Fuel starvation?

[HazzaBridges]

New poster! (less than 10 posts)

Hi all,

I've recently put a c1j in a 5 campus and I am having trouble with it running wise.
The car will start and tick over lovely for about 30 seconds and then will suddenly start hunting and cut out within a matter of seconds. Afr gauge is fluctuating between 12-13 until it starts leaning off and shoots up to 17-18. Also it will pull away and boost in 1st no problem but as soon as you let off boost it cuts out, and if you put it into second, as soon as you touch the throttle it leans off and hunts then cuts out :confused: any ideas? All help or suggestions will be greatly appreciated!

Cheers

[GTphil]

Welcome to RTOC :agree:

Sounds like either an air leak or your idle jet needs a good old clean up.

Start with the easy things first, The idle jet is the large brass screw on the side of the carb, remove this and give it a good clean out with carb/brake cleaner. You may have to do this a few times.

For air leaks you want to spray some easy start around the inlet manifold around the base of the carb, if this improves things you will have an air leak. Check all the vacume hoses for splits also.:agree:

[Matt Cole]

Check the accelerator pump jet arm. It should move when you depress the throttle.

[HazzaBridges]

New poster! (less than 10 posts)

Thank you for the prompt replies!

I will clean the idle jet up tonight after work and try the easy start around the carb and get back to you with the result on that!

And with the accelerator pump jet, what do you mean by it should move? It squirts fuel as I move the throttle but can't see it moving? Sorry if I'm being a tool but I've not had much experience with carbs! :scared:

[tiff_lee]

Hang on is there two separate problems here? You say it is struggling to idle but then you go on to say it cuts out when shifting up into second?

I would sort one issue (i.e the idling) before going on to the next.

Does it run fine for about 30 seconds everytime prior to the hunting and cutout? Personally I wouldn't of thought it was an airleak as that would be present from the get go and would consistently cause hunting rather than waiting 30 odd seconds to have an impact.

[Brigsy]

What fuel pump are you using. Are you using the gtt pump and fuel pressure regulator?

[HazzaBridges]

New poster! (less than 10 posts)


Hang on is there two separate problems here? You say it is struggling to idle but then you go on to say it cuts out when shifting up into second?

I would sort one issue (i.e the idling) before going on to the next.

Does it run fine for about 30 seconds everytime prior to the hunting and cutout? Personally I wouldn't of thought it was an airleak as that would be present from the get go and would consistently cause hunting rather than waiting 30 odd seconds to have an impact.

Hi mate if I'm being honest I thought it would of been the same thing but now you've said that it could quite possibly be seperate issues.

With the idling it's the same every time where it will idle nicely for about 30 seconds and starts hunting and cutting out.

If I put it straight into 1st and pull away it's fine and will boost no problem but as soon i let off the throttle it cuts out.
If I pull away in 1st and shift into second it will hunt and cut out :confused:

Sorry it this isn't making much sense!

[HazzaBridges]

What fuel pump are you using. Are you using the gtt pump and fuel pressure regulator?

Hi mate it's a gt turbo fuel pump and fpr, they were both being used with the engine on the car it was previously in :(

[tiff_lee]

Only reason I asked was you were describing two separate issues yet they mau have one root cause so best to do one thing at a time rather than a shotgun approach as you'll never know what sorted it.

Can you confirm fuel pump is still running once you have started the car? sounds like it is sucking the float bowl dry.

[HazzaBridges]

Yeh can understand that mate!

I beleive it is as it will cruise along in first at low revs (it will eventually lean off and cut out) but can keep her running longer his way

[Brigsy]

Assuming its all plumbed in properly, i would try another fuel pump and see if that makes any difference. Change fuel filter if it hasnt been done already.

[HazzaBridges]

Took the top of the carb off tonight and cleaned accelerator jet again thoroughly and also cleaned idle jet a few times through out the course of the evening neither of which having any effect on the issues I have. I sprayed a generous amount of easy start around the carb when it was running, this also had no effect on it!
I will be putting a new fuel filter on it this weekend and a fuel pump as soon as I can fund one but until then hopefully I find it's something else.

Another thing that I noticed tonight was when it cuts out after boosting or shifting up, I have no dash lights for about 5-10 seconds then it wil all suddenly come back, does this make a difference to what it could be?

Thanks for the help/suggestions so far it's greatly appreciated!

[tiff_lee]

Personally i'd just sort out the idling problem first and go from there.

I would let idle for the 30 odd seconds until it cuts out then whip the top off the carb and see how much fuel if any is in the float bowl. If it is cutting out consistently within the same time frame either your ignition is on a timer and cuts out ..... or that's how long it is taking to use all the fuel up

[HazzaBridges]

Personally i'd just sort out the idling problem first and go from there.

I would let idle for the 30 odd seconds until it cuts out then whip the top off the carb and see how much fuel if any is in the float bowl. If it is cutting out consistently within the same time frame either your ignition is on a timer and cuts out ..... or that's how long it is taking to use all the fuel up

Ok mate I will give that a go :) if it is draining the float bowl would that most likely be a fuel pump?

[tiff_lee]

Well if their is no fuel in there that would suggest the fuel pump isn't running but then saying that the easiest thing to do is start the car let it idle and pop your head under the rear end and see, that's the only way I can see why it would consistently cut out after 30 secs.

Yeah it's probably easier to double check the pump is actually running first while the car is idling.

[Ian S]

Does it have the fuel pump module / relay fitted?

The might fill the float chamber then switch off the pump if it doesn't detect a tacho signal, or something?

[tiff_lee]

Does it have the fuel pump module / relay fitted?

The might fill the float chamber then switch off the pump if it doesn't detect a tacho signal, or something?

That is what i'm thinking, the pump runs while cranking (ignition at starting position) but once back to the 'on' position it no longer runs and the car then supps all the fuel which was just pumped

[HazzaBridges]

I'm going to have a play with it tonight to see of I can hear fuel Pump running and take carb top Off after it's cut out and il let you know my findings!

[HazzaBridges]

Turns out there isn't a fuel module/ relay? Or not one I can find anyway! And exactly as said the fuel Pump was priming then not running. Done a quick temporary job of fitting a switch from the battery to the fuel pump so it's either on or off and it runs sweet as a nut :D so I think I will do a proper job of fitting a switch and run it that way!
Big thank you to everyone that got involved with this wouldn't be sorted with out your help!! :agree: :D

[B18ftMOJO5]

Great news. Good to hear you got it sorted.:agree:

[tiff_lee]

Can you confirm fuel pump is still running once you have started the car? sounds like it is sucking the float bowl dry.
Boom !

Glad you got it sorted mate, just to be sure to wire it up in an appropriate manner (either OE method or your own way) and not just via off a on/off switch