintosh]

Originally Posted by gsxrken

There’s a sticky on the turbo board about no starts.
I’d check your fuel control pressures and system pressures first. You also need to verify spark with a screwdriver to a spark plug wire lead and holding an 1/8” away from a ground.
If you don’t have spark, that’s a lot of reading to do.
Come on over to the turbo board for more help.

Thanks Ken, I'll get on that and start working through the sticky!

[spoke]

Originally Posted by Farintosh

...It often cranks for a bit before it catches, but after the first cough of life if it's good to go...

I had a similar issue with my '86 930. Would crank but not start; maybe would give just a hint of running but nothing. I found spraying starting fluid in the intake could get it started 100% of the time.

Traced the issue to the contact switch in the metering plate. The switch grounds when air is going into the intake and keeps the fuel pumps running. I grounded the switch and now the pumps run any time the key is on and the car starts every time. Next project is to fix the switch.

[bkreigsr]

Are both fuel pumps working when you crank?

The car will run on the rear (pressure) pump only, but it relies on the front (suction) pump to start predictably.

This might only apply to the first generation non-intercooled, so not sure about the 86.

Bill K

[Farintosh]

Originally Posted by bkreigsr

Are both fuel pumps working when you crank?

The car will run on the rear (pressure) pump only, but it relies on the front (suction) pump to start predictably.

This might only apply to the first generation non-intercooled, so not sure about the 86.

Bill K

Good call. Both pumps are cranking as soon as the ignition is on, although the rear is a bit loud and making strange sounds. It almost sounds like it's having trouble building pressure? I can feel fuel moving through the lines but also through the accumulator return line. I'm wondering if the fuel accumulator diaphragm is letting through too much and stopping the system from fully pressurizing. I found another thread where the car had a similar issue and this ended up being the case.

"I finally narrowed the problem down to a bad fuel accumulator which was letting fuel pass straight into the return line meaning the pressure was too low."

As I mentioned earlier I've had starting problems for a while, especially when hot, and wonder if it's finally manifested into a complete non-start.

I'm reading ways to test the accumulator now, I'll try to check it out soon

[1Bad86]

The accumulator issue is usually hot re start problems as you mentioned before and I experienced the same thing with my 86. You need a good set of CIS pressure gauges to test cold pressure first and see where your at. Sounds like the injectors are loosing their prime after it sits for a while. Remove the air box and with key on with pumps running(green switch on rear of meter plate housing disconnected) depress the meter plate slightly until you hear the metal lines "sing" for a second or so. This will prime the lines and possibly get it to start. Don't hold the meter plate down for more than a few seconds as it will be filling the cylinders with fuel. Since it would start on starting fluid before this makes me think it's a prime issue. Keep a fire extinguisher close. The turbo section may get you some help as well.

[1Bad86]

A 3/4 spark plug socket used upside down will fit the drain plug on the fuel tank. Pelican tip!!

[Farintosh]

Originally Posted by 1Bad86

The accumulator issue is usually hot re start problems as you mentioned before and I experienced the same thing with my 86. You need a good set of CIS pressure gauges to test cold pressure first and see where your at. Sounds like the injectors are loosing their prime after it sits for a while. Remove the air box and with key on with pumps running(green switch on rear of meter plate housing disconnected) depress the meter plate slightly until you hear the metal lines "sing" for a second or so. This will prime the lines and possibly get it to start. Don't hold the meter plate down for more than a few seconds as it will be filling the cylinders with fuel. Since it would start on starting fluid before this makes me think it's a prime issue. Keep a fire extinguisher close. The turbo section may get you some help as well.

A 3/4 spark plug socket used upside down will fit the drain plug on the fuel tank. Pelican tip!!

That's an interesting tip, I'll see if I have any that work! It might be a good idea to drain the tank completely and fill it with fresh stuff before I go any further.

I tried pushing down on the metering plate for a couple seconds while the pumps were running but couldn't hear even a hint of the injectors squealing/singing/humming. Again I'm wondering if the system pressure is way too low? That being said I can smell some raw fuel out of the exhaust when I'm cranking.
I'll keep my eye out for a set of CIS pressure gauges, I imagine they'll pay for themselves in time.
I haven't tried it with starting fluid yet. I've heard horror stories but it might be worth it to narrow down the issue.
Thanks for the tips!

[1Bad86]

Hmm raw fuel smell makes me think a bit more. Does the CDI box whine with the key on? Checking for spark would be a good idea before proceeding further if you have a helper. Spend for a good set of gauges and they will be helpful in the long run.

[Farintosh]

Originally Posted by 1Bad86

Hmm raw fuel smell makes me think a bit more. Does the CDI box whine with the key on? Checking for spark would be a good idea before proceeding further if you have a helper. Spend for a good set of gauges and they will be helpful in the long run.

I finally got around to checking and spark looks good. I'll take a look for some compatible gauges here in Canada and go from there

[1Bad86]

Unplug the WUR while tinkering so it keeps it in the cold start position while power is being applied to the rest of the system. Test the connections on the plug with key on to make sure power is getting to the WUR. It does sound rich on start though, maybe unplug tinker for a bit and then plug back in and turn on the key for a few minutes so the WUR warms up and leans out the mixture assuming that is is working. Try starting again after it warms up and see if you continue to smell gas. Swap around the round fuses in the trunk to test if its a weak fuse at the fuel pump circuit. Read up on the yellow relay in the rear trunk and how to jumper it. Let me know if you need any pictures of anything

[gsxrken]

I know life gets in the way but two months ago we suggested you check your fuel pressures.
https://www.amazon.ca/CTA-Tools-3420-Jetronic-Injection/dp/B008FJXA3M

As these cars get older, this is an essential part of ownership. A Porsche shop would bend you over for hundreds if not into the $1,000s diagnosing and fixing the root cause of your no-start condition. If you have the time (and that’s not always the case) you can absolutely chase this down yourself.

Oh and http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/547032-sticky-common-answers-why-my-car-doesnt-start.html

[Farintosh]

Originally Posted by 1Bad86

Unplug the WUR while tinkering so it keeps it in the cold start position while power is being applied to the rest of the system. Test the connections on the plug with key on to make sure power is getting to the WUR. It does sound rich on start though, maybe unplug tinker for a bit and then plug back in and turn on the key for a few minutes so the WUR warms up and leans out the mixture assuming that is is working. Try starting again after it warms up and see if you continue to smell gas. Swap around the round fuses in the trunk to test if its a weak fuse at the fuel pump circuit. Read up on the yellow relay in the rear trunk and how to jumper it. Let me know if you need any pictures of anything

Thanks for the advice, I tried unplugging the WUR but no luck. The wiring in this car is all over the place unfortunately but I'll start chasing down some of the connections.

I should mention the fuel smell is very faint and only right at the exhaust tip, I just wanted to acknowledge I could indeed smell some fuel.

I took off the fuel filter and accumulator. I was surprised the fuel filter didn't spill a drop and was nearly empty. The accumulator had fuel in it and dripped out the bottom. With the top outlet plugged I can blow air through the top inlet and out the bottom return port. There's a lot more resistance than the outlet but I feel like there shouldn't be any air escaping at such a low pressure? I'm wondering if the diaphragm is so worn out that the fuel is leaving out the return line before a significant amount/pressure makes it through the outlet to the fuel filter and engine? Does this make sense/justify a new accumulator?
Thanks again!

Originally Posted by gsxrken

I know life gets in the way but two months ago we suggested you check your fuel pressures.
https://www.amazon.ca/CTA-Tools-3420-Jetronic-Injection/dp/B008FJXA3M

As these cars get older, this is an essential part of ownership. A Porsche shop would bend you over for hundreds if not into the $1,000s diagnosing and fixing the root cause of your no-start condition. If you have the time (and that’s not always the case) you can absolutely chase this down yourself.

Oh and http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/547032-sticky-common-answers-why-my-car-doesnt-start.html

I agree! It's a bit embarrassing but I really struggled to find one that will work haha. I appreciate the link but unfortunately that one doesn't come with the correct fittings for a 911. I put an order for this one as a few members have recommended it: https://www.tooldiscounter.com/product/s-and-g-tool-aid-cis-k-jetronic-tester-sag33800.

[JSV798]

Perhaps the fuel filter is blocked. When was it last changed? Since it is a service item it would be worth fitting a new one.

[Farintosh]

Originally Posted by JSV798

Perhaps the fuel filter is blocked. When was it last changed? Since it is a service item it would be worth fitting a new one.

It was last changed 6 years ago so that's very possible. I ordered one the other day as well. It probably has less than 1000miles and the fuel inside was clean but there's some resistance when I blow through it - far more than a new bmw e28 filter I have here at least.

[991gts6s]

check the green dizzy wire.. Mine was a totally gremlin all the time...

[gomezoneill]

You have to get a fuel pressure gauge before you go any further otherwise you're just guessing. I'd bet there's a Porsche fan who would gladly lend you one.

[7783911]

Ken

"I know life gets in the way but two months ago we suggested you check your fuel pressures.
https://www.amazon.ca/CTA-Tools-3420-Jetronic-Injection/dp/B008FJXA3M"

looking at user ratings, this kit seems to be lacking..what has been your experience with it?

[1Bad86]

I have a Mac set. They've worked for years