88GTANOTCH

hope you guys can help me . I"m working on my friends 89 firebird 305tbi. the first prob was she melted the bat cable to the header and melted that , which in turn melted the bat ground cable right off the battery. new bat, new cables and the car drove fine for a week. it died one morning while she was warming it up and would not restart. was turning over very hard.I pulled the codes and got 42. checked the ecm was getting very warm(hot) replaced ecm and prom. same very slow hard start . replaced starter bingo problem solved , turned over fine started and ran better than it ever has.
the next morning (still turning over normal ) no start. checked spark would only spark at the coil every now and then , and the coil was discharging its spark as it should with the key in the on position with the engine not running.I noticed the fuel pump relay was very hot , removed connector melted relay.I replaced the relay and put in a new ignition module. car started right up and ran fine!!!next morning guess what (still turning over normal)no start. i checked the spark and it was big blue and beautiful.checked the fuel at the throttle body(opened the line and was getting fuel. the injectors would not pulse . broke out the handy fuel injector and harness tester and the injectorsand the harness both checked out ok.
the next morning car still in pieces and me very angry!!!!!check the fuel pressure 11p.si. but it takes a long time to get up there ,and will not hold the pressure at all.I know this is not normal on a tpi but i'm not sure on the tbi?the gas cap does not hiss when you open it like it does on my tpi either.the car will start and run but only when it feels like ( read only when you don't have to go anywhere) the fuse to the fuel pump near the bat, was a little corroded i cleaned it up and put it back in .this thing is driving me nuts please help!!!!! oh btw her father is a diehard ford fanatic and knows nothing about computer controlled cars and keeps busting my ***** to no end . I WILL FIX THIS TURD!!!!!!!!!

Dewey316

how long is a long time for the FP to build? it should build very quickly (the fuel pump only primes for a couple of seconds). might be the fuel pump is on its way out, as you know it is fairly common with these cars.

the injectors not pulsing is another issue. could be ECM problems. i would guess what with the number of melted wires and relays you have going on, this problem is going to be fixed until the electrical issues are all taken care of.

swerve-driver

Could he have partially fried a fusible link down near the starter?
S-D

88GTANOTCH

the pressure will not build at all with just the key on . but when cranking it takes about 1 minute to build 11psi. another thing i forgot to mention is that the injector on the drivers side after 5 mins of idling turns into a dribble and the psi on that side fuel line drops to zero. everything tells me pump, but i don't want to buy parts i don't need . the ecm is new and as far as i can see all the wires going to it are ok.

RBob

iTrader: (1)

Sounds like that fuel pump relay again.

When the ignition is first turned on the fuel pump should run for 2 seconds. This is done via the ECM enabling the relay. Can hear the pump run at key on, no crank.

The oil pressure backup switch is probably kicking the pump on after you crank for a while.

At the injectors: with the ignition on one wire to each injector should have battery voltage. There is a fuse for this. The ECM will fire an injector each time a distributor reference pulse (DRP) is seen. No DRP's, no injector firings.

RBob.

Dewey316

everything here says fuel pump to me. check the voltage after the relay going to the fuel pump. possibley the relay is bad, and the pump is still good. the injector getting 0psi and just dripping would indicate it is not getitng fuel.

Slade1

Try feeding the pump 12 V. The power to the pump runs along the drivers side to the middle of the back seat under the carpet. With 12 V feed you can see if its a problem with the pump, or something else in the front.

88GTANOTCH

I did replace the fuel pump relay , but the connector was f'ed up too maybe i'll try replacing the relay connector first. I tested the injectors, they both open and close fine , the harness tested ok also , but what i can't understand is the car would not start fuel pressure was reading 0 . I pulsed the injector w/ my tester and it sprayed fuel and the car tried to start! later today I'm gonna try to test the voltage @ the injector to see what the voltage is . I know the tester is throwing full batt voltage at it and it is firing. perhaps i have a drop in voltage in the harness some where . it did light the continuity light on my tester and also blinked the led every time i turned it over. judging by the past electrical problem I'm guessing i'm fighting more than one problem.

88GTANOTCH

there are 2 lines going into the throttlebody (one on pass side one on drivers side) are they both feed lines or is one a return line ? and if one is a return line which one is it? i've only cracked the drivers side line and when i do there is always fuel flowing(not much pressure , but always flow. could a clogged fuel filter be one of my problems? no history on the car but i'll bet it is original. appox 120,000 miles . sorry to keep babbling but I figure as much info as i can give will help.

Dewey316

i beleive the drivers side is the feed line, i'd have to look to remeber for sure, it should be the larger diameter line.

a clogged fuel filter will cause problems, i have had the best luck replacing it ever 20k or so. but have zero pressure is REALLY clogged.

88GTANOTCH

checked the fuel pump ... it is priming with the key, rechecked the injectors , all is good. the fuel pressure is still in the toilet but now i am questioning the gauge? the key is a cheap aftermarket with very tiny connectors at the chip . one side is worn almost flush. I am now almost certain I have a vats problem , but my question is does vats disable fuel or spark? or both?I am 99% sure it is the vats ! when trying to start and the injectors don't fire if you wiggle the key the injectors fire and the car starts and runs fine! what do you guys think? VATS or no VATS?

RBob

iTrader: (1)

On a stock operational VATs system the starter motor and the injectors are both disabled. After a start attempt with an invalid key there is a 4-5 minute lockout period.

RBob.

88GTANOTCH

RBob you are mistaken a vats sytem will still turn over ....I.E. engage the starter. but it will not fire! I am assuming it cuts the fuel ? but it may also cut the spark. I have spark, no fuel so I am assuming it cuts the fuel. I am still going with the faulty key theory and will keep you guys posted later this week when I disable the vats. now it is time to search for a faq search on the vats!

88GTANOTCH

RBob I retract that last statement .... the vats does disable the starter also......... WTF ! I am at a loss guys ? could the ignition switch contacts cause a problem like this ? apparently this is an ongoing problem not related to the melting of the bat cable ... has been having these problems(intermittant start) for at least 6 mos.
so at least I have fixed all the problems from the bat cable ! but this one is still pissing me off! any other ideas?

RBob

iTrader: (1)

Hmm, I recall reading a post not long ago where the ignition cylinder housing can come loose. I can't remember the particulars. Maybe a search will bring it up. I don't believe it was on the TBI board, maybe the tech/engine board.

Anyway, the ignition cylinder/housing connects to a rod that actuates the actual ignition switch further down the column. The problem is that the turning of the key doesn't move the rod enough and the car won't start.

RBob.

88GTANOTCH

ok just to verify.... the injectors recieve the signal to pulse from the ecm(which i already replaced), which tells them to only after receiving a signal from the ignition module(which i already replaced), and the fuel pump relay (which i already replaced). I am going in circles with this car and my head hurts!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
the problem is intermittant and only happens on start up. once the car is running it never shuts off or stops pulsing until i turn it off. it will start up normal 15-20 times in a row , then out of the blue no pulse aaaaarrrrggghhhh!!!!!!!!

RBob

iTrader: (1)

Yes to the injector firing above. Here is a run-down in a different order:

Key on (no crank), ECM enables fuel pump relay for 2 seconds to build fuel pressure.

Key in crank position, as engine rotates distributor sends reference pulses to ECM. The ECM will: re-enable fuel pump relay, and fire an injector with each reference pulse (inj's alternate on each spark plug firing).

RBob.

Liqued212

My car has a problem simular except sometimes it would start fine then sometimes it would crank over but no start so I prime it and it fires up and runs. Well then it got to where it would just crank every time and not start unless i primed it or ran 12volts to fuel pump to make it work .. well now it wont run even if i prime it ..sometimes itll run for a couple seconds tthen die.. well i ttok it to my mechanic and he said it was the fuel pump which I will install tomorrow and see what happens.. If yours is the same ill let you know something tomorrow..

88GTANOTCH

I checked and re-checked all the connections, all checked ok. I then kept starting the vehicle till the problem came back and kept messing with the ignition switch and got it to the point where I could start it every time. what was (is) happening is if you turn the key all the wayto the start position it will turn over but only fire the injectors sometimes. if you back off the key a bit the injectors pulse and the car starts. so it was definately the igniton switch giving me all those fits!!!!! I have alot less hair now from this friggin car!!!!!

Dewey316

glad you found it. i really hate electrical issues, they are so freakin' hard to to troubleshoot sometimes.

Liqued212

yeah mine was partially the ignition switch too the fuel pump was ok after i tore it alaway out..

metalhead212121

Interesting/Informative thread...

Instead of me starting ANOTHER thread...I'll add on some questions of my own.

~What's fuel pressure supposed to be with the TBI'ed car RUNNING?

~What's fuel pressure supposed to be with the key in the on position?

~What's fuel pressure supposed to be at while crusing/acceleration?

I have a friend with TBI motor in his 92 Camaro. In short..the car is just a DOG. The car has very low milage and has "tuned up" by myself and a friend (new plugs, wires, cap, rotor air filter/gas filter). Yes..the old parts had seen better days. At first I thought maybe the ignition coil is weak (its orignal) or the timing is way off BUT now Im thinking MAYBE its fuel related..... The car runs very smooth...doesnt miss but the stupid thing cant get out of its own way.

Thanks in advance..

Dan

88GTANOTCH

I believe fp on a tbi should be between 9-15 psi . I got 11 at idle and it would slowly drop off on acceleration to 7-8 psi. too low in my opinion. the car I was working on still needs a fuel pump and filter. but the girls parents don't want to throw any money into the car so it is still acting up. I showed her how to turn the key to get it started (they didn't even want to replace the ignition switch)and washed my hands of the whole deal! I had about 35hrs of labor and troubleshooting into it and they spent about $330 on replacing fried parts from the cooked bat cable.they paid me for parts and I guess my time is free.

metalhead212121

I hear ya... BUT at least you learned something in the process....

Can anybody else give me info on what fuel pressure readings should be???

Dan