Stump the chump, round two. Rough start... | Ford Explorer Forums - Serious Explorations

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Stump the chump, round two. Rough start...


November 4, 2016
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Year, Model & Trim Level
1992 Explorer
Hey guys, im posting from my phone bare with me...

Well, I drove from MI to FL this week. The truck is running fine for the most part and not overheating....but the rough starts have not gone away. Its getting worse. I changed the ECT and Ignition control, and IAC, and fuel pump.

Every morning starts right up, but there are so many stop and go town driving the explorer is taking a beating in the hot heat but it is NOT overheating, thank god.

Once we get to where we are going and turn off the engine, when we start back up, it starts right up, then acts like its gonna die. Now, its never died yet. It surges, like 2 rpm, then, nothing, then little surge or nothing. Or it just kicks and idles so rough. I give it gas with clutch in, slam on gas, get on the road and its fine!!! I can idle at lights and what not and drive fine on highway.

These next things might be clues or just in my head.
First, when I turn the key to the on position right before I crank it I hear this low hum which I think is coming from under the hood engaging something...when it starts hard it almost sounds like this hum isn't smooth like normal and a little weak/clicks.

Second, when it starts hard it smells way more like exhaust or something, but this could be because im flooring the thing...who knows.

Help me get through this winter please!!

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What year is your X?

Have you checked for codes using the paperclip method? Is your radiator full and have fluid in the overflow?

Sounds to me like a battery going south and a clocked cat issue.

The radiator should be full,brand new and flushed but I'll recheck. I don't have a check engine light on. I have two batteries in the truck, both brand new.

Can someone please answer this. When I turn the key to on, under the hood, something makes a sound, like it is engaging something. Hums for about a second or two then stops then I turn the key all the way to crank on. What part is engaging when I turn the key to on?

Year, 1992. I have a previous thread, thanks guys.

Can someone please answer this. When I turn the key to on, under the hood, something makes a sound, like it is engaging something. Hums for about a second or two then stops then I turn the key all the way to crank on. What part is engaging when I turn the key to on?
Most likely the fuel pump, though that is in the fuel tank. Are you absolutely certain the sound is coming from under the hood? If it is, is it coming from the fuel system?

Rough hot starts are frequently from a failed FPR. The diaphragm develops a lead, allowing the gas to leak into the intake while the engine sits, effectively "flooding" the engine. Remove the vacuum line from the FPR and see if there is gas in there.

In your other thread, I suggested a fuel pressure test, did you ever try that? If the sound at startup you are hearing is the fuel pump, then the changes in that sound could indicate something changing in the fuel system. A quick fuel pressure test (when it is acting up) should tell you if the changes/problems are due to low pressure or high pressure, or if the pressure is normal and the problem lies elsewhere.

Thanks Mr shorty. The sound could be from the pump, but I just changed it...I haven't done the fuel pressure check like you said, to be honest it seemed overwhelming and i have no idea how the fuel system works, do I need any special tools? At this point I think you're right. We are on the road, no home base for a while. Is there a quick fix you can think of, or if it is high or low what are my your opinion what are your thoughts on the problem, replace FPR?

Alright, I found the FPR. I don't see a vacuum line, there is something coming off the top, and something coming in the back side, which one is the vacuum line. Also, im going to go buy that tool to check the fuel pressure...but how do I check it when it is acting up? Do I start it, see its acting up, then turn off the truck, bleed it? Attach, then hook up and start the truck again ? Or when it is acting up while on, can I just pull the cap cover and attach? It only happens sometimes when I start, been a lot lately though, everytime its warmed up for an hour or so?

Ok, I pulled the vacuum line off the FPR. No gas I can see leaked out of it, but the engine is cold right now

I'd guess fuel injectors.

how do I check it when it is acting up?
Any way you can. There was a time when I was diagnosing an intermittent problem that I hooked my pressure gauge up, made certain it didn't leak and that it would rest under the hood without touching anything and drove. When it would act up, the pressure gauge was already attached and ready to read. I have even threaded the pressure gauge up under the hood and tied it to the windshield so I could see the pressure gauge while I was driving (be careful not to become too distracted by it). There have been other times where, just having the gauge on hand so that I could attach it while it was acting up was enough. Whatever works.

On edit: this is a basic run through of testing fuel pressure on these:

I'm gonna get the gauge and check the fuel pressure tomorrow when it stalls out and I will report back. Thanks for all the help.

I laid out what has to be done in your first post. This problem is most likely electrical. Either your coil packs, crank position sensor, cam position sensor, or the wiring between.

And thank you two stroke. Its just that there was so much info, it was hard to take it all in. Im very much a novice and was starting easy. I did change the ignition coil no luck. I will look into the sensors you posted.

Also to mrshorty. I can't afford the fuel test kit yet, I do have just enough money for a fuel pressure regulator Im thinking of buying to replace....

It was bad today. I drove it 30 miles through town, parked on a slight hill with the front of the truck facing uphill, and i started it and it stalled right out...started, weak, then stalled, I coasted down the hill backwards till flat land, started, slammed the gas, chugged along, then she started running fine the 30 minutes home. I really can't thank everyone enough, for putting up with the reposts and trying to help. I start work this week, bartender in naples Fl, so when I start having more cash I will start to change out more things and report back. Me and my girlfriend are living out of the truck all winter. No backseats, built bed, added camper fridge, extra battery, DC converter, small tv and antenna, so you guys are key to making through this winter.

This a story about who I am, and the journey.

Thanks again, for all the help. I need to fix this, and I will keep updating until we do.

Don't just start replacing parts and seeing if things fix on their own. To test the FPR, remove the vacuum line, plug it and start the engine. Wait 2 good minutes and watch the nipple on the FPR. If you see fuel come out, it needs replacing. If not, it's fine.

Being a 1992, yours should not have EGR or a camshaft position sensor. Since you said you replaced the coil packs, and ICM (ignition control module), I can only speculate the problem will be the crankshaft position sensor or the wiring. If you find a harbor freight, a fuel pressure gauge costs around $20, and you can totally eliminate any fuel problem as the culprit with that one tool. We can help by posting electrical diagrams, however, an EVTM is the most valuable book you can have for working on this vehicle. That along with a multi-meter. This is a serious problem that will leave you stranded sooner or later. This is the kind of thing people ignore and it turns out to be a loose or corroded ground to the ICM or PCM. Definitely do not just replace parts without testing them.