jstringer50

Hey everyone,
Im new to the Camaro world and recently bought a 1989 with the 2.8 multiport. Sometimes after driving the car (usually 20-30 min. of driving), when I get home and shut the car down the fuel pump will continue to run (sounds like the prime you get before startup), somtimes for 3 or 4 minutes. I cant imagine this being normal. Any insight would be appreciated

jv9999

iTrader: (1)

Sticky fuel pump relay maybe. Cheap enough to change.

CamaroRider

Recently another fellow found his fuel pump stayed on for about 15 seconds when he switched his ignition from CRANK to RUN (but the engine did not start) then turned his ignition key off and pull it out. That got me interested. The fuel pump must be getting +12 volts from somewhere and it was not related to having the key in the ignition.

On my 1989 Camaro 305 FI Vin E (TBI) there is a fuse located behind the battery, inside a covered fuse holder. The cover is screwed to the passenger's side of the car right behind the battery and at the end of a protective flexible wire sheath. That [20 amp] fuse stays energized even when the key is removed from the ignition and I think it powers the ECM and I found it DOES feed power to the circuit used by the fuel pump relay and the oil pressure switch, both which can send power to the fuel pump. If I remove the fuse I cannot get the fuel pump to run. So that was the SOURCE of the voltage being delivered to the fuel pump when the ignition key was out.

The next question was 'What was sending that power to the fuel pump?' I could only think of TWO things:

1. A sticking fuel pump relay.
2. The oil pressure switch.

In his case the engine has been sitting unused for many years and I suspect there is gummy oil in his oil pressure switch causing it to react slowly. It is supposed to apply 12 volts to the fuel pump when the oil pressure is 6 PSI or more. It is also supposed to stop applying that voltage to the fuel pump when the oil pressure drops below 6 PSI. So if that switch is not reacting properly it might continue to supply the 12 volts to the fuel pump until it starts to behave properly.

So you should check out both of those items for problems. The fuel pump relay is more convenient to reach so you might start there.

Some people have had the oil pressure switch start to leak and deliver oil to the exterior of the oil pressure switch which might cause a problem until the oil drips away.

Let us know if you find the solution to your problem.

jstringer50

cool-im going to do some snooping around today to see if i can sort it out.
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by the way, where is the fuel pump relay located on these cars?

CamaroRider

My 1989 Camaro 305 FI Vin E (TBI) has the fuel pump relay mounted on the driver's side inside the engine area. It is mounted on a 'stand off' (away from the firewall), by two sheet metal type screws that have hex heads. It has 5 wires attached that all exit on the bottom of the relay. The relay itself has a black plastic cover. It could be described as being the second component from the driver's side front fender, against the firewall.

On my relay the 5 wire colors are:
red, orange, dark green/white, black/white and tan/white.

The dark green/white wire actuates the relay when +12 volts is applied from the ECM.
The black/white wire is ground.

The tan/white wire is the wire that runs to the fuel pump.

The orange wire (fused +12 volts) runs to the fuel pump relay as well as the 'oil pressure switch'.

The red wire goes to the ALDL connector.

On my vehicle the 'oil pressure switch' is located just above the oil filter.

I would personally suspect a problem at the oil pressure switch. You should look at it and see if it is coated with oil. It should be dry. If it is coated with oil then remove the oil and see if that helps or at least changes the length of time that the fuel pump remains ON after you remove the key. The oil might be coming from a 'leaking' of the oil pressure switch.

I am not sure I could easily remove the cover on my fuel pump relay to physically look at it. If so, then that would be an easy way to see if it was 'sticking' when you are experiencing your problem.

My gut feeling is that the relay is functioning properly since it is inside a protected cover but one never knows for sure. I would prefer to actually SEE what the relay is PHYSICALLY DOING when your problem shows up so that I can either definitely see the relay contacts stick or definitely see the relay contacts do NOT stick during the time you are experiencing the problem.

Of course you could simply replace the fuel pump relay and see if you still have the problem. If you do still have the problem then suspect the oil pressure switch, and keep the old fuel pump relay as a spare.

jstringer50

well, found the problem-when it kept running today, I started looking into it. A few taps with a prybar on the oil pressure sender and it quits, so i think ill just replace the sender with a new one-not too expensive. thanks for everyones help!

jv9999

iTrader: (1)

Except that the OP sensor is a backup. It should be getting power through the fuel pump relay. It will start faster too.