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Discussion Starter · #1 ·
While working on the Speed Distance sensor issue on my Turbo Z another gremlin surfaced. After letting the car idle for 20 minutes or so it died out of the blue.... wouldnt restart..... changed HEP... started ran fine for 10 minutes.... died again..... You can hear the ASD click and fuel pump turn on but wont start... this happens several times. If you let the car sit for a couple minutes with the key on You can hear it come back to life (fan turns on, starts normal), runs for 10 minutes then dies. The only thing I havent replaced in the last year is the Power module, there is pressure at the rail, No codes.... 1985 Turbo Z, w 1990 2.5 TII, 1987 GLHS electronics w FWD perf. custom cal. Anybody have any ideas????
 

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yes but I have no input so I didn't post except for a failing fuel pump it sounds like to me. when you say you have pressure at the rail is it there when the car stalls or are you only checking it when the thing is running?

NAJ usually finds the tech pages flow charts and post them and he will, just be patient.
 

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Discussion Starter · #6 ·
got home let it run hooked up gauges.... 24 in vac at 4500 ft, 50 psi at rail during idle, 900 rpm, turn off ignition 55 psi at rail..... ran for an hour didn't die once. Replaced throttle body, ais, tps with one from my 90 CS, seems to have cured the high idle problem too. This weekend I will do more shaking of wires to see if it dies again. Still have a slight miss at mid range boost. I will have to tape the fuel pressure gauge to the windshield and take for a drive. Maybe the pump is week... 50 psi seems a tad low.
 

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55 PSI static pressure is right in spec.
Rail Pressure will drop 1 PSI for every 2" HG applied to the FPR so 55 PSI is always maintained across the injector tip.
Rail pressure will increase 1 PSI for every lb of boost.

If you want to see the pumps capability with your gauge connected and key on/engine off and the ASD actuated momentarily pinch off the return line.
Pressure should increase immediately to max output, a minimum of 80 PSI.
If pressure does not climb immediately to max the pump will not be able to keep up with fuel demands.
With your higher boost demands 80 PSI may be low for you, you should be running a Walbro.

Also with your higher boost demands you may want to close the spark plug gap slightly.
 

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Discussion Starter · #8 ·
Thanks :) I updated the pump to a Walbro several years ago, but the car has sat in the garage for 6 yrs so I'm not sure of the condition of the pump as well as some of the other parts (seals mostly have been my biggest problem) Guess the lack of driving the Z in the past few years is catching up. But with gas prices being what they are the urge to drive something that gets better than 8 mpg like my cuda & '29 Ford is pretty strong. I have always loved my Z anyway, just need to get it running right again.
I'm pretty sure with everybody's help on this board that will happen. I kinda missed all of my TD friends from here anyway....(not sure anyone here remembers me) It's good to be back!!!!
 

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I would make sure there aren't any faulty grounds.

From what it sounds like -

"I let it sit and an hour later it comes back to life, fan kicks on, etc."

- It would appear you have a weak ground, that heats up with operation. If wires are frayed/broken inside that can cause a ground issue, then that will do it.

When you did the T-II conversion how long didi you drive it before it got parked for 6 years? I see it a lot, make sure you replaced the intake/fuel rail ground, that goes from the intake to the firewall behind it, if that gorund is missing the injector circuits get a weak ground, which sometimes will run great, depending on how well the grafoil gasket and 8 intake bolts decide they want to transfer electricity that day. I can see it fluctuating with rising operating temps, intake pressures, etc.

If you do have this ground installed, I can say I just wasted 2 minuets of your life of pointless reading.
 

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I have a side question that goes along with what you said Turismo about grounds.

is the strap I had on mine for as long as I have had it in the wrong place because it never went to the rail harness bolt where the harness is. ( one piece 89 manifold )

I do have the ground from the block to the bat, but never had a ground actually ON the railbolt, always on that little bracket that holds the O2 sensor connector at the back of the manifold as it had 2 holes in it and I always thought it went there. Also I never had the strap that straddled the 2 sides of the pass side motor mount.

The pic shows the replacement ground as the strap was corroded and I ziptied the o2 connector to other wires because the washers I used for the new eye covered the other hole, but it was never attached to the actual intake bolt, always on this bracket.


I added the the heavy alt strap physically on the alt in the middle pic when the strap that was thru the main alt bolt fell apart as I thought it would work better.
 

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I dont see that as an issue, the issue arises when there is no ground strap off the intake to the frame/battery at all. This can cause intermittent fueling issues, as the injectors need to ground to work.

As long as a strap runs from the intake it should be fine. Seen it both ways (from the intake and from the rail) I ran it from the rail because thats how it was before I converted mine (86 TI LOG)
 
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