Hot start/running problems

[maff 10]

Recently took ownership of an old corrado vr6 that has been stood for 3 years in underground storage, before i sold the car it had all blue black and yellow temps

sensors changed, new lambda.

Now after fresh fuel the car will start but when water temp gets to 80 degrees the engine wants to die and reluctant to rev like its flooding almost, also won’t start again when warm

 

My mechanic friend who has the car has suggested fuel pump and crank sensor as the culprits but as always don’t really want to waste money replacing good parts. If i were to replace the crank sensor what’s a good one to use now?

 

Also thought blue temp sensor but that was replaced less then 1000 miles ago? but has been sitting so may have corroded up?

 

Thanks in advance

[fendervg 30]

Get hold VCDS and diagnostic cable and check for any fault codes. Some possible things to look out for are:

- Crank sensor on it's way out

- Cam sensor/hall sender depending on if you have a coil pack/distributor

- Fuel pressure regulator

- Blue temp sender

 

Fuel pressure can be easily checked by hooking up a gauge to the injector rail. As it's temperature related, it could also be caused by a vac hose or an electrical connector expanding with the heat and leaking or losing contact. The ECU should switch to the normal map at 80C so it could be that it's not getting the correct reading to allow it to do that - diagnostics will help with trying to figure that out.

[maff 10]

Thanks for info, we installed a pressure gauge on the fuel rail and when the engine is at operating temp the pressure drops so have ordered a whole complete fuel pump inside the tank, the swirl pot and the pump as all the seals were shot on the old unit, i’m praying this fixes it..

We tried an old crank sensor from a golf vr6 which didn’t make a difference, plus it had new blue, black and yellow senders under 1000 miles ago but it has been sitting for a few years in underground storage.

 

Will update when the pumps fitted, heater matrix is going in today as well, pig of a job

Edited January 18, 2019 by maff

[seanl82 23]

Hope it sorts it for you. Out of interest, where did you get the fuel pump and parts from?

[maff 10]

My mechanic pal has an account with bromsgrove motor factors which are a sister company to gsf so it came from there, £90

[seanl82 23]

Thanks mate. :thumbleft:

[maff 10]

Thanks mate. :thumbleft:

 

They actually sent the wrong one and in the end it was £71.

 

Plus.. it lives! The fuel pump solved the problem and now it's so smooth to rev but not driven the car yet.

Pressure gauge on fuel line shows 3.5 bar at idle and 4 when revved with no dropping, really can't wait for a drive

[seanl82 23]

Glad you've got it sorted! My gauge drops when climbing (or descending, I can't remember it's been so long since I've driven it!), so thinking of replacing it at some point as I think the mounts have gone. I need to open it up to inspect really, but need some nice big oil filter pliers or something to undo the top nut as it's stuck fast!

[maff 10]

Can’t be a bad thing to replace, my car had done near 200,000 miles, enginerrbuilt though, so the pump was never going to be strong. Just think of the extra ponies it should help replace

[seanl82 23]

Well it produced 195.9 bhp, 196 lb ft torque on the RR at stealth (a couple of years ago but only about 1k miles ago) so don't think it's struggling to get fuel. Always worth having one at the ready for £70 though!

[robrado974 1]

I thought The Bosch pump was £58.00 or around that price Sean ?. I’ve been looking into getting one as well .

[seanl82 23]

Even better Rob! I don't really know how they're made up but I think the in tank unit is made up of a few parts from what I remember. The pump itself sits in a housing which is mounted on rubber feet from what I remember. I've heard that these break down so the pump rolls around a bit which has caused cutting out issues when cornering for some. I need to investigate a bit more to see what is going on. My tank isn't connected but I strapped it back on to the underside for transportation when I moved house. We will be finished with the house renovation by Summer so I can put some time into the poor girl then!

[_Matt_ 26]

Maff - great you got your car sorted. I was having some warm start issues but installed a one way valve near the pump, renewed the pump relay and installed a new fuel filler cap (just because mine was manky and it was £8quid) and it's fixed for now.

 

Anyone got part numbers or links for these pump though? I thought VR pumps were uber expensive (£350+ ) and hard to source. What's the difference betweens ones sold in a case and others that look like they are without a case?

 

Thanks,

Matt

[maff 10]

The fuel pump is in two parts, the swirl pot and float for level sensor and top cap, the fuel pump then slides into the top of the unit which then fits into and up stems in the bottom of the tank.

So if your seeing a fuel pump for 30-£50 then it’s just fuel pump itself, i bought the complete unit as when we removed it from the tank all the seals were perished.

 

I’ve got videos of the pressure gauge teed into the fuel feed line which clearly shows how bad pressure was on the old pump dropping to 0.5 bar when revved and then when the new pump installed at idle sits at 3.5 bar and when revved increases to near 4 bar.

 

Ill try to post up pics and part numbers when i can if anyone needs them.

I got the complete unit from gsf in the end for £71 whereas others were coming in at £250-180, £130 etc, pays to shop around!

 

Going for a spin in the car tonight, can’t wait.

[_Matt_ 26]

Thanks Maff for the info - it’s cleared it up a treat for me! Enjoy the spin :)

[fendervg 30]

There are early and late type pump units (Pierburg vs VDO)as well and you may need to change the fuel gauges sender assembly when swapping over. And watch out for fuel pump units for 2.8 VR6 engines like in the Golf, which are rated at 3 bar whereas the Corrado unit is 4 bar.

[robrado974 1]

Even better Rob! I don't really know how they're made up but I think the in tank unit is made up of a few parts from what I remember. The pump itself sits in a housing which is mounted on rubber feet from what I remember. I've heard that these break down so the pump rolls around a bit which has caused cutting out issues when cornering for some. I need to investigate a bit more to see what is going on. My tank isn't connected but I strapped it back on to the underside for transportation when I moved house. We will be finished with the house renovation by Summer so I can put some time into the poor girl then!

This could be what’s wrong with mine Sean . It does happen on corners. I’m going through a non interest stage at the moment. I’m doing bits but when I feel like it . Maybe it’s the weather lol .

[fendervg 30]

The 3 bar pumps from the Golf VR seem to be a lot cheaper and more available - I often wonder if it would be possible to run a 3 bar one on a 2.9 ABV engine instead of the 4 bar one, and would you need to change the FPR to 3 bar to match as well? It's kind of tempting because I can buy a complete Pierburg OE fuel delivery unit with cap and sender unit for the same price as just a 4 bar pump unit.

[seanl82 23]

I reckon you probably could. The amount of 2.8 lumps with all ancilliaries including FPR that were originally attached to a 2.9 are plentiful, and although its the other way around there have never been reports of any issues. I've seen plenty of 2.9 lumps in Golf VRs as well and don't think any of that has been changed. They see it as a bit of an upgrade, although the inlet manifold will be just as effective as the entire engine with regard to power!

[_Matt_ 26]

How come VW went to the effort to stick a different fuelling system in the Corrado? Was it to do with the schrick inlet (read they might have been built stock with them at one point).

[maff 10]

Test drive went ok, but annoyingly stalled a few times coming to junctions and oil temp warmed up before water which is weird. idled nice when warm though.

Power was strong, especially low down.

Pal who did the work just returned a storm to a customer and he says it pulls harder than it.

 

It hasn’t been run in 4 years so probably needs a good run and maybe i’ll have a look at the isvs for cleaning?

 

It has a k&n filter on there at the mo which is very dirty so not sure whether to fit a bmc or something else

[fendervg 30]

The stalling at junctions could be a dirty throttle body or a vacuum leak.

 

For the air filter, the stock air box with a paper filter is plenty good enough unless you want more noise - none of the other options give a proven performance gain, except maybe for the BMC CDA, where the jury is still out.

[Jim Bowen 1]

Oil should warm up before the coolant imo as the coolant should be cooling the oil, if the coolant was hotter than the oil i'd be worried.

 

Have you tried fuel pump relay, i used to have stalling and hot start issues until i changed mine. quite cheap and easy,. maybe worth a try

[maff 10]

Will try the relay thanks.

 

My m3 coolant warms up to 80 degrees in probably 2-3 miles and the oil can take up to 10 miles to get to 80-90 degrees.

I had the csl warm up lights on a previous car which took ages to go out so got to know when it was save to open her up, i always thought coolant warms up before the engine oil?

 

The coolant temps are good on the dash on the vr, heaters are not super warm so might bleed the coolant again, plus it’s pushing a bit of coolant out of the expansion tank and a new cap solved it last time so i’ll check the cap again

Edited January 24, 2019 by maff

[maff 10]

Cheers fendervg, i had a bmc on the last car and it sounded great, a bit boomy low down but love the look of them under the hood so might get another