Rb20det Starting Issues

[niclol]

Hi all

I'm having an issue with my silver top RB20 intermittently not starting properly. If I turn the car on and it's dead cold it starts but if I turn it off straight away and try to start it again it sometimes wont start or even sound like it's close to starting. For it to start again it needs to left for several hours it seems.

The car has been sitting for the last 6 months however prior to that I've had no trouble with it starting in my 5 years of ownership.

At one point when it wasn't starting it ran out of fuel I think (dodgy fuel gauge) as the pump started making a loud noise. I've since filled it up so the fuel in it should all be fresh.

I also had an issue with the car running badly above 2000 rpm and swapped to a new AFM however this hasn't changed the starting issue at all.

If anyone has any suggestions that would be great as I'm at a real loss at what to do

[Sinista32]

Battery

& Fouled spark plugs

Test fuel pump

Edited February 3, 2015 by Sinista32

[Dose Pipe Sutututu]

When this happens, try and unplug your water temp sensor on the coolant neck. It's the 2x wire one that goes to the ECU, see if that helps or unplug the AFM

It could be when your car is warm/warmer the cranking enrichment isn't enough to get the motor going.. it could be a mixture of things, dirty/faulty AFM, faulty FPR, dirty injectors, etc.

[niclol]

Changed the spark plugs today, while the car seems to run smoother now it didn't change the starting issue

I tired unplugging the wire on the coolant neck while it wasn't starting but that didn't make a difference.

I should mention that I've been turning the car on for max 30 seconds before turning it off and trying to start it so I don't think the problem is really heat related. That said if you leave it for a few hours and come back it will start first time.

How would a go about testing the fuel pump? And could that cause an issue with just start up?

[Dose Pipe Sutututu]

Changed the spark plugs today, while the car seems to run smoother now it didn't change the starting issue

I tired unplugging the wire on the coolant neck while it wasn't starting but that didn't make a difference.

I should mention that I've been turning the car on for max 30 seconds before turning it off and trying to start it so I don't think the problem is really heat related. That said if you leave it for a few hours and come back it will start first time.

How would a go about testing the fuel pump? And could that cause an issue with just start up?

did you disconnect the coolant sensor for the ECU or the one for the dash? the ECU one has 2-wires not 1...

[niclol]

I disconnected the one with 2 wires coming out of it

[Dose Pipe Sutututu]

(not sure how related this is to you but here goes)

do you have access to a wideband o2?

back in the days when I knew nothing about cars (10+ yrs ago).. I had the same issue with my RB20DET, a mate that was doing engineering at uni suggested I hooked up his wideband. Ended up finding out the car was running lean in general when it was in vacuum, turned out my injectors were all clogged.

As soon as got all the injectors serviced, new o-rings put in the car started easily and idle was back to stoich.

[jiffo]

Probably a combination of clogged fuel filter and worn fuel pump.

Pump will be running at low voltage under start conditions, may not be sufficient to pump fuel through the blocked filter?

[niclol]

That's kinda of what I've been thinking.

Would the only filters be the the one in the engine bay and the sock on the end of the fuel pump? This is in an aus spec R31

[niclol]

Changed the filter in the engine bay but starting problem is still there

[Sinista32]

Humour me a little and just try a mates battery

Don't use a jump pack or try jump it off another car

Connect direct to terminals

Ps. Every time you try to start it and it doesn't start your plugs get a bit dirtier and eventually fouled again.

Edited February 6, 2015 by Sinista32

[niclol]

Ok I'll swap battery tomorrow and see what happens.

[niclol]

Just tried a battery out of a car that gets driven every day, had slightly higher cca as well. Result was still the same though.

While it wasn't starting I also took the line off the fuel filter and primed the car and tons of fuel came out. I don't know know if that tells me if the pump is working fine though.

[Sinista32]

Ignitor

coil pack loom

are you getting spark to each cylinder ?

[jmknights93]

Are you only having this problem when it's dead cold? for example after it's sat overnight?

It may also be worth checking your AAC Valve. Give that a clean also.

Edited February 12, 2015 by jmknights93

[niclol]

Just to let everyone know the issue has been fixed. The problem was a fault in the wiring that was causing the voltage to drop to 6 volts, or some such thing. The wiring issue was a result of the way the conversion was done and can't occur in a standard R32.