VW Polo 1994 issue, after help please

[Anglevan]

My lad has a 1994 VW Polo 1.3. He's had it a couple of years now and it's done 40k ish. It's been pretty reliable but in the last 6 months it's been randomly cutting out. There is no pattern to it, in the time he's had it I had to replace the fuel tank and recently swapped the spurious fuel pump for a second hand VW one. I thought I'd fixed it as for a couple of weeks no issues but it's started again. Problem is when ever I drive it its fine but I've never had the opportunity to do long test drives.

Basically when it cuts out, if you leave it 5 to 20 mins it will restart and it's fine again. No pattern if tank full or empty (not hissing when you remove fuel cap)

It does have an Autojack immobiliser and wonder if that's the issue but that cuts the starter out or does anyone know if they cut more than one circuit?

 

Any other ideas?

[michael1703]

Fuel pump relay?

[DS20]

Fuel pump relay, if it's not been done with the replacement pump?

[Anglevan]

No didn't replace the relay, is this in main fuse box ?

[DS20]

I think it's below and to the right of the steering wheel on these cars, behind the little driver's side glovebox (if fitted). At least it was on my mate's 1997 1.4

[Anglevan]

I'll give it a go and report back. Ta

[nisfan]

Is it a 90-94 or 94 onwards polo? If its an earlier one its in the scuttle under the plastic tray

[the judge]

Ignition modules on these can go on these in the same manner when i was a mechanic many moons ago

[Melchior]

Maybe you don't even have to replace the relay - just check the connections are free from rust/corrision.  Rub them over with wire wool or similar and see if that helps - do the same for the fuel pump fuse too (probably worth doing on all fuses and relays, since it costs nothing and doesn't take long)

[Billy SR]

my mums 96' polo had this problem, we never did manage to get to the bottom of it!

[Anglevan]

It's a 94 mk2f coupe. I've spoke to a few people I know but no definate cause. So plan is to just check connections/ fuse box / relays etc. I have a spare ecu but can't remember if it was off a 1.0 or 1.3. I think it's going to be just one of those problems !

[DS20]

As it's a coupe, ignore what I said about location of relays - sorry 

[derskine]

Fuel pump relay is on the passengers bulkhead tray, it's attached to the fuse box as I recall from the 1L I had.

If it just stops dead then it's likely to be something to do with that immobiliser I reckon as I've never had any issues that completely stopped the car, any sensor faults and it usually still runs just badly.

[Vince70]

I had the same problem with a Golf I had and it cost me a kings ransom to get to the bottom of it.

 

I had a new fuel pump and a fuel filler neck plus the tank was cleaned out and when that didn't work I had a complete fuse box swapped over then the garage decided it must be the immobiliser so I also had that removed plus a new battery fitted just for good measure.

 

It still was the same after blowing about £600 on the car only for my dads mate to have a quick look over it and 10 minutes later to discover It had a kinked fuel line as it got damaged from driving over a Steep hump getting on and off my drive.

[Anglevan]

That's interesting Vince? As I did replace the tank some time ago as original was leaking. I wonder if I'd trapped a pipe. The last time it stalled was about 800 yards from a very busy roundabout so wonder if he floored it from the roundabout and it just starved itself of fuel. Doesn't explain why it takes 10 minutes to restart.

[derskine]

Can you try taking the fuel pipe off the throttlebody when it cuts out, put it into a jar, and turn the key to the first position so that it primes? It will at least tell you if it's a fuel delivery problem.

[plasticvandan]

im assuming both the electric pump in the tank and the mechanical pump are working?

[derskine]

No mechanical pump on a facelift polo but good point there is an electric lift pump in the tank as well as the electric external pump.

It's not unknown for them to run without one of them though, I've ran mine on just the external pump, but still worth a check maybe.

[plasticvandan]

my mistake,i knew there was two pumps on them,ive just got the mechanical one on my mk2.

[derskine]

The lift pump in the tank potentially does more work than the external one on a single point injection car like this one, so it is worth checking.

If you lift the rear seat base you'll see a black plate, unscrew that and the lift pump is under it, you'll be able to feel if it's running or not.

 

When it next cuts out quickly remove air filter pan, by removing the top plate and then unscrewing the 3 nuts, which will reveal the injector/throttlebody.

Remove the banjo bolt for the fuel inlet, there will be a < cast into the injection housing, and put it into a jar, turn ignition to first position and look for fuel in the jar.

 

The fuel pump relay is an ordinary 4 pin relay, so you could get one from Maplin and fit it.

[4wheeledstool]

Sounds as though the coil is on its way out chief.

[plasticvandan]

a friend of mine with a 2f had a lot of random cutting out and lumpy running issues,it was the coil as well.