Saab 900 Fuel pump probs
Discussion
Hello all,
I Have a Classic 1993 Saab 900SE 16v.
The other day about 20 seconds after setting off to work, the car just died.
I managed to re-start but revs were all over the place, I could put my foot down and get it to rev but it would then drop back down and almost stall, each time I just managed to keep it reving.
I decided to limp back to the house and take a taxi but by the time I got back up the street it had settled a bit.... but just a bit.
Anyway just made it to work about a mile but no way would it re-start.
After a bit of advice from collueges I had a look at the fuel pump, if I put a meter on the pump plug (pump not connected)I got 10V while turning over, I accepted this as just the starter motor pulling the voltage down... but I could be wrong.
So I put a re-connected the pump and put a length of hose on the outlet at the top of the tank and turned the key, starter motor turning but no fuel being pumped at all.
So I took out the pump assembly and removed the pump and took it home for the weekend, after cutting a rubber blank to block the hole in the tank.
Now I made my first mistake, I tested the pump in a bowl of water, bad idea.... the pump worked fine connected straight onto a battery but there are mild steel parts in the pump and now it's knackered so I'll have to get a new one.
Any way I'm now looking for the fuel pump relay but can't find it!!! it's not listed in the main fusebox and it's not under the back seat.
To cut a long story short I'm now well and truly stuck. Can any one suggest a way to proceed or can anyone answer the following questions.
Is 10vdc acceptable when the starter motor's turning?
Should the pump even be pumping when the cars turning over?
Is there a fuel pump relay on the later models and where is it?
What else can I check to try and sort this out?
All comments are gratefully received even if the're just taking the piss.
Thanks Aidy.
I Have a Classic 1993 Saab 900SE 16v.
The other day about 20 seconds after setting off to work, the car just died.
I managed to re-start but revs were all over the place, I could put my foot down and get it to rev but it would then drop back down and almost stall, each time I just managed to keep it reving.
I decided to limp back to the house and take a taxi but by the time I got back up the street it had settled a bit.... but just a bit.
Anyway just made it to work about a mile but no way would it re-start.
After a bit of advice from collueges I had a look at the fuel pump, if I put a meter on the pump plug (pump not connected)I got 10V while turning over, I accepted this as just the starter motor pulling the voltage down... but I could be wrong.
So I put a re-connected the pump and put a length of hose on the outlet at the top of the tank and turned the key, starter motor turning but no fuel being pumped at all.
So I took out the pump assembly and removed the pump and took it home for the weekend, after cutting a rubber blank to block the hole in the tank.
Now I made my first mistake, I tested the pump in a bowl of water, bad idea.... the pump worked fine connected straight onto a battery but there are mild steel parts in the pump and now it's knackered so I'll have to get a new one.
Any way I'm now looking for the fuel pump relay but can't find it!!! it's not listed in the main fusebox and it's not under the back seat.
To cut a long story short I'm now well and truly stuck. Can any one suggest a way to proceed or can anyone answer the following questions.
Is 10vdc acceptable when the starter motor's turning?
Should the pump even be pumping when the cars turning over?
Is there a fuel pump relay on the later models and where is it?
What else can I check to try and sort this out?
All comments are gratefully received even if the're just taking the piss.
Thanks Aidy.
If you have 10v at the pump whilst the engine is cranking, I wouldnt be worried.
No sense worrying about relays, as you've just said you have 10v at the pump when cranking.
So assuming you have 10v or more and a sound ground, the pump has enough power that it should work.
And yes the pump should run whilst the engine is turning.
No sense worrying about relays, as you've just said you have 10v at the pump when cranking.
So assuming you have 10v or more and a sound ground, the pump has enough power that it should work.
And yes the pump should run whilst the engine is turning.
I'd be surprised if the pump is dead just because of a short test with water unless you just left it to rust for a substantial amount of time. If you take it apart and clean up any surface rust on the rollers and other bits with a nylon scourer or fine wet and dry paper and there's no major rust it should be ok. Paraffin is the best thing to test it with - less flammable than petrol. It should be putting out about 3 pints per minute but you could manage with a bit less. Average petrol engines require about 1 pint per minute per 100 bhp.
I'd try a new fuel filter when you put everything back together.
I'd try a new fuel filter when you put everything back together.
Have you got a Bentley Workshop manual? Mine is in the garage and I'm on the sofa so I can't check just now about the relay, but surely it should either be in the main fusebox or under the back seat on a '93?
Try asking on one of the Saab forums (saabcentral, saabscene, uksaabs, uksaabscentral).
Where are you in the country?
Try asking on one of the Saab forums (saabcentral, saabscene, uksaabs, uksaabscentral).
Where are you in the country?
thanks for the posts I can't bear to scrap this car.
I opened the pump to confirm mild steel parts, but had to cut it open... it was siezed with rust.
The other thing I noticed was that the rubber seals that mounted the pump had shrunk and gone hard when dried out.
I recon it would be impossible to re-build as it was, can you soak them in petrol and get them soft again?
however I just got a whole secondhand pump assembly of ebay so will post back after fitting.
I only have a Haynes manual which isn't much use it dosen't list a location for pump relay after 91.
I can only assume it was incorporated into an ignition relay, there's a few in the main fusebox.
As I had power at the pump plug but no fuel pumping and then the pump worked when removed, I can only think that either the relay contacts are poor and can supply voltage to a meter but no load to the pump, or there was a bad connection in the pump housing which i'll check.
I fitted a new fuel filter a couple of years ago so am fairly confident on that score.
I'm in North Yorks by the way.
I opened the pump to confirm mild steel parts, but had to cut it open... it was siezed with rust.
The other thing I noticed was that the rubber seals that mounted the pump had shrunk and gone hard when dried out.
I recon it would be impossible to re-build as it was, can you soak them in petrol and get them soft again?
however I just got a whole secondhand pump assembly of ebay so will post back after fitting.
I only have a Haynes manual which isn't much use it dosen't list a location for pump relay after 91.
I can only assume it was incorporated into an ignition relay, there's a few in the main fusebox.
As I had power at the pump plug but no fuel pumping and then the pump worked when removed, I can only think that either the relay contacts are poor and can supply voltage to a meter but no load to the pump, or there was a bad connection in the pump housing which i'll check.
I fitted a new fuel filter a couple of years ago so am fairly confident on that score.
I'm in North Yorks by the way.
I think all the 16 valves had Lucas fuel injection (check under the bonnet - does it have a big gold metal resistor on the offside wing near the power steering reservoir?) The Bentley manual only covers the Bosch LH FI system but I acquired a service manual for Lucas a while back (just been for a rummage in the garage to find it!)
The fact that the c900 had 2 entirely different FI systems means that the relays are not all in the same place - as far as I can see, the Lucas main and fuel-pump relays are mounted on the same mounting plate that the ECU is on. Basically, remove the carpet retainers in the driver footwell, and the ECU is bolted to the footwell in front of the door. According to the manual I've got it looks like the PS reservoir needs draining to remove the relays, not sure why.
If you want to test the relays it might be easier. I have the official Lucas service manual, any questions just shout!
Did you get any check engine lights? You can pull the codes fairly easily using a DIY switched jumper lead.
I'm sure I saw a PDF of it kicking around somewhere but I can't find it now. Some of it is here in the troubleshooting guide - see if this helps:
http://saab.doda.se/Dokumentation/Lucas/lucas-cu14...
I still think your best bet is posting on one of the Saab boards. Somebody will be able to help you. Don't scrap the car for what is probably a simple fault!
The fact that the c900 had 2 entirely different FI systems means that the relays are not all in the same place - as far as I can see, the Lucas main and fuel-pump relays are mounted on the same mounting plate that the ECU is on. Basically, remove the carpet retainers in the driver footwell, and the ECU is bolted to the footwell in front of the door. According to the manual I've got it looks like the PS reservoir needs draining to remove the relays, not sure why.
If you want to test the relays it might be easier. I have the official Lucas service manual, any questions just shout!
Did you get any check engine lights? You can pull the codes fairly easily using a DIY switched jumper lead.
I'm sure I saw a PDF of it kicking around somewhere but I can't find it now. Some of it is here in the troubleshooting guide - see if this helps:
http://saab.doda.se/Dokumentation/Lucas/lucas-cu14...
I still think your best bet is posting on one of the Saab boards. Somebody will be able to help you. Don't scrap the car for what is probably a simple fault!
Edited by NiceCupOfTea on Wednesday 19th October 23:38
Hello, thanks again.
I put meter back on pump plug = 10vdc
then wired a bulb onto it = nowt
So back to chasing the pump relay, I don't have a resistor in engine bay.. I've seen them on photos but always assumed they were some sort of fix.
My ECU is on the inside of the passenger wing though there is also some sort of "hi Tech" box under the rear seat on the other side to the aux fuse box.
I'll try one of the Saab forums and post back when I get somewhere.
I put meter back on pump plug = 10vdc
then wired a bulb onto it = nowt
So back to chasing the pump relay, I don't have a resistor in engine bay.. I've seen them on photos but always assumed they were some sort of fix.
My ECU is on the inside of the passenger wing though there is also some sort of "hi Tech" box under the rear seat on the other side to the aux fuse box.
I'll try one of the Saab forums and post back when I get somewhere.
aidymitton said:
Hello, thanks again.
I put meter back on pump plug = 10vdc
then wired a bulb onto it = nowt
So back to chasing the pump relay, I don't have a resistor in engine bay.. I've seen them on photos but always assumed they were some sort of fix.
My ECU is on the inside of the passenger wing though there is also some sort of "hi Tech" box under the rear seat on the other side to the aux fuse box.
I'll try one of the Saab forums and post back when I get somewhere.
hi tech box under the back seat is likely the ABS control unit. inside of passenger wing sounds like the APC (boost controller) but yours is non turbo I put meter back on pump plug = 10vdc
then wired a bulb onto it = nowt
So back to chasing the pump relay, I don't have a resistor in engine bay.. I've seen them on photos but always assumed they were some sort of fix.
My ECU is on the inside of the passenger wing though there is also some sort of "hi Tech" box under the rear seat on the other side to the aux fuse box.
I'll try one of the Saab forums and post back when I get somewhere.
All that's in that wing should be fusebox and cruise control from memory... Can you take a photo or give a part number of the box?If you have a '93 non turbo running Bosch it will be LH 2.4.2 according to my manual - ECU, main relay, & fuel pump relay are all "forward of right front door, behind trim". Pull the carpet up and have a look.
The relays are above the ECU. You can't really get to them without taking out the knee-board or un-bolting the ECU from the mounting bracket and then the mounting bracket from the car. When you take the ECU mounting bracket out of the car you will find the two relays attached to the top of the ECU mounting bracket. Simple to get to if you know these cars. Nightmare for the novice.
I know everything about these cars so if you have any questions then just ask. Register on my forum: http://www.saabsforum.com / http://www.uksaabscentral.co.uk (I have two URLs) - I saw you put the question on UKSaabs. Wouldn't bother with that lot.
I know everything about these cars so if you have any questions then just ask. Register on my forum: http://www.saabsforum.com / http://www.uksaabscentral.co.uk (I have two URLs) - I saw you put the question on UKSaabs. Wouldn't bother with that lot.
Take out the knee-board and bridge the relay, i can't see running it in water would knacker it unless it was left for a while.
Nice to see sad emmett still having pops at other Saab forums, he didn't like the fact that they were not run the way he wanted and started his own expecting everyone to move over to it, they didn't apart from 4/5 of his mates, now it is just sad, 5 or six posts a week, 4 blokes moaning at each other, stick to the main successful sites and you will get somewhere.
Nice to see sad emmett still having pops at other Saab forums, he didn't like the fact that they were not run the way he wanted and started his own expecting everyone to move over to it, they didn't apart from 4/5 of his mates, now it is just sad, 5 or six posts a week, 4 blokes moaning at each other, stick to the main successful sites and you will get somewhere.
I've always found that single make forums can get quite cliquey and political. For sure there is a huge amount of knowledge on UKS but the moderation does seem a little heavy handed at times. Credit to Emmett for putting his money where his mouth was and starting a new forum rather than just moaning about it.
Room for all the forums I think, good that there is still so much support for these old girls
Back on topic: O/P, have you located those relays yet? Haynes should detail it, but remove centre console (bolt behind ashtray, 2 more under trim in front of gearlever, 2 either side attaching it to the rear carpet bit of centre console), then open doors and drop down knee board (one bolt behind ashtry again, one each accessed from engine compartment in each corner). Don't forget to remove the lower bit of the plastic steering column cover. Doesn't take long to do and you will be able to access the relays.
Better still, get yourself the Bentley Bible!:
http://www.partsforsaabs.com/product_info.php?prod...
Worth every penny.
Room for all the forums I think, good that there is still so much support for these old girls
Back on topic: O/P, have you located those relays yet? Haynes should detail it, but remove centre console (bolt behind ashtray, 2 more under trim in front of gearlever, 2 either side attaching it to the rear carpet bit of centre console), then open doors and drop down knee board (one bolt behind ashtry again, one each accessed from engine compartment in each corner). Don't forget to remove the lower bit of the plastic steering column cover. Doesn't take long to do and you will be able to access the relays.
Better still, get yourself the Bentley Bible!:
http://www.partsforsaabs.com/product_info.php?prod...
Worth every penny.
Bridge terminal 30 and 87 at the relay to see if the pump runs, from your other posts i see you are getting power at the pump side, try Saab Tech Talk and Saab Central as well to get as many suggestions as possible.
I would have been nice if emmett had tried to help the OP here rather than just trying to send him to his site and feeling the need to bad mouthing other forums.
I would have been nice if emmett had tried to help the OP here rather than just trying to send him to his site and feeling the need to bad mouthing other forums.
Most fuel pumps are cooled by the fuel that runs through them (or immersion, for in-tank pumps) and some can get cranky with age , esp in-tank pumps if the car has been run around with the tank mostly near empty!
Having had fuel pump probs on Saabs in the past, my end-run around (for any car) is to temporarily rig a new cable of adequate size (ie rated min. 15A or more) from a switched-live feed (rig up a relay and fuse to do this if needed) and run the pump off that. If the car then drives ok, you know you have a wiring/fusebox issue, not a pump problem.
Not directly applicable but maybe interesting: in my last NG900 it wasn't the fuel pump at fault nor the fuse nor relay: the wiring from battery to fusebox had got cooked-out instead about 6inches short of the fusebox ... it took a while to find that!
Having had fuel pump probs on Saabs in the past, my end-run around (for any car) is to temporarily rig a new cable of adequate size (ie rated min. 15A or more) from a switched-live feed (rig up a relay and fuse to do this if needed) and run the pump off that. If the car then drives ok, you know you have a wiring/fusebox issue, not a pump problem.
Not directly applicable but maybe interesting: in my last NG900 it wasn't the fuel pump at fault nor the fuse nor relay: the wiring from battery to fusebox had got cooked-out instead about 6inches short of the fusebox ... it took a while to find that!
aidymitton said:
thanks for the posts I can't bear to scrap this car.
I opened the pump to confirm mild steel parts, but had to cut it open... it was siezed with rust.
Sounds like you might have water in the petrol tank too then. Draining and cleaning that wouldn't go amiss while the pump is out.I opened the pump to confirm mild steel parts, but had to cut it open... it was siezed with rust.
Right. sorry for the delay I now have an update.
Fitted the new fuel pump and took battery off for charging.
Re-fitted battery and tried to start the car, it turned over but no start.
Tried a bulb on the pump socket.....nowt.
So I lashed the fuel pump straight onto the battery and it ran fine and pumped fuel.
Tried to start the car with the pump lashed up and running and managed to start the car but it wouldn't tick over.
Engine seemed to run ok when kept above 2000rpm but poor at lower revs.
I checked two relays in the fuse box labelled "ignition relay" and "ignition lock".
Both these relays switched so I'm now a bit stuck.
The hi-tech box in the engine bay on the passenger side wing says BOSCH on it. Is this to do with the Injection system?
Thanks for all your posts so far.
Fitted the new fuel pump and took battery off for charging.
Re-fitted battery and tried to start the car, it turned over but no start.
Tried a bulb on the pump socket.....nowt.
So I lashed the fuel pump straight onto the battery and it ran fine and pumped fuel.
Tried to start the car with the pump lashed up and running and managed to start the car but it wouldn't tick over.
Engine seemed to run ok when kept above 2000rpm but poor at lower revs.
I checked two relays in the fuse box labelled "ignition relay" and "ignition lock".
Both these relays switched so I'm now a bit stuck.
The hi-tech box in the engine bay on the passenger side wing says BOSCH on it. Is this to do with the Injection system?
Thanks for all your posts so far.
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