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Re: '86-'87 C900 ig. amp. fix w/photo Posted by Cmyles [Email] (#1126) [Profile/Gallery] (more from Cmyles) on Mon, 18 Oct 2021 10:48:28
In Reply to: Re: '86-'87 C900 ig. amp. fix w/photo, Phoebe, Mon, 18 Oct 2021 09:45:36 Members do not see ads below this line. - Help Keep This Site Online - Signup
It seems like you should return to the basics for diagnosis here. You say the car runs fine at times so we can rule out engine issues like valve timing or low compression and that leaves only a fuel delivery or ignition issue. So step one is to determine which of those it is. One of the easiest things you can do along those lines is next time it stalls dead crack the banjo fitting on the front end of the fuel rail. If fuel does not spray out (no smoking!) then you should look for a fuel delivery issue and not an ignition issue. It's a one-way test, if fuel does spray out that doesn't mean it's getting into the cylinders but if there's no pressure in the rail when the car dies you definitely have a fuel delivery issue. So if there's no pressure work backwards towards the pump looking for the cause of that. If there is pressure, check for voltage at the injectors and you might need to pull them out see if they spray properly (no smoking!).
Have you investigated the fuel pump relay (very common failure) and the main relay? When those go bad the injection system is turned off and they are little, crappy, 30 year old relays that can certainly fail intermittently. If you find no pressure at the rail immediately after it dies then jumper the fuel pump at fuse #30 and if the car starts you probably have a bad fuel pump relay. To prove the main relay is defective you need to install a good one or install a test jumper. Remove the bolster for better access to those relays.
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