91 Caddy Misses & stalls when hot

Uncle's 91 Caddy RWD Brougham 5.7 V8 stalls, misses & lacks power when it gets hot. Usually after about a 40 + mile ride.
Temp light doesn't come on. Sometimes you can restart the car after it
stalls , other times it cranks for a real long time.
Any Hot Running Issues with this engine? Its a Chevy Caprice 5.7 V8 engine.
========Harryface ======== 1991 Pontiac Bonneville LE 3800 V6 ( C ), Black/Slate Grey _~_~_~282,525 miles_~_~_
~_~_~_~_U.S.A._~_~_~_~_~_
~~~The Former Fleet ~~~ 89 Cavalier Z 24 convertible 78 Holiday 88 coupe 68 LeSabre convertible 73 Impala sedan
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Harry Face wrote:

Sounds like! hahahaha
But seriously, HF, you have been reading this group long enough to know that you can just hook up a scan tool to it and see what sensors are saying what, when it starts to act up. Could be anything. GW
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I would check for spark when it has stalled and won't restart. If no spark then I would try to get a scanner to check for an rpm reading while cranking to narrow it down. If it has spark, I would be checking fuel pressure. If it is low, it could be a bad fuel pump. He has changed his fuel filter in the last 30,00 miles right?

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@webtv.net says...

Is that the basic 5.7L Chebby with TBI injection or did Caddy get something special?
I would replace the cap, rotor, plugs, and spark plug wires. If they are original they are due for replacing.
You may want to take your multi meter and check the TPS voltage too. It should be around .54V idle and 3.5-4.0 volts at WOT.
--
______________________________________________________________

Dennis Smith
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Don't rule out the dreaded crank sensor and PCM.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Here is a long shot possible solution.
30 miles is about how far I could drive my old truck before it would quit. As it turns out someone had installed a non-vented fuel cap on it. It should have had a vented cap. Because air could not go into the fuel tank to replace the fuel that was being consumed, the pump could not pull any more fuel out of the tank. It was an easy diagnosis because as I opened the fuel cap there was a tremendous whooshing of air into the tank. I just leave the cap on loosely now and don't have any problems.
If none of the other people's posts work, maybe try loosening the fuel cap next time it stalls and see if that is the issue.
Jon

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Try looking into the injectors.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.