My new ranger and need help

[Kyonic]

I just got a 1991 Ford Ranger 4.0 4X4 last weekend and love it. except for a few problems which I was hoping to get some help with.
OK first off I drove the truck last weekend without any problems after buying a new battery for it.

1. Noticed that after starting the truck today that it idled fine for about 10min while I was getting some cleaning done in the garage. After about 10 min the truck began to run rough and idle way down. I went to it and gave it some gas and it seemed to not want to do anything and got rougher.
-I then got in her about 2 hours later and drove it down the road and it got warm and then started running rough again. I did have the defrost on today because i used it a week ago and let the truck sit. It never had anymore problems running rough for the rest of todays drive, so I am not sure if the defrost had anything to do with it.

2. Voltage is showing to be really high about 3/4 all the time so im not sure why it is like this. I will say that when it was running rough the voltage would really drop fast with the rough spells.

Well hopefully these are easy fixes. Let me know

 

[Nhaz]

The in dash volt meter is not a good judge of voltage output. its really only good for: yes you have voltage or no you don't mine sits at 3/4 while driving and drops at idle.

How long was the truck sitting? its possible it needs something as simple as a fuel filter.

 

[Kyonic]

it sit ffor 5 days

 

[aeraceranthony]

Sounds like when it goes int open lope, its running rough. The means its a bad sensor or a vaccum line. Your best bet is check the MAF and the 02 sensors. Also go over all vaccum lines in the vehicle.

 

[pillen140]

the voltage would probably jump cause the engine is bucking. if its over heating, make sure the cooling fan is spinning, and the thermostat is good. and make sure its got coolant. unless your ac compressor clutch is not disengaging? if the defroster is on the ac is on... if it has it? idk, just tryin to give ideas?

 

[Kyonic]

also when it does run rough the CHECK ENGINE LIGHT comes on as it runs rough. When I drove it it did it to me twice acted like it had no power. I gave it some gas and it didnt want to do anything but then cleared up.
It is just very strange because it worked fine up until I let it sit for 5 days. Like I said the only thing that is different today was the fact the defrost was not on.

 

[Nhaz]

If you have a check engine light. you can pull a code out of the computer. but not for long on the older computers. the code may not even be right ive been given wrong codes. but it gives you a place to start.

 

[Kyonic]

okay i just went out and started it up and let it sit for a bit. it ran ok this time. i think i might have figured it out though. when i shut her down and went to the front while hood was up i heard an air hissing sound which was coming from the brake booster. at the top of the booster is a vacum line and when i pushed pressure on it, then it stopped hissing and you could not feel the air any longer. i guess i could put some silicone here? or just replace something? do you think this is the cause of yesterdays problem?

 

[SoLongStang9499]

It could be, replace the rubber hose going from the brake booster to the intake manifold on the drivers side. And above all things use real hose clamps, not those mickey mouse quick clamps.

 

[Nhaz]

Ive had trouble with that elbow going into the booster. I replaced the 90 degree elbow with another from my donor truck and fixed the leak.