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Topic: just wont rev

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just wont rev (1/25)
 7/2/12 12:11am
ANNICORVETTE
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BILOXI, MS - USA

Vette(s):
1990


Joined: 3/19/2009
Posts: 27

a few months ago my wife says her 1990 is running funny so i took it for a ride (50 miles round trip) it started out running a little slugish drove 25 miles no drastic problems noticed about 5 miles from home it acted like it was out of fuel then died, i got it started and crawled home - engine just would not rev no power obtained at most 5 MPH. I have drained the tank cleaned and changed the in tank fuel pump including the sock and gauge sending unit as well as the inline filter (by the way the manual only covers the inline filter replacement on coups it is much/much more work on a ragtop) still idles very/very rough and only crawls.
desperately seaking advice !!!
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Re: just wont rev (2/25)
 7/2/12 7:24am
SAYWHEN
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Posts: 82

Since you have Multec fuel injectors and they're known to fail...I'd start by checking each injectors resistance with a volt/ohm meter...each should measure around 16 ohms. The point is readings should be close to the same for each one. Remember to check when COLD....then run to operating temp. and check again when hot. I've seen bad injectors read low 2-3 ohms or high 40+ ohms. Either way the ECM on your Vette has a internal "driver" which pulses 4 injectors at the same time (most refer to this as batch fired)....one bad injector will cause the "driver" to shut down and kill 4 cylinders. I may be way off base, but that's where I'd start unless you know the injectors have been upgraded.   JMOSmile
Re: just wont rev (3/25)
 7/2/12 7:59am
CaledoniaBrian
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, - Canada

Vette(s):
1988 Convertable


Joined: 11/3/2011
Posts: 150

 Is there a code showing.........no sense just throwing parts at it....
 
 Fuel injectors was also my first thought........ but see if you can find a code.


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Re: just wont rev (4/25)
 7/2/12 11:01pm
Adams' Apple
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Duncanville, TX - USA

Vette(s):
1985 Coupe-L98/Auto,Bright Red/Carmine. 1974 Coupe-L48/4speed, Medium Red Metallic/Black Deluxe.


Joined: 3/18/2009
Posts: 2230

Howard...is it setting any codes, or turning the "Check Engine/Service Engine Soon"" light on? That would be the first place to go...check for codes.
Along with infector issues already noted, I would also suggest the ignition module could be taking a poop.
Check for codes first...that will usually point you in the right direction, so you'll have an idea of where to start.

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Re: just wont rev (5/25)
 7/2/12 11:40pm
eddie20890
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lanoka harbor, NJ - USA

Vette(s):
1990 L-98 white/ red/black leather interior targa top auto 1975 L48 blue/black leather interior t tops auto


Joined: 3/22/2009
Posts: 1363

check the codes as joel suggests but they are shown next to the speedometer digits. just another thought here...wonder if the egr valve is stuck open. by any chance have you taken a fuel pressure reading. with the key in the on position, it should be approx. 42 psi. when running it should be about 36 (in that area).

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Re: just wont rev (6/25)
 7/3/12 2:54pm
ANNICORVETTE
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BILOXI, MS - USA

Vette(s):
1990


Joined: 3/19/2009
Posts: 27

there are no check engine light lit and no codes ??????
Re: just wont rev (7/25)
 7/4/12 2:20pm
redvette89
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Huron, OH - USA

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1989 Red Convertible - 160,000 fun-filled miles -


Joined: 12/5/2009
Posts: 179

You're descibing similar symptoms I had a few years back..... no power and no check engine light on my '89. Took it to our local GM dealer and they said it was the ECM so I paid for that but it wasn't the problem. They came back and said it was the fuel pump. Nursed the car home and replaced the fuel pump myself but that didn't help either. After much research I decided to replace all 8 injectors and bingo, car ran like new. The car had 120,000 miles on it at the time which made the decision a little easier. I believe the 89 and 90 both use the same injector and I found seceral technical articles explaining the original OEM injectors had an average life span of less than 75k miles.  

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Re: just wont rev (8/25)
 7/5/12 12:41pm
jonneyone
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galion, OH - USA

Vette(s):
1984 base coupe 17,000 miles all original. very low production number.red on red 3853. pro num.


Joined: 5/31/2012
Posts: 413

it sounds like injectors however have you checked the cat converter it might be pluged . when it gets pluged you'll experance the same condetion no power.  you can check it with a vacum gage  or just unhook your cat..converter. let me ask you this does it idel ok. 

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Re: just wont rev (9/25)
 7/5/12 8:37pm
ANNICORVETTE
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BILOXI, MS - USA

Vette(s):
1990


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IT IDLES LIKE A BULL RIDE IN THE RODEO. haven't had time to get back on the problem since the holiday. my wifes 90 has 16000 miles.
Re: just wont rev (10/25)
 7/5/12 9:49pm
ANNICORVETTE
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BILOXI, MS - USA

Vette(s):
1990


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Posts: 27

in my last post the 90 wasn't ideling worth a ----. just moved the 78 and started the 90 to move it to a working area, the 90 started up and ideled fine pulled it out of the shop and wsnted to go for a drive a noticed the fuel gauge indicated the end of the driveway may be as far as i could get. will get gas tomarrow and check the fuel gauge reading. I just hate it when things act like the fixed themself.
Re: just wont rev (11/25)
 7/9/12 8:04pm
jonneyone
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galion, OH - USA

Vette(s):
1984 base coupe 17,000 miles all original. very low production number.red on red 3853. pro num.


Joined: 5/31/2012
Posts: 413

i wonder if you just had some bad gas.  theres alot of it going around now days.  take for intance i just filled up my 2012 electic gluide hd.  it started to spit and spuder. ran like shi....if you know what i mean.  it was sunoco 93 octain.  whet home and drain the tank. i found a bunch of water among other things. i went back to the station and told them about it.  they said oh well. what a waste of money.  however it does happen.   i hope your proplem stays fixed for you. 

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Re: just wont rev (12/25)
 7/9/12 9:56pm
ANNICORVETTE
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BILOXI, MS - USA

Vette(s):
1990


Joined: 3/19/2009
Posts: 27

put new gas in the 90 yesterday and got distracted didn't get a chance to check it out, today had an appointment at the hospital.
Re: just wont rev (13/25)
 7/9/12 10:36pm
Adams' Apple
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Duncanville, TX - USA

Vette(s):
1985 Coupe-L98/Auto,Bright Red/Carmine. 1974 Coupe-L48/4speed, Medium Red Metallic/Black Deluxe.


Joined: 3/18/2009
Posts: 2230

Unfortunately, water in the fuel isn't gunna go away. The amount of ethanol they are putting in is the main cause, but some stations also have really old tanks that have water in them.
Water in the fuel can certainly cause plenty of problems, from fuel pumps/filters, to infectors. Water don't burn very well...unless you have a hydrogen powered vehicle....LOL

Hope it turns out to be something simple. Howard.


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Re: just wont rev (14/25)
 7/13/12 12:37pm
ANNICORVETTE
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BILOXI, MS - USA

Vette(s):
1990


Joined: 3/19/2009
Posts: 27

took the 90 for a drive wednesday afternoon (4 miles to the americian legion- had a drink ) the 90 ran a little off normal that i attributed to the computer making adjustments to my repairs anyway i got about 2 miles from home then #$%^ happens again same problem. i now believe it is an electronic heat problem. anyway i got the 90 home it completely shut down on the front lawn i waited for 2 hrs and went out to put it inside same problem (first time it has ever been out all night). this morning i went out did a little checking to no avail got in it started up immediately idled fine and a moved it in front of the garage. i did notice on the slow trip home the instrument panel where it shows miles / gal and various other things flashed what i believe was  SYS every time the 90 lost power then it went away. any ideas?
Re: just wont rev (15/25)
 7/13/12 2:18pm
Adams' Apple
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Duncanville, TX - USA

Vette(s):
1985 Coupe-L98/Auto,Bright Red/Carmine. 1974 Coupe-L48/4speed, Medium Red Metallic/Black Deluxe.


Joined: 3/18/2009
Posts: 2230

I think you're looking at a failing ignition module, Howard. Classic symptoms. The "SYS" on the dash readout usually has to do with the traction control/abs, but I'd need to check on the '90. Perhaps Dave( eddie20890 ) would know, since he has a '90 model. It would help if there were any codes...

|UPDATED|7/13/2012 11:18:45 AM (AZT)|/UPDATED|


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Re: just wont rev (16/25)
 7/13/12 5:09pm
SAYWHEN
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I agree with Joel....it sounds like symptoms of failing ign. module....eng. hot no and/or poor spark...engine cooled down ign. system works great until hot again. The SYS light can also come on with a weak/failing battery even though the charging system is good ( not meaning to imply that's your problem..just sayin' )
 
Have you actually checked for codes using the paper clip method from Joels' previuos post since the SYS light was on? It's possible a "history" code may show up.
Re: just wont rev (17/25)
 7/13/12 7:42pm
ANNICORVETTE
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BILOXI, MS - USA

Vette(s):
1990


Joined: 3/19/2009
Posts: 27

it has a new battery (been checked twice ).
 if it rains tonight i will try the clip method tomarrow if it doesn't ran i will spend the day mowing the front lawn (approx 6 acres ). any pics of the ignition module being posted?
Re: just wont rev (18/25)
 7/13/12 9:38pm
SAYWHEN
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This is a pic of the module...remove the dist cap and rotor and you'll see it. They can be tested at some parts stores .but IMO a waste of time when the module in your case may be intermitant...they would be testing it cold..not hot when you have your issue. As i said in my post i didn't mean to say your battery was bad..I was simply saying that is one thing which can turn on the SYS light (usually with out your running issues) as will ABS..ASR and believe it or not sometimes a aftermarket radioThumbs Up 
Re: just wont rev (19/25)
 7/13/12 11:14pm
ANNICORVETTE
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BILOXI, MS - USA

Vette(s):
1990


Joined: 3/19/2009
Posts: 27

started researching distributor modules for the 90 (only corvette would do this)guess i will run the codes and check which module is on the 90 tomarrow.





(resized large image-aapple)


|UPDATED|7/13/2012 8:14:34 PM (AZT)|/UPDATED|
Re: just wont rev (20/25)
 7/13/12 11:06pm
Adams' Apple
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Duncanville, TX - USA

Vette(s):
1985 Coupe-L98/Auto,Bright Red/Carmine. 1974 Coupe-L48/4speed, Medium Red Metallic/Black Deluxe.


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Posts: 2230

The module is inside the distributor. You'll need to remove the cap and rotor, as has been noted. Then there are two small screws that hold the module to the dist., and two wire connectors. These connectors get brittle over time, so if you change the module, be careful unplugging it. New modules usually come with a small package of grease....USE IT. It needs to be smeared all over the bottom of the module, where it fits on the distributor. Not using this grease will cause the module to overheat quickly, and you'll be right back where you started...replacing the module. Sometimes, a bad coil will cause the module to fry, too. It's best to replace the coil if you replace the module...



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Re: just wont rev (21/25)
 7/14/12 8:40am
eddie20890
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lanoka harbor, NJ - USA

Vette(s):
1990 L-98 white/ red/black leather interior targa top auto 1975 L48 blue/black leather interior t tops auto


Joined: 3/22/2009
Posts: 1363

ANNICORVETTE said: started researching distributor modules for the 90 (only corvette would do this)guess i will run the codes and check which module is on the 90 tomarrow.





(resized large image-aapple)



the top module is what is in my 90. also if it stock distributor, coil is in the cap. as joel said you have to use the pack of grease that comes with it. if not there use diselectric grease. make sure both surfaces are clean and spread a thin even coat. just another tip--make sure if you replace the coil (or even if you don't) that the secondary ground strap is installed. when i bought mine i was tuning it up and there wasn't one there. figured with the computers they figured out another method. WRONG. was having a lot of trouble and finally decided to replace the coil and in the box in bold letters was DONT FORGET TO INSTALL SECONDARY GROUND STRAP. a $2.00 part caused me a lot of headaches. without it it will burn out a module.

years back if the module went the car wouldn't run. newer modules seem to do as you are describing---act up and then don't, until they get to the point of no return. if you bring it to autozone they will check it for you but if you go thru the trouble of removing it, for roughly $25.00 you can put a new one.

hope you can figure this out and if you need anything let me know.

dave




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Re: just wont rev (22/25)
 9/26/12 2:41am
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BILOXI, MS - USA

Vette(s):
1990


Joined: 3/19/2009
Posts: 27

well i am back to working on the 90 still wont run when it heats up. have checked everything that has been mentioned in this thread. still no codes even had the code checked at a shop last week replaced the whole distributor with the same results. i feel it has to be electrical in some way. just i am so stuborn i want to find the problem, anyway the dealships here wont touch it and everyone i talk to gives me the same things i have allready done.
 
still needing HELP
Re: just wont rev (23/25)
 9/26/12 11:08am
davep85c4
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Oh, come on. This is the classic multec injector issue. The second post in the thread describes the multecs, and describes how to check them.

So, Have You Checked Them? Go buy a $5 meter at harbor freight, and do it.
Re: just wont rev (24/25)
 9/26/12 11:26am
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BILOXI, MS - USA

Vette(s):
1990


Joined: 3/19/2009
Posts: 27

have a meter and all injectors read approx 16 ohms, did notice that several of the wires to the injectors looked like they had been repaired and electrical tape covering the repairs, aybe i should untape and check these repairs.
Re: just wont rev (25/25)
 9/26/12 1:47pm
396c4
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Old school checks the fuel system first. New school - check the electrical first. Seems odd to me that you would loose 8 injectors at once and you appear to have been through the distributor and the battery. That leaves me with one more, obvious and mostly over looked link ... grounding. If the battery ground is good and I assume it is with the battery change, I'd be checking the other end. Your manual will tell you where the major ground points are but the one that bolts to the (driver's side) bell housing has a bunch on a common stud, even though stud connections are "no-no" by most electrical standards. I don't know why GM doesn't add proper ground blocks. You might stringing some jumpers to see if that makes any difference. I've added ground runs from the bellhousing stud, MSD and data logging equipment directly back to a ground block at the battery to eliminate chassis/engine block issues and electrical noise. Only the starter relies on chassis ground. Good luck.

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