Hi everyone .. I've been searching this problem for months now. Have a 98 Blazer .. 4.7 L , 186 k miles.. one day it started dying on the road and wouldn't start til the engine cooled off. It cranks over but wont start.
We thought it was the fuel pump .. Couldn't hear it prime when I turned the key and I could go under the truck and tap the fuel pump and then hear it prime.Then it would start .. so I replaced the fuel pump.
Ran great for weeks .. even did a long road trip ..no problems ..thought it was fixed..then one day it died on her again.. but she mentioned lack of power and sputtering , then it died..
I did a tune up, changed the cap, rotor, plugs, air filter, the wires are a like a year old so I didn't change them ... again it ran good for a couple day...then again it died. That's when we noticed it only died on her way home from work.. hot days . Ran fine in the morning but as the day got hot.. it would die on the road. Cant trust it anymore don't know where its gonna leave her.
Did some research.. suggestions were change the ICM and coil.. I did.. AC Delco parts. Took it for a ride.. been having above 100 degree days. Seems to drive fine ..Ok power ..no sputtering ,stalls or anything.. Got home turned it off. Tried to restart .. not happening.. cranks but will not start. As it cools off it will start up..
Not thinking its a fuel thing.. haven't bought a gauge to check the fuel pressure.. but it's done the same thing with two different fuel pumps.

Again this seems to be related to the heat ... Thanks for any help anyone can offer. Sorry for the long story..

 

Since my post I read some threads about the MAF sensor and EGR causing the lack of power issues like I'm seeing... Spent my 4th of July taking these parts off and cleaning them.. not a hard job nor expensive..thank god.. I'm getting tired of putting money into this problem... Really hot day .. didn't seem to help anything.. still bogged down , sputtered and die and then wouldn't start... Gonna take into the shop today and see if they can figure this out ..

 

It's obviously an electrical problem, but I can't direct you where to even start looking. It seems that as a connection gets hot, it's expanding and losing contact. Then when it cools off, it makes contact again. I had a two way Motorola radio in a delivery vehicle years ago that would do that. On hot days, I could receive, but not transmit. After cooling it off with the a/c, it would work properly once again. Guys at the Motorola shop finally gave up on it and installed a new radio. I hope you have deep pockets, because electrical trouble shooting can be very expensive. It may just be a bad control module in the distributor.

 

So I took into the shop and they say that I have a bad Fuel pump .. only getting like 40ish psi ...should be in the Sixties... So I got a bunk FP ?? Really ???So this is gonna be the third FP on this issue.. Man I'm so fed up with this problem.. I'm having them change it out ... that's right .. I believe this is the first time I've paid for maintenance on this truck...asked them to keep the old pump so I can try and get my money back for it .. not sure how that's gonna go.. Lets see how it goes..keep you all informed.

 

Sounds more like vapor lock to me...

 

I don't think EFI systems can vapor lock. That's really more of a thing of the past with carburetor engines.

 

Well the shop said it was a bad Fuel Pump... I had them change it out... just done messing with this thing ... Got my money back for the old FP.Told Kragens that the shop said it was from the source and they gave me a refund. So far so good... Driving and starting fine so far.... Keep ya updated

 

That's the biggest problem I have with todays cars. Putting the fuel pumps in the gas tanks. I liked them on the side of the block back in the good ole days when you could change out out yourself and inexpensively.

 

I had the same problem. I replaced the fuel pump and the fuel injectors that was no help. I changed the computer and it solved the problem.
Good Luck hope it helps