This is my thread...hear me ROAR!!!

[timstone]

Ok...I am fed up with the way this vehicle of mine is running. It's a 1991 Ranger regular cab with the 4.0. When I got it, it pretty much ran fine..it has some noise in the motor but it's nothing to get excited about.

For the last 3 or more months it has been getting increasingly worse. If I start it when it's cold I sometimes need to keep my foot on the gas for a few minutes to keep it running...although this is pretty rare. Other times it will run without having to do this but the idle seems a bit rough. It seems to idle around 500 RPM.

When the truck is like this....even if I let it warm up for a good 15 minutes before actually leaving anywhere as soon as I put it in drive and push on the pedal there is hesitation and it almost wants to die on me....sometimes it actually will die on me. The battery gauge in this state always reads lower than normal (somewhere around the N is where the needle points) but when the gas pedal is pushed down it will jump back up to the normal reading...as soon as I get to a stop sign it will drop again. It does this constantly until the truck is fully warmed up and sometimes will even do it then.

So far I've replaced the positive battery cable. The solenoid that is on the starter, the PCV valve, and all the plugs and wires. None of this has fixed the issue or even made it better.

Some people will tell me to check the battery and starter. But I have done both of these and they both tested good. I even went through the trouble to actually buy a new battery to put in the truck but even with the new battery it still had the same symptoms.

I'm lost and I can not figure this out....I don't really want to put any other money into it until I have a better idea of what could possibly be happening.

If anyone has any ideas PLEASE HALP!!!!! If you need any more information than what I have provided here...because honestly I could have left something out. Just post your question here. I'll respond ASAP.

 

[99RangerBoss]

Im thinking maybe coils or 02 sensors anybody? Fuel filter?

 

[timstone]

Cleaning the IAC as I type this....hoping this will at the very least solve the rough idle....as far as the voltage problem I'm in the dust on that one still....every time I try to explain to my dad about the whole voltage thing he tries to tell me that all voltage gauges dont read properly all the time but i know that it is because when the voltage is low my lights are dim and when i hit the gas the voltage goes up and my lights get brighter

Also...going to replace the fuel filter tomorrow after work if the IAC cleaning doesn't work

 

[Earl43P]

This sounds like a ground problem.

Check your Neg Bat cable; clean where it attaches, rad support, block, etc.

Wigglethem while idling and someone watches the gage. Replace as indicated.

You didn't have the alternator tested? If the problem varies with engine rpm, I'd suspect it.

 

[timstone]

This sounds like a ground problem.

Check your Neg Bat cable; clean where it attaches, rad support, block, etc.

Wigglethem while idling and someone watches the gage. Replace as indicated.

You didn't have the alternator tested? If the problem varies with engine rpm, I'd suspect it.

I did have it tested...tested good. Someone else mentioned maybe a bad ground. I'm not sure where all the ground cables go to...do you know where each of them are so I can check and clean the surface where they mount?

I know I saw one on the block where the POS cable routes under the engine but I can't get to it unless I remove the oil filter and don't want to do that til I have to change the oil cause I've only got a few hundred miles on this oil change.

 

[badtxz]

I just pulled the old 4.0 out of my 90 ranger. The main ground(neg cable)connection, behind the right motor mount on the right side of the block, was a mess. It was rust and gunked up. I'm surprised it made a connection! Try cleaning that ground.

 

[timstone]

I just pulled the old 4.0 out of my 90 ranger. The main ground(neg cable)connection, behind the right motor mount on the right side of the block, was a mess. It was rust and gunked up. I'm surprised it made a connection! Try cleaning that ground.

Yea that's the one that is hard to get to...I can't really take the bolt out unless I remove the oil filter...maybe I will have a look at it tomorrow...might be able to fit a box wrench in there or something

 

[Sevensecondsuv]

Usually problems during warm up that go away once it's warm can be traced to the coolant temperature sensor. I've seen them do exactly what you describe. You can get to it just by removing the air intake tube and it's right in the lower intake manifold beneath the throttle body. The part should be about $20.

My theory is that the coolant temp sensor is messed up causing the engine to run like crap. Idling at 500 RPM is not really fast enough to get full voltage out of the alternator, which would explain the voltage jumping up when you hit the gas.

There's only a few sensors that will screw with the computer like a failed coolant temp sensor.

 

[Nhaz]

Have you confirmed that the IAC is functioning?

As for a ground wire. I don't bother looking for a old busted ground. Just add a new one. saves time and you KNOW that its got a good ground when you are done.

 

[timstone]

Have you confirmed that the IAC is functioning?

As for a ground wire. I don't bother looking for a old busted ground. Just add a new one. saves time and you KNOW that its got a good ground when you are done.

I don't have a voltmeter and actually don't even know anyone that does.

 

[C_Root]

I know you said above that you would replace the fuel filter but never posted if you followed through??? Thats my vote, would explain why you would have to hold the gas, the pump having to FORCE fuel through the plugged up filter...? mabey? best of luck.
croot

 

[timstone]

I know you said above that you would replace the fuel filter but never posted if you followed through??? Thats my vote, would explain why you would have to hold the gas, the pump having to FORCE fuel through the plugged up filter...? mabey? best of luck.
croot

Somewhat makes sense but doesn't at the same time because it doesn't have the hesitation once it's been running for a while.

 

[timstone]

Well I was pretty disappointed just now when I went out to start the truck. I replaced the POS battery cable all the way down to the starter over the past weekend hoping to fix this issue but apparently it was a waste of time. I went to go start it and like it used to do the starter would click like once and all the lights would go dim..the way to solve this is to open the hood, loosen the POS cable and wiggle it a bit..then retry...usually takes a few attempts to get it to start...I don't think this is the problem with my other issues.......or is it?

 

[Big Jim M]

Good post

Well I was pretty disappointed just now when I went out to start the truck. I replaced the POS battery cable all the way down to the starter over the past weekend hoping to fix this issue but apparently it was a waste of time. I went to go start it and like it used to do the starter would click like once and all the lights would go dim..the way to solve this is to open the hood, loosen the POS cable and wiggle it a bit..then retry...usually takes a few attempts to get it to start...I don't think this is the problem with my other issues.......or is it?

Now THAT tells us a story. Plain and simple that indicates dirty cable connections.. AND most likely a older battery that is low on amperage. I'd take them cables off and clean the posts up to shiny grey and then clean the inside of the cable ends to the same shiny grey.. After reinstalling if they don't do what needs to be done then take the battery to an auto parts house and get it tested..
If you had a volt-meter you could check the voltage at the battery and check out your system yourself.
Big JIm

 

[timstone]

Now THAT tells us a story. Plain and simple that indicates dirty cable connections.. AND most likely a older battery that is low on amperage. I'd take them cables off and clean the posts up to shiny grey and then clean the inside of the cable ends to the same shiny grey.. After reinstalling if they don't do what needs to be done then take the battery to an auto parts house and get it tested..
If you had a volt-meter you could check the voltage at the battery and check out your system yourself.
Big JIm

I think I am going to just buy a new volt meter...I used to have one and it stopped working and since I never really used it I just never replaced it. I am also going to try and get to that ground on the block tonight and clean up the surface with a dremel or something...going to do the same with both battery posts and the terminals...hopefully this will fix the problem...but even still I have the low idle at around 500 rpm that hasn't been fixed yet. I guess we'll see what happens after cleaning stuff up and go from there.

Also remember that I just put a brand new POS cable on over the past weekend...so it can't be that cable.