ThreeOhFive

My 1991 Z28 just had to be towed home, it won't stay running! It is in excellent condition, 95,000 miles, and is a 5-speed. Bought it two months ago, drove it two weeks, no problems. Problems started after running it to the empty line on a hot summer day a month ago. Filled it up, started bogging out and dying on me frequently. Wouldn't start for hours once it died. Would turn over, run like garbage and shake, and then kill. Ran Seafoam in gas and oil, put two tanks of 93 through it, changed plugs and wires, it got a little better, but ran very rich, and wouldn't run unless the eigth injector was unplugged. It drove sluggish and would bog heavily under more than half throttle. The car would restart if it had just died, but would not start if you left it for a few minutes and then tried to start it. Switched back to 87 octane, last two tanks of gas, ran a bottle of concentrated injector cleaner in it as well. Last few days it was running, it would lose power at random times, and you'd have to let it idle or it would die. Parked it a few hours two weeks ago, now it starts, shakes, and kills. If you give it gas, it dies. The oil is getting really dirty and smells like gas. Just changed the fuel filter, it still won't run. It has compression, and the fuel pump primes well before starting it.

I've had several people look at it, have done a lot of research and have talked to dozens of people. I get different answers from every person. Fuel pump out, bad O2 sensor, plugged cat, bad fuel pressure regulator, injector problems, knock sensor, throttle position sensor, bad ground, fuel sending unit, motor is shot (lol yeah right), the list goes on!

1killerolds

iTrader: (1)

first thing I would do is ohm out the injector coils. should be around 12-14 ohms I think. the key is to ohm them all and look for one or more that is way lower than the rest. very common problem on the tpi engines. Just replaced two sets, one on a vette and one on a firebird.

old z mzn

iTrader: (1)

if stock injectors definitely check them out. I had 2 sets go bad

Iroc zseven

i have had the same problem with mine i thought it was the timing but the shop said its prom timed so no setting is needed i tuned it up changed the oil put injector cleaner in to it the only thing i didnt do was change the injectors can anyone point me in the rite area

ThreeOhFive

The injectors ohm'd alright on the driver side fuel rail. The passenger side was a different story. Had three of four injectors that were under 5 ohms. Just replaced injectors (19 lb/hr. Bosch), fuel filter, plugs (again), wires, computer, oil change, coolant flush, oil pan seal, rear dif seal, had the whole car looked over. Start it up, expecting it to run like new, hmm, nope, had to give it gas just to start it. It ran (seems to be missing STILL), and then died at idle. Great. Just poured $1,500 into this damn thing and nothing!!! This will be my last tpi car I will ever own. I am irrate!!! It now runs with all eight injectors plugged in though.

JJBJR

I'm have the same problem car comes on runs very very rough when I press the gas cuts off what should u do ?????

JJBJR

??

crazymonkey16

ThreeOhFive, you said your oil smelled of gas... you're not getting any blue smoke, are you? Might not be a bad idea to take a day and do some gasket replacements. Sounds like you've already done almost everything else.

TTOP350

iTrader: (8)

A 20yr old car with 100k on it will need some parts and work. Its not a new car.
1st check vac hose on fuel psi reg for raw fuel. if none, all is well.
Check fuel psi. should b 47 ish
Ohm INJs. if they are stock, I'd bet you have a bad one or more.
With your miles and if you havent yet, I'd pull the dizzy/check it out for rust and or broken parts, put in a new pickup coil, icm,coil, cap, plugs, wires and fuel filter.
I would lean towards the fuel pump and or injs bad.

No amount of chemicals will fix a electrical problem.

RRUHL

im having simular issues from hell on a 91 tpi, it would idle fine die the second id put my foot on it had to feather it like crazy to get it to move......problems get worse....... i thought it would be a good idea to run fuel injector cleaner lucus of course...my dumb *** put the hole botle in for 25 with like 5 gallons of gas car instantly shut off, filledd the tank still nothing. checked ac delco plugs i put in yesterday had enough black carbon to have been ten years old..cleane them put them back disconected my fuel line drained the tank filled it with 89 and car is still yet to crank over cant figure it out should i toss the plugs?

RRUHL

Just pulled the entire tpi and manifold rebuilt it aqll new gaskets, new fpr diapham egr blocked off.....still cant get fuel pressure wont fire up at all new fuel filter pump runs cant figue this out to save my life any help please???? realllly apreciated

irocZ281986

Are you testing the fuel pressure at the rails? Should be around 40 psi. If not start back tracing towards the tank is my advice. If you ran the gas low on hot day the stress and heat may have toasted the fuel pump. strange things happen sometimes.

KingsHustleLA

My TPI is acting up too, when i'm on the freeway & it stays moving At 55MPH+ it runs fine but lacks power, when i'm in stop & go traffic after about 20 minutes my car heats up to about 220 & the idle gets retarded then the car starts to shake & turns off. It fires right back up but repeats itself right away and when i try to throttle it the engine starts struggling and misfiring. after i leave it for 45+ minutes with the hood open as long as there's not too much traffic it will run good until i get home. I tested my injectors today and they all read about 19.1 Ohms. tomorrow i'm going to check the pickup coil, i'm just thinking about replacing it. if that doesn't work than ****, I just want to think positive & hope changing that pickup coil works lol

old z mzn

iTrader: (1)

mine was the fuel pump

KingsHustleLA

What are symptoms of a bad O2 sensor? Better yet, who's had a bad O2 sensor and what was it causing your car to do? I checked all my injectors when they were still hot & they were all around 19.1 ohms. I tested my pick up coil twice, when it was cold it read like 856 Ohms then after i drove it around and tested it when it was warm it read 973 Ohms, it's in the 800-1000 range so i figure it's good? but can an O2 sensor cause these problems some of us are having?

poloaa008

ThreeOhFive, you said your oil smelled of gas.

RRUHL

Ive been having tons of issues fixed my main one cracked fuel line in tank replaced and regulator tps idles strong now alil high can rev the h*** out oif it in park but as soon as i put it in drive instant kill or reverse is worse its like it slams in reverse and dies instantly....its a 91 L98 350 in a 92 rs changed the kick down cable and ecm with swap ohh speedo doesnt work guages fine idk if there related also rebuilt tpi and manifold any ideas one please??? really need to get it back on the road and am at a loss on ideas

KingsHustleLA

Does anyone have anymore ideas? My car has been like this for months & i'm having pretty much the exact same problem the guy who created this post is having, my car lacks power, runs decent for a few minutes on the streets then starts doing exactly what this guy is saying, my injectors all tested fine, just replaced the icm with an after market then i put another stock icm in so changed that twice, plus i changed my O2 sensor, and when my car starts ******* out i have to hold the gas pedal when i stop and the idle still drops and goes up 500 rpms, it runs real shitty plus it starts heating up. is there something electrical that can seem fine at first but then starts malfunctioning after a few minutes in stop and go traffic? Can someone please help this is getting really frustrating X(

What can make you lose power all together & start causing these problems after heating up? my pick up coil tested fine too but maybe can that still get messed up when the car heats up? i just don't know this thing is just kicking my *** big time

irocZ281986

From a guy that's not an expert. At least try this test. Disconnect your maf if you have one and see if the car runs the same with it disconnected. If it's working properly the engine will struggle hardcore and there will be a massive difference when you disconnect it. If no change then suspect that it's bad. Can't remember what year yours is so it may or may not be maf or map. Worth a shot for all its worth.

ninetyone

iTrader: (2)

yes, i would unplug maf first, you may need to keep your foot on the gas after you start it and keep it at like 2k rpm for a few seconds tho, until it can re-adjust and idle on its own, then see if stays running. If not, then ohm your injectors. Check for codes.

KingsHustleLA

My Iroc-Z is a '90 so it doesn't have a MAF sensor on the intake like the others. Plus I have 3 other MAP sensors i tried & the plug was messed up so i swapped that out too. Any other sensors you guys would think to check next??

ninetyone

iTrader: (2)

Did u check for codes? Just so you know, a bad fuel injector will not throw a code. Ohm them out and post the results.

jorge.esbri

i have a simmailar problem my 87 comaro 4 barrel 350 ho was running fine , i parked when i got deployed . i came back one year later she will turn over but she wont stay on

al55as

Sounds like the hose that connects fuel pump to tubing in the tank.
With the ethenale in the gas these days will make the hose real soggy and blow
a hole in the side of it.
remove the gas cap and have somone turn on to let the fule pump prime for the
2 seconds. Than take hose put in the filler tube at the same time and listen for
the gas splash sound in the tank.
Check the fuel pressure.

RRUHL

THAT was what happened to mine cracked fuel line in tank rubber hose blew it would start idle rough rev alil. would not get more then 10 feet before it stalled out. hows ur actual ignition coil? fuel pressure? and did you set your timing with the tan wire on pass side near ac unplugged? sounds like you also have a shot thermastat or failing water pump. vhave you checked codes at the aldl plug under your steering wheel to the left? take paper clip or short wire and connect top right pin to second or 3rd forget the pin letters. also check ur sensor under ur plenium in the back that helped mine alot as far as ur sensor ? and clean ur iac valve with tb cleaner then lube the shaft back up wit wd40 might help ur idle if u already replaced tp sensor

eseibel67

This is the only post al55as has ever put up. Very clever.

A more typical single post goes more like "how do I get my rotted out Berlinetta into the 11's. My buget is $80."

KingsHustleLA

So a line cracked inside the gas tank close to the fuel pump? I tested my ignition coil and the voltage seemed fine but i tested it when my car was cold, I was thinking of just replacing it anyway, even if it's not the problem now it won't be a problem in the near future either, honestly i haven't checked none of that and yeah my thermostat doesn't pop until the temp hits 220 it used to pop sooner. But yesterday on the freeway my check engine light went on so i thought hmm maybe after i park i should see if i can get a code and sure enough it flashed a code 32 which i guess is the EGR valve, maybe that could be what's causing all my problems? They seem kind of pricey, is there a way i could just clean it out or something to see if that works 1st before buying a new one?

whoaru99

Should seriously consider getting a factory service manual if you're going to try to troubleshoot your car. Sure, it costs a little money but changing parts that aren't the problem costs more.

RRUHL

SOUNDS LIKE MY **** WAS DOING TURNED OUT EVERY ONE WAS RIGHT. CRACKED FUEL LINE IN TANK...sorry caps.......down towards the bottom some one explians how to check for it with out droping the tank.

dads old blue 9

I had the same problem with my car . would start and only stay running if I feather the pedal pump turns on so I thought thats not it weeks later I did a fuel pressure ck almost none pulled the tank and the 2 inch rubber conector had a slice in it . and it felt like a marshmello replaced the line (and pump since I was there anyway) ran like new thats the problem with most of our cars . these lines only last so long . and the ethonal finishes them off. even though you can hear the pump prime ,doesn't mean its getting feul.

s10sbc350

wait wheere does it explain how to check for a cracked fuel line without having to drop ur tank, as my tpi 350 is having this issue of starts for a few seconds then dies, and my injectors checked all at .017 ohms, all 8, and i unpluged fuel line by motor and it shot fuel everywhere when i turned the key on, so its not that or the filter, so does that mean its the line cracked, and agin how do you check without droping,it thanx

ZROSSA91

Hello Gentlemen,

15 yrs ago i had the start and stall problem and turned out to be injectors. Changed all 8 it ran like a top since. This car sits more than its driven. Now its starting for 5-10 seconds and stalling. Then it wont start for a day or 2 and does it again.
Once after it started and ran for 30 minutes and i shut her down. Never started again. Now the pump does not even prime so i think its a pump. Ran into another fellow same car same problem been to hell and back figuring it out. Turns out it was his ignition module the whole time. So i might try the $70.00 part first before dropping exhaust and tank.
Any ways hope this helps and any help is appreciated.
Ciao, Vince