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Cold Start Engine Prob

Andyn

By Andyn,
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Andyn Community Regular

Andyn

Posted
Posted

I hear this is a common problem but every morning if i try to start the car it chokes and won't start (even after waiting for the fuel pump to kick in for a bit).

To get it start i have to give it some revs as Im starting the car. Then it start fine. The car drives beautifully ones it starts. This start issue only happens when its cold. After its started for the day, i can turn it on normally after that (while its warmish).

Anyone know a solution to this?

Andy

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RCEBNR Rising Star

RCEBNR

Posted
Posted

i had a reco'd unit installed by the repco service centre near my work for 360odd with a 12 month warranty. my car has always had cold starty probs and ive put it down to the fact (what the previous owner told me) the car having a bigger afm (from an rb25 i think)... new alternator has fixed all my probs with start ups

nismoskyline32 Collaborator

nismoskyline32

Posted
Posted
nismoskyline32: Did it fix the problem after your replaced the fuel pump?

no man...it happen after i put a new fuel pump. someone said there is not enough fuel go to the engine and someone said losing pressure because there is no :P "chiiiiiiiiiiiiii" when i open the fuel cap

  • 4 weeks later...
Andyn Community Regular

Andyn

Posted
  • Author
Posted (edited)

Just an update with this issue. Still have not gotten to the bottom of it.

I have searched in these forums and tried two culprits of idling issues - I have cleaned the AFM and the AAC valve (and reset the ecu). I have noticed improvement of the responsiveness of the car, however it hasn't fixed my original issue, as above.

Two things that I have noticed which may or may not be related to my issue. When the car is idling, if I use both the window electrics simultaneously the revs drop, until i stop using them. (Alternator issue?)

Also my boost controller, reads 760mmhg, when i start the car. After driving around (not up/down a mountain) it drops down to 580mmhg. I don't remember it dropping down. It used to always stay 760. Not sure if the hotter weather may affect this.

As I said, not sure if these two things relate to my original problem. Can someone confirm if any of these two things happens to them, or whether it is actually 'normal'. Im keen to get to the bottom of this. Been bugging me for a while now.

Any comments are most welcome.

Edited by Andyn
blind_elk Grand Master

blind_elk

Posted
Posted
...Also my boost controller, reads 760mmhg, when i start the car. After driving around (not up/down a mountain) it drops down to 580mmhg. I don't remember it dropping down. It used to always stay 760. ...
760mm Hg is "atmospheric" pressure - ie, what we are all currently exposed to. Engines get air and fuel into the cylinders by creating a vacuum - something less than 760 mmHg.

If your gauge didn't show less than 760 while the engine was running, I'd be worried.

Back to your original problem - have you had the injectors cleaned recently. Also, check the Cold Start Air valve is operating correctly. And check the water temp sender is functioning correctly.

MBS206 Grand Master

MBS206

Posted
Posted

760mmHg is more vacuum then 580mmHg, you may have extra electrical loads on the motor (Fan etc) hence, the ECU adds up slight revs, and the vacuum drops (As if the throttle is opened) after sitting for a while, does the vacuum go down again?

I've been told it's vacuum leaks, (As my car also does it) and the needing to pump the throttle is to get the air to go through the AFM, instead of the leak.

Andyn Community Regular

Andyn

Posted
  • Author
Posted
760mmHg is more vacuum then 580mmHg, you may have extra electrical loads on the motor (Fan etc) hence, the ECU adds up slight revs, and the vacuum drops (As if the throttle is opened) after sitting for a while, does the vacuum go down again?

I've been told it's vacuum leaks, (As my car also does it) and the needing to pump the throttle is to get the air to go through the AFM, instead of the leak.

Yeh after sitting a while the vacuum does go down (after driving around today it got to 590mmhg). Might have to get some 'startyabastard' and see if i there is a leak somewhere.

760mm Hg is "atmospheric" pressure - ie, what we are all currently exposed to. Engines get air and fuel into the cylinders by creating a vacuum - something less than 760 mmHg.

If your gauge didn't show less than 760 while the engine was running, I'd be worried.

Back to your original problem - have you had the injectors cleaned recently. Also, check the Cold Start Air valve is operating correctly. And check the water temp sender is functioning correctly.

THe gauge shows 760 for a while, when the car is started and still after 10 mins of driving around. (old avcr boost controller). After a bit of driving then it starts decreasing. No i did speak with a mechanic about the injectors (may get them done down the track). Also how would one go about testing the cold start valve & watr temp sender? Do u need any special tools?

-----------------------------------------

insu Rising Star

insu

Posted
Posted
Yeh after sitting a while the vacuum does go down (after driving around today it got to 590mmhg). Might have to get some 'startyabastard' and see if i there is a leak somewhere.

THe gauge shows 760 for a while, when the car is started and still after 10 mins of driving around. (old avcr boost controller). After a bit of driving then it starts decreasing. No i did speak with a mechanic about the injectors (may get them done down the track). Also how would one go about testing the cold start valve & watr temp sender? Do u need any special tools?

-----------------------------------------

Easiest way to test your water temp sensor is if you have access to consult or someone who does. If you don't you can read the resistance across the sensor and again as the temperature goes up, then check these values against normal operating values. Shouldn't be too hard to find that info on the site here.

GTS4-32 Rising Star

GTS4-32

Posted
Posted (edited)

I also have the same problem with cold starts, but mine tends to need abit of gas even when warm to start her up nice. But really struggles when cold.

My fuel pump has definatley got something to do with it.

Probebly sound stupid but i was just wondering if there was some special way of removing the fuel pump myself without damaging anything, to check for any blockages, posibly give it a clean or something. Would be helpful having a look at it before getting it changed. btw its a aftermarket fuel pump (bosch)

Not much knowledge with these littel things.

So any helpfull tips would be great and anything i should be aware of?

Edited by RB26DETT_GODZILLA
SKY031 Grand Master

SKY031

Posted
Posted
no man...it happen after i put a new fuel pump. someone said there is not enough fuel go to the engine and someone said losing pressure because there is no :laugh: "chiiiiiiiiiiiiii" when i open the fuel cap

Dunno how different the RB's are in regards to fuel pumps/starting issues, but here's a couple of things I've learned about fuel pumps and starting issues with the RB30.

You need to make sure there is a good seal when replacing the internal pump.

Stick the rubber seal in the freezer for a while before replacing it. (the cold helps it to shrink a bit, to ensure a snug seal)

I had a cold start issue that went on for months.

Replaced so many parts it was ridiculous.

Once it had started it was OK, and it was fine on warm starts.

It cranked fine, the fuel pump made a pumping noise, so we put it down to something electrical.

All the usual culprits were checked and/or replaced, afm, cas, aac, fuel pump, fuel lines, injectors, plugs etc.

There was also an intermittent fuel smell.

One day while trying to start it, fuel could be smelled.

Nismo R31 Jet (from this forum) happened to be with me at the time, and he said "try pulling the fuel pump fuse"

We pulled the fuse, and the car started.

It seemed that it had somehow flooded.... something that an EFI motor shouldn't really do... :laugh:

Driving home one day, I again noticed that I could smell strong fuel fumes.

The car started idling like a tractor, and I had great plumes of white smoke coming out the exhaust.

I chewed through more than $20 of petrol over a distance of less than 1km.

After months of frustration and trial and error, it turned out that the problem was a broken diaphragm inside the fuel pressure regulator, which had been slowly getting worse.

It's amazing how something so little can cause so many headaches. :woot:

20/25/26 are probably totally different with their bits, but I thought I'd share my nightmare, in case it can help someone out. :wub:

WazR32GTSt Grand Master

WazR32GTSt

Posted
Posted

have had this issue for 4 years

tried changing almost every sensor on the car, and itsrunning an aftermarket fuel pump that made no difference

if anyone find anything real, not just "i suspect that its my fuel pump" without any evidence, please help us all out...

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