i posted this on another forum just thought i'd hit up ht for more traffic on this thread..i'm having a problem with my 91 GS. the car just dies while driving when i push in the clutch the rpm's just go down and the motor kills. it does this after being warmed up on the road. if i put the clutch back in gear when rolling the motor will turn back on again and keep going. and if i'm at a stop light and the rpm's kill the motor, i can easily start the car back up again. i'm thinking to change the cap and rotor asap as i haven't done that yet but i'm also thinking it could be the fuel pump? any input?

 

Check the pgmfi main relay.

 

Check the main relay and ignition switch too.

 

Check alternator, alt grounds.

 

should i just replace the main relay? i don't hear three clicks when i start the car, not sure if this how you check the main relay. also i had the car checked at autozone for battery and alternator and it passed. had a problem where my battery died and had to charge it at o'reily's where their machine said i had a problem in the electrical but it wouldn't say which part it was coming from.

 

just replace the main relay..
if its not the main relay,then id say you have some kind of igntion issue or something..

 

You need a multimeter or 12V test light to properly check the PGM-FI Main Relay.

The simple test is to just listen, turn the ign. switch on to the run position, not all the way to start, do you hear the PGM-FI Main Relay "click" twice and hear the fuel pump priming, [running for a few sec.]?

If not, you will have to access the PGM-FI Main Relay to do some testing with the meter or test light.

First thing to test for is powers and ground.

Unplug the relay and test fallowing leads/terminals...

Yellow/white, 12V+, [hot at all times] fuse 36-10A, engine bay fuse box.
Black/yellow, 12V+, [hot when ign. is in run and start positions] fuse 24-15A, underdash fuse box.
Blue/white, 12V+, [hot in start only] fuse 18.7.5A, underdash fuse box.
Black, ground, full continuity to chassis ground at all times.

Let me know what you find. 94

 

well fcm i did some testing and this is what i got.

fuse 36 10A (there were two 10A fuses and i tested both, there were no numbers so i couldn't tell which was number 36) i got 11.9

fuse 24 15A w/ignition on gave me 11.34

fuse 18 7.5A .51 with ignition off, .56 w/ignition on. didn't give me much of a reading.

let know how these numbers turn out, i checked o reilly's and they want 52 bux for a new main relay oe.

 

aside from testing the MFR, as fcm has instructed, i think what i'd want to figure out first is whether the problem is ignition or fuel related. when diagnosing a problem with many possibilities, you want to start from the top and narrow down until you've reached the issue. to do so, you'll need to install a fuel pressure gauge and have it mounted somewhere that you can see while driving. i usually like to zip tie it to the windshield wiper arm.while driving, pay attention to the gauge. when the stall occurs, if the needle on the gauge drops PRIOR to stalling, problem is fuel related. if pressure holds while stalling, problem is more likely to be ignition related. once that's been figured, you can move forward in your diagnosis to zero in on the problem.
if the car stalls just while idling, you don't even need to drive it. just watch that gauge when it stalls

 

i wanted to add that i can hear two clicks when i put the car in the start position and i can hear the fuel pump priming. i hear one click and then another when the check engine light turns off. not sure when to listen for the third click, the engine makes to much noise to listen for it.

i have never hooked up a fuel pressure gauge, can i just rent one from autozone and can you tell me where to hook it up? what pressure should it be at? sorry for the newb questions.

i started my car today and the idle was fine, the rpm's didn't go down and kill the motor like i been explaining. but i didn't drive it any where.

 

should be able to rent one from autozone. tee into the banjo bolt at the fuel filter.
get one with a line since the problem seems to occur while driving only. pressure should be roughly 35-40psi. the pressure is not important. what's important is what happens to it when the stall occurs. that's what you want to know. fuel cuts out before the engine stalls, it's fuel related. if pressure holds even after it stalls, look to ignition.
usually a fuel related issue is going to result in a sputter to stall. if it just drops out all of a sudden, i'd be inclined to think ignition. but test with a gauge first and we'll move on from there

 

another thing is that the battery light just comes on when the car dies. i'll see when i can get that fuel pressure gauge from autozone. now i got other problems like no oil on the dipstick and my reg. is suspended for insurance reason. sux that this car needs so much work, but i think it'll be worth it when it's fixed.

 

the battery light will come on after it stalls. since the alternator isn't being turned.
as long as it's not coming on before it stalls. which i doubt it is, since you say the car fires right up after. wouldn't see it as being a charging system issue

 

uh huh.

 

ok this is one that i'd want to rule out since i had issues at o'reilly's with a dead battery and their charging system machine.

now i checked while doing other things with the car that the oil on the dipstick is not even measuring, the dipstick is all the way dry. so i'm going to go to the auto parts store and pick up some oil, pans, cap and rotor and fuel filter. i took apart the main relay and all the solder joints looked intact. i'm running out of options on this car and think that i just get each of the issues taken care of one by one i should be ok. also i'll check on the fuel pressure gauge too if i can get one of those.

if it is the ignition switch, how do i check if it's good?

 

The PGM-FI Main Relay is working, fuse 18-7.5A will not show any power untill the ign. is turned to start, [engine cranking].

The PGM-FI Main Relay is "clicking" 3 times, the first click is the fuel injector relay turning on, the second click is the fuel pump relay turning on, these first two clicks are very close together and can sound like one click, we know both the clicks are there because the fuel pump primes.

The 3rd click is the fuel pump relay turning off, fuel pump stops priming and CEL goes out.

Because the engine will restart right away or even while rolling, it is unlikely the problem is fuel related, unless the injectors stop "firing", but it is still a possibility.

The next thing I would do is redo, [remove/clean/reconnect] your main grounds and powers, even if it is not your problem, it can't hurt to do so on a 21 year old car.

DO NOT just eyeball the connections, disconnect them, clean the contact surfaces and then reconnect, for the main grounds it will be the neg.(-) batt. post and neg.(-) cable clamp, the batt. to chassis ground, [under the batt.] and the chassis to engine ground, the VC to rad support ground.

For the main powers it will be the pos.(+) batt. post and cable clamp, the batt, to engine bay fuse box, the main fuses in the engine bay fuse box, [the screw down ones] and the alt. to engine bay fuse box, [charge line].

Again the above may or may not be your problem, but it is the only way to eliminate them as the possible problem.

One more thing, the 11.9 and 11.34 volt readings you are getting indicate a voltage drop, if voltage at the batt. is higher, it pretty much confirms a connection problem, most likely a ground, depending on what the voltage is at the batt.94

 

Dont forget the Thermostat housing ground