DIY Fuel pressure test gauge

nicci21paul said

nicci21paul said

nicci21paul said

nicci21paul said

gregpank said

Good news is all the parts turned up and have assembled the kit.

Bad news is i cant separate these two parts on the metering head. Im just double checking this in fact two parts and not one?

Two parts just had one to bits today must try harder

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End result absolutely mint dx in a stunning rivage

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Mark Dempseys rivage

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That is Mark in the picture not myself

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When you can help out hands on puts the smile on a members face and your own self satisfaction

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Thanks chaps. will exert more ‘persuasion’ on the  14mm spanners tomorrow after leaving wd40 on it overnight.
Nice looking motor there!


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WD40 is a rubbish penetrating oil, try Plusgas

PlusGas Formula A Dismantling Lubricant 400ml - Screwfix

A great thing to use for penetrating oil is a 50/50 mix of Acetone/Automatic Transmission Fluid.

Ok Golf Pros(!) so finally got that apart and connected up my new homemade pressure test kit. It all fits!
Here’s what happened…
1. As before had to jump the pump, lift the metering plate to get fuel to the injectors for 20/30 seconds, then she eventually started.
(Its 26 degrees in the garage today at 4.13pm ).
[Also worth noting i have a TSR modified 1.6EG bored out to 1680cc so sometimes the manual figures are a bit off for me…]
Cold start is connected as is WUR electrical plug.
2. On cold start got 4.65bar, idle 1100rpm, tap open
3. Turned the tap off - no difference[!?]. Still 4.65bar. Reopened tap.
4. Let it run for 10mins, still 4.65b
5. Turned it off, pressure fell to 2.6b
6. Waited 30 secs, started up again first time, 4.65b
7. Switched it off. After 10mins - 1.3b
8. Switched it on, 4.65b but now idle is 1500rpm.
Couple of revs, dropped to 1400, couple of minutes later, couple more revs and dropped to 1300.

What do you think?…

I'll reply properly tomorrow but pressure checks should be done with engine off but pump running. Pull the plug for the WUR to test cold pressure first. Do you have a Haynes or Bentley manual for the procedure?

Thanks [mention]paceman [/mention]   I’ll try again tomorrow with pump, no ignition. Yes have Haynes and also the 7 page pdf with tests from one of the resources you mentioned. Will read through more carefully and try again tomorrow/weekend. Thanks again mate for any further advice


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Did a cold start, pump only, no ignition: 4.65b.
Pump off: drops to 2.6b immediately
After 10mins: 1.0b


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Any thoughts [mention]paceman [/mention] [mention]nicci21paul [/mention] . I know its a lovely sunny weekend so expect you’re out in your lovely Cabrios …

Cabriolet?! Wash your mouth out
Been busy making a parcel shelf and prepping for my retro modern DIY audio install!
Will update build thread when it's done…
Anyway, cold pressure with the plug disconnected from wur should bei 1.35 to 1.65 bar. Engine should be stone cold.
Plug the WUR back in and run the engine (or put 12v to the WUR (I have 2 lengths of wire with crocodile clips on to do this). You should see the pressure climb until it levels off after a couple of minutes. At this point pressure should be 3.65 to 3.75 bar. As your engine has been modified you probably want the lower value. Turn the pump off and it should hold at about 1.9 bar for 10 mins, and after another 10 1.5 bar. This is basically your residual pressure. No residual pressure can give hot start problems.
Final test with pump running, engine off is system pressure, shut the tap off and you should get 4.5 to 5.1 bar. This proves the pump is doing what it should.
Hope that helps!

Haha well Im with you on the tintop Vs cabrio debate .
I’ll try those various tests.
And in the meantime, you may find this short video of mine interesting. It’s quite short but I was pleased!

Mk1 Golf GTi DIY Rear Parcel Shelf with speakers for less than £150! - YouTube


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Can i check a couple of things please [mention]paceman [/mention] ?

1. Right, let me just confirm the final pump test first: With pump running, engine off i get 4.65 bar. So am pretty sure my new pump is fine.

2. Back to the first test you specified: You said
“cold pressure with WUR plug disconnnected should be 1.3 to 1.65 bar. Engine should be stone cold”.
How do i conduct this ‘cold pressure’ test? The car is completely cold now (hasn’t been started for days and the pressure guage reads zero (with either the tap open or closed).
Do you mean:
 start her up
 with pressure guage tap open from stone cold
 and 1.3 to 1.65 should be the initial reading before she warms up?.

3. This leaves what i’m assuming is the ‘warm pressure test’, which is as above but reconnect the WUR (still tap open) to hopefully get 3.6 to 3.7

4. And finally is the residual pressure test which is checking it twice, 10 mins apart each time. Think i’m clear on that one.

Just points 2 and 3 i need confirming. Ive looked in Haynes and i think thats it, but wanted to check please mate.

Tbh with the checks ive done, (even if a bit wrong), all i seem to get is full pressure of 4.65. Which make me suspect my WUR is faulty.
Im guessing that would explain my cold start issue as the system pressure is so high its preventing the air sensor plate from lifting and therefore no fuel is being sent to the injectors. If i’ve understood the system correctly…

2. Ok, had a re-read of Haynes and worked out how to do the cold pressure test. So, cold engine, wur unplugged, preesure went immediately to system level of 4.65.
3. Did the warm pressure test too, but with wur plugged in - but same result

Residual pressure also dropped too quickly but think thats for later…

So do we think its a duff WUR and if so best place to get a refurb kit?

You certainly shouldn't see system pressure being the same as control pressure. That system pressure does seem to be on the lower end.
Anyway, I have bought wur and fuel distributor refurb kits from this chap on ebay - https://www.ebay.co.uk/str/missingpartsde
Good chap, decent instructions.
I'd suggest it is worth stripping the wur and giving it a thorough clean out.

Have been liaising with missing.parts for a WIR rebuild kit and turns out my (modified) engine has a 85> Scirocco KR 16v WUR. No idea why as engine was this way when I bought it. Some kind of upgrade?


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Ilkley that's got a vacuum port on it. This allows enrichment at wide open throttle (WOT). At WOT the vacuum drops which allows the WUR control pressure to drop giving a richer mixture. I put one on mine (it's got a mild cam and ported head etc). I set mine up without worrying about the vacuum (although it is connected) as I didnt have any info to guide me otherwise. I have read stuff since but haven't got round to re doing it.

Yeah after posting I googled and saw that it seemed like a popular mod back in the day! Have you got a picture of it connected to the vacuum system? Any guide how to set it up?

FYI the WUR rebuild Kit from Germany for this later Model is almost triple the cost.
Ah well, still a cheap repair at £90!
Thanks as ever for all the knowledge sharing [mention]paceman [/mention]


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Have a look at the basic wur setup doc on here - Rebuild manuals – K-Jet Specialists
There are also instructions for rebuilding the double diaphram wur (which is what you have). The instructions you get a very detailed, but an alternate version can't hurt.
Before you completely strip your WUR I'd check to see if the vac diaphram is ok. You should not be able to suck any air through the side outlet. If you can, you'll need to do the full rebuild. If you can't then I wouldn't separate the diaphram part of the wur, just remove the larger top half.
I'll get some pics of how mine is connected.

When it comes to setting up your WUR, I didn't have those instructions that ref setting it up with vac, so I still have to come back round to look at that, but my warm and cold control pressures are good.
As you have to set warm first, I removed the bimetallic strip entirely, put the WUR back together and set the warm pressure. Put it all back in, and then set the cold pressure. Bit of a faff, but I couldn't adjust one without it impacting the other until I did that.

Update: Received the rebuild kit for it (turns out i have an upgraded WUR from a Scirocco mk2 (KR).
Worked my way through it using the instructions supplied rather than the one you mentioned in post #38.
Reconnected it to the pressure guage with the following results:
Cold start: 2.4 bar - this seems high as think it should be about 2.0
Warm start: 3.4 - ok i think
System pressure: 4.6 - ok i think
Residual pressure after 10 mins off: 1.0 - way too low
After 20mins: 0.5 - way too low

Overall good news in that she starts and runs which is great!
Cold start is a bit low but hopefully tolerable.
Residual pressure is way too low so going to tighten up the fittings (could here one hissing slightly) and hope that sorts it…