Thomas Stahel

iTrader: (1)

Hey everyone

My car (Camaro, '88, TBI, Vin E) won't start anymore and I suspect it's the fuel pump. I can't hear it anymore when I turn the ignition on. Well, I could, yesterday when the car started and ran for a short time. But the sound was more a dull humming than the more bright kind of buzzing from earlier days. What I could see as well was that the spray of the injectors decreased when the car began stuttering and slowing down (at idle). Today I asked my mother to turn the key and try to start the car while I watched the injectors. I couldn't see any spray of fuel. And as I said, I couldn't hear the fuel pump anymore. I could hear the two clicks from the relais but not the pump.

Do you think this is now a shure sign for the pump to be dead or is there another "easy" way to check the pump? In my service manual they talk about a fuel pump test terminal. As I found out from this forum, this is the same as the relay. It's the red wire. I just want to test the pump, so I wouldn't have to apply 12 volts to the red wire but instead I can unplug the relais and apply 12 volts directly to the pump (ckt 120, the brown wire?), is that correct?

How long can I do this to check whether the pump is running?

Any other suggestions on what and how to test?

Thanks,
Thomas

RS-Chevy-SS

Check the fuse near the battery. May be blown. If it isn't, i would assume the pump is blown since you hear the relays

Thomas Stahel

iTrader: (1)

Today I was looking after the fuel pump.

I can't hear it anymore when turning the igniton on. I checked the in-car fuses for the injectors and the fuel pump, they were both okay.

I also checked the relais and then I put 12 volts directly to the fuel pump (that was the brown wire 'A' which goes into the relais). I couldn't hear any sound from the rear, so I guess, it's really the fuel pump.

I wasn't able to find the fuse that you were talking about. Next to the battery I can see a connector, but the wire comes from the negative pole. So I guess that's not the one I should be looking for. From the positive pole there's a big black wire without anything and two smaller ones attached to the battery's positive. I can see a short black plastic "housing" around the red cable.

I don't know now, I've checked what is to be checked. My service manual says that in this case it can only be a defective pump, open CKT-120 wire or faulty pump ground. Can I check the last two somehow?

Oh and actually there were two error codes from the ECM. 44 and 54. At least 54 is explicable because I unplugged the relais. But 44 has to do with oxygen sensor. Well there is a connection to error 54 because bad fuel pressure can cause error 44.

Today I tried spraying some starter help spray directly into the TBI where the injectors normally spray the fuel. While cranking the engine showed a very short sign of wanting to start but didn't. Now again I'm unsure... is there a way to spray fuel manually into the TBI or at least remove the fuel line to check whether there is really no pressure?

Thanks a lot,
Thomas

Schurkey

Could be the fuel pump, could be the wiring to the pump, could be the ground wire coming from the fuel pump.

The in-tank wire harness is a common problem. Some fuel pumps ship with a replacement in-tank harness; otherwise they're about $20. Breaks in the harness outside the tank are repaired in the usual way--find the problem, splice in good wire or new connections, secure the harness so it doesn't happen again.

TBI fuel pressure requires an in-line test adapter since there's no service port on the TBI fuel plumbing. Some fuel pressure gauges ship with a TBI adapter. One kind of adapter screws into the back of the throttle body; another kind attaches where the fuel filter is--the filter comes out, the test adapter temporarily replaces it.

Thomas Stahel

iTrader: (1)

Ok, thanks.

So am I right that the connector from the fuel pump is inside the tank? So there is no possibility to check the pump plugging a wire 12v directly to the connector or to perform a continuity test of the fuel pump itself? And there is also no possibility to test the wire from the pump to the relay? What about the ground wire from the pump?

Another question: If I had to drop the rear to get to the tank, how high should the jack be able to lift the rear? Is 50cm enough or do I ned 80cm to get enough clearance the tank out?

Thanks,
Thomas

Schurkey

My '92 and '93 Luminas have a red wire near the battery that is a fuel pump relay bypass. Connect battery power to that wire, the fuel pump runs. Perhaps GM did something similar on the Camaro/Firebird.

You could remove the fuel pump relay, and jump a wire across the appropriate receptacles in the harness. That will power the pump.

Otherwise, find the wire harness connector closest to the fuel tank, open it, and route power and ground to the appropriate tank wires. That should also run the fuel pump.

I've never measured how high I "needed" to raise the vehicle. I put it up as high as my floor jack and jack stands allow. More room is nearly always better.

whatif3387

I don't know if its the same for the TBI cars as it is the TBI trucks but I was having a similar issue with my truck and it turned out to be the ICM. If the ICM is bad the pump wont turn on and the injectors won't fire.