FAQ: Rough / Slow / No Start - Symptoms, Causes, Solutions

Ok first off sry guys, I couldn't find my original post to coninue this topic on. This past weekend I was able to do some work/look at the car a bit closer. My problem is occasionally my car won't start - and by this I mean even turn over, no sound whatsoever when I turn the key. Here are the pointers I think are important:

Battery is fully charged

Security Light is OFF when I can't start it (turning the key, no flashes, nothing)

I can start it 1 time in the morning without any issues(seems like when it is cold) but after warming up I won't be able to

The shift gauge in the dash flashes sometimes or tells me the wrong gear (even though the car responds as it should regardless of gear the dash says I am in)

Alternator is good

Fuses are good (as far as I can tell)

Check engine light is on - but haven't gotten it coded yet as 95 is a crappy expensive year to get that done at dealer.

I am thinking it is something to do with the NSS and I have one to replace it but haven't yet. Is there something else that might be at fault?? I've heard maybe ignition switch, but I would think the gear detection would be more likely. Thanks guys for any input.

dude this is just a shot in the dark but try replacing the neutral safty switch, sounds like that thing be going bad. Its that big piece that sits on top of the tranny. it runs about 150 buck or so and it only take about an hour to change. take of the air filter tube it will can you more room to work with.

It's really important to distinguish "WON'T START", from "WON'T CRANK". Those are 2 different things. It sounds like you have a won't crank problem. Always check the simple things first. Battery, cables (clean and tight). Then move on from there to the starter motor. Is the solenoid terminal getting 12 volts when you turn the key to crank the engine.

That is correct Larry, if it doesn't "CRANK" does it make a click near de bottom of the engine...? it could be a bad starter solenoid or a bad starter. To check the solenoid you will have to remove the starter and verify it with a 12volts current, to see if it turns the motor, sometimes it could turn but doesn't have the power to turn the flywheel.

Now if you say that it can be started when it is cold, it could be a bad CKP (crankshaft position sensor) because when they are mulfunctioning when they get hot the engine may not "START" and you'll have to wait about 10 - 15 minutes before you try it again, or you can try to move the cables near the ignition coils (the one that goes to the bottom of the crankshaft pulley) due to a bad wiring to the CKP sensor.

Okay, I went to another mechanic for a second opinion and he says I need a fuel pump. He says I should an AC Delco one otherwise I'll be replacing it again in 6 months. Know where I can get one cheap?

http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/product__3961559-P_N3339K_P%7CGRP2030P____?zoneAssigned=1

I found this one on advance auto parts for $95. So cheap. Is this the correct one?

Ryan, did the mechanic tell you why you needed the pump? Did he measure zero fuel pressure at the rail?

Here's how you tell if your pump is working. Sit in the car with the windows rolled up, engine off. turn the key "on", but do not start. You should hear a faint whine from the rear of the car. That's the pump turning on. If you instead hear a lower pitched motorized sound, that's the auto leveling control, raising the rear suspension. If you hear this, wait until it stops, turn the engine off, and try again. Listen for the whine. You can also open the trunk and listen - have someone else turn the key.

If you can't hear anything, the pump is either frozen, burnt out, or disconnected. If it's frozen, you may be able to free it temporarily by opening the trunk and hitting the floor with a rubber hammer or other heavy object. Hit it firmly, but not too hard, just above the spare tire well. You might also try this with the key on. If it works, this buys you a few more starts until it happens again. Obviously, you would then know for sure a frozen pump is the culprit.

No he didnt go in-depth, I just told him everything that went down so far. He said he's certain its the fuel pump because of the no-start sometimes and low fuel pressure. I asked if maybe it could be the regulator and he said he knows GM's (gotta lot in philly) n its gotta be my pump. I wanna take it in there sometime this week to get a full body check to be certain but if it is the pump I'd like to have one on deck that he can put in for me. It def whines though.

hi all..

i have a 95 supercharged riviera.. and it don't start and i'm kind of stuck i guess..

it cranks and will run on starting spray, so i guess it is not getting gas maybe.. some people have gave me "suggestions", but i think they are getting out of thier expertise..

it cranks.. will run on starting fluid. i can hear the pump in the trunk area run, and i got a gauge that says it has 40 pounds of fuel pressure(up by the injectors, there is a connector there for a gauge)., not sure if that is good or not, i need to fix this, but money is thin, can't take it somewhere to have it fixed.. i would appreciate any help you all can give..

thanks..
pix..

Hello and welcome!

Have you check fuel injector pulse? you will need an injector NOID, it's a tool with a LED light which you can get at AutoZone to check if they are getting signal from the PCM which is eventually coming from the camshaft position sensor. Check for any blown fuses. You can check the resistance for the injectors as well but I do not know the specs, someone else in here can point that out.



Please indicate what Engine and how many Miles for a better diagnostic.

hi..
i'm sorry.. it has a 3800 supercharged V6, whatever one came with the car when it was built.. it has like 77,000 miles on it..

i don't have one of those noid things.. i'll see about getting one tomorrow..

Here's some helpful information about testing Fuel injectors with the NOID

http://troubleshootmyvehicle.com/gm_noid_light_3.8L/testing_noid_light_1.php

thanks..

they don't look too hard.. i'll get the light thing tomorrow..

You are Welcome!

hi..

i got a light thing and checked it, it seems to be good.. it actually started and ran today, but at first when i tried to "rev" the engine, it sort of like dies out, and would really only idle. the fuel pressure was atr 38 ~ 40 when it was idleing, and would jump up to like 52 when i tried to rev it, and eventually dropped to like 35 after a while, it is running like crap, like sort of shakey, and i have no clue why this is happening or what to do about it..

Hi Pix. Sometimes the fuel pump can go out intermittently, running fine at times, and then getting "stuck" at other times, especially when at idle or when the car has been shut off. Your pressure measurement of 35-40 PSI and 50+ PSI are normal. 35 does seem a bit low.

If you can acquire a fuel pressure gauge, next time it won't start, take a reading. If it's zero, the pump is stuck. If you don't have a gauge, try listening for the pump when you turn the key to "on". You may need to go to the rear of the car, or open up the trunk to listen. If no sound, give the trunk floor a whack with a rubber hammer (above the false floor, beneath the rear deck). If the car starts, the pump was stuck.

You could have more than one problem causing the different symptoms. The pump may be acting up, causing the no start, while something else might be causing it to run rough. Oh, have you ever replaced the fuel filter?

hi..
i have the guage.. yesterday when it wouldn't start it had like 40 pounds of pressure.. and i could hear the pump run.. the gauge connects to the pipe where the injectors are on the engine.. and it is still messed up, it would run but can't really run faster than idle.. if i try to go above that or drive it it like stalls.. i just looked at the fuel filter and the connector for it is totally rusted, i am kind of afraid to touch it because idk how to fix it if it breaks.. it is like a nut on a tube, would the whole tube need to be replaced? or is there some way to fix just the nut??

If you've measured pressure at 40 and 52 PSI when starting and running, I'd hold off on the filter for now. It would have to be pretty clogged to cause your engine to run that badly.

What is the history of the car? Did this problem just begin, or has it been going on for a while? Has it been getting progressively worse? Have you done any other maintenance? Have you put in fresh gas in lately?

it has been running ok.. last time i used it it ran ok, been parked for about a month though, needed to get the money up to re-register it.. does gas go bad in a month?? someone moved and gave me the car about a year ago, all i have done is change the oil, but he took pretty good care of it before i got it.. i really like this car, it is so nice to drive it..

You should first try to change the fuel filter, if you try to push (accelerate) more fuel through the fuel line and if the filter Its pretty clogged it would not allow enough fuel to flow, causing the engine to stall because of the "lean" condition (too much air / not enough fuel). You can spray some WD40 in the threads on the fuel filter nut and let it absorb it for a few minutes then try to remove the nut.

Check:

1.-Do you have the Check Engine Light (CEL) on?
2.-When the car is idling have you let the car to "warm up" and then try to accelerate it?
3.-Does it act different with temp changes?
4.-Have you checked for any vacuum leaks? it could have a leak big enough letting more air coming when the throttle is opening
5.-Have you checked the ignition system? wires & plugs
6.-What's the condition of the Air Filter?
7.-Have you cleaned the MAF already? clean it with electronics cleaner or MAF cleaner. NOT CARB CLEANER!
8.-Test the TPS to verify if it is responding to throttle changes?
Check it here: http://easyautodiagnostics.com/gm_tps_3.8L/troubleshoot_bad_tps_1.php



Here are my results when testing my TPS for a L67 series II:
https://rivperformance.editboard.com/t8713p30-car-hesitating-when-accelerates#137371

This conditions can cause stalling problems. The fuel pump might get to the right pressure but it could have insufficient fuel flow (caused by a clogged fuel line and/or fuel filter).

Here Is how you can test it:

You can disconnect the incoming fuel line (before you do this have the system depressurize by disconnecting the fuel pump relay located in the backseat and try to start the car, the car would not even start) and use a hose and some clamps to attach it to the line and put the end of the hose in an appropriate container that can hold enough fluid (fuel) then have an assistance to turn the KEY to the ON and OFF positions several times to energize the fuel pump and observe the fuel flow coming from the hose, it should flow plenty of it and with no obstructions, if the flow is very poorly the Fuel line and/or fuel filter are clogged somewhere in between.

hi..
thanks..
is that the "middle" fuel line? hard to see it in the picture.. sorry..

i don't have a check engine light on.. and i let it run for like half an hour to see if it died.. acted the same cold or hot..

the rest i'll have to check.
air filter was changed when he gave it to me.. he had one, so he put it on(in?) so about 1 year old and 5,000 or so miles on it....

the rest i'll have to check.

pix wrote:

is that the "middle" fuel line? hard to see it in the picture.. sorry..

Hey!
Yes is the one in the middle my apologies.

Good, I was asking for the temp changes as my car was acting funny in cold starts happened to be a vacuum leak.

With some tests/diagnostics you can pin-point the problem and might spend some time but not too much money

time i can do.. money is thin..

this does the same thing when it is cold or hot.. i hope it is something dumb and cheap.. so i can laugh about it later...

send us pix of yer car pix....

pix of my car.. just a plain car.. nowhere close to yours.. i can dream though..

i'll take some soon.. nighttime now..