Stall when letting go of key

[ZenMartian]

My engine starts up just fine, but when letting go of the key it stalls. I replaced the ignition but it’s still ongoing so it needs to be something else.

It happened after I installed a new radio, but all i did was just connecting a red, yellow and a ground wire + speaker wires.

Also there’s two blue wires, seems to be cut off in two, with a white line. one has load when I turn the key, but not the other. I might have accidentally cut this in two? They seem to be going thru the firewall into a buss bar where one is connected to “right turn“ and the other to “B2”.

The wires to the ignition are as follows:
*IGN relay
*ground
*start saf sw
*accessories
*lamp test
*ign battery

I believe it should be wired correctly now because I’m back at the same issue I first had, when i had not even touched the ignition. When I first noticed it back then all I did was installing the radio.

This is part two of last weeks issues. I got the solenoid fuel shut off replaced with a new and I’m back to square one.

[code2e]

Originally Posted by ZenMartian

My engine starts up just fine, but when letting go of the key it stalls. I replaced the ignition but it’s still ongoing so it needs to be something else.

It happened after I installed a new radio, but all i did was just connecting a red, yellow and a ground wire + speaker wires.

Also there’s two blue wires, seems to be cut off in two, with a white line. one has load when I turn the key, but not the other. I might have accidentally cut this in two? They seem to be going thru the firewall into a buss bar where one is connected to “right turn“ and the other to “B2”.

The wires to the ignition are as follows:
*IGN relay
*ground
*start saf sw
*accessories
*lamp test
*ign battery

I believe it should be wired correctly now because I’m back at the same issue I first had, when i had not even touched the ignition. When I first noticed it back then all I did was installing the radio.

This is part two of last weeks issues. I got the solenoid fuel shut off replaced with a new and I’m back to square one.

Since your ignition switch has individual wires with only spade connectors, I would suspect a wire either left off or misconnected on the switch. Picture shows at least one switch terminal unused.

Starter solenoids often have a terminal to feed battery power to the ignition during cranking. This is to overcome voltage drop from the key switch. That would explain the engine starting on crank but stalling on run.

Always a good idea to take a picture before disconnecting anything. Helpful when reconnecting.

[ZenMartian]

Thanks for replying. Appreciate it very much. Yes this picture shows me just connecting the wires back like i remember it.

The thing is that i had this issue earlier as well with the original switch. Making me think the switch was faulty. I got a new ignition switch which i thought worked but my wiring mistake ended up with a a melted solenoid fuel shut off.

I replaced the solenoid with a new together with a new ignition. (Same as original), but the problem is the same so back to square one.

Obviously i wouldn’t have had to go thru the ignition replacement in the first place cause now it seems like it worked anyway and the mistake were somewhere else.

I attached a picture of the ignition and I’m only using one of the ground and one of the batteries. That’s what the original was from what i remember, unless one wire dropped out before i got to look at it. I’ve been looking for any missing wires in my dashboard around the ignition area that don’t seem to have a home, but i can’t find any.

The only thing I did when i first noticed it would stall on run was after i installed a new radio. It was just speaker wires plus one battery wire, one hot wire and a ground. Nothing major.

Also when i tried to check for voltage on the hold side of the solenoid during cranking i got none. (See second picture)

[code2e]

Can you tell me what we are working on? year and engine model / size.

Might be able to look up some info.

Looking at the pic of the ingition switch terminals, I see one marked Ign. Are you able to back probe that with a meter or test light? Be certain your meter or light has a solid ground, back probe IGN with key on. Should have battery voltage. Key off, no voltage.

If you don't get those results, back probe the BAT terminal. Should be battery voltage always, key on or off.

[ZenMartian]

It’s a 1994 Firan with a Spartan chassi with 8.3 Cummins 250hp and Allison automatic transmission.

I do have battery voltage. The SOL gets powered on crank and the IGN and ACC gets powered on Run position.

There’s no voltage on any with the key off (except the two BATT terminals).

I guess when it goes back to run after cranking the SOL terminal will return to no power?

[code2e]

Originally Posted by ZenMartian

It’s a 1994 Firan with a Spartan chassi with 8.3 Cummins 250hp and Allison automatic transmission.

I do have battery voltage. The SOL gets powered on crank and the IGN and ACC gets powered on Run position.

There’s no voltage on any with the key off (except the two BATT terminals).

I guess when it goes back to run after cranking the SOL terminal will return to no power?

Ignition switch is functioning normal. Yes, the SOL should be no power in every position except crank.

The IGN terminal should be going to the fuel shutdown solenoid on the engine fuel injection pump.

The SOL terminal likely feeds a relay that activates your cranking motor by way of a solenoid. There should be a wire from either the relay output or the cranking motor solenoid that also goes to the fuel shutdown solenoid.

The fuel shutdown solenoid should have 3 wires. From IGN, from SOL and to ground. Fuel shutdown solenoid default is shutdown. It needs power to allow engine to run. Cranking motor amp draw is so high, that SOL wire is to insure fuel shutdown can function. IGN keeps fuel shutdown solenoid active so engine can run. SOL goes to no power when cranking motor stops.

Your trouble seems to be the IGN feed not getting to the fuel shutdown solenoid to keep engine running. Or a defect in the fuel shutdown solenoid. As is common in constant duty solenoids, there will be separate windings for SOL and IGN functions. One can fail while the other still works.