tourville

iTrader: (2)

Alright heres the situation, fuel pump died on me. Replaced the fuel pump noticed my lines were rotted and ended up breaking one when trying to get the old fuel filter out. Engine is a 1987 TPI in my 1991 Camaro. Converted the engine and updated it to a 1991 350 harness + cpu and all the 91 sensors. So really its a 1991 350 TPI.

Bought all new fuel lines, installed the new fuel lines, new fuel filter, and new fuel pump.
Tested the fuel pressure at the fuel filter and had 42-44 on the fuel pressure gauge.
Tested the fuel pressure at the fuel rail and had 42-44 on the fuel pressure gauge, and also have the same pressure when cranking the car.

Car starts for a second and then stalls just like its starving for fuel.

Im at a loss and no idea what to check or try now Car ran fine before the pump died.

Elcooke

Check your oil pressure switch. They are setup to run for a few seconds then looks for oil pressure. If the ecm does not see the oil pressure it will remove voltage from the fuel pump.

tourville

iTrader: (2)

is that the sensor that is on the driverside? oil pressure sensor or w/e? if so its not even 3 months old, swapped the 91 in there when i switched over to the 91 harness. and how do i test it and what do i look for?

Elcooke

There are several ways to test this. The oil pressure switch has three wires; tan for the gauge, orange is 12v hot from battery and a gray that goes to the fuel pump. The ECM will supply 12v to terminal D of the pump relay (dark green with white wire) for several seconds to run the pump until the oil pressure comes up. You can check the oil pressure circuit by looking for 12v on the fuel pump test connector. You will not have 12v on initial startup but it will show up when the oil pressure switch makes. I have heard that some have not been able to find this connector so you can also check terminal “
E” on the pump relay. This will show 12v when you turn on the switch but will disappear after several seconds if you do not start the engine. You may want to check that first. It should be ok since your car will start. If you start your car and watch the 12v there and see if it falls off the same time the engine quits. If it does then it will have to be the oil pressure switch.

tourville

iTrader: (2)

nope i did test what you had said and even while cranking/after crank/start/die i still have the 12 volts at the connector. the relay is in 100% working order its brand new.. and i have tried more than one.

Have correct voltage at the fuel pump when key is in on position/when cranking and initial start.
New fuel lines, Fuel pump, Fuel filter, Correct pressure at fuel filter and fuel rail. and the oil pressure switch is obviously working also! i hate fuel problems!

Elcooke

does the voltage at the fuel pump fall off at anytime?

tourville

iTrader: (2)

not 100% positive let me ask my buddy who was looking at the meter... but im pretty sure it didnt fall off at all

Jay

iTrader: (2)

This is completely wrong. The ONLY thing the oil pressure circuit does is provide a failsafe to the main supply.

The ECM primes the fuel system by running the pump for 2 seconds when you turn the key to the ON position. It's not waiting for oil pressure, it is a programmed routine. There is nothing connecting to the ECM related to oil pressure.

Orr89RocZ

iTrader: (20)

you sure its fuel related and not the IAC or ignition related/timing?

tourville

iTrader: (2)

not 100% sure its fuel... but how could i test the iac? and i dont think its ignition related/timing when it worked before the fuel pump died.

AC

iTrader: (3)

I was there helping tourville last Sunday. We ran a hose from the new feed line into a bucket. He cranked it over and it was "gooshin" fuel into the bucket. He borrowed my FP guage and tested the rail. He also tested before the fuel filter. Both had ~42 PSI. When he would try and start it the engine would fire up for 1-3 seconds then cut out. No sputter, fart, windmill or anything, just die. Like the fuel supply that let the engine start was no longer being provided. I even tried to feather the throttle blades once it did fire up and it would still die. Yes, could possibly be the IAC right? Weird thing is though that before all this started happening to him I think his car ran relatively fine.

Elcooke

If the fuel pump dies (looses voltage or pressure) after a few seconds then the oil pressure switch did not make. The ecm will supply voltage to the pump relay for 2 to 3 seconds after the switch is turned on then that voltage will go away. The oil pressure switch will then make upon having pressure and supply voltage to the pump thru the pressure switch. After that first initial few seconds the only way the pump will see voltage is thru the oil switch. The system is designed that way to keep from causing damage to the engine in the event of loosing oil pressure. The single item that has not been verified is - did the pump loose voltage just before the engine died or just after? When it looses its voltage means alot in determing the cause. It is a typical problem of an engine going dead after a few seconds from the loss of fuel because of the oil pressure circuit not holding the fuel pump on. The reason there is a test connector for the fuel pump is to see if the oil pressure circuit is feeding voltage to the pump. You will only see voltage on the test connector if the pressure switch supplie it, not thru the relay. The oil pressure switch is the main supply of voltage to run the fuel pump, the ecm only primes its. If you know what you are doing you can jump the pump relay out to keep it on and see if the engine dies again.

Jay

iTrader: (2)

I will repeat. THE ONLY THING THE OIL PRESSURE SWITCH DOES IS SERVE AS A FAILSAFE IF THE MAIN CIRCUIT LOSES VOLTAGE. This misinformation has been corrected many time on this board, if you look at the wiring diagram it clearly shows how it all works, and I have owned a car that I didn't use the oil switch on because I didn't feel like switching to the newer style when I swapped from MAF wiring to SD. Want proof? Disconnect it.. the car still runs.

The fuel pump is supplied voltage through the relay. This is taken directly from the factory service manual in reference to the ECM control, wire D (green /white ) on the relay "Energizes relay for 2 seconds after key is in run, then continues energizing as long as there are ignition pulses"

AC

iTrader: (3)

Jay, good info. I told tourville he needs to hook up his laptop and aldl cable to see what the ECM is saying. Distributor reference pulses ??? I wouldn't think so because of the engine actually firing up for the few seconds it does.

Elcooke

Whatever. The oil pressure is designed to prevent the engine from continuing to run if oil pressure is lost, which will keep you from killing your engine, not as a backup voltage supply to keep it running.

BigBadLou

iTrader: (3)

Elcooke, please don't confuse other members here. The oil pressure switch does NOT turn off the fuel pump.
Please go look at the diagrams again to check how the fuel pump power system works, you'll see that - with all due respect - you are wrong about this.


Tom, if does the engine die suddenly (like if you turn off the key) instead of sputtering to a halt, tha's an indication that it's not fuel starvation. If it shuts off suddently, it's an electrical/ECM issue.

Also, if you try to open throttle and it still dies, it's not IAC.

Didn't you have VATS issues before or is my memory fooling me? You need to check (with a voltmeter or scope) whether the injectors keep firing when the engine shuts down.

Lou

Lou

tourville

iTrader: (2)

i had thought i was a vats issue before but it was not and i figured that out... but i will check the injectors asap!

BigBadLou

iTrader: (3)

Tom, one more thing came to mind. You have DataMaster or some logging software, right? Did you try logging the data and seeing what is happening? Maybe you can find something there. Just an idea.

Btw, if you want to make completely sure it's not your fuel system, you can jump the fuel pump relay (from the orange wire to the tan/white wire) and if it keeps 40+ psi and still doesn't idle, it's for sure not fuel.

Lou

86Z

iTrader: (4)

thanks for your help, you need to check the service manual, funny i dont use my oil pressure switch...

good point, but if he has an electrical issue where the injectors stop firing that won't help.

tourville

iTrader: (2)

i tried it with jumpering the relay and still did not stay running. Tested the two terminals on the injector and had voltage of 3 when started and went to 1 while running and then turned 0 after it was dead. Tried to keep it running with carb cleaner also and still did not stay running.. not sure if i did it right so i sprayed some in had mom start car.. then feathred the throttle body and did small sprays to try and keep it goin.. that didnt work so then i tried leaving the throttle body somewhat open and sprayed small doses and got the same results. wouldnt stay running.

Not sure what to try next but biglou talked to me on aim and said to burn a chip and take off the vats flag and try putting that in... well i have the laptop and all that stuff. and extra chips just dont know how to do it so this weekend ill call him and he will walk me through it.

BigBadLou

iTrader: (3)

So spraying carb cleaner didn't get it to sputter a little longer or anything? That would rule out lack of fuel (from injectors). Than it must be spark. But that is VERY strange.

Try unplugging the set-timing connector (single wire, passenger side, by the heater box). That way, the ECM has no control over the spark.

Lou

tourville

iTrader: (2)

nope maybe a second longer but here and there without carb cleaner it goes longer. and ill try the set timing connector and let you know what happens

tourville

iTrader: (2)

Alright, update.. I burned a chip with vats disabled to see if vats was shutting the fuel off to the engine or causing any problems. The new chip showed no difference . Going to try and find an ecm that i can tryout or just buy one and see if thats what is wrong. It seems as if the ecm is shutting off fuel for some reason. Not sure what to try next besides the ecm thing. Also i tried unplugging the connector that controls the spark from the ecm and no difference.

tourville

iTrader: (2)

Tried a new ecm that i borrowed from AC, which has very low miles on it so to say =D and made no difference either. i guess next step is to try and change the fuel pressure regulator which ill be looking at later today or tomorrow

BigBadLou

iTrader: (3)

Guys, anybody got a suggestoin? Suspicion? Hint? Advice? Tom sure could use some.

Please help out if you can.

Lou

thirdgenlover

do you have any codes? so it runs that it just dies as if you turned the key off, if so mine does that too. i have some kind of issue with fuel too in my thread of https://www.thirdgen.org/forums/tpi/...ll-issues.html i also have found a code for 43 for the esc (electronic spark control). i have also been able to unhook my canister lines from the tank coming off the hard line and disconnecting the smaller line from the purge valve that leads over to the manifold which i think leads back into the intake some how, and it acts like nothing ever happen. i use to have issues with it stubbling out. now its misfiring. but i has having the same mysterious shut off while its sitting and idling?

tourville

iTrader: (2)

not while sitting and idling thirdgenlover... the fuel pump died.. i replaced it and the fuel lines and fuel filter and for some reason the car wont start now.. i have constant pressure at the fuel rail and it holds it. i have tried a new ecm.. my injectors are firing, checked spark and thats great.. all plugs are on and in right order havnt touched em... now im going to try the modual in the distributor today in about an hour

tourville

iTrader: (2)

w0000!!!! it was the modual in the distributor! thanks everyone for putting input and helping me out!... also thank you ac for giving me that modual very much appreciated. keep in mind if yours dies i owe you one!

BigBadLou

iTrader: (3)

Dude, glad you found it.
That would explain why spraying the carb cleaner into the intake didn't prolong the running. The ESC module simply stopped sending signal to the ECM and stopped giving spark. Good catch!!

Lou

tourville

iTrader: (2)

eh i cant take the credit.. 86z(chris) from our club sait it was it =D but very happy shes runnin again! thanks again!
tom

thirdgenlover

now which one was it, tourville you said the one in the distributor which i call the ignition module. BIgBabyLou responded below with the esc, which i thought were two different things. Because mine fires up, just dies all of a sudden, might be this esc then?

P.S. THIS THREAD SEEMS TO BE REAL ACTIVE, DOES ANYBODY KNOW IF THE CANISTER PURGE VALVE CAN GO BAD, ON MY CAR ITS RIGHT IN FRONT OF THE COOLANT RESIVIOR. COMES FROM THE HARD LINE FROM FUEL TANK, THEN RUBBER HOSE AND THERE IT IS.

tourville

iTrader: (2)

it was the little black thing in the distributor that was mounted with 2 screws... dont know the exact name for it... just know its a module . and if biglou said its the esc them im guessing its called the esc and is also known as the ignition modual...

thirdgenlover

hum... well i believe the one in the distr. is called the est, ive heard the esc module has a five wire connector going to it and its located in between the fender and brake booster. Again does anybody have experience with their canister purge valve going bad, replaced it and it works now. Or please tell me if anyone has created a system where they got away from the canister all together and how did you do it, its just talking up space right now