1HD-T Fuel Pump Cold start

[robbed666]

Hi All,
I have an 80 with a 4.2 1HD-T engine. The idle speed when hot is too high. I've traced the fault to what appears to be the cold start solenoid. This is connected to the engine water cooling system. It has a piston that pushes against spring and lever that moves the injector pump arm to increase the idle speed/and injection, when the engine is cold. The trouble is, mine doesn't change positon when hot, ie the piston should extend ?. Has any one know of this problem?, or experienced the same?

Thanks

Rob

 

[jcolvin]

Mine is the same. Seems a very common problem with the 1HD-T. You can adjust the idle with the set screw, but this seems a bit hit and miss since the gizmo also adjusts fuel pump timing. By the way, it is not a solenoid but a wax gizmo, AKA "thermo wax", aka ACSD (automatic cold start device, I presume).

I'm looing into getting a replacement, about $300 I think. Then adjusting the timing seems a pain in the donkey, at least judging by the manual.

Jonathan Colvin

1990 HDJ81

 

[hdj105]

I'm not sure how important or signifcant the timing advance is when cold, but I've heard a diesel shop here in Aus say when people baulk at the price of a new unit, he also offers them the blanking plate to allow it all to be removed.

If the truck is running fine when hot (i.e. the timing appears to be right) just adjust the hot idle to be correct and see how it starts in the cold. You could always use the hand throttle to bump the idle when cold.

 

[Kalawang]

Hi All,
I have an 80 with a 4.2 1HD-T engine. The idle speed when hot is too high. I've traced the fault to what appears to be the cold start solenoid. This is connected to the engine water cooling system. It has a piston that pushes against spring and lever that moves the injector pump arm to increase the idle speed/and injection, when the engine is cold. The trouble is, mine doesn't change positon when hot, ie the piston should extend ?. Has any one know of this problem?, or experienced the same?

Thanks

Rob

What kind of rpm's are we looking at as too high ?


Kalawang

 

[roscoFJ73]

I'm not sure how important or signifcant the timing advance is when cold, but I've heard a diesel shop here in Aus say when people baulk at the price of a new unit, he also offers them the blanking plate to allow it all to be removed.

If the truck is running fine when hot (i.e. the timing appears to be right) just adjust the hot idle to be correct and see how it starts in the cold. You could always use the hand throttle to bump the idle when cold.

I got told the same thing. Its only there as an emissions requirement.
It advances the pump timing whle the engine is cold.
Use the blanking plate off a 1HZ.
When these lever mechanisms get some wear on them they begin to rattle and if ignored can break off inside the injector pump with catastrophic consequences

 

[jcolvin]

Use the blanking plate? Great idea! Ok, I'm calling ENS today and getting one!

I use the hand throttle anyway when its cold.

Jonathan Colvin

1990 HDJ81 Galiano Island

 

[Tapage]

anyone know if I ( by myself ) can adjust the idle in my 1HD-T .. ? seems to low at hot with tranny in D position.

 

[jcolvin]

As per the repair manual you want around 800 rpm at idle for an auto, 700 for a manual. You can adjust this with a set screw on the lever that presses against the cold start device (the gizmo on the side of the fuel pump that has a little plunger coming out of it). There are two set screws on mine, the one against the plunger sets timing (and idle), the other sets idle. You want to adjust the uppermost set screw.

I personally have set my idle lower, around 700 rpm for my auto, since this gives me less engine-creep in D and makes braking to a stop easier. I dont notice any vibration when stopped in D at this setting.

Jonathan Colvin, Galiano Island
1990 HDJ-81