The Stovebolt Site Forums The Shop Area The Electrical Bay Starting problem

I took my truck out for the first time this year.It stalled a couple of times till it had some heat.then it ran fine.After some errands I went to start it.This is when it gets weird.It cranked fine but didn't fire,when I let go of the key,it fired up.I shut off and tried again.Same thing.Drove home,shut off and tried again.Same thing.I have never come across this before.I put the batery charger on it the last 2 hrs,still no change.
It's a Chev 350 with GM HEI ,2yr old battery,Any idea's

BC52,

I have seen this happen. It's almost like the HEI module isn't getting enough voltage while the starter is gobbling it up as it cranks, but when you let go of the key, there is now enough for the distributor and it leaps to life.

I don't think it's the key switch but it could be a failing HEI module.

Stuart

Sounds like the bypass signal wire from the starter is open,
Scott

Although I'm not 100% sure on this, I didn't think a HEI system would use a bypass circuit. The distributor doesn't require a inline resistor of any sort and I thought the keyswitch, when turned to START or RUN supplied voltage through it to the HEI.

I have been wrong many times before though!

Stuart

BC52,

The condition you describe is typical of ignition switch or resistor bypass failure. As atomarc says, I also don't think the HEI system uses either a ballast resistor or a bypass circuit, although I think there is usually a 'Start' position on the ignition switch. If this is a conversion from the original six volt system, there is no 'Start' position on the switch. Also, if you didn't provide for the higher primary current the HEI system takes, my first thought is that you have ignition switch trouble. The original ignition switch can't/won't handle the primary current that the HEI system takes. I am not familiar with HEI conversions for older vehicles, so I don't know if those conversions provide for the higher primary current they take. Published information about OEM HEI primary current is somewhat misleading because those systems use a current-limiting circuit to prevent discharging the vehicle battery if the ignition switch is left on without the engine running. The published current level with that condition is something around 0.2 amps, if I remember correctly (key on, engine off). When you crank the engine with one of those systems, the current limiter function turns off and the full primary current reaches something around 20 amps- I don't remember exactly. Without the current limiter, the battery wouldn't hold up for long with the key on, engine stopped. Even with the engine running, there is still a current limiting circuit that functions at low engine speed when the dwell time is long enough to permit adequate coil saturation with a lower current.

Maybe this is more than you wanted to know, but the HEI ignition system is not a 'plug-and-play' system as it is often perceived to be. And again, I am not familiar with the HEI after-market conversion kits, so I'll defer to the experience of others on that topic. But without more information on those conversions, I remain skeptical of their long-term merit and reliability.

Harvester

I guess we really need to know what age or vehicle the wiring harness is from. Does the HEI have a big red wire with a factory style connector on it or is it homemade and adapted to fit the harness. I presume it has a new column with a key start system so to diagnose the problem, you can test the fuse box and find a 12 volt power source that's hot while cranking and plug that into your distributor. If it starts normally, it's probably a wiring problem which I suspect since it happened all of a sudden. Regardless, I think we need some more info on what's in the truck,
Scott

Thanks for the replies.Oddly,the problem has gone away,and I can't find why.I know it will rear it's head again,but what the heck it's OK now