ok so i have his 91 z28 with the auto trany 5.7 tpi i just replaced the ecm and spark plugs. it starts up just fine but as soon as i touch the gas it bogs down and dies. dont have any service lights on or any indications on the dash for something to be wrong and at idle i runs great just can not drive or do anything else just sit at idle????? any ideas on what it might be oease help me out?!?!??!?!?!?!

 

My first thought is fuel pump and or fuel filter.
Sounds crazy but,I had a tpi car several months ago with the same problem.
Idled great but once you gave it a little throttle blah!It stalled instantly.
joffer,I would get a fuel pressure gauge hooked to it and see what the pressure is at idle.My problem car ended up having 13lbs of pressure instead of the needed 40-45lbs.
Just a thought,hope that helps!
oh yeah,welcome to the site!

 

thanks for the help i will be sure t check i asap Timmy. that could very well be my problem cuz i was having problems with the ecm turned out it was shot i have only had the car a few months. so i got a new ecm yesterday and new spark plugs today cuz the old ones were toast. I am sill earning so if anybody has any other ideas please let me know!!!!!

 

YEA GET AN OHM METER AND CHECK THOSE CRAP MULTEC INJECTORS THEY SHOUD READ 14 TO 16 OHMS.. BELOW 10 THEY ARE GARBAGE AND WON'T FIRE..

 

Hi irocuroc;

Just a question. What about if I have more than 16 OHMs. I have 7 injectors with 16.5 OHMS and only one in 13.6 OHMs? The car cranks but will not start. I have already checked the pump pressure (40-45 psi) ,has spark and check the injectors' electrical connectors with a niod light and all they flashed. i really don't know what else to do...

 

electrically those injectors are ok. if you rule out everything else, maybe they are just clogged... are the plugs looking like they are wet? does it start on starting fluid if it does you are going to have to pull the injectors. But before you do check the voltage on the tps with a volt meter.. should be .57 at idle and close to 5vlts at WOT. do this with the engine off key on

 

I took the plugs twice and they are dry . The car start without problems with starting fluid and then die. I'll test the tps and tell you later. thanks

 

I have 0.55V with throttle closed and 4.25V at WOT. Reference has 4.98 V.

 

when i had this problem, it was the brake booster line unplugged.

make sure you don't have any vac leaks?

 

If you have a 91, it should be a speed density car. These came with non adjustable TPS. Voltage at no throttle should be somewhere between 0.7 and 1 volt. At WOT it should be over 5 volts. I don't know if this is the reason you are experiencing problems, but thought I should mention this. Also, make sure that your base timing is set properly.
Have you tried measuring the fuel pressure with the car running, vacuum port connected while applying the throttle? Fuel pressure should drop by a couple of pounds initially, but it should rise immediately after that.

 

First thing ide check is for any kind of a vacuum leak. Im not terrably familiar with the later MAP style tpi set up but genrally speaking when a car dies out when you give it some throttle its not getting enriched as it needs to be or is already running lean.

 

Hi everybody;

I didn't explained myself well the first post so, I ll 'do my best now so you guys can help me.

1. The car is an Iroc '89 350.I bough it two years ago.

2. After buying the car it started to have problem starting. I poured some starting fluid and it started.After starting it could be easily started again .

3. I had to repair some other things on it and left the project for two years.

4. At the beginning I was hoping the car could start with starting fluid only but I couldn't. The car starts but as soon as the fluid is consumed it die.Therefore I know I have spark in there.

5 Then I changed the fuel filter and checked the pump finding 40-45 psi.

6. Then I checked the injector's harness using a noid and found they are pulsing (noid light flashed in all of them).

7. Finally I checked the resistance between the injectors port and found that 7 of them have 16.5 OHMs and one of then 13.6 OHMs .

8. I also checked the tps shows .55 V closed and 4.5 V WOT . Nevertheless, I think this is not the problem since the car won't start at all.

I think that the problem should be in the injectors, but are they all clogged?
Another question is if there is a minimum voltage that the injector should receive to open. Maybe the noid flashes but the injector valve could not be open due to low voltage.

Thanks in advance guys.
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I checked all of them and seem to be good. The car start with starting fluid so it could start but the fuel is not getting into the combustion chamber due to an unknown reason???

 

I couldn't check it because the car won't start. It start only with starting fluid and last several seconds after.

 

Where are you located? I have a few sets of injectors that I could sell you cheap (50 bucks + shippping and can guarentee they work). Pulled them out of my car to put in bigger injectors.

 

so the fuel pump was not he problem, thats new now lol. so my next possibity is the tps acording to my 3rd gen local mech any other ideas???????

 

did you un out of gas? lol



Dont forget to check that too!!!
Sounds immediately like a fueling issue, ie filter, pump, pump strainer (if our cars even have them), pressure regulator, injectors etc.
Throw a scan tool for the easiest way to diagnose it. Also check out a fuel injection pressure tester. Or the ALDL cable and the right program. less than $100. easier than throwing parts and money at it.

Good luck.

 

Have you checked your fuel rail pressure and or relay and fuse?

 

thanks boldguy yeah i was bright and did the fuel pump with 3/4 tan i know it has the gas. now here something new i remembered when i bought the car i didn't know at 1/4 tank on the gauge it was empty and it stalled on me. started back up and got it to a station but could that have screwed the injectors up??????
how do i check the fuel rail pressure?????

 

sounds like the tps.

 

You can check the TPS voltage closed, wide open, and also how linear the change in voltage is from closed to open. If this is the 91 (two posts going on) TPS is not adjustable and should read anywhere between .7 and 1 volt closed, and over 5 volts open. Double check that all your vacuum hoses are intact and plugged in where they need to go. Also check the hose that goes between the intake manifold and the MAP sensor, make sure that it is not unhooked or torn. Make sure all connectors are well connected.

 

the only thing was that was like 2 months ago however thats when i started having problems!!!!

 

there is a cap on the fuel rail that has a cap on it like a valve stem on the drivers side of the engine bay.

 

yes mine is the 91 so likeyou were saying its non adjustable. a quick question how many vacuum lines are there???? should i go get a haynes or chilton and would those really help???
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speedster i seen that and know that it as a release but how do i check he actual pressure

 

Go to your local advance auto and they will rent you a fuel rail pressure gauge that will be refunded in full when you return it. The fuel rail pressure should be in the 35 to 45 range.

 

There are a couple that are easy to accidentally disconnect while testing fuel pressure and TPS. If you have not checked fuel pressure, do that. Fuel pressure port is on the passenger side on top of the fuel right by the distributor cover. You may have to remove the cover, and unbolt the MAP sensor from the plenum to get access to it. You will see a vacuum hose that goes from the plenum to the MAP sensor, and one that goes to your fuel pressure regulator. Test fuel pressure with the engine off, key to on position and vacuum port disconnected. Also test pressure with vacuum port connected and engine running. Pressure should be a few pounds lower with the port connected and engine running. Also look at fuel pressure decay, this could indicate leaking fuel injectors, but could also be a bad fuel pump check valve, or a bad fuel pressure regulator. Make sure that when you disconnect the vacuum port from the FPR and you turn the ignition to the on positon, that you don't have any fuel comming out of the vacuum port.
There is also a vacuum line that goes into the throtle body that is also easy to break / disconnect while messing with the TPS.
You should definitelly get a service and repair manual. I know that for the TPS, the Haynes manual for our cars only mentions the voltage specs for the older, adjustable TPS. That had me confused until I had found out that speed density cars have a different TPS.

 

speedster i took off the cap and it spewed when i pushed the center pin down. so i will get that gauge tester and check it out as soon as i can get a car to go get it nyways lol

 

ok ts not the problem so i still need to test the fuel pressure reglator???? any other ideas, haven't found a vacum leak eiether doesn' mean i isn't there though haven't been abe to chek thoroughly

 

I would check out the IAC valve. check to make sure its clean and not siezed up. Personally if its in question i would replace it. While your at it i would just remove the throttle body and clean it out with carb cleaner or brake cleaner just dont get too crazy with it as it will destroy rubber seals. Becides its easier to do the IAC valve with the throttle body removed.

 

so it idles fines and then you give it any throttle it loads up and dies?

if thats whats going on im thinking the map sensor or theres something wrong with spark system.

id looking at map sensor if it were me and then maybe a issue with vacuum system

 

screw it i give up anybody want a 91 z28 project?????

 

91 does it have vats

 

sure does

 

never mind should have read your first post a little slower

 

its all good thanks for the attempt lol

 

so i wonder if you attempt to start the car without starting fluid, and you crank it a little, then pull a spark plug - will it be covered in fuel?

(because you said you think fuel may not be going into your cylinders)