Discussion
Hi folks.
I suspect the fuel pump (or it's relay) on my 1981 928S is not working. The car won't start, not even fire. I've checked and the plugs are sparking. I've put fresh petrol and a water scavenger in the fuel tank. Even after a minute or so of trying to start in a confined space there was no smell of petrol. All of which leads me to suspect the pump or relay. Does anybody know where the fuel pump is or have any other advice?
thanks
Dan
I suspect the fuel pump (or it's relay) on my 1981 928S is not working. The car won't start, not even fire. I've checked and the plugs are sparking. I've put fresh petrol and a water scavenger in the fuel tank. Even after a minute or so of trying to start in a confined space there was no smell of petrol. All of which leads me to suspect the pump or relay. Does anybody know where the fuel pump is or have any other advice?
thanks
Dan
Hi Dan,
The fuel pump is at the back of the car, on the right hand (driver's) side, just behind the bumper. If you look closely you will see a metal cover, which is attached with two screws to the bumper and then tucks into the fuel tank cover. Take the screws off and slide the little cover out. Voila! You can see your fuel pump and your fuel filter.
You can see pictures here:
[url]http://sis125.berkeley.edu/928/[/url]
If your fuel pump is ok then you will need to test your fuel pump relay
You can find a chart of the relays here:
[url]www.928gt.com/928specs/81-82relay.htm[/url]
The fuel pump is at the back of the car, on the right hand (driver's) side, just behind the bumper. If you look closely you will see a metal cover, which is attached with two screws to the bumper and then tucks into the fuel tank cover. Take the screws off and slide the little cover out. Voila! You can see your fuel pump and your fuel filter.
You can see pictures here:
[url]http://sis125.berkeley.edu/928/[/url]
If your fuel pump is ok then you will need to test your fuel pump relay
You can find a chart of the relays here:
[url]www.928gt.com/928specs/81-82relay.htm[/url]
My bet is it's the relay. If it's original it will be a metal casing, if it's new it may ("may") be plastic depending on where it was manufactured. I got a couple the other day from Hungary and they were plastic. The case can be pulled off and you can hotwire the relay by just putting the contacts together in some manner, for testing of course. If you do this, better plan on installing a new one pronto.
I don't know how many gallons one of those pumps will pump before they die, but if you have 125,000 miles on the car chances are the pump has moved 1500 gallons over the years, one drop at a time. Filters are also an issue on the older cars too. Good luck.
Dogsharks
I don't know how many gallons one of those pumps will pump before they die, but if you have 125,000 miles on the car chances are the pump has moved 1500 gallons over the years, one drop at a time. Filters are also an issue on the older cars too. Good luck.
Dogsharks
Thanks Dogsharks.
The car has done 135k miles. It's got the moulded plastic relays, but I happen to have some patch cables for hotwiring relays, after having had a problem with a pop up light relay. If the relay has got the normal schematic on it somewhere, I should be able to work out how to "run a bypass".
I'm really hoping it's just the relay!
The car has done 135k miles. It's got the moulded plastic relays, but I happen to have some patch cables for hotwiring relays, after having had a problem with a pop up light relay. If the relay has got the normal schematic on it somewhere, I should be able to work out how to "run a bypass".
I'm really hoping it's just the relay!
danhay said:
...I'm really hoping it's just the relay!
Dan,
Call Paul Anderson on 0781 666 8088 or at enquiries@928spares.co.uk He has both the pump and the relay in stock (Bosch OEM) and charges about a third of the normal OPC price. Good for servicing 928s too - charges £25ph and knows them inside out. Hope that helps.
Well the relay is definately broke.
I took it off, and discovered that although it's got a plastic case rather than a metal one, it's not moulded, and I was able to remove the plastic casing. I observed that the relay didn't switch when the ignition key was turned.
I inserted a plastic tab to lock the relay in the on condition, this elicited a small spark from the contacts and a single click from the fuel pump. Whenever I switch the relay either on or off, I get a single click from the fuel pump.
I tried to start it for about 60 seconds in total...first with about 20 secs of cranking, then with shorter bursts of 10 secs or so with a gap in between.
But alas still no sign of firing at all from the engine and no smell of unburnt petrol from the exhaust either.
I think a call to Mr Anderson may well be in order.
I took it off, and discovered that although it's got a plastic case rather than a metal one, it's not moulded, and I was able to remove the plastic casing. I observed that the relay didn't switch when the ignition key was turned.
I inserted a plastic tab to lock the relay in the on condition, this elicited a small spark from the contacts and a single click from the fuel pump. Whenever I switch the relay either on or off, I get a single click from the fuel pump.
I tried to start it for about 60 seconds in total...first with about 20 secs of cranking, then with shorter bursts of 10 secs or so with a gap in between.
But alas still no sign of firing at all from the engine and no smell of unburnt petrol from the exhaust either.
I think a call to Mr Anderson may well be in order.
It Lives!!!
I was beginning to doubt I'd ever see the day, but I got the 928 started for the first time in 2 years.
I have replaced the fuel pump and it caught on the first turn. It ran beautifully for a couple of seconds then died. After several minutes of restarting it was running ok, and even managed to move under it's own power. Once up to temperature it promplty started emptying the contents of it's cooling system through a hole in the radiator...
Next step I think will be a new Thermo Time Switch and possibly a Temp II sensor in a bid to sort out the misfire when cold.
I was beginning to doubt I'd ever see the day, but I got the 928 started for the first time in 2 years.
I have replaced the fuel pump and it caught on the first turn. It ran beautifully for a couple of seconds then died. After several minutes of restarting it was running ok, and even managed to move under it's own power. Once up to temperature it promplty started emptying the contents of it's cooling system through a hole in the radiator...
Next step I think will be a new Thermo Time Switch and possibly a Temp II sensor in a bid to sort out the misfire when cold.
The TTS and T2S are actually almost "side by side" on the front of the motor. They both look essentially like a water temp sensor for a water temp gauge. If you can find one, you can find the other because it's only a few inches away. Just be sure you put the proper device into the right location.
regards, Dogsharks
regards, Dogsharks
Thanks Dogsharks.
I've found the Thermo Time Switch, which was quite well hidden, though easy enough to get at once you know where it is! It's mounted horizontally, in line with the engine and goes into the cooling system. Am I right in thinking that the Temp II sensor goes into the cylinder head? Is it vertically mounted?
Will have another look.
>> Edited by danhay on Saturday 15th May 14:37
I've found the Thermo Time Switch, which was quite well hidden, though easy enough to get at once you know where it is! It's mounted horizontally, in line with the engine and goes into the cooling system. Am I right in thinking that the Temp II sensor goes into the cylinder head? Is it vertically mounted?
Will have another look.
>> Edited by danhay on Saturday 15th May 14:37
I have a '83 US, you might have a '81 Euro for all I know, but on my '83 the Temp II sensor is on the US driver side of the car, on the front of the motor, in the water flow area. The TTS is about six inches away on the US passenger side of the motor, again in the water flow system on the front of the motor. Buy the parts, then hunt them down, don't replace anything unless it looks exactly like the part you bought called the TTS. Good luck. (My US has another Temp II sensor, mounted in the back of the motor almost under the air filter, and that one is tough to get to.
good luck, Dogsharks
good luck, Dogsharks
Thanks once more DS. 
I've received a new Thermo Time Switch and Temp II Sensor today. I managed to find the Thermo Time Switch at the front of the engine in the location you mentioned before, and it matched the old one exactly. It's the Temp II Sensor I'm having a problem finding. I've found another water temp sensor pretty much underneath the Oil Filler pot thingy, near the TTS. I've had it off, and it doesn't match the replacement Temp II sensor I've got at all. In fact it's got VDO written on it which leads me to believe it's the sender for the water temp gauge. I think I might check at the back of the engine as there's nothing matching the new bit I've got at the front!
I've received a new Thermo Time Switch and Temp II Sensor today. I managed to find the Thermo Time Switch at the front of the engine in the location you mentioned before, and it matched the old one exactly. It's the Temp II Sensor I'm having a problem finding. I've found another water temp sensor pretty much underneath the Oil Filler pot thingy, near the TTS. I've had it off, and it doesn't match the replacement Temp II sensor I've got at all. In fact it's got VDO written on it which leads me to believe it's the sender for the water temp gauge. I think I might check at the back of the engine as there's nothing matching the new bit I've got at the front!
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