Hi,
I have been chasing my tail with a problem I have been having.

When I start my truck, it idles fast for a few minutes then settles down.
When I park up I get preignition when I switch off.

When I get back to the truck and start it. It tries to idle at low rpm for some reason. (some times it cuts out its at such low revs).

I have been told that it may be the timing chain.

Any thoughts on this. As I dont want to change the timing chain to find it is not the timing chain at fault.

Thanks,

 

It is probably not the timing chain. Sounds like a fuel issue.

 

Hi, on the fuel side I changed the carburetor to a new one and the issues still continued.
So, that would only leave the fuel pump right. The original mechanical type.

Could the fuel pump cause this kind of issue?

 

I would suggest getting back to basics before condemning and changing parts. Did you check the ignition timing ? Did you check the distributor vacuum advance ? Did you check the distributor plate for free movement & not stuck or binding from rust ? Did you check the idle stop solenoid to make sure that it isn't touching the throttle tab when the key is off ?

 

Hi, in gettingback to this. Thinking about it the other way around.

When I have used the truck and park up and come to startup again.
Apart from having to keep the revs up for a while to get the engine to continue to run and not cut out.
It is then closer to 700 rpm. As to when it is started first thing where the revs are 1400 rpm +. I dont have the choke wired up? But may be this is causing high revs. I'm in Australia for my sins.
However, it is summer and is rarely below 15 deg C.

Thanks,

 

Am I correct in assuming you have an electric choke?
If you don't have it wired up it will never fully open, which will keep it in fast idle, and make it more likely to diesel after you shut it off. That would also make it idle poorly once it's warmed up because the engine would be trying to flood out...

 

Hi, I have a SUM-RM08600VS carburetor. However, I did have an older holley with a mechanical choke and I had the same issues. Thanks,

 

There was a good suggestion in post 4, but you've completely ignored it !

Australia produces Two Wheel Gods, Bayliss, Stoner, Corser, Dooyan, so I think your sins must be minimal !

 

Air fuel spark. One or 2 of these is off. Check everything related to the spark & fuel. Something is wrong there. Might be a combination of both.

 

No, did'nt ignore anything. Infact a neighbour and I went over the points made again the other day.

 

I agree, finding what, is proving to be a pain. However, I know its easy to throw money at these things to find that it was something else entirely. Thanks,

 

We won't know that you've checked the ignition timing and dizzy unless you say so.

What is the timing set at ?

Is the truck an auto ?

The behaviour of the engine is changing between when it's hot and cold at idle, but what's it like when driving around ?

Check the plug conditions.

Check the HT leads.

Check the coil.

Are there any vacuums leaks ?

Do a vacuum reading at idle. (Is the needle steady and at what level?)

Are the fuel lines away from heat sources ?

Yes, it may be that the timing chain is too loose and screwing up your timing. Can you hear a clattering as if there's something loose ?

 

My bet is intermittent vacuum leak - when warm its not as bad, and the idle is adjusted so the engine starts decently when cold. It'd explain the hot run-on, too, as the lean mix would be causing high plug temps.

Try finding a vacuum leak with WD40 or degreaser when the engine is running.

- boingk

 

Hi, the heat gave up a little today and it remained overcast.
So I took a quick look at the truck.
Took the distributor cap off.
Turned the crank shaft with a breaker bar.

The slop was about 5 - 10mm angular movement at the end of the breaker bar.
Breaker bar approx 12" long. Before the rotor arm began to trun in iether direction.

I have nothing to compare to. Any one with experience care to confirm answer?

Thanks,

 

Less than 1/2 inch of slop at the end of a 12" bar is no big deal.