I have a recently purchased '88 K5 that cuts out while driving in hot weather. There is no sputtering and I can pop it into neutral and restart immediately after it happens. It seems indicative of an electrical issue, and had it into a mechanic who replace distributor, but that didn't seem to help. Took it back, and after a day they said they have no idea. Currently, I plan to go through and manually test the wiring underload with something I can wire up at home, but am open to any other suggestions, idea, or tricks in trouble shooting this type of issue. Also, interested in hearing thought on whetehr it could be something other then electrical issue.

Recently replaced parts: Distributor, MAP sensor, coolant temp sensors, water pump.

 

bad coils can do this

 

yeah cracked coil can possibly cause this. only other thing i can think of, might be unrelated to heat is the egr valves like to go bad on these trucks and will make the trucks randomly just shut off due to them opening wide up at idle or cruising speed. last one i diagnosed i just put it in drive against a tree and watched the egr open up and the truck died, was a 91 chevy but should be the same engine

 

Mechanic checked distributor, coil, and spark control module.

 

Update, went to junk yard got $35 ECU swapped it out, didn't help. There has been some vibration when accelerating and getting worse(pre-ECU swap), assuming misfire?

Update: pulled rear u joint, one cap had all pin bearings turned to dust. New U joint fixed all vibrations.

Still sounds like some pining and occasionally feels like bogs down when accelerating.

 

Have you ever had luck cleaning one yourself or do you just go get a new one?

 

if your talking about a EGR valve yeah i always just bought a new one. in my case it wasnt clogged the diaphragm inside of it broke so it wouldnt hold vacuum and was just leaking all over.

 

Okay, another sunday spent working on this thing. Previously had mechanic replace distributor and it didn't fix the issue so I got money back and had old one put in, I put in a new one today just for peace of mind. Got timing all dialed in and it helped with some of the loss of power and added a little more pep all around, but the issue still remains.

Seems symptoms have lessened a bit, currently through 25-35mph at moderate acceleration it bogs down for about 2 seconds every 10 seconds or so. If I put petal to floor it goes away. Big ole cloud of smoke(fuel) when starting and runs rich all the time. Did notice EGR vacuum hose disconnected along with AIR pump etc. Also, good amount of gas in with the air filter/intake. Current thoughts, attack the TBI and if i get it to start running leaner maybe replace the cat.

Any Ideas, thoughts, comments are greatly appreciated.

 

I have the exact same issue with my 88 and i've replaced

Brand new goodwrench
Coil
distributer
swaped ecm
oxygen sensor
rebuilt tbi
swapped injecters
new escm
new temp sensor
new knock sensor
Map sensor
idle air control valve swap
new vacume lines

What helped the most was a collecter gasket

It has a whole new motor and runs like crap

p.s. has single plane with tbi