Sorry for the length, but ...

’97 Explorer 4.0 SOHC, 98000 miles, 2WD.

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Occasional hard starting. Turns over fine, just won’t start. Seems most prevalent after a rain. Must sit for 5+ hours to have the problem. Once started, runs great as soon as it starts. No codes set or pending.

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Today (after t-storm last night), it was particularly hard to start. I hooked up a timing light and saw no spark at all. However, when I gave a 1 second shot of carb cleaner into the intake pipe between the MAF and throttle plate (pulled the PVC hose and shot the carb cleaner in the hole), it fired right up and ran great. Once started, there are no other symptoms at all.

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I do not understand how carb cleaner in the intake can correct a no spark problem. Is there something in that area that controls spark? Wiggled all the wires near there before I tried the carb cleaner. In fact, I wiggled every wire I could get to before trying the carb cleaner. This is the 2<SUP>nd</SUP> time carb cleaner sprayed here has made it start. Other time I was in a hurry and did 5 or 6 things at the same time so I wasn’t sure the carb cleaner was the fix – especially after seeing no spark. However this time, it had failed to start 6 or 7 tries and the only thing between the 7<SUP>th</SUP> no start and a successful start was pulling the PVC hose, 1 second shot of carb cleaner, replace the hose and turn the key. Cranked maybe 1 second before it fired and ran wonderfully.

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Yes, I hear the fuel pump run when I turn the key. After reading some posts on hard starting Explorers, I tried the “start it like a diesel” method, but that didn’t work today though it has in the past. (It has been doing this for about a year off and on, but is gradually getting worse.) Replaced the fuel pump relay about 3 months ago.

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Any ideas?

 

Symptoms sounds exactly like Cold Temp sensor, but you said no codes.
I guess the carb cleaner is more combustible than gas....I know "Engine starter" is (available at auto parts. I now suspect a fuel pressure problem...it isn't holding the pressure when off, so after hours of sitting, you crank it, no pressure. The shot of carb cleaner kicks it right over.

 

tvulcan, I wish someone would respond to your description -- we have the identical problem on our 97 and no mechanic or ford dealer has been able to diagnose. Ford acted like they've never seen it. Ford said I shouldn't be using starter fluid since it could damage the carb over time -- so I said 'give me another way to prevent this problem!' silence....Only happens on first start of the day, usually after a storm.

 

I'm just guessing, but perhaps your coil pack needs to be replaced if its allowing moisture inside. I'm not sure why carb cleaner would help your truck start, though. I would have my coil pack tested to rule out the possibility of moisture getting into the distributor. Good luck.

 

I thinking the crankshaft position sensor or ckp same thing. The cps sound like it's out of wack or going bad. It will keep you from getting a spark. The pcm (powertrain control module) get the signal from the cps and that gos to the coils. The powertrain control module unit can go bad to.

 

Found this out the Powertrain control module need to be reset this is done by dealer only and it take two days to do it. The main sys. does not read this sys. so you will not get a check light. Need to ask the dealer to run a OBD ll Drive Cycle. This info is from fords own tech. book.

 

Well, I think I've fixed mine.

I removed the plug going to the crank position sensor, cleaned and greased it, then plugged it back in. That was a week ago. Since then, it's rained 2 times at night and it's started great every time I tried since I worked on the plug.

I think the carb cleaner was just a coincendence.

Funny thing is, it also runs smoother and seems to have more pep.

And all I did was clean and grease the plug and plug it in. I think it must have been just a bit loose or something.

 

tvulcan...I took your lead this morning; the truck wouldn't start (even though it was in the garage and there was no rain, hmmm). nevertheless, same issue, and I would usually fire the engine starter into the carb to get things going. But,after reading your post, I located the cps, pulled off the plug and cleaned out with a toothbrush (I'm not sure what you mean about "greasing" an electrical connection). Also found a small coolant leak directly above the cps, which had been dripping coolant directly onto the cps' wire connection - don't know if that was a factor. Anyway, after cleaning, re-attaching the cps, and taping up, she started right up. (wife was amazed at my ingenuity and I gave you credit). So, perhaps moisture from puddles, rain, or even dripping coolant gets into that connection and interferes with electrical conductivity -- just don't know, but I'll cross my fingers and hope.

 

Actually, your reply gives me hope that I may have really found the root of the problem!!!


By greasing it, I meant I applied some dielectric grease specically made for waterproofing electrical connections.

I'll keep my fingers crossed for both of us!!