mb2hurley

i got a 88 iroc 5 speed 305 tbi not running only 100 bucks
the tank was gone, i replaced the tank and fuel assemlby, had to weld a panel over the tank back on before putting gas back in the car, tested the pump once installed and heard it buzz. weld the panel and had to replace the ignition tumbler as well, key was stuck. went to start it and nothing, all electronics work but dont hear the pump anymore and no fuel getting to the throttle body. had it on a batter charger, thinkin about changing the starter and fuel pump relay, unless there might be something else to check???

not sure if i should just scrap the car for parts before i get to crazy into it or continue to try and get her running, id love to be able to drive it.

Damon

Obviously, check the fuses.

There are two ways that power gets to the in-tank electric fuel pump on these cars.

1. Through an ECM-controlled fuel pump relay (one of the square black boxes you'll see up near the power brake booster). ECM supplies a ground on the low-current (control side) of the relay, the relay is triggered and power is sent from the battery to the fuel pump on the high load side of the relay. If everything is working properly the ECM will prime the pump for 2 seconds at key-on via this system. Obviously, it activates it during starting as well, but it's more difficult to hear if the fuel pump is running while the starter is flipping the motor over.

2. Through the Oil Pressure Sending unit. This is the "backup circuit" to get power to the fuel pump. It's screwed into the block just above the oil filter boss. It's got 3 wires. One runs the oil pressure gague. The other 2 are for the fuel pump circuit. One is battery-hot (always hot). When oil pressure rises above about 5-6 PSI a circuit closes and connects the batter-hot wire to the other wire which goes back to the fuel pump. Obviously, there is no oil pressure when the engine is off. Even cranking on the starter this circuit is not guaranteed to be connected, unless you can generate more than the required 5-6 PSI of oil pressure to close the connection and complete the circuit.

Hope that helps your diagnosis at least a little.

mb2hurley

i checked all the fuses and there all good. ill check that relay. im wondering if putting the battery charger on it to the 200amp quick start might of blew it, the battery was dead. or maybe did damage else where, but all my gauges and lights did work, but even when i went to start the started clicked once and then after that nothing, i beat on it for a min and still nothing.

Damon

Get a new battery first, would be my recommendation. If you're relying on hot boxes and such just to get it to flip over you're headed for frustration. There are likely multiple reasons it's not going to start right now, but you won't find them until you get a reliable power source to run things.

It is unlikely you blew out a relay no matter how bad you botched up the jumping process. Fueses can blow, so can the fusible links about 8" up the main wiring harness power wires that attach to the positive battery cable post on the starter. But blowing out a relay because of those kind of shenanigans is unlikely. The relays could be dead for other reasons (dead the day you bought the car or other wiring/ECM problems that prevent them from working) but it is unlikely you murdered them.

Guest

IROC's never came with a 305 TBI

mb2hurley

my vin number reads as 88 camaro iroc z 305 tbi and thats whats in there, id much rather have it be the tpi

mb2hurley

http://www.iroczone.com/2009/10/1988...pecifications/

there is one model of the irocz with a 305 tbi motor

mb2hurley

ok so i replaced the starter and the motor cranks over, but im not gettin any fuel pressure, i opened the lines up at the fuel filter and no fuel, there is gas in the tank and im not hearing the pump come on at all, its a brand new pump, when i installed it i accidentally turned the key to on with no gas in the tank but i did hear the pump turn on. being a brand new pump i dont think one dry run would damage it, could i be wrong?? all my fuses under the dash are good, i cant find my fuel pump relay, i looked it up online theres a relay behind on brake booster but it looks different then from what i saw. i really dont want to drop the tank again to buy a new pump. any ideas?

mb2hurley

ok i looked again there was another relay but it was broken and hangin in the engine compartment, i only have 2 relays right there one has 3 wires goin to it, and the other 5

mb2hurley

i still dont have power to my fuel pump, i followed the wire to a relay under the hood on the fire wall and replaced that relay. still nothing at the pump, i found another relay on the driverside kick panel, i heard it has something to do with fuel, i dont know how the relay works only one terminal has power, but nothing else, im not sure if its bad, it also had a ground wire that was cut, i dont know where it went to, but was grouned into the screw that held it to the body.




what is this relay called? and how do you test it?

yaj15

iTrader: (3)

From 1988-1989 the base IROC motor was the L03 TBI 305 motor.

In 1990 the LB9 305 TPI motor became the standard motor in the IROC.

Guest

My bad I just never thought they did. Weird.

yaj15

iTrader: (3)

Ha yeah I understand. Nothing wrong with the L03 and I'm not trying to start a TBI vs. TPI motor debate here. Its just in the scheme of things the L03 was lower on the performance chart than the LB9 & L98 motors were. Thats why a lot of people are surprised that you could get the L03 in the IROC camaro which was at the top of the food chain back then.

The L03 motors don't make a great amount of power in stock form compaired to the LB9 & L98 motors but, they are very reliable and rack up many miles with little to no problems if maintained well.