Random hard hot starts and slight rough idle

[Tyler P]

Hey all, looking for some advice on my 1992 3.0 Ranger. Bought it and it’s been off the road for a couple years. It has random hard starts when it gets hot. The part that is confusing me is that it doesn’t happen all of the time, maybe 1/10 times I start it, but only happens after I let the engine warm up and let it sit for 15-20 minutes.

When cold it starts like normal, I’ll drive it around and park to get some gas. I’ll try to start it and it’ll crank for 5-10 seconds before it catches. It’ll then bog down and the engine will die. I go to start the engine again and it start up great like nothing happened.

At idle there’s a slight shake in the cab. Nothing crazy but it just doesn’t feel like it should.

I’ve replaced plugs, IAC, coolant temp sensor, intake temp sensor, fuel filter and cleaned my Maf. I’ve done an oil change recently and the intake filter looks good.

Im thinking about replacing my fuel pressure regulator and cleaning the injectors. I didn’t see any gas in the vacuum line but it’s the original and I don’t fully trust it. Just wondering if any of yall had some wisdom.

 

[sgtsandman]

Try running a bottle of fuel system cleaner and see if it helps any. Pour it in as you fill the tank and run the tank dang near empty to get the full effect. I like Techron but Gumout and others have a good reputation as well. That should take care of any injector issues you might have as far as clogging or build up on the tip. I do this twice a year with my vehicles.

 

[ShhhhhDougsHere]

@Tyler P I'm just a novice around here so sorry to say I can't help you with your problem.

I just wanted to say you're in the right place.
Someone or maybe more than one will help you in some way shape or form.
They never fell here at TheRangerStation.

And most of all I want welcome you to TheRangerStation.

So:
WELCOME TO THERANGERSTATION.

 

[nickname23]

Hey all, looking for some advice on my 1992 3.0 Ranger. Bought it and it’s been off the road for a couple years. It has random hard starts when it gets hot. The part that is confusing me is that it doesn’t happen all of the time, maybe 1/10 times I start it, but only happens after I let the engine warm up and let it sit for 15-20 minutes.

When cold it starts like normal, I’ll drive it around and park to get some gas. I’ll try to start it and it’ll crank for 5-10 seconds before it catches. It’ll then bog down and the engine will die. I go to start the engine again and it start up great like nothing happened.

At idle there’s a slight shake in the cab. Nothing crazy but it just doesn’t feel like it should.

Misfire, any codes? Either fuel, either way my money's on lean condition.

Check for vacuum leaks first if you haven't already. Intake could be an issue or a weak fuel pump.

 

[lil_Blue_Ford]

Fuel pressure is a likely culprit. Since you have the older return system, the next time it doesn’t want to hot start, try cycling the key from off to run and back without cranking. You should hear the pump cycle for about 2 seconds every time you turn the key on, wait for that to stop before cycling again. Do that a few times to push fresh gas into the rail, then try starting. If it fires right up then, either the pump or the regulator is going or the injectors are leaking down. At that point, you need a fuel pressure gauge to determine what’s going on.

Also, when was the last time the oxygen sensor was changed? The catalyst in them is only good for about 10 years…

 

[Tyler P]

Misfire, any codes? Either fuel, either way my money's on lean condition.

Check for vacuum leaks first if you haven't already. Intake could be an issue or a weak fuel pump.

Nope no codes. Checked for vacuum leaks with a smoke tester. Replaced the pump with a Delphi one. Aside from the hard starts and idle issues, the engine seems to run pretty good when I’m moving. I could probably record a video if that’d help.

 

[Tyler P]

Fuel pressure is a likely culprit. Since you have the older return system, the next time it doesn’t want to hot start, try cycling the key from off to run and back without cranking. You should hear the pump cycle for about 2 seconds every time you turn the key on, wait for that to stop before cycling again. Do that a few times to push fresh gas into the rail, then try starting. If it fires right up then, either the pump or the regulator is going or the injectors are leaking down. At that point, you need a fuel pressure gauge to determine what’s going on.

Also, when was the last time the oxygen sensor was changed? The catalyst in them is only good for about 10 years…

I forgot to mention, I replaced the O2 sensors when I got the truck. I’ll try that next time it’s giving me issues. It’s been hard for me to diagnose because it happens so randomly.

I bought a new fuel pressure regulator but it looks like I’ll have to pull the fuel lines to replace it so I’m waiting for new injector orings to come in. I figured I’d clean the injectors while the line is off too.

 

[Tyler P]

Today I cleaned the injectors and replaced the fuel pressure regulator… No difference. Not even the placebo effect.

I took my cap and rotor off to find that they look burnt up? I have a new cap and rotor on the way but I want to make sure that I don’t burn up that set too. Is this just caused by wear and tear or is there something I need to look into further?

 

[ShhhhhDougsHere]

Honestly @Tyler P I myself don't know but it does look like wear and tear it's me.
However I said before I'm just a novice when it comes to everything. One of the other guys probably know a lot better than I will.

Once again good luck brother.

 

[SenorNoob]

Looks to me like you had a very hot spark jumping a pretty good gap in there...