Will not idle

[87sc302]

Help -----about 3 weeks ago my Ranger died when a wire came off the fuel pump relay. While looking for the problem of the wire I pulled the relay and left the ignition on till the next day. I fixed the wire but then the pertronix ignition was fried (6 years old) so I bought a new one but the truck would not start so I had to return it to the Pertronix. While waiting for the replacement I read up on the Duraspark II and installed the system on my Ranger.

It starts but will not idle below about 1000 rpm. I have replaced the distributor twice, the module twice, the coil, the alternator,and the battery has been checked. I have checked all the grounds and even tried different carburator. The fuel pressure is 4 to 5 psi and all cylinders are 150 to150 psi compression.

When lights or heater fan is turned on the engine wants to die. The engine used to idle at about 800 rpm all day long.

Any ideas?????

[v8ranger]

This may sound like a stupid question, but, are you sure the alternater is charging 13.5 volts? not sure it would fix your ideling problem. I would check and see what its charging when you have everything on. It should still be charging 13 volts, even with everything on. You said you left the key on, it could have fried the voltage regulator also. With the alt not spinning, there is nothing to keep it cool, and therefore could have fried it.... Just a thought.

[87sc302]

Replaced the alternator. Both were putting out about 14v.
I do wonder if the Duraspark II requires more power.
The alternator is a 75Amp

I did get the replacement Pertronix back so I may try it.

[plowboy34]

Don't know if you have got this problem fixed yet or not but I would check for a vacuum leak. I know all this started after a electrical problem but it has happened to me before. One thing goes wrong and get that fixed and another problem out of blue pops up. Vacuum leak will cause idle problems big time. Maybe vacuum advance in duraspark leaked. Just a thought.

[87sc302]

Plowboy
No vacuuum leaks even switched out distributor vacuum advance.
The engine will idle at about 950 to1000 rpm but below that the voltage seems to drop. Even at about 950 rpm when I turn on headlights the idle starts dropping. I found several alternator wires that had been spliced and they were burnt and fraid, just knew this was problem but no such luck.
I tried battery out of my F150 today,same problem.

Tommorrow I am going to try the alternator again.

[v8ranger]

Plowboy
No vacuuum leaks even switched out distributor vacuum advance.
The engine will idle at about 950 to1000 rpm but below that the voltage seems to drop. Even at about 950 rpm when I turn on headlights the idle starts dropping. I found several alternator wires that had been spliced and they were burnt and fraid, just knew this was problem but no such luck.
I tried battery out of my F150 today,same problem.

Tommorrow I am going to try the alternator again.

What is the Voltage dropping to?

[plowboy34]

Do you have the internal or external voltage regulator on your truck?

[87sc302]

Voltage starts dropping at idle from about 14.2 to 12 and lower as idle drops off.
The alternator is 75amp with internal regulator.
I am going take the truck and get the alternator checked on vehicle tomorrow.

[v8ranger]

Do you have underdrive pullys on it by any chance???

[87sc302]

No underdrive pulleys

[v8ranger]

Sounds like the alt is not spinning fast enough..... Maybe the pulley on it is to big??

[87sc302]

I am thinking same thing about alternator, not enough rpm. ASP makes an overdrive pulley.

My question is does Duraspark II system (new to truck) require more power than the pertronix that I replaced?
The truck would idle at 750 rpm with the pertronix.

[plowboy34]

I just don't think it's cause of low voltage, the duraspark just didn't draw that much voltage. By chance have you changed anything on the duraspark??

[rojam18801]

i had the same problem with alt charging. was changing everything like you have with no change in charging. the fix was a ground wire from alt brackets to frame. the alt needs to have a good ground. dont know why alt would'nt ground to engine. engine was grounded to the frame. just a 12 gage wire from alt brackets to frame did it for me. after a month of time and a lot of money and choice words. why the @@@@ dont this work right....the old trucker

[87sc302]

Old trucker
Changing the pulley (smaller) on alternator has made the idle much better, at least it is drivable. But I think there is still a ground problem somewhere. I will try the alternator ground, Thanks for the suggestion.