Engine quit (Page 4/5)
theogre FEB 20, 06:13 PM
If you get 12.6 to ~ 13v at the battery...
then get ~ 11.3v at other places...

then yes, likely have crap Grounds and likely power connections/wires too.

You have to start a 1 spot like the battery and engine and clean/fix all grounds, + box under C500, etc.
Then do same for other Grounds listed in my Cave, Wire Service

Before try to clean/fix problems w/ I-switch and more delivering power.

⚠️ Careful: Even after clean/fixed all of that, hi amp draw things like HL Bulbs other have ~ 0.5v less when On because have so many switches and other issues causing V-dropping covered in Electric Motors even when was a New Car.

So ~ 11.3 or even less is a problem... you likely never see exact volts at the battery and alt output at other places.
Even ECM Data Stream Volts reported by Scanners are different then "battery volts" because has switches, long wire path, etc. to get power to use and read volts.

4 ref: Just the Starter Solenoid draws ~ 30 amps normally before Starter Motors draws 120+ amps on Full Charge Battery. Car w/ iffy Wiring cause Low Volts then Solenoid or both tries to pull more amps and can't get that and just make noise or do nothing.
Starter Motor has Big cables to the Battery but the 30 amps to run the Soleniod has a long path thru the I-switch on the S-column.

[This message has been edited by theogre (edited 02-20-2023).]

stevep914 FEB 20, 06:37 PM
Thankyou much! Wired, but just fiddling around with all the wires at c500, got the car started. I have no idea why, and don’t trust it until I do more thorough cleaning and checking. A couple of years ago I installed a racing type interrupter battery switch, to cut battery power when not using the car. There was a small battery drain going on before that. I will post final results after going after the ground cables. Thanks to all for the responses! Steve
theogre FEB 20, 07:08 PM

quote
Originally posted by stevep914:
A couple of years ago I installed a racing type interrupter battery switch, to cut battery power when not using the car.

Bought from Where?
Amacon, Eflay, and other cheap battery disconnects can cause you problem.
Example: read https://www.fiero.nl/forum/Forum2/HTML/146657.html

the cheap "switch" type can mount everywhere have same problem. More so if they get "water" on them going thru Fiero engine vents etc.
Patrick FEB 20, 11:20 PM

quote
Originally posted by stevep914:

Patrick, I cleaned both the terminal posts on the connection you have indicated, and their corresponding connection wires. Before trying to engage the starter, with power through the ignition ( all dash lights on) the voltage at the terminal is 11.34 volts. After trying to engage the starter ( which immediately cuts all power off) the reading is still 11.34 volts.



I've suspected all along that there's a poor battery or ground connection somewhere (probably on the battery itself), which is why I wanted to know what the reading was off the battery junction terminal... as all power to the car (except for the starter) goes through there. As others have addressed, 11.34 volts is not what it should be.

I understand you've now gotten the car to start (yeah!)... but out of curiosity (and to rule out a "weak" battery), what is the voltage reading directly off the battery terminals?

[This message has been edited by Patrick (edited 02-20-2023).]

stevep914 FEB 21, 05:29 PM
Patrick, , I have 12.6 volts at the battery, and 14.5 at the battery when the engine is running. I am going to attack all the ground strap connections before I trust driving the car anywhere. Will continue to update…
Patrick FEB 21, 08:54 PM

quote
Originally posted by stevep914:

...12.6 volts at the battery, and 14.5 at the battery when the engine is running.



Excellent.
stevep914 FEB 23, 08:59 PM
Well as I hope, a final on the engine starting and running issue, I went over the ground straps I could find, and because this is a replica, and somebody eliminated some of the factory ground straps, the only one I could find was a big one from the negative battery terminal to a stud on the front of the engine head near the front exhaust manifold. It looked corroded enough I was hesitant to try undoing the nut. Instead, I purchased a new ground cable ( nobody here carries the braided flat ones) and ran it from battery negative, to a threaded empty socket on the block above the water pump. Cleaned everything before the install, and got 12 volts from the block to the connector pins on the terminal below the C500. The engine starts fine , but I have not run the car yet on the road. I figure while I got it up on jackstands, I may as well do a oil and filter change.
Is still have to repower my two engine bay cooling fans that used to run from the old air compressor relay. I would still love to have them powered from there, but have no idea which of the three non negative wires on the relay do what. There is a 4 th wire that is obviously ground. Any suggestions here? . The original wire harness that was connected to this is dead from what my testing indicates. I can’t thank you all enough for all the input. The car looks and drives so nice , one tends to forget it is a 38 year old car! Steve
Patrick FEB 24, 06:20 PM

quote
Originally posted by stevep914:

Well as I hope, a final on the engine starting and running issue... The engine starts fine... I can’t thank you all enough for all the input.



Sounds good, Steve. Hopefully the car will be alright now. Getting those auxiliary fans to operate shouldn't be an insurmountable challenge.
stevep914 FEB 25, 05:44 PM
Thanks Patrick, got at this on my day off, and wired the fans into a circuit without the relay. I could not find anything going on with the relay when I tried to put power to it. I fused the line at 20 amps, and there is no heating of the wires. ( they are not large fans) Maybe the relay is why the cooling fans quit in the first place. Took the car out for its usual spin, and everything is working perfectly! Despite all the old car grief, it is worth it for the way this car behaves on the twisty road I take it on. I had a stock Fiero which I drove for awhile, and then stripped it for parts. Night and day between how the two cars behave. My Fiero/Ferrari is 1 and 1/2 feet wider, and runs on 245 tires up front, and 275’s on the back, and drives like it is on rails.
Thanks to you, and all who helped me on this. Maybe at some point I will become knowledgeable enough to be able to assist others. Steve
maryjane FEB 25, 08:41 PM

quote
Originally posted by stevep914:

As an afterthought- I think this relay where the three port connecter plugs into the relay is burnt, is the fuel pump relay. My two engine cooling fans are powered by a wire that connects to one of the three female ports on the connecter. If they don’t come on when the ignition is turned on, it would be reasonable to assume the fuel pump is not being activated by the relay either. Could it be this simple why the engine quit? If this were so, the only confusion would be why it all unpowers, when I try to engage the starter.


Am I reading that right, that you (or a previous owner) had the 2 cooling fans connected to the same relay that energizes the fuel pump?

(It all 'unpowered' because you had poor connections that showed to have 12.5 VOLTS but the high resistance connections wouldn't allow enough CURRENT to flow. You can connect 9 AA batteries in series to produce approx 13.5 VOLTS but that doesn't mean they will turn a starter.

The fuel pump relay is fed by a 'hot at all times' orange wire from fuse block (10amp fuse) that transitions to an orange/blk wire at one of the connectors (c-203?) . A good OEM fuel pump probably won't pull but about 6 amps, but those fans have to be included in total current running to and/or thru the relay. They (fans)need to be on their own protected circuit even if you may have gotten by using the power input side of the relay as supply voltage for the fans.

The other thing to remember is that IF the engine is running and IF your oil pressure switch is good, the fuel pump can/will be powered thru the OP switch even if the fuel pump relay fails. But, a major bad connection at battery or at a fusible kink or at the battery junction can prevent the fp from recieving any power.

[This message has been edited by maryjane (edited 02-25-2023).]