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Help me diagnose this engine problem please...


Kalwren

Well-Known Member
Joined
Apr 1, 2009
Messages
118
Vehicle Year
1994
Transmission
Manual
I have a 6cyl 3.0 engine in a 1994 Ford Ranger.

I can start it up and it runs like a champ. Pulls hard and strong on a 5 speed manual transmission.

I can drive quite a ways on the freeway, pull off and go to work. I can start the engine at night and drive home with no issues.

However, once the engine is off and has been sitting for 15 to 20 minutes and baking in its own heat, it won't start until it's cooled off quite a bit. If it does start, it runs VERY rough and acts like a piston isn't firing. If I step on the throttle, I get no response. It usually sputters and dies. It may or may not start back up but it does the same thing, it won't rev up until after the engine has cooled off.

I can duplicate this issue while driving through stop and go traffic. Eventually the engine will start to sputter and die. Sometimes it restarts, but the problem comes back within minutes. Sometimes it restarts and runs really rough and if I step on the gas it'll sputter and die.

I just bought this vehicle a week ago and it was a rude shock to find this problem. I took it in to a mechanic and they were unable to duplicate the issue, as I didn't give them as much detailed information as I have here. I hadn't figured out what the common denominator was until a few days ago.

When I took it to the mechanic, they did find a coolant leak. They hooked up a pressure thingy to my radiator and found coolant leaking. They believe it's leaking from the intake manifold. They said to continue to drive it, but watch my fluid level. I've driven it for 4 days like this and have only had to add coolant twice. It's like it's not leaking now as the radiator is staying full.

I'm taking it back to the mechanic in a couple days.

Anyone have any suggestions as to what this problem might be? I don't know these engines that well as I've not had the vehicle long enough to learn it all yet. :)

Thanks in advance, sorry for the long post and I appreciate your time!
 
hmmm not sure what to tell you here. Im sure somebody else here will be of more help, but I would start by pulling the codes and seeing if anything comes up.
 
after it sits 15 - 20 min and then is hard starting ......... is it like flooding when it does that? do you get a strong gassy smell?
 
hmmm not sure what to tell you here. Im sure somebody else here will be of more help, but I would start by pulling the codes and seeing if anything comes up.

Ah, yeah. Sorry. I forgot to mention... they pulled the codes and there were none. They said the computer showed clear. No codes at all.
 
after it sits 15 - 20 min and then is hard starting ......... is it like flooding when it does that? do you get a strong gassy smell?

I haven't noticed a gassy smell at all. I would have noticed it last night though, as I popped the hood as soon as I got off the road. I didn't smell anything out of the ordinary.
 
im just throwin this out there, but i had a Mass air sensor do about the same thing to me.
beef
 
im just throwin this out there, but i had a Mass air sensor do about the same thing to me.
beef

I was wondering about that, too. I don't know much about fuel injected engines yet though. I'm wondering if it's part of my RPM issue...

I have a question to the other 3.0 owners out there - those of you that have a manual transmission and you're starting from a stop... What kind of RPM to keep the engine at?

I've noticed that if I drop it to 1000 or less, it bogs pretty hard and you have to step into the accelerator. If I keep it around 1500 RPM it takes off pretty fast and feels like I'm pulling harder than I need to.

If I start out on a slight incline, I really need to be at 1500 RPM in order to not bog the engine down.

I find this odd, as the cruising speed on the freeway in 5th gear is at 2000 RPM @ 70 mph.

I'm used to driving a 4 cylinder so high RPM wasn't a big deal. I'm concerned that I'm pushing this engine harder than I need to. But I'm not familiar with it yet and I'm not sure what a reasonable RPM is to use for starting out in first gear.
 
The 3.0 likes its high RPM alot of people find it sluggish for that reason.
 
I don't know much about 94's and I don't know if the vulcan had this option in 94 or if it does to this day, but are you sure you're not having a heat issue something as simple as a stuck T-stat...I know a lot of more engines have the feature of stopping the ignition of several cylinders locking the exhaust valve open and using the pistons simply as a "air pump" to cool the engine. Many of the symptoms are the same in other engines such as severe power loss or even failure to start and run. I had a friend with a brand new equinox that had this issue and the garage couldn't figure out issue either, no codes, anything...changed out the T-Stat on a hunch that this was the issue and problem solved.....however i'm really just throwing that out there...best of luck to you
 
I don't know much about 94's and I don't know if the vulcan had this option in 94 or if it does to this day, but are you sure you're not having a heat issue something as simple as a stuck T-stat...I know a lot of more engines have the feature of stopping the ignition of several cylinders locking the exhaust valve open and using the pistons simply as a "air pump" to cool the engine. Many of the symptoms are the same in other engines such as severe power loss or even failure to start and run. I had a friend with a brand new equinox that had this issue and the garage couldn't figure out issue either, no codes, anything...changed out the T-Stat on a hunch that this was the issue and problem solved.....however i'm really just throwing that out there...best of luck to you

I appreciate your comment!

If the T-stat is the thermostat, then I think it's working correctly. As I drive down the freeway, the temperature gauge only moves a little. It stays in the dead center and then every so often, it drops down a little bit.

I think thats tells me that the Thermostat is opening like it's supposed to, and pulling in cold water.

The engine temperature gauge has never showed that it was running hot and I've been eyeing that gauge like a hawk for the last 3 days.
 
Yeah sometimes things like my post are a long shot, i really hope you can figure this one out....i'm sure there are alot of other things to rule out, best of luck i know how frustrating things like this are.
 
My truck did the same thing and the heat from the engine was killing the ignition coil and module. My coil is located on top of the intake manifold and my module is located on the rad support next to the rad.
 
My truck did the same thing and the heat from the engine was killing the ignition coil and module. My coil is located on top of the intake manifold and my module is located on the rad support next to the rad.

2nd Tinman's comments, sounds alot like an old coil cooking in the heat...:icon_confused:
 
Excellent information, thank you. I'll forward this on to my mechanic when they work on my truck in a couple days.

Your truck was doing the EXACT same thing?

My truck did the same thing and the heat from the engine was killing the ignition coil and module. My coil is located on top of the intake manifold and my module is located on the rad support next to the rad.
 
if you look at the coil usually a bad one will look burned on either or both sides. just slightly different coloring. that's a pretty good sign of a fried coil.
 

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