Engine surge

[Wayne Smithlily]

Hi again. I have a question about engine surge on the Izusu NPR400 Winnebago. Have replaced thre injectors and it is still happening. thinking it might be  the diesel pressure relief valve failing?  Engine drops to zero accelerator and idle when hot and loaded.

 

[John Canfield]

Welcome Wayne. What year and model of the RV?

 

[Gary RV_Wizard]

Curious that you replaced only 3 injectors on a 4 cylinder engine? Are you sure the 4th isn't the cause?

Can you describe the "surge" further? To me, surge means a brief increase in rpms.  Are you saying the throttle drops to zero under load? Intermittent or every time? Does it drop and recover, or just stay there.

 

[Bobtop46]

Curious that you replaced only 3 injectors on a 4 cylinder engine? Are you sure the 4th isn't the cause?

Can you describe the "surge" further? To me, surge means a brief increase in rpms.  Are you saying the throttle drops to zero under load? Intermittent or every time? Does it drop and recover, or just stay there.

Gary I believe this might be a fat finger situation and that the OP meant "the" vice "thre."  The keys are side by side.

 

[Wayne Smithlily]

Hello. The bus is a 2007 Izusu NPR400. I replaced all 4 injectors and today replaced the rail pressure return valve. Bus still died on the first hill. There were lots if surges, by that I mean loss of power then picks up, until it shut down and I had accelerator to 1225 revs but mo more with engine warning light on. I disconnected the diesel chip and after engine cooled was able to druve. Will take to mechanic tommorrow and replace the suction control  solenoid and pray!! Any one with similar problems?

 

[John Canfield]

Wayne - we need the make and model of your RV. Is this a Winnebago product?

 

[Matt_C]

Wayne,

That engine should have an OBDII data port.  You can either connect a code reader and see if the engine thinks it has a complaint, or get a hold of an active reader that will display many of the inputs and outputs in real time.  That should help.

Matt

 

[ChasA]

I think Wayne is in Australia. Google found some ads for it. It looks like it was a Lance TC sitting on an Isuzu chassis and it bore the Winnebago badge.

 

[Wayne Smithlily]

Gidday. Yes I am in Australia. The bus is a B class motorhome built by winnebago in Emu Plains, Sydney in 2007 before they became Avida. The Winnebago sits on an Izusu NPR400 truck chassis. I have had computor check and it is a fuel fault. I have replaced the injectors and the fuel pressure return valve and tommorrow will replace the suction control solenoid. Fuel filters replaced but mechanic noted some soot in the fuel rail. Bus constantly loses power particularly under load, like hills, and eventually drops to idle with accelerator only to 1250 revs with engine light on. After being off for an hour or two, engine warning light goes off and I can continue driving until it starts all over again. Pretty annoying. Any ideas?? Cheers. Wayne

 

[John Canfield]

Ah, Wayne is down under  ) . I've watched an an Aussie electronics engineering vlog (EEVBlog) for a few years and have picked up some of the 'lingo' as we call it.

I don't have much in the way of advice for you, I do have a few diesels around the ranch and my last sailboat had a 4 cylinder diesel for auxiliary power. That one was very simple and easy to diagnose. Having said that...

All a diesel needs to run is air and fuel but there's all of the electronic monitoring now and fuel pressures have dramatically increased to reduce emissions.

Does that engine have a turbo? Were the injectors you used brand new? Have you had the injection pump evaluated? As routine maintenance item I had my boat's injection pump inspected and rebuilt.

Maybe find an Isuzu forum for more specific advice? Those diesels are extremely popular world-wide.

 

[Gary RV_Wizard]

Winnebago Australia is a totally different company than Winnebago in the USA.  Not even a subsidiary.  Rather than continue court battles with Winnebago USA over use of the name, the Australian company is changing its product brand name to Avida.

 

[Neal]

When you say, fails under load, it brings to mind a car we had, acting similar. Turned out to be trash in fuel tank. Every time it bogged down, we would pull over and kill the engine. Restart and might run fine for a while, even under load.