Dry Start Only When Engine Warm 1996 Suburban

As for fuel system cleaners, nothing seems to work quite as well as Techron. And although it is somewhat expensive many parts stores sell it as a store brand at about 1/2 price.

this may be a long shot but here is what I found regarding replacement coolant temperature sensors (bwd, autozone’s etc - all except ford’s oem motorcraft). Measuring them right out of the box they didn’t meet specs given in the ford owner’s manual (something like 10(?) ohms cold). I couldn’t believe how the 2 “replacement” brands agreed, but yet were 2x the ford specified value - and the motorcraft part was priced 3-4x! If you can get a real figure off the manufacturer’s manuals you can measure the sensor to see if it might be incorrectly signaling the computer.

Hey Rod Knox, thanks for your opinion on cleaners. Techron has been my go-to cleaner when I thought something might need it. Figured I’d try some MMO, just to see if it did something. I mean, it is in a red bottle so it must have special powers.

As a general update, I think (I stress “think”) the problem MIGHT be getting better. I dumped a bottle of MMO into the tank and wound up putting about 200 miles on the Burb on Sunday. First thing in the morning, I got the dry start. But throughout the day, I got several chances to try to get it again and it didn’t do it. Putting the MMO in and simply running it for much of the day might be cleaning out some varnish. I don’t know. Seems to be trending that direction. I’m going to run another tank through with some more cleaner and see if it doesn’t keep moving in the right direction.

Replycartalk, No I don’t think it’s such a long shot. I’m so incredibly skeptical of parts these days that nothing would surprise me. Well, maybe if every part worked just like it was supposed to, then I’d be surprised. What you say makes perfect sense. I’ve been wondering about the same thing since I swapped out the coolant temp sensors. How close to spec is it really? Maybe the fuel cleaners are getting rid of my problem, but the problem still behaves as if the engine coolant temp sensor is bad/fickle.

I’ll see if I can find the specs in the service manuals and then put my meter on the sensor under the hood and see if there’s a significant difference. Too bad it’s dark out. Now you’ve got my curiosity up. I’ll let you know what I find. Thanks for suggesting it. I should have thought to check it before installing it.

I had to take a break to let some fuel system cleaner run through a couple tanks. 42 gallons per tank so that a few miles. Takes me a while as I don’t put a gob of miles on each day typically. And I had to have some surgery done.

I haven’t been able to bend around under the hood (healing), but will be good to go within a few more days.

I’m going to pursue some of the other suggestions thrown out here. The oil pressure switch idea has kept my attention because it seems to make sense. Something I’m going to look at.

Any opinion on these next two paragraphs?

As far as cleaners go, I’ve now run a tank with Techron, one or two tanks with Lucas fuel cleaner in it, and now two tanks with Mystery Oil in it. I’ve added the recommended amounts. That’s roughly 200 gallons of fuel with a variety of cleaners. If the problem was varnish (i.e. sticky poppets…sounds like a British pastry), would I have seen at least some improvement by now?

I can’t imagine how this could play a role in this issue, but at this point I’m nearly willing to accept that it’s an issue with the glove box latch. A few months ago, one of my cats failed so I had it replaced. There are two cats on my Burb. This isn’t the kind of problem that could be caused by the old (original) cat still on there acting up before it decides to bite the dust?

Got a new oil pressure sensor/fuel pump switch today and will hopefully put it on tomorrow.

I put in the new switch. I can’t scroll back to see who mentioned it, but there is one sensor that performs these three functions:

  1. Measures oil pressure.
  2. Sends that pressure reading to the gauge.
  3. Cuts off the fuel pump when oil pressure is below a certain threshold.

The original one was in bad shape. The plastic housing broke apart when I was putting the socket on it. Not because I was being rough. Whatever plastic was used was obviously at the end of its life. Even if it didn’t fix the issue, I’m glad it was mentioned and that I changed it. It may not have been an issue at the moment, but it was most likely going to be one before long. A $25 part that would have left me sitting somewhere, waiting for a tow truck.

I wasn’t able to put it to any real test today, but should be able to tomorrow or the next day. I’ll chime back in with whether it got rid of the problem.

Are the plug wires OEM?  If not I suggest you try OEM.  Higher cost or fancy looks does not insure higher quality.

Plug wires are Borg Warner.

Okay, so I replaced the oil sender/sensor/fuel pump cutoff switch yesterday or day before. The sensor was in severely rough condition so I’m glad someone mentioned it and I changed it. But there was no change in the dry start symptoms afterwards.

Yesterday, per someone else’s recommendation here on this forum, I pulled out the IAC and it looked like an ash tray. I cleaned all the carbon build-up off of it and I think this might just be where the root of my problem has been. I’ve done three warm-ups, 10-min wait, then a restart and there has been only a momentarily longer delay in the engine starting than when the engine is cold. I haven’t had the Burb out driving it on hot roads yet so that the entire undercarriage and everything is quite hot to really give it an equal test to see if the problem is originating from a dirty throttle body.

I can’t remember if the sensor that is located next to the IAC is the throttle position sensor, but I’ll look in the service manual again. If it’s half as dirty as the IAC was, then I can see this being the source of the dry start issues…just too much carbon built up inside the throttle body.

I’ll just pull the throttle body off and clean the whole thing up soon because it looked quite dirty. If the view where the IAC pops in is any indication of how dirty the rest of the inside of the throttle body is, it’s long overdue for a good cleaning. Even if it’s not causing problems now, it can’t be that good for it to have a lot of carbon build up inside it. Plus, I’ve never pulled one off before and I like variety.

It’s going to be mid-90s beginning tomorrow so I’ll be able to find out if cleaning the IAC made an improvement and perhaps points the way to finally figuring out the cause of the hot dry start issue.

I’m so grateful for every suggestion/idea that has been offered on this forum.

I’ll chime back in to tell if the issue is better.

If anyone else has other ideas, please feel free to spit them out.

Okay, so the dry start issue is still present. Got a chance to get the Burb out and pound it around in hot temps today (mid-90s and sunny). The dry start was still there. No change by cleaning the IAC up.

Is it probable that the IAC could be bad (that it wasn’t simply dirty)?

Would a faulty throttle position sensor cause this kind of symptom?

Is a throttle body with carbon build-up able to cause this kind of dry start when warm?

My brain is kind of shot now. I’ve tried like crazy to get onto CarTalk while they’re on the air because I’ve suspected that this could be a candidate for “stump the chumps.” I’ve ruled out so many things now that it seems very fit to stump the chumps. I’d love to give the guys a run at figuring this one out for me. If only I could get something other than a busy signal.

If anyone has any thoughts or ideas, I’m all ears because, frankly, I’m running out of ideas. I’d just rather figure this out now while I can fix it in my driveway than for it to stop running somewhere and have to pay a shop to troubleshoot this nemesis of an issue. I’ve already put it in front of the best mechanics I know around here and they were unable to figure it out.


Do you think an issue with plug wires could deliver this kind of dry-start issue? I can’t see how it would, considering that it runs perfectly fine after it starts. But it’s entirely possible I’m ignorant of something you see as a possibility. If you’ve got any further thoughts (or anyone else for that matter), I’d love to read what you’re thinking.

Figured I’d clarify something real quick. I was searching through symptoms of various sensors to see if I had missed anything and noticed the term “dry start” referring to an engine starting without proper lubrication in the cylinders.

This is NOT what I mean by a dry start. I mean it acts like there’s no fuel in the tank for about five seconds before starting when engine compartment is hot and has sat for 10-15 minutes. Then it starts up and runs as fine as I’ve ever known it to run.

One more random thought (I’m throwing darts blindly at this point).

I keep thinking engine control, but could it be that it’s the original muffler? When I was running E10 and watching water pour out the tail pipe pretty well assures me that the inside of the muffler is nothing but rust, assuming it’s all still there and in the places where the pieces are supposed to be.

Anything about a muffler that could make it temporarily constricting when hot, but after the motor has cranked for five seconds, enough air has moved through the pipe to push whatever might be moving (if anything is moving around) back out of the way, opening up the airway again?

Like I said, resorted to throwing darts now.

Time for a leakdown pressure test on the system. http://www.harborfreight.com/cylinder-leak-down-tester-94190.html
Suspect bad head gasket, my wag

Hey Barkydog,

Could very well be. My oil looks like oil when I change it and the coolant level has remained constant. I would expect one of those to change if there’s a bad head gasket(s). But let’s hold that idea off for a few days.

So, here’s the weird part.

My wife and I are shopping for some land. Today, we again departed and drove all over creation. It was mid-90s so we had the air running all day. The entire Burb definitely had no problems getting warm from front to rear.

The weird part…it never once gave me that “lack of fuel” start. I had a chance to restart it after walking a piece of ground (anywhere from 10 minutes to 45 minutes each on about a dozen tracts scattered all over the place). It turned out to be a great testing day.

But not once was there a delay on a hot restart after a shutoff of 10 minutes or longer. It fired up the second I turned the key every time. I was delighted, but am still skeptical that the issue is really gone. It has been such a stubborn pain in the fanny to root out.

This was just one long day so I’ll see if it continues to appear to be solved.

If it is solved, I guess maybe something about the IAC began working as it was supposed to. I don’t know. After I cleaned it and put it back in, I did the simple procedure GM says to do to reset the IAC. Perhaps now that it’s functional (maybe) the computer needed some restarts and some run time to reset the operation of the IAC. Honestly, I don’t know.

I’m hoping that today’s lack of symptoms proves to be the case for the next few days.


The MAP sensor was the nemesis for which I have so long been seeking to root out. I had ruled it out long ago because A) No engine code was stored and B) The symptoms didn’t fit a MAP sensor going out, at least symptoms I’ve ever heard or read about.

So, in case you’re reading this in search of the cause of something similar in your vehicle one day, don’t look past the MAP (manifold absolute pressure) sensor.

And good heavens, what a massive increase in acceleration. I had noticed a steady decline in acceleration over the past month due to what sounded like too rich of a mixture under hard acceleration and that’s what led me to swapping out the MAP sensor. Just so happened to be the root of the problem I wasn’t sure I’d ever find.

Thanks to everyone who chimed in to help me with this one. I greatly appreciate all of your comments.

Congratulations on finding the problem. Let us know what effect it has on your mpg, especially with E10.

One question: you said you noticed water “pouring out of the tailpipe” when using E10. As you know, water is a byproduct of combustion of both gasoline and ehtanol, and there shouldn’t be much difference in the amount of water created by E10 vs pure gas. So…under what conditions was the water “pouring out?” Because what that says is, the exhaust system was cool enough to condense the water vapor leaving the engine in the exhaust stream. So water will drip from a tailpipe until the exhaust system has heated up sufficiently to keep the water in vapor form.

But if your engine was running rich, or too cool (from, say, a stuck open thermostat), it would (a) reduce your mpg and (b) take longer for your exhaust system to heat up, producing more water condensate.

So, under what conditions was the water “pouring out?” Because that could be another clue as to why your mpg was so poor on E10.

Hey Jesmed,

I haven’t logged onto here for a while. I just noticed something from your last comment.

You know, my Burb has, based on the gauge, always run cool (ie. about 160-165 F on gauge). It has a 5-gal cooling system and who knows how accurate a 17 year-old gauge is so I’ve not been concerned with it since shortly after I bought it.

When I bought it, I replaced the thermostat among several other maintenance components that I’m just used to swapping out initially since I’ve always driven old vehicles (I have an affinity for them).

According to the gauge, it looked like a low operating temp so I yanked out the SuperStat (by Stant) I had installed and put another one in, just to make sure I didn’t get a bad thermostat. Gauge didn’t change.

It’s a 195-degree stat, but the only time the gauge shows it hitting 200 is in between initial startup and just before the stat opens.

My Burb runs cool anyway, even with front and rear air on, sitting at idle for long periods of time. I’ve always chocked it up to an efficient cooling system and, again, who knows if the gauge is accurate.

I guess if my head was attached, I could just put my IR thermometer on the engine coolant temp sensor and see how hot the fitting is when it’s up at operating temp. I’ll get the temp of the radiator cap as well. A normal person would have thought of that a couple years ago, before he put in the second stat.

I’ll see what kind of temp readings I get. I could pop the radiator cap and try to get a good reading of the scalding hot coolant just before it slams into my face. My IR thermometer is “instant,” but I don’t know if it’s that instant.

Never mind. Glad you found the problem.

I didn’t see the engine temp sensor on the list of items replaced. The techs should have seen what the reading from the sensor was compared to the engine temp, but if the sensor is bad it can cause a delayed start because it is not adjusting the fuel according to the actual engine temp. Turning the key on and off a few times will confirm whether you’ve got a leaky injector.

Hey Bing,

No, actually, I have NOT found the solution, but I think I’m headed in the right direction and I think you were too.

Based on two shops’ inspections, I trust them when they tell me there is zero injector issues with the Burb.

But I spoke with one of those mechanics this morning on a whim. He said, based on the increasing returns for faulty parts (especially ignition related) by BWD in the past year or so, he said it’s within possibility that our Burb doesn’t like the BWD coil and ICM. It also has a BWD engine coolant temp sensor in it.

You’re the second person to mention that the coolant temp sensor may not be up to spec. The other person who chimed in a while back mentioned that when cold, the aftermarket sensor he bought was fine, but when hot, resistance went way outside of OE specs.

I went ahead and ordered an OE engine coolant temp sensor. I’m hearing just enough feedback from different places about hiccups from BWD, which I’ve always associated as stellar quality, that I figured I’d try the OE. Two shops, an auto parts store that leads with BWD everything, and now two of you mentioning that maybe the sensor isn’t up to snuff here on this forum. To me, it’s worth $20 to find out if that’s the issue.

Thanks for chiming in.

Hey Jesmed,

I put my IR thermometer on the radiator cap and engine coolant temp sensor this afternoon when the eng compartment was hot. Rad cap was 155-degrees, coolant temp sensor was 181 (measured, of course, outside so there was a lot of heat circulating from everything else).

Thanks for mentioning the temp thing. Talk about a 2-year brain fart! Fan clutch was shot. Put a new one on this evening and it’s now running warmer, up around 300-degrees.

Yes, that’s a joke. It is running warmer than 160 now. I can see the temp move up and down periodically now, which is more than what has been happening.

Sometimes, I am so slowwwwwwww.