12HT cold start issue

[roma042987]

jimmy i agree with the others from that last video it sure sounds like it's wanting to start but the shutter is killing the engine.

 

[Mr Cimarron]

When I was at the barn on Sunday we pulled the intake horn and confirmed the butterfly was open. So that takes that out of the mix. It did start with foot on accelerator.

 

[ceylonfj40nut]

The 2H engine injection pump works off vacuum. Not sure if 12HT does. Might wanna look see if vac is impacting this.

 

[12HTHJ47]

View attachment 1869164 I’m trav

traveling for work but plan to test this when I get back. Early on before I wired in the VSV I ran an open system. Just used a vac line from the butterfly and one from the alternator and kept them in the cab. Touched them together to shut down. So the other morning I’m pretty sure I unplug the vac line from the diaphragm controlling the butterfly and there was no change in starting. Will confirm with another test. Here’s a pic of my original shut down system (a bit ghetto). Still thinking of adding a vacuum lever/dial type switch inside my cab and deleting the VSV. I had a similar situation last summer doing 75MPH way out in West TX and the motor shut down. By the time I coasted to a stop it dawned on me the VSV had to be the culprit.

What did you end up finding to be the problem with your cold starts?

 

[CenTXFJ60]

What did you end up finding to be the problem with your cold starts?

Man that’s a good question. Really just figured out I can hold the throttle on the floor when I hit the key and it comes to life. Smokes a lot at first but clears out pretty quickly.

 

[12HTHJ47]

Man that’s a good question. Really just figured out I can hold the throttle on the floor when I hit the key and it comes to life. Smokes a lot at first but clears out pretty quickly.

Mine literally does the exact same thing. I’m thinking I have issues with vacuum. My idle up doesn’t kick in until it’s started and been running for 5-10 seconds, also takes a couple of seconds to turn off when I turn the key off sometimes

 

[CenTXFJ60]

Mine literally does the exact same thing. I’m thinking I have issues with vacuum. My idle up doesn’t kick in until it’s started and been running for 5-10 seconds, also takes a couple of seconds to turn off when I turn the key off sometimes

Have you tested your vsv shutdown switch. As you mentioned above that’s where I was having issues and it would shut down on me periodically when I was driving. I’m running a 12v system as mine is a conversion. This is why I went to a vacuum switch on the dash.

 

[12HTHJ47]

Have you tested your vsv shutdown switch. As you mentioned above that’s where I was having issues and it would shut down on me periodically when I was driving. I’m running a 12v system as mine is a conversion. This is why I went to a vacuum switch on the dash.

Yeah I replaced the switch last week and it’s still doing the same thing, I’m leaning more towards the old hoses being an issue. I’m going to replace all of them and if that doesn’t solve the issue then I’ll be looking at the vacuum temperature switch, the one on the side of the engine with 2 vacuum hoses on it.

I’ve recently had the injectors rebuilt but haven’t checked timing on the pump. Potentially the pump might be slightly retarded and where I live now is much colder than where the vehicle was originally from.

A few things to look at anyway as usual.

 

[CenTXFJ60]

Yeah I replaced the switch last week and it’s still doing the same thing, I’m leaning more towards the old hoses being an issue. I’m going to replace all of them and if that doesn’t solve the issue then I’ll be looking at the vacuum temperature switch, the one on the side of the engine with 2 vacuum hoses on it.

I’ve recently had the injectors rebuilt but haven’t checked timing on the pump. Potentially the pump might be slightly retarded and where I live now is much colder than where the vehicle was originally from.

A few things to look at anyway as usual.

Ah yes. I know the temp switch you’re talking about. My 12HT was a test motor so it was actually never in a vehicle before I picked it up 8-10 years ago. It does not have that sensor on the side. Thinking about it now…that could part of my issue. That and the fact I don’t have the heaters hooked up on the intake

 

[12HTHJ47]

Ah yes. I know the temp switch you’re talking about. My 12HT was a test motor so it was actually never in a vehicle before I picked it up 8-10 years ago. It does not have that sensor on the side. Thinking about it now…that could part of my issue. That and the fact I don’t have the heaters hooked up on the intakeView attachment 3064802

Yeah I’ve been told that the 12HT does require the extra bit of throttle on a cold start. We get well below 0 degrees where I am and it definitely needs the extra help. Warmer months it starts no issue

 

[drenmaster]

@CenTXFJ60

 

[fitzmooney]

I have a vacuum gauge on my HJ60 and I know the condition of my system all the time. No guessing.

 

[12HTHJ47]

Have you tried advancing the pump? Apparently that helps but I haven’t tried it on mIne yet

 

[relaxedcruiser]

Sorry, I haven't read through the whole thread - but have you tried to disconnect the vacuum lines at the shut off butterfly and making sure it's actually open ?
The butterfly is normaly open and closes after the vsw allows vacuum to it. Would be good to eliminate the whole system behind it.
It's winter here and although not really cold - on some mornings with 0 or 1 °C (~33°F) my 12ht needs approx 3 revolutions of the crank to start. I removed all the glow screens years ago. If it doesnt get much colder the engine does not need any glow aid. The only thing I do is having that idle up on the third click to get 1000 rpm after starting. have no automatic idle u devices either. Starts always fine with only a bit of slight smoke as you would expect.
As said before, it is important to have the ip timing as any other tuneable or serviceable components of the engine spot as a basis for troubleshooting.
Hope you have solved the problem by now.