Hesitation - Anyone in Bris with a spare fuel pump?

Hi guys,

My hesitation issue has returned.

I will try to describe whats happening.

When accelerating you get to any revs from 2k rpm to 5k rpm and the car acts like its been shut off. If you keep your foot down the revs drop to about 1.5k and then it tries to rev up again. Get to any point in the 2k -5k range and do the same thing.

The hesitation is severe, literally feels like the car has been turned off and you jerk forward. Idles perfect and if you drive in light throttle you can drive around ok. I have noticed that if you put the clutch in and keep your foot down while it is hesitating it makes no difference until the revs drop down and rise again. If you keep your foot on the clutch it will rev right out to the red line. If not it splutters and the revs drops.

Now how we got here.....

My original hesitation was all down to rust in the fuel tank that killed the old pump. Put another secondhand pump and then got a new fuel tank. Problem solved Since then I have replaced the PTU with a series 2 and the car has been running great for the last 4 months. The other week I drove 200km and in the last 5 kms the car started to hesitate. I drove the last part on part throttle and got home fine. Drove the car next day and it was fine.

Now at the weekend I drove 60km to the Gold Coast and a similar thing happened on the return leg. Drove part throttle and got home fine up until yesterday....... drove to work and after 10km the car hesitated and drove really bad.

Today car is hesitating even from the get go....grrrrrrrrrr

Each time the car started playing up I pulled over turned the car off wiggled all the connections on the injectors/coilpacks and re-sat the plugs on the PTU. Each time I did this the car would run fine for about 2 mins. Rev fine, pull hard etc.

Well the wiggle trick is not helping at all now so I assume its either really bad or nothing to do with my issue.

I checked the PTU for continuity on the injectors and they are all fine. Checked all the injector plugs and they are clean and sat properly. (seems the wiggle trick was just coincidence)

I have gone through all the other connectors and check them.

I have today noticed the fuel pump is really noisy..... Really only noticed it on the way home and now its wining really loud, you can hear it change pitch if you touch the throttle.

So after all this I think the new (secondhand) fuel pump is giving up.

I was wondering if anyone had any other idea's to check? or

If anyone in Brisbane has a spare fuel pump that I could try just in case this isn't the issue.

Cheers

Beavis

 

id say fuel pump is on it last legs
you did change all the fuel fillters and dampner may also be sus from rubbish from old fuel tank
sounds like a lack of fuel .

 

Still sounds like fuel starvation

got to eliminate the basic culprits, starting with a NEW fuel pump. Even your originally "known working" 2nd hand fuel pump is going to be circa 20 years old by now and like many electrical items, they are failing.

I'd be getting a new fuel pump and fuel filter and get the fuel lines blown out with a high pressure airgun to be sure there are no blockages. from there you can start with the basic engine-related hesitation issues but you need to have the core basics of fuel delivery sorted.

 

you can borrow my fuel pressure gauge if need to Chris. do tha tbeofre fiddling with anything under the bonnet. then you will know tis a fuel delivery issue and work back from there

 

I have a fuel pump from Aus spec N/A

 

Cheers for the input guys.

Thanks Naill I'll pop over soon and get the pressure tested.

I'm sure these cars are here to test out patience

BEavis

 

Mike has a spare Z in his garage

 

Sorry haven't replied. Going to be doing some troubleshooting this weekend.

Beavis

 

Fuel Pump sounding odd - Video

Right just did a FPCU Bypass and my pump got really really noisy.

I know this is normal for it to increase in volume but mine didn't make a steady noise.

Basically it sounds a bit ill.

I have attached a video, you might have to turn it up to hear the pump. This is my bypassing the FPCU.

http://www.youtube.com/watch?v=4CsUBpIrIJI

Any thoughts?

Will be getting the fuel system pressure tested later today but I think it might be the fuel pump.

 

Just for giggles loosen your fuel cap.

 

Just undid the cap and there was some pressure, just like when you have an empty tank and you fill up at the pump. Drove it for 5 mins. (still hesitating and noisy pump) and there was pressure again ?????

Is this normal for the tank to be pressurised so soon?

Beavis

 

is the carbon canister fitted? if connected wrong that could be the cause of pressurising. sorry i missed your call the other day, do u want to grab that fuel gauge?

 

There should be no or very little pressure really it should vent, do you have an oem fuel cap ?

 

My understanding is excess pressure vents outwards to the carbon canister, and negative pressure is adjusted through the cap.

Someone sucked a tank inside out a while back.

After a reasonable drive as fuel is used and air is not allowed back in, it could make a pump work quiet hard and burn it out I would imagine.

Something to consider, check your cap as below, or just leave it loose.

If it is the cause, your pump could be toast still and loosening the cap may not fix the problem.

EDIT: Looking at the very bottom diagram, it seems that air can come back from your canister as well.

 

Hi Naill, No worries about missing the call.

I would come and get the gauge but I don't think the car will make it there, It wont rev over 2k and thats makes driving through town a bit of a pain.

Also I haven;t installed the carbon canister back in yet. The car is currently running without a carbon canister, the pips haven't been blocked just left to vent to air at the moment. Only think blocked is the vacuum line from the engine bay to the Carbon canister.

Does the vacuum line for the carbon canister have anything to do with the fuel check valve?

I think my tank is pressurising quote a lot.

Where is the fuel check valve located?

Beavis

 

Yep got the OEM Nissan cap

Beavis

 

Just thinking about the fuel pressure issue. I have noticed that the car makes a funny noise on start up.

When you start the car something vibrates behind the passenger seat. It sounds similar to if the exhaust rattled against the car for a split second.

Could this be the fuel check valve not opening and thus pressurising the tank.....

And then the pressurising leading to the fuel pump dying.......

Does anyone know where the fuel check valve is?

Beavis

 

Correction it must be up under neath the rear not far from the tank, in fast anyway, little different 2+2 to 2 seater.

There is a short set of hardlines that are connected to the fuel tank by some short hoses, the other end of those hardlines somewhere.