1HZ Turbo - sputters/stall after idle for long period (1 Viewer)

[Hzj73tn]

Hey guys, hoping someone can help diagnose an issue I have intermittently.

1990 HZJ73 JDM - Safari Turbo kit

After idling for long periods or low RPM driving it will sputter and run poorly for a mile or so, then smooth again and no issues. Occasionally it will also start to sputter around 3k in 3rd gear only. 255k km, new fuel filter. Runs perfect aside from that happening occasionally, mostly after idling for several minutes.

 

[roscoFJ73]

Have you checked for air getting into the fuel lines? Do you have much fuel coming out of the return line? Is your fuel system modified with low micron filters etc? Any smoke, colour?

 

[Hzj73tn]

Have you checked for air getting into the fuel lines? Do you have much fuel coming out of the return line? Is your fuel system modified with low micron filters etc? Any smoke, colour?

Fuel system is all factory, with OEM Toyota fuel filter. No smoke aside from some white smoke under acceleration when cold. What would be the best method to check for air getting into lines? I can check for fuel coming from return. It does seem to happen more when fuel is around 1/4 of a tank.

I am trying to pay attention for details when this is happening because it does not happen regularly and is very intermittent.

 

[roscoFJ73]

I would temporarily put a length of clear plastic line between the fuel filter and injection pump and watch for air bubbles.

If its not air then it will be fuel starvation from an obstruction around the fuel pick up or something inside the pump.
Is your injection pump making any noise?
At 250klms+ fuel injection pumps on 1HZ etc are on borrowed time, although many can go to 300000klms and beyond.

One way of isolating the problem is to rig up another fuel supply in the engine bay, 4-5 litres is about right. Then see if it will happen with the alternative fuel supply.

 

[Hzj73tn]

I would temporarily put a length of clear plastic line between the fuel filter and injection pump and watch for air bubbles.

If its not air then it will be fuel starvation from an obstruction around the fuel pick up or something inside the pump.
Is your injection pump making any noise?
At 250klms+ fuel injection pumps on 1HZ etc are on borrowed time, although many can go to 300000klms and beyond.

One way of isolating the problem is to rig up another fuel supply in the engine bay, 4-5 litres is about right. Then see if it will happen with the alternative fuel supply.

Ok, I will give that a try! Thank you for the help!

I am not sure if the pump has been serviced previously, but was leaking pretty bad when I got it. I removed it and replaced the seals on it. It doesn't make any noise.

I deleted the ACSD on it also hoping that's what was causing the leak before I replaced seals.

 

[mudgudgeon]

I agree with Rosco

Definitely sounds like air getting in to the fuel.
Typical culprit is a perished diaphragm in the primer pump, but can also be from a split or loose fuel hose, a loose fuel filter, or damaged oring on the fuel filter

Clear hose from the fuel filter to injection pump can show the problem.
Clear hose from before the filter to the injection pump can tell you if it's the filter assembly

 

[Hzj73tn]

So, just an update. I was looking at my feed lines from the filter to the pump. There is slight cracking around edges. Could this be allowing air in? I put clamps on the ends as opposed to the factory squeeze type clamps and it seems to have improved.

I purchased some fuel injection hose and plan on replacing everything rubber between filter and pump. Anything particular to bleed the air out afterwards?

When I resealed my pump I just turned the engine over until it fired to push air out.

Is there any other pump on the vehicle to push fuel from tank to pump or is the IP the only fuel pumping device on the truck?

Thanks guys!

 

[mongoose2231]

Is your vehicle equipped with a priming pump? I am not familiar with the HZ engine but it's pretty darn close to the 2H I'd say..

 

[mudgudgeon]

IP is the only pump to deliver fuel.

Prime the lines with the hand pump on the filter assembly.

Should only take 10 to 20 pumps.
Maybe more if the entire fuel line has been drained.

And yes, a cracked hose can be enough to let air get sucked in without any visible fuel leak.

 

[Hzj73tn]

Thanks for the help guys! going to replace the lines between filter and pump. hoping that fixes it. It has been running much better since changing the clamps alone.

 

[roscoFJ73]

Stop hoping and isolate the problem the first time. A little video of mine with some clear hose beteen the filter and injection pump. Led me to find it was the fuel filter letting air in.
As the engine slows down I have to pump the primer to get the fuel volume in the injection pump high enough to keep it feeding fuel into the high pressure side.

 

[Hzj73tn]

Stop hoping and isolate the problem the first time. A little video of mine with some clear hose beteen the filter and injection pump. Led me to find it was the fuel filter letting air in.
As the engine slows down I have to pump the primer to get the fuel volume in the injection pump high enough to keep it feeding fuel into the high pressure side.