I'm going to look at a 1994 Z28 that's for sale later this week and would like some thoughts on a fault that the car has developed.
The car has done 113,000 miles but has been fully serviced and well looked after. Apparently, instead of starting instantly it now requires cranking over for 5 or 6 seconds at which point it starts and runs as normal. The odd thing is that the cooling fans start operating immediately and the 'Service Engine Soon' light comes on.
The owner say's it had the same fault about a year ago and the Auto Shop found the Air Pump fuse had blown. He believes they also cleaned out the Pump and relevant pipework and this solved the problem. This time though the fuse hasn't blown.
Have any of you Guys encountered this before? Could it be the Air Pump is failing? It doesn't sound like a serious fault but i don't want to end up throwing money into a bottomless pit .
Any ideas and advice would be a great help.
Thanks,
Mel

 

sounds like the fuel pump is thinking of failing. what trouble codes came up?

 

Thanks for your reply craby,
I'm not aware of any codes: The owner's bought a newer Camaro and the car has been stored in his friends garage for just over 3 weeks. It was fine when he parked it up and the fault has re-occurred when he came to start it up to make sure everything was ok before sale.
I'm new to emission stuff on cars so excuse me if this is a dumb question, but why would a failing fuel pump cause the cooling fans to operate?

 

If the check engine light is on, there should be a code. Have the PCM scanned and see what it is complaining about. Most likely, as Craby mentioned, it is a fuel problem, and the fuel pressure is dropping when the engine is shut off. Do not buy a car that has the check engine light lit, unless you know the cause.

 

im thinking there is more than one issue, first thing would be to have it scanned for trouble codes. there are a few things it could be and rather than throwing parts at it it would be better to see if the car will tell us were the issues are that it sees. could be vats, 02 sensors, maf, map, fuel pressure regulator, fuel pump, maybe even the opti.

 

I know the opti did fail at one point. He said it was the only time it has let him down and it was changed for a new one. I think it was about 20,000 miles ago.
According to the ad there's a 'Sunpro' code scanner with the car: it may be worth asking if he can get the fault code(s) and see what's happening.
I'll let you know...

 

1. I don't see where the air pump would make the engine hard to start.
2. When you turn the ignition switch to the "on" position, can you hear the fuel pump prime then shut off? If not, then the problem is probably with the fuel pump relay or circuit.
The fuel system has a fail-safe backup (through the oil pressure switch) to supply power to the fuel pump should the pump relay fail.
That could explain the extended time it takes for the engine to start as the engine cranks to build up oil pressure.
Contrary to popular belief, the oil pressure switch is not a safety shutoff to kill the fuel pump in case the engine loses oil pressure, it's quite the opposite.

 

The owner is going to use the code scanner to try and find what the problem is.
I haven't seen the car yet, i'm about 70 miles away! If he can't sort it out i may have to find a dealer in the area who can run a diagnostic when i go to view.
I couldn't understand either how a blown fuse on the air pump affected starting but that's what the Garage told him .
I'll see what happens when he calls!

 

All the air pump does is puff air into the exhaust manifolds to help warm the cat converter faster, to keep cold engine emissions down.
It has nothing to do with ignition or fuel supply. A bad circuit/blown fuse will trip the SES light, but still not affect start-ability.

 

It sounds like the air pump fuse was just a coincidence. Whatever the fault was a year ago somehow got 'cured' when the garage were working on the car. And now it's back!
I'll ask him to check to see if the fuel pump primes when he calls about the error code: it's 23.20 here and i don't think he'd be too happy if i phoned him now!
Thanks for your help guys.