Hot Start problem on DGS here we go :(

[Dan6457]

Yesterday afternoon the car had been sat for about 24 hours, I pushed the flap and NO resistance whatsoever. The car started up perfectly. I went for a drive to warm it up, turned it off and pushed flap again. LOADS of resistance. Left the car sitting and tried flap again after 20 mins and pretty much all the resistance had worn off.

[NickT]

The car will have started up because you injected fuel into the cylinders by pressing the flap down.

Do the same test as before but press the flap fully down once.
Leave it for a couple of minutes then press down again.
Repeat.
There should be enough reserve in the accumulator to keep the resistance there.

The fuel pressure test will confirm if it is OK or a duff check valve/ o ring or whatever.

Note: as before when pressing the flap down will inject fuel into the bores. Do not try and start the engine after this particular test.

Have a look through an paperwork you have and see if the accumulator has been replaced.

Out of curiosity, when you first put the key into position 2, does the fuel pump run for 1 to 3 seconds to prime the fuel system?

NickT.

[Guinney1971]

NickT Wrote:

A Van Wrote:He likes his gravy too........

......especially on Chips !

Gravy on chips.......... wrong on so many levels!!

[Dan6457]

NickT Wrote:The car will have started up because you injected fuel into the cylinders by pressing the flap down.

It always starts perfectly when its completly cold without touching the flap

NickT Wrote:Do the same test as before but press the flap fully down once.
Leave it for a couple of minutes then press down again.
Repeat.
There should be enough reserve in the accumulator to keep the resistance there.

Thats basicly what I did, pressing the flap after it had been run there was resistance, then a short while later nearly all the resistance had worn off.

NickT Wrote:Out of curiosity, when you first put the key into position 2, does the fuel pump run for 1 to 3 seconds to prime the fuel system?

How loud should it be? I can't hear anything in the tank area from inside the car.... I do get a buzing noise from the engine compartment though in key position 2. Its not frequency valve becuase I don't have one.

[NickT]

The sound should be from the fuel pump and is located at the front of the car.

Open bonnet and remove the spare wheel.
You should be able to hear the pump run.
Get a friend to move the key to position 2 and listen for the fuel pump running.

Sounds like the best thing forward is to do the fuel pressure test.

Try and find out the last time the accumulator was changed if you can.

NickT.

[bozzzydmc]

The workshop manual states the minimum rest pressure in the fuel system should be 1.7 Bar after 10 mins, as Nick says a fuel pressure test will see if this is so.

After doing the same thing on my car a few weeks ago , mine was still 2.5 bar after an hour.

[Dan6457]

I'll check the pump this afternoon when I'm back home. Fingers crossed thats ok. Then I think i'll leave it until eurotec for some proper tests Doing the pressure tests will also prove if my metering head has been shimmed or not.

[bozzzydmc]

My primary pump pressure is around 5.3 bar on a standard metering head / pump ( manual states max 5.5 bar ) hence I didnt bother 'reshiming' it . Be interesting to see what yours is running at on a 'stage 1'

[Dan6457]

Apparantly it should be the same pressure. The only reason it might have been re-shimed was to make it run without changing the metering flap to the matching volvo one. I now have the volvo one to fit, so it will need shimming back to standard again possibly. :wink:

[bozzzydmc]

What exhaust system have you got on your car Dan?

[Dan6457]

Just a standard one with no cat :?

[Darren C]

Hi Dan,

Sounds as if the accumulator is ok, but you wont know 100% until you do the pressure test. You may have a dodgy Fuel pump relay, and just experienced an intermittent fault the other day.

Just a thought.

Best Regards
D

[bozzzydmc]

I have a couple of spare new fuel pump relays, might be worth swapping it with yours temporarily just so you can hear / see the difference with the pump priming. The 555 timer chips can start to go baps up after a few years

[steve.s]

Hi

my car has had similar things happening since i had it.

had a new pump, filter, pickup system. new plugs, airfilter, rotor arm, squirted injectors into glass jars, new cs valve, new warm up regulator. New accumulator.

and still it sometimes fails when warm.

now i did change the coil and seemed to get better, but then back to its old self.

then last week went for a beer with Phil and Rob, and Phil did say with his LHD, had running problems then he dremmel cleaned all the leads to/from the coil.

so Saturday backed mine out and warmed up while i bled all the brakes.

then would not hot start.

so took the leads off the coil, WD40'd them plugged back in and she fired up!.

so now i will fully clean or replace them.

have you tried cleaning these. initially the fault on mine i thought was fuel related, but i don't think this is always the case.

just thought its worth a try as its a free fix!

[Dan6457]

I had a good listen yesterday and I can't hear the fuel pump prime at all...

Also i tracked down the buzzing noise in the back and its the cold start valve, I assume thats normal to make a buzz when the engines cold?