1987 Fiero, 2.5L 4 cylinder with throttle body flooding. Unknown previous history but recent upgrades include direct ignition system(module, coils, sensor), plugs, wires, fuel pump, injector, throttle position switch, fuel regulator and most recently ECM with original eprom. When key is turned to 1st position it dumps fuel in throttle body for about 2 second and when you try to start it basically floods. If fuel pump fuse is pulled and starter fluid is used, engine will run for a bit. No ECM codes either. Any thoughts on next steps would be appreciated. Video link below.
Holy craps! Either the injector o rings are blown or the injector is way stuck open! Tbi rebuild is in order. For that much fuel dumping, my money is on the o rings. Ron
Holy craps! Either the injector o rings are blown or the injector is way stuck open! Tbi rebuild is in order. For that much fuel dumping, my money is on the o rings. Ron
Injector and its o rings are brand new. can you specify what you mean by tbi rebuild?
Check injector O-rings! Carefully remove the injector (first disconnect the two wire connector) using a flat screwdriver on the bottom of the injector connector body, and check both o-rings. If you change the o rings lube them before insert again. I would check the injector, could be stuck open. BTW...if fuel reached the MAT and it was exposed for long time perhaps you need change it. The same for intake body gasket.
First unplug the injector. If it stops then problem is electric. injector get power all the time on red wire. Opens when ECM or anything else ground it thru blue wire.
if not then is plumbing problem. Most often means Iffy O-rings, bad or stuck injector.
2 O-rings on the injector... 1 bad then most time fuel does not spray but drip to flow. Injector should have 2 screens. Missing either or both then dirt can easy jam the valve open. See my Cave, 700 TBI and read Throttle Bodies - Multec Bottom Feed. pdf Only top o-ring shown there.
------------------ Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should. (Jurassic Park)
First unplug the injector. If it stops then problem is electric. injector get power all the time on red wire. Opens when ECM or anything else ground it thru blue wire.
if not then is plumbing problem. Most often means Iffy O-rings, bad or stuck injector.
2 O-rings on the injector... 1 bad then most time fuel does not spray but drip to flow. Injector should have 2 screens. Missing either or both then dirt can easy jam the valve open. See my Cave, 700 TBI and read Throttle Bodies - Multec Bottom Feed. pdf Only top o-ring shown there.
Unplugged injector and tried to start, fuel stopped flowing out, which means electrical problem, like you said. Need some advice on what check next to determine where/what the problem is. Thinking it could be a short in the harness somewhere or a bad ePROM. Any advice helps.
You said the injector dumps fuel for about 2 seconds when you turn the key on. The fuel pump also runs for about 2 seconds when you turn the key on. Since it apparently isn't a leak, then maybe the fuel injector wiring and fuel pump wiring somehow got intermingled? The only other thing I can think of is an internal fault in the ECM.
You said the injector dumps fuel for about 2 seconds when you turn the key on. The fuel pump also runs for about 2 seconds when you turn the key on. Since it apparently isn't a leak, then maybe the fuel injector wiring and fuel pump wiring somehow got intermingled? The only other thing I can think of is an internal fault in the ECM.
No fault codes on ECM... could it be the ePROM chip?
Originally posted by gefmeister: No fault codes on ECM... could it be the ePROM chip?
No. More likely Bad wiring or bad ECM. Carefully put Volt meter between two Injector plugs wires. CAREFULLY use needles so won't damage the plug. If you short the plug then you will blow the ECM injector driver circuit. (If not the problem now...) Turn key to run. My guess injector is on even after fuel pump is shut off. If so unplug ECM. Still on then Wiring. Is off then "dead" ECM.
Wiring can fry and short when melted by exhaust leaks etc. Exhaust manifold etc can leak/break. Very easy w/ iffy dog bone... See my Cave, Torque Strut
ECM may turn off if hit etc to remove ECM plug(s) and work again but better to replace it. If have Crack solder etc causing this then will fail again most likely far from home on the highway.
Most ECM will not turn on the injector when "dead" but is not uncommon to have injector on when ECM is "dead." See my Cave, ECM Heat too. New ECM will be happy w/ better air flow.
[This message has been edited by theogre (edited 11-12-2017).]
Originally posted by gefmeister: No fault codes on ECM... could it be the ePROM chip?
The ECM doesn't monitor the fuel injector. The ECMs only interaction with the fuel injector is to activate it. Try to imagine yourself flipping a switch that controls a light, but the light is in another room and you can't see it. That's basically what the ECM is doing with the fuel injector.
That said, if the injector has a short to ground on the wire going to the ECM, it could be held continuously on. That would make it dump fuel constantly anytime the fuel pump is running. I'd suggest checking to see if that wire is pinched under something and/or the insulation is damaged somewhere.
The fueil injector, when activated will SPRAY fuel into the throttle body. Fuel pouring into the throttle body like that is not an electrical issue. There is something wrong with your fuel injector.
PROM bad is unlikely. This works or "dead." 1 iffy data or other pins should keep ECM from running. If MIL light only displays code 12 then ECM is running. (Fiero ALDL/ALCL can be install two ways.) More proof get a scanner. Turn key on then scanner should get data from ECM. Is why I believe ECM or wire(s) to it first. If you find someone to burn a chip or find one @ RA etc. use chip # in cave, See my Cave, 87-88 DIS Duke ECM
quote
Originally posted by phonedawgz: The fueil injector, when activated will SPRAY fuel into the throttle body. Fuel pouring into the throttle body like that is not an electrical issue. There is something wrong with your fuel injector.
He's already proved is electric by unplugging the injector... Doesn't say if replacement ECM new or used... new ECM likely not the problem (could be DOA) but used ECM often are "dead" too. Unplug ECM either way as above.
You've never seen 700 series TBI injector @ 100% on? Even at WOT the ECM doesn't run injector(s) @ 100% on most engines. Engine @ idle TBI can be confusing to most people and look "flooded" but is normal. Far lower then 100% is like trying to watch spray patterns on old style bathroom shower w/o water saver features at full flow @ 60-80psi water pressure. TBI w/ the injector @ 100% can literally flood TBI bore w/ throttle close because tiny openings often won't drain fuel fast enough. Worse if not carefully can cause other problems like major gas getting to oil thru the rings. Very bad can cause hydro locking type damages. Once flood problem is found and fix... I would change oil for safety.
