Engine seems to be starving for fuel under load

[robmacca]

Gents....

Just recently I've started to notice my D22 ZD30 seem to "miss" or be starving for fuel under acceleration. I did have a 2nd Fuel FIlter and thought that might be the issue but I've since bypassed it so I still have the main Fuel Filter & its still doing it. The Car Idles fine and u can rev it standing and no worries. It just seems like its struggling for fuel as it gives a stutter under acceleration. The fuel tank is not empty but will top it up tomorrow is see if that's changes anything. Driving normally its ok, just when u are under heavy acceleration.

It's got 160k on the clock, It also has a Intercooler/catch can/ EGR blanked, etc. Been fine & has never had played up b4.....


Any ideas ???

 

[tweak'e]

gearbox neutral switch?
otherwise replace fuel filter.
check for air in fuel lines.

bypass the chip.

 

[Old.Tony]

As above. Air is a prime candidate, as is a blocked filter - both will affect how much fuel can be drawn through, and at high acceleration loads you're looking at the peak of the pump's performance.

Forget EGR at that point, it wouldn't be active even if it were unblocked. The catch can has nothing much to do with combustion.

A partially crushed fuel line will do it (flow restriction) - that's happened to another user here who had a LR tank fitted. Foaming fuel will also do it when the tank nears empty, as well as debris in the tank blocking the pickup.

 

[robmacca]

As above. Air is a prime candidate, as is a blocked filter - both will affect how much fuel can be drawn through, and at high acceleration loads you're looking at the peak of the pump's performance.

Forget EGR at that point, it wouldn't be active even if it were unblocked. The catch can has nothing much to do with combustion.

A partially crushed fuel line will do it (flow restriction) - that's happened to another user here who had a LR tank fitted. Foaming fuel will also do it when the tank nears empty, as well as debris in the tank blocking the pickup.

I've got a LR tank as well, but it's never caused an issue b4. The AUX Fuel Filter I thought would be the cause as I did find a partially crushed Fuel line to the AUX Filter. I've since bypassed that today putting it back to stock. I don't believe the OEM Fuel Filter would be blocked as the 10micron AUX Filter would have filtered out any crap, etc b4 it reached the OEM Filter.

The Neutral Switch.... That's something that I didn't think of.... What sort of Symptoms does a Faulty Neutral Switch produce? Can this Neutral Switch be bypassed or just unplugged to determine if it is the cause or not ??

The LR Tank has probably only got a 1/4 tank of fuel in it currently but again, I've had it a lot lower than that b4 w/o any issues...... I will fill up the tank tomorrow to see if that clears the problem.... but I doubt it. I don't believe it would be a sensor at all as I believe u would feel it all through the rev ranges and therefore I can't really see it being the Ditronic Chip either as it's been in since I've owned the car w/o causing any troubles....

I don't know any thing about the Neutral Switch & what it does.... but if its not that, I can only assume it's either Fuel &/or Air..... I can't see any air leaks of fuel leaks in the fuel system but I was wondering if others can tell me if the Fuel Primer on top of the Fule Filter on their cars is easy to prime one or 2 pumps b4 it gets hard to push down while the engine is running ??

any advice or comments much appreciated

 

[Farmer Joe]

I had the same problem a couple of weeks ago and yes it was the NPS. I disconnected this and the problem is fixed. fj

 

[robmacca]

I had the same problem a couple of weeks ago and yes it was the NPS. I disconnected this and the problem is fixed. fj

Cool... I hope that's all it is.... How can I identify where its located and which plug I can unplug to remove the Neutral Switch to find if it solves my issue?

 

[Farmer Joe]

There is four switches on the gearbox, the nps is the hardest [of course] one to get at on top of the gearbox. I have a pit, so I did it from underneath, but other people on here say they pull the rubber boot off the gearstick and do from the top. your choice!
fj

 

[robmacca]

There is four switches on the gearbox, the nps is the hardest [of course] one to get at on top of the gearbox. I have a pit, so I did it from underneath, but other people on here say they pull the rubber boot off the gearstick and do from the top. your choice!
fj

Thanks for that..... I replaced the Reversing Switch some months ago and I assume the NPS is the next one back from that one..... Well, that's what the manual is showing me at least.... It's not quite on top of the box but the plug is easy to get to as least.
I've disconnected the plug to the Switch that I'm assuming is the NPS and I went for a little drive around the block until the engine warmed up..... No signs of it missing or struggling for fuel.... but I guess I will find out for sure when I go to work tonight

So if that's it, then u guys have saved me a few $$ then from having to take it to a mechanic who probably would have spent hours trying to find it & would have changed everything else w/o actually resolving it.... BIG THANKS to you all for your helpful advice

I'm getting it ready to sell soon as I no longer need a ute & plan on going back to a 4WD wagon of some sort......Last thing I wanted to was to have spend a lot of $$ in chasing faults, problems, etc as the vehicle has been trouble free for since owning it.

BTW: What does the NPS do ??? Any issues with leaving it disconnected ???

 

[Rumpig]

The" heat switch" (high idle) won't work with it unplugged, otherwise it does bugger all.

 

[robmacca]

The" heat switch" (high idle) won't work with it unplugged, otherwise it does bugger all.

Yeah, I tried the Heat switch and it didn't idle up lie it use to(which I was expecting), but the revs did go up a small amount though which surprised me as I wasn't expecting any rev change.... then it got me thinking if I got the right switch plug.... but I'm sure I've got the right one though after checking

 

[Farmer Joe]

Yeah, I tried the Heat switch and it didn't idle up lie it use to(which I was expecting), but the revs did go up a small amount though which surprised me as I wasn't expecting any rev change.... then it got me thinking if I got the right switch plug.... but I'm sure I've got the right one though after checking

Yes mine does rev slightly higher with the switch on, but not 1200rpm like it used to when switch was connected.
fj

 

[smithbro]

My truck had this exact problem for months, got a bit better after running some diesel additive, then got much worse in recent weeks. I couldn't get the truck above 100kph without constant hesitations.

Change your standard fuel filter. The one I pulled out didn't seem too gunked up, but it fixed this problem 100%.

 

[jjohn]

Fuel algae will block the filter easily.
If you storing fuel in cans that may have condensation it will grow.

 

[smithbro]

Fuel algae will block the filter easily.
If you storing fuel in cans that may have condensation it will grow.

Yeah I'm not sure as to whether or not my tank has algae in it. This is the additive I used, which made the problem go away for a few weeks;

http://www.supercheapauto.com.au/on...-Fuel-Conditioner-275mL.aspx?pid=120027#Cross

Will be doing another shock treatment of this with my next tank of diesel.

 

[joffo81]

I had a similar issue a couple of months ago and a fresh fuel filter did the trick for me. Good luck!

 

[robmacca]

Guys..... Certainly not a fuel algae issue due to regular fuel filling + I run 2 fuel filters inline. I originally thought it was a squash fuel line but the issue was still there when I took out the 2nd Filter...

The problem/issue came down to being the Neutral Position Switch (NPS) and since I've disconnected the NPS switch, the car has run beautifully w/o any issues at all.....

My truck had this exact problem for months, got a bit better after running some diesel additive, then got much worse in recent weeks. I couldn't get the truck above 100kph without constant hesitations.

Change your standard fuel filter. The one I pulled out didn't seem too gunked up, but it fixed this problem 100%.

Fuel algae will block the filter easily.
If you storing fuel in cans that may have condensation it will grow.

Yeah I'm not sure as to whether or not my tank has algae in it. This is the additive I used, which made the problem go away for a few weeks;

http://www.supercheapauto.com.au/on...-Fuel-Conditioner-275mL.aspx?pid=120027#Cross

Will be doing another shock treatment of this with my next tank of diesel.

 

[jjohn]

Awesome

 

[smithbro]

Good to hear. I did try disconnecting the NPS to fix mine. Obviously not the same issue.

 

[robmacca]

Good to hear. I did try disconnecting the NPS to fix mine. Obviously not the same issue.

Did u disconnect the right one ??? Once u disconnect it, turn on the switch inside the Cab to see if the Revs increase....Revs should only vary a small amount?