Fuel Not Getting Through

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peteinnit
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Re: Fuel Not Getting Through

Post by peteinnit »

It is on a camber so that maybe why there is no flow from gravity. I've got at least 1/3 of a tank in there and when I hooked the pump to separate 12V it has half filled the filter which was empty. I can't see that the position of the pump is the problem as it's been in the same place for over 10 years with no issue.

Thinking about it a bit more I think I understand why it wouldn't work when I tried it on the separate 12V insitu. The pump has 2 terminals, one goes to earth and one goes to a switch/split box. Out of the switch box comes a red and a black which goes to the coil and an earth. When I tested underneath with the original earth, I was only connecting the terminal to the +ive, whereas I think it needs to connected to both +ive and -ive, hence why it worked when I hooked each terminal up to both 12V terminals.

If that's the case, then I think the problem may be the switch box, or the coil. I'm pretty sure there are no blockages as I've had all the pipe out and blown through and have sucked some petrol out from the tank. I'll have one more go in the morning (weather permitting), then call someone in I think. I'll also get someone to turn it over whilst I listen again, but it's pretty hard to hear anything when it's being turned over, as it's mounted near the starter.
T25 2.0l Aircooled CI - 1982

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937carrera
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Re: Fuel Not Getting Through

Post by 937carrera »

You need to create an electrical circuit for the pump, that means connecting both +ve and -ve to the terminals on the pump. You should disconnect the +ve feed from the vehicle and insulate it

If you can do that you should be able to see fuel flowing through the little clear plastic inline fuel filter - they rarely look full anyway. You should then be able to start the van relying on the separate power supply to the pump. If that's all OK, then disconnect the external feed, reconnect the vehicle wiring and try again. If it doesn't start, then you know it is something electrical on the power supply to the pump (or a poor earth from the pump).

Do you have a multimeter ?
1981 RHD 2.0 Aircooled Leisuredrive project, CU engine
1990 RHD 1.9 Auto Sleeper with DF/DG engine

peteinnit
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Re: Fuel Not Getting Through

Post by peteinnit »

I've only got a battery tester, not a multimeter. I did set up a temp circuit and ran the pump insitu, but without trying to start it, so will try that tomorrow.
T25 2.0l Aircooled CI - 1982

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937carrera
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Re: Fuel Not Getting Through

Post by 937carrera »

It's really worth getting a multimeter - you'll get one for less than a tenner on ebay.

If you need to you can make up a test bulb circuit as an alternative https://www.youtube.com/watch?v=sbzBFyn6V2c, but that's for tomorrow if needed
1981 RHD 2.0 Aircooled Leisuredrive project, CU engine
1990 RHD 1.9 Auto Sleeper with DF/DG engine

peteinnit
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Re: Fuel Not Getting Through

Post by peteinnit »

OK, so got it started with pump on separate circuit. Removed the +ive and -ive connections to the coil and connected to separate 12V and nothing, so I think it's the pump relay. Trying to find a new one the same, it comes from a Saab apparently! Only ones I can find are in Europe!

Another stupid question alert...... is the pump onky required for starting up, or is it running all the time the engine is running? If it's only required for start up, I guess I can use the separate circuit for that until I can get a new relay and at least I'll be able to move it.
T25 2.0l Aircooled CI - 1982

peteinnit
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Re: Fuel Not Getting Through

Post by peteinnit »

So it looks like I won't be able to get a new relay before I go away, so temporary measure required. Am I right in thinking the relay is more a safety device in regulating the flow and cuting it off? In order to move it I'm thinking to bypass the relay and hook it up directly to the coil (or separate 12V), and obviously disconnect it at journey's end. I've left the 2 wires that I used to create the separate circuit attached, so I will just extend them to the coil, putting a fuse in the +ive one. Obviously not the desired method, but would I be mad to do this? I only need to do about 10 miles.
T25 2.0l Aircooled CI - 1982

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937carrera
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Re: Fuel Not Getting Through

Post by 937carrera »

Saab fuel pump relays are generally OK - it's the headlight ones that fail :D On the other hand Porsche 924 ones fail all the time

So, a relay is simply a switch, using a low current to switch a higher current. What you need to do is use a heavy gauge wire with a couple of spades on each end. Use those in replacement for the connection that the relay creates when the relay is engaged.
Take a look at these posts:

http://www.saabcentral.com/forums/showt ... p?t=414890 - original Saab wiring

http://forums.pelicanparts.com/porsche- ... ypass.html - Porsche wiring - ignore athe reference to terminal 87b, that was only used on later 924s.

The connection you need to create is the one between terminal 30 and terminal 87. The terminal references should be shown on the relay.

Use two runs of wire onto the spades if you don't have heavy enough gauge wire. The wire might get a bit warm. Be aware that this will be a permanent live, so the pump will run as soon as the ignition is switched on (or even as soon as the spades are inserted into the connections for the relay socket), it probably will not be fused and the pump will continue to run even if the engine is off.

Should get you there :) , don't have an accident :oops:

E D I T:

(what I suggested above is normally easier than running wires to the coil, but that will work as an alternative, fuse it as you suggest if you can and make sure the live will not chafe to earth on the journey)
1981 RHD 2.0 Aircooled Leisuredrive project, CU engine
1990 RHD 1.9 Auto Sleeper with DF/DG engine

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937carrera
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Re: Fuel Not Getting Through

Post by 937carrera »

Did you try ECP for a new relay ? https://www.eurocarparts.com/search/450880030 I think that's the right one - they have one in stock at Wembley who are open at 10 in the morning
1981 RHD 2.0 Aircooled Leisuredrive project, CU engine
1990 RHD 1.9 Auto Sleeper with DF/DG engine

peteinnit
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Re: Fuel Not Getting Through

Post by peteinnit »

Thanks for that explanation, very helpful. I did go to ECP in Enfield, but they couldn't match it. They sent me to a little independent who sent me to Neo Brothers in Waltham Cross who apparently will definitely have it, alas they're closed until the 2nd now. Knowing I can bypass it for a short journey gives me some peace of mind knowing I can at least move it to secure parking until I get back and can fix it properly if Neo's don't have one. Many thanks.
T25 2.0l Aircooled CI - 1982

peteinnit
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Re: Fuel Not Getting Through

Post by peteinnit »

I joined 30 and 87 as suggested, but it still didn't run the pump. My relay doesn't have the numbers marked on it, but I matched it with pictures online, so think I had the right terminals. It's got 5 pins which from online drawings are number as below:-

30 |

15 | 31 _ 31b |

87 _

Only way I can get it running is by connecting to separate 12V. If I can't get the new relay I'll use the separate 12V to get it to my parking space.

I did also try connecting to the coil, but it fried the cable! The pump has 2 terminals, I have one connected to the +ive and the other connected to the -ive and earth. With separate 12V this works, but when I connected the -ive/earth to the coil and switched on ignition, it fried the cable. so will stick with that as temp fix.
Last edited by peteinnit on 31 Dec 2017, 15:35, edited 1 time in total.
T25 2.0l Aircooled CI - 1982

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937carrera
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Re: Fuel Not Getting Through

Post by 937carrera »

Terminal 30 is live from battery, terminal 87 is feed to the pump.

Terminal 15 is the feed to the relay coil, with 31/31b being the earth route.

https://www.autoelectricsupplies.co.uk/ ... nal_coding

If jumping terminals 30 and 87 didn't get the pump to run then I suspect the problem lies in the wiring, rather than the relay.

On the assumption that you don't have a multimeter yet, you could use the test bulb method to

1. Confirm there is voltage at terminal 30 (which should be a direct feed from the battery, so permanently live, unless wired in a non standard way)
2. Assuming that is fine, disconnect the normal +ve connection from the pump, put the jumper wire across terminals 30 and 87, and then do the same to the loose wire at the fuel pump.

Remind us again where the fuse for the fuel pump is located in the circuit
1981 RHD 2.0 Aircooled Leisuredrive project, CU engine
1990 RHD 1.9 Auto Sleeper with DF/DG engine

peteinnit
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Re: Fuel Not Getting Through

Post by peteinnit »

The fuse is between the pump and the relay. On the original set up, there is only one cable going into the relay and one to earth. From the relay there is +ive, -ive and earth. I'm really short on time now, so I think I will use the separate 12V and sort it out when I get back.
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937carrera
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Re: Fuel Not Getting Through

Post by 937carrera »

OK, so it could also be a connection problem to the fuseholder or the fuse itself.

I think you know how you're going to move the van, but when you have moved it you're still going to need to find the original fault

Let us know how things work out :)
1981 RHD 2.0 Aircooled Leisuredrive project, CU engine
1990 RHD 1.9 Auto Sleeper with DF/DG engine

peteinnit
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Re: Fuel Not Getting Through

Post by peteinnit »

The fuse is good and I have tried a new one as well and fuse holder looks OK. It's all quite a small circuit so I think I will replace it all when I get back from my travels. I'm leaving the country for a few months and moving out of flat by 5th Jan, so it's been an added stress that I could've done without, but I will fix it properly when I get back. Thanks for all of your advice, it is much appreciated.
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Re: Fuel Not Getting Through

Post by Bowton Lad »

peteinnit wrote:I don't get any flow from gravity, even if I disconnect the hose to the tank!

I once had the problem where no fuel would come out of the tank when the fuel hose was disconnected. There is an internal strainer in the bottom corner of the fuel tank and this can become blocked with particles of rust/crud etc. I used a short length of new fuel hose connected to a 12 volt air compressor and blew air into the tank. It cleared the blockage. If you remove the fuel filler cap you should be able to hear the air blowing bubbles in the tank.
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