1HDT Surging

I am not a mechanic so I can't help you if you did it yourself but if not then go back to who did it and get them to fix it.

Phil

I would tend to think that it may be a pump issue, I know they are different but the 1HZ surges when the pump isn't right.

Hi Micheal , i had the same issue when i fitted the 1hdft to my 105 series ,strange how it occurred after fitment . In my case it was the fuel tank vent in the cap that was blocked starving it from air. I would think the diesel shop who rebuild the pump would honour there workmanship and correct your fault

I tried removing the fuel cap few days ago and still the same issue, Engine was rebuilt by the old man and I, pump was sent to perth to be rebuild(Got a few prices in Darwin and they were real rich around the 4.5k mark for a rebuild).
Tried running fuel lines to a independant fuel supply(aka coke bottle) and drove with the same issues.
Even going up through gears from 1-5 you get around 2.5-3.0+ you feel it pull back.

Michael - Surging in a diesel engine is generally caused by air in the fuel, or by fuel starvation.
Air can get into the fuel on the suction side of the pump via old, cracked hoses, loose connections, pinholes in steel lines caused by rust, and via old hardened or cracked seals on filters.

Crack a fuel injector line at the injector when the engine is idling, by slackening the nut just enough so that fuel leaks out.
If there's air getting in the fuel, bubbles should be visible.

However, if the leak is tiny, and only affecting the engine at highway RPM's, air may not be visible in the cracked fuel injector line at idle.
Alternatively, it could be a governor problem. But - if the pump has been overhauled properly, there should be no problem with the governor.

The other potential problem area of fuel starvation can be caused by a fuel line blockage - or the suction screen in the fuel tank could be blocked.

Visit your local fuel injection specialist, and they will soon put you right.

Cheers, Ron.

You say the problem is more noticeable around/above 90kph.
This indicates the turbo is in boost mode, I would be looking at the wastegate diaphragm and mechanism, injection pump boost diaphragm (aneroid) and the piping in between.
mike

hi Michael W21
just because the filters have only done 1000 km's doesn't mean they are not partially blocked (have you bought fuel since the filters were changed or are you still using the fuel you had in the tank/s before the repairs) and starving the engine of fuel to me the symptoms indicate lack of fuel or air in the system changing the fuel filters is an easy option and bleeding all the injectors at idle... are you sure one of the fuel filter seals isn't letting air in at road speed doesn't take much to cause surging
some filter bodies have square profile seals and others have round orings if the square profile type aren't seated correctly and are twisted they will let air through cheers
barry

G'day,
When I had my 100 series, it did start to have these symptoms. The fuel filter was replaced, but the surging still carried on. When I swapped tanks, however, the surging vanished. On investigation, I discovered that the installer of my long range tank had put an in-line filter in the fuel line from the long range tank. When I removed it, the surging disappeared.

When these 1HDT Toyotas first came onto the market they had a issue with surging on some vehicles there was a mod bought out by denso and toyota to solve the problem if you contact your local denso diesel injection dealer they should be able to help you ,there was a major dealer in each state doing the mod,there is a toyota bulletin on it, the problem is that after a pump is overhauled it can become a issue through no fault of the diesel injector repairer i am involved the pump repair industry and it was a huge issue