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Noah930's Avatar
 
Join Date: May 2005
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Warm (No) Start Problem

I thought I had it licked. But last week it resurfaced.

The car starts just fine when it's been sitting. But if I shut it down, and then try to restart it, the starter just cranks. No fire. I need to wait 10-15 minutes and then the motor restarts like nothing's happened.

I've cleaned all the relays and spread their pins (front and rear). They're not hot or melted. I replaced the fuel filter (cheap things first). It fixed it....for a couple months. I replaced the fuel accumulator. Fixed it for a few more months. The battery's charged. I cleaned the transmission ground strap. I have hard time hearing/discriminating the fuel pumps while driving the car, but I hear something buzzing and they both feel like they're vibrating when the motor is running (put my hand on them today).

What else am I missing?

I tried replacing the external check valve at the front fuel pump today, but couldn't get the blasted banjo bolt off (whole assembly of bolt, outflow tube, and washers all spin together, and I don't have a wrench that's narrow/fine enough to hold the valve still while wrenching on the banjo bolt). And I haven't checked the residual pressures at the fuel pumps for lack of gauges.

What else can I try to FUBAR before giving in and taking the car into people who do this sort of thing for a living?
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1987 Venetian Blue (really looks like grey) 930 Coupe
Old 02-21-2014, 07:21 PM
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Just grind the wrench thinner to make it fit.in a few years you will have a whole tool box full of special wrenches for stuff like this.
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88 turbo Guards red Targa slant nose, and yes I am a horsepower junkie, 3.4liter,7.5 to 1 JE pistons, Adjustable WUR, Imagine fuel head, 1 bar waste gate headers,allthe cis toys. Now apart to become the next EFI monster. fabbing my own intake, headers Individual throttle bodies, MS-3, pauter rods, Xtreme twin plugged heads, gt-2 evo cams cop's.
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Old 02-21-2014, 07:45 PM
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Change the fuel accumulator
Old 02-21-2014, 07:48 PM
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I know what you mean about trying to remove the cap nut from the front fuel pump check valve and the whole check valve turns instead. I do have an old skinny 17mm open end wrench that will fit in there and hold the thin 6 point wrench flats on the check valve but I've also used vise grips on the banjo fitting to hold it.
It doesn't hurt that thick banjo fitting, just leaves some nice reusable teeth marks in the side of it and it works. You can see them in my pics.

For your no start problem check out the multi pin plug on the speed relay under the driver seat. It's the aluminum color relay closest to the door. It's the factory rev limiter and disconnects the fuel pump relay grounds at 7200rpm and the overboost sensor white wire also connects to it.

It's worth a try and it caused problems like that on my car more than once and at the worst times in traffic until I cleaned all the pins on the relay and the plug. It's just as bad or worse after 25 years as the yellow relay on the rear relay console.

good luck with it.
Old 02-21-2014, 07:56 PM
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Try to replace your CD unit.
Old 02-21-2014, 07:57 PM
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Are your fuel pumps running after shut down? If they do try to use start pilot to see if your missing fuel or not. If she fires right up your missing fuel or not enough of it. At least then you know which way to go for. There are just to many things that can cause this issue so try to eliminate as much as possible without a lot of spare parts or labor.
Old 02-21-2014, 11:43 PM
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Quote:
Originally Posted by JFairman View Post
For your no start problem check out the multi pin plug on the speed relay under the driver seat. It's the aluminum color relay closest to the door. It's the factory rev limiter and disconnects the fuel pump relay grounds at 7200rpm and the overboost sensor white wire also connects to it.
It's worth a try and it caused problems like that on my car more than once and at the worst times in traffic until I cleaned all the pins on the relay and the plug. It's just as bad or worse after 25 years as the yellow relay on the rear relay console.
This^^^
Jim posted a similar recommendation a few years ago and I mentally filed it away. A little later I was on my way to some event in a suit at night and I hit a pot hole and the car turned off like I used the key, no fuel pumps even with key on and the harness unplugged from the back of the fuel head. I went under the seat with the key on and wiggled the speed relay and the pumps went back on. I was on my way.
The next day I cleaned that relays pins and it has never happened again.
Thanks Jim! I owe you one.
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Old 02-22-2014, 09:01 AM
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Quote:
Originally Posted by gsxrken View Post
This^^^
Jim posted a similar recommendation a few years ago and I mentally filed it away. A little later I was on my way to some event in a suit at night and I hit a pot hole and the car turned off like I used the key, no fuel pumps even with key on and the harness unplugged from the back of the fuel head. I went under the seat with the key on and wiggled the speed relay and the pumps went back on. I was on my way.
The next day I cleaned that relays pins and it has never happened again.
Thanks Jim! I owe you one.
IF that ends up being your problem (as many of us have experienced) and simply pulling the plug and cleaning doesn't do the trick, then pull off the can covering to get inside. Clean the back side of the circuit board with electrical contact spray cleaner, and re-solder every solder joint that you can get to...particularly those that go to the pins. That fixed mine permanently (until the next time, that is).
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Mark H. 1987 930, GP White, Wevo shifter, Borla exhaust, stock everything else. The result of a massive Pelicanite good will fire recovery effort. Truely an open book, ready for the slippery slopes to modification.
Old 02-22-2014, 09:20 AM
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I'll look under the seat again. I haven't taken the seat off, but I reached underneath to unplug (and replug) the connections yesterday. Obviously that didn't do the trick. I might have to give in to the PITA job of taking the seat off to get to those components.

Fuel pumps shut off immediately when I turn off the ignition. All I can hear is the CD box whine.
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Old 02-22-2014, 09:29 AM
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Quote:
Originally Posted by Noah930 View Post
I'll look under the seat again. I haven't taken the seat off, but I reached underneath to unplug (and replug) the connections yesterday. Obviously that didn't do the trick. I might have to give in to the PITA job of taking the seat off to get to those components.

Fuel pumps shut off immediately when I turn off the ignition. All I can hear is the CD box whine.
Did you find your problem?
Old 02-25-2014, 11:19 PM
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Could just be that your mixture is off - to lean and not enough pressure to hot start~?
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Old 02-26-2014, 03:49 AM
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when you turn the key to ON, you should hear the FP' s make a very short buzz. if they do, your FP circuit is good. if you still feel it is FP related, pull the connector off the back of the AFM so the FPs run all the time.


mixture is a good check, along with the plugs cap and rotor.

i dont know how often the TTS goes bad, but if the switch in side is not opening up, you are dumping too much fuel in when hot. like i said, i have not heard of this happening, but just keep it in the back of your head.

again, if the car runs fine, i doubt you have a FP problem but, if you pull the connector off the AFM, you can remove each FP relay one at a time to listen for each pump running.
if you dont want to pull the connector, turn the key on and off 4 or 5 times before starting. this may run the pumps enough to build pressure if that is your problem.
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Old 02-26-2014, 04:28 AM
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Originally Posted by klefroid View Post
Did you find your problem?
No.

The fuel pumps are running. I can hear them both buzzing away while the car is idling.

I'm stumped, because other than the fuel pump check valve, I've pretty much tried everything reasonable that's been recommended in this thread. So I dropped it off at TRE to have them test the pump flow (put some gauges on it). Give them a crack on it before I embark on the Targa California next month.
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1987 Venetian Blue (really looks like grey) 930 Coupe

Last edited by Noah930; 02-26-2014 at 07:21 PM..
Old 02-26-2014, 07:18 PM
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