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A friends 89 Trans Am with a 5.7 (L98) PFI stalls and will crank, but not restart until the car sits for a few minutes. I haven't actually looked at it yet. I'm guessing something is getting heat soaked and cutting out.

I'm aware that fuel injectors when hot can go out of resistance and cause no starts. But do they also cause stalling?

I've ran into a no-start L98 in a Corvette before but it never stalled. I forget the numbers but the injectors ohmed all over the place. I believe that when a injector shorts or is open the engine computer will shutdown the injector driver. The way the wiring diagram shows it there are only 2 injector drivers, one for each bank. In the case of the Corvette it had multiple injector failures on each side.

I also was thinking about a fuel pump relay but I remember that if for some reason the fuel pump relay fails it uses the oil pressure switch circuit to power the pump. I suppose the oil pressure switch could be bad as well.

I'm unsure of the failure rate of ignition coils/control modules on these. Is the Ignition Control Module mounted on the head like a LT1? Or is it built into the distributor?

I haven't gotten any useful information over the phone and plan on looking at it during the weekend.

Thoughts?


Update

Turns out the fuel pump, filter and regulator diaphragm were swapped out already. Fuel pressure is at a pretty steady 40psi.

Had good spark and fuel pressure after the stall.

Ohm'd the injectors some were as low as 0.2Ω and some close to spec in the 15.xΩ range. Looks like it's time for 8 new injectors.

  • Try starting fluid... (sprayed into the engine intake near the air filter) If that keeps it running, then you could probably assume its a fuel delivery issue. – user3188168 May 26 '16 at 18:50
  • This doesn't have an ICM like the LT1. I don't remember what year GM cut from the HEI to the newer type distributor, but my 86 IROC-Z has an HEI, while my son's 91 has the newer. The HEI has all of it inside the distributor. The newer one may be computer controlled. I haven't dug into them enough to know the electronics involved in the newer, so cannot tell you. – Pᴀᴜʟsᴛᴇʀ2 May 27 '16 at 20:11
  • @Pᴀᴜʟsᴛᴇʀ2 Thanks, I was just thinking about it since heat soaking of the ICM was an issue on the LT1 IIRC. I did a quick review on the wiring for the 89 and it's in the distributor as you said. – Ben May 27 '16 at 20:24
  • Yup, I know all about the LT1 ... I used to own a 94 Z28 M6 ... argh. – Pᴀᴜʟsᴛᴇʀ2 May 27 '16 at 20:55
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My guess is fuel pressure, a bad pump or clogged fuel filter.

I would put a fuel pressure gauge on it and see what the pressure is next time it stalls and you try to restart.

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