My '94 XLT Explorer needs some special TLC

[tech1cw@comcast.]

Hello all,

Got my '94 XLT Explorer back in '98, it had 48,000 miles on it, got a nice deal cause it is only 2WD. I had a company car up until last year so it wasn't driven much, it had 74,000 last Jan when I started my new job that requires 300-500 miles per week as a field tech. It has held up well, last summer I had the radiator flushed and a leaky heater valve replaced, surpentine belt replaced, trans serviced, fuel filter replaced, plugs, etc. It has 99,600 and still runs great, I get good mpg, and best of all it's paid for. It does however have one annoying problem. The problem shows up after a decent drive that gets the engine fully hot, after shutting engine off. If you restart immediately or within say, 10 minutes, there is no problem. But if you restart engine within say, 45 minutes to an hour, engine will miss badly, liked a fouled out plug for approx. 2-3 minutes, it will slowly clear and return to normal idle. Sometimes though, after a long trip and a 45 minute restart it will idle so rough it stalls out, and then it will not turn over for an extended waiting period. I have found out that raising the hood will cut the waiting time in half, allowing the engine (or a sensor) to cool down. the recovery is sudden, i can try restarting every 5 minutes or so and it wont run, just stalls right back out,
then all of a sudden after waiting another 5 minutes it will fire right off and idle perfectly, as if I had never sat there 45 minutes waiting. I know this sounds weird but if it wasn't for this problem, the truck would be perfect. The annoying part is having to wait for whatever it is to cool down so it will restart, wasting my time during the day going from place to place. It has had this problem I think ever since I've had it. The mechanic at the garage that I have it serviced at replaced the temp sensor (he said) when I had it in for the tuneup. After the tuneup it seemed to go away for a while but gradually the problem came back again.I have tried cleaning the MAF sensor filaments with contact cleaner, (someone told me about), but that had no effect on the problem. I don't want to sink a lot of cash in this truck, especially for diagnostic reasons. If anyone has heard of this type of problem, please let me know what I need to replace.
Thanks, CW

 

[JDraper]

Welcome to another PA Explorer!!

Not sure on your problem. Could be fuel pump related or fuel pressure regulator related. When it's running rough, does it put any smoke out the exhaust pipe?

BTW, moving this to the stock 91-94 forum for more visibility.

Good Luck!

 

[tech1cw@comcast.]

Thanks for the input, when the engine is idling rough I have never seen any smoke from the tailpipe, I have gotten out and looked. You do smell fuel though, but not regular fuel smell, almost like an improperly processed fuel smell, but goes away quickly as soon as engine smooths out.

 

[JDraper]

You could have your fuel pressure regulator going south on you, or maybe a damaged coil pack. Heat would affect a coil pack more than the fuel pressure regulator.

 

[tech1cw@comcast.]

don't know much about these parts, but it gives me something to go on. The reason I thought it would be a sensor is because of the recovery it makes, amost like flipping a switch. all you have to do is pop the hood and let it sit. it will go from not idling at all and stalling out to idling perfectly, when the temperature threshold has been reached. the temp gauge never goes past halfway, so i don't believe it is an overheating issue.

 

[mikeinri]

If I were you, I would start searching this site for the items the previous posters indicated (coil pack and fuel regulator). There should be info here on how to troubleshoot these items.

Are you getting any CELs? You could have the codes pulled anyway, just to be sure.

Not sure if this is your problem, but I once had a bad temp sensor (which is a DIFFERENT part than the sender for the dash gauge) which made the truck run very badly. This is a cheap and easy thing to replace if you want to try part-swapping without doing full diagnostics.

Good luck, keep us posted.

Mike

 

[tech1cw@comcast.]

Good idea Mike, I think I will replace temp sensor for the hell of it. Believe it or not, the check engine light rarely comes on, only for a second while starting, and occasionally on the highway when I need to get into the motor to pass a truck, but it always goes out once I let off the accelerator, so I'm not sure if any codes are stored or not. Thx.

 

[colindo94]

I have the same problem if I'm starting the engine and shutting it down a lot in a short amount of time. Some times its so bad that It will stall out over and over when I first start it up. I was told it could also be the Fuel pressure regulator. Don't know if that helps...I will be replacing mine soon.

 

[Jason94sport]

You should clean your IAC & MAS sensors first. They are notorious for causing all sorts of problems. Also your EGR sensor could be going as well. Sounds more sensor related to me them a fuel system problem. The X sat a while & wasn't driven much. That adds to early sensor failure.

 

[ma96782]

I have a '94 XLT that had intermittent starting problems last year. On an infrequent and random basis the engine would crank fine but doesn't catch. After wiggling the wires and tapping on the fuel tank it would start, but eventually I was told the fuel pump was failing. I knew it was 12 years old so I had it replaced and everything's OK for eight months, but now the same problem is occuring. When it's working, you can hear the whine of the fuel pump when the key is turned. When it's not, no whine so I don't think the fuel pump is getting power. Once the engine is running I've never had any problems, so I'm not sure it ever was a fuel pump problem. Sometimes it won't start, then after sitting for an hour it will. Any suggestions?

______________________________________________________________________



Did you change the fule pump relay? My 94 XLT (with 180K) had a problem to start right after the engin was off for 10 to 20 minutes, when the engin was cool, it can start again and runs fine. I traced to the fule pump relay and bought one from AutoZoe for $6.00 and have not have any problems since.

_______________________________________________________________________


My 95 Explorer would occasionally crank but not start. Occurred ONLY when engine was warm -- never on the first start of the day. After waiting anywhere from a few minutes to 2 hours, the engine would then start normally. Happened between once every few months and 2 - 3 times a week, and VERY intermittently. When I drove it to work and then it sat for several hours, it would always start. When I monitored the EEC-IV codes, it would always start, of course. Finally took it to a dealer I trust and left it for 2 days so they could try to repeat the problem. They finally got it to happen and determined that there was no fuel pump pressure when the engine was in this state. They replaced both the Fuel Pump Relay and the EEC Power Relay. After these replacements, they could no longer duplicate the problem. This was almost 4 weeks ago, and I have not experienced the problem. It could just be the odds, or the relays may have been intermittent. Since it is a cheap repair you can easily do yourself, replacing these two relays would be my recommendation as a starting point.

I saved these for such an occasion.

Aloha, Mark

 

[tech1cw@comcast.]

update to the problem I was having: Happened to notice some rubber tubing going to a canister that looks to be part of the whole emmissions thing. I showed it to my mechanic doing oil change and he said " don't worry about it, it's only part of emissions, not really needed anyway". Well, it bothered me and I picked up a universal vacuum hose kit off of Ebay. When it arrived I went out to the truck and replaced it. Upon further inspection I saw two other vacuum hoses that were split wide open and not accomplishing anything. Ifigured what the hell and replaced any tubing that was old and cracked. That was 3 weeks ago, and the problem of not starting or running rough after restarting when engine is hot has not re-occurred. I have purposely gone outside to restart after letting it sit when hot and starts up perfectly when, normally it would not have. I know this sounds crazy, but I really think lack of vacuum pressure was the cause of my problem. I will post back if proven wrong.. hope this will help out anyone else with this problem..Chuck

 

[Bmwz389]

Haha I had this problem for 5 months and I finally fixed it (crosses fingers)

I went through many processes.

I cleaned the air filter (k&n), cleaned my IAC, changed spark plugs, Changed spark wires and ran seafoam.

It turned out to be the wires, one had turned corroded and green on the coil pack end of the wire. I don't know why i hadn't checked them sooner, but ever since then I have ran pretty good for being a 15 year old truck =)

I have read about vacuum lines blown and not getting enough pressure will cause your engine to bog, ultimately stalling it. So fixing it probably fixed your stumble (at least we hope).

I know of the vacuum line you are talking about, it runs to 2 black canisters (charcoal) with an inline sensor i believe. They have pretty stiff lines so after the years those could easily snap...

Good job on finding your problem bud! You'll find out soon, that these forums save you a hell of a lot of money (even more when you DIY)

- Brandon

 

[tech1cw@comcast.]

update: vehicle still running strong..with new vacuum hoses the starting when hot problem has not showed back up. We have had 90+ temps in this area, still testing it during these times, no problems. The truck is now what I've wanted it to be, reliable and cheap to drive! Got a JVC head unit with USB port and Sirius in the dash and a Kenwood sub in the back, I'm all set. Guys, make sure your vacuum hoses are in good shape, what a hell of a difference it makes.. Thanks for the feedback and help, and I still hope this info helps someone else - Chuck